CN106821500A

CN106821500A - One kind is used for minimally invasive operation navigating system and method

Info

Publication number: CN106821500A
Application number: CN201710167799.7A
Authority: CN
Inventors: 罗会俊
Original assignee: Dalian Ruipu Science And Technology Co Ltd
Current assignee: Nanjing Tuobao Medical Technology Co ltd
Priority date: 2017-03-21
Filing date: 2017-03-21
Publication date: 2017-06-13
Anticipated expiration: 2037-03-21
Also published as: CN106821500B

Abstract

It is used for minimally invasive operation navigating system and method the invention discloses one kind.It is that biplane circular polarisation type, gradient coil design are biplane main coil and in the additional biplane axial shield coil in outside that the system features for needing transformation for being navigated in Minimally Invasive Surgery and art relate generally to open U-shaped magnet structure, magnet gap more than 500mm, radio-frequency receiving-transmitting coil design；And it is related to the clinical Navigation Control flow being applicable and the imaging method that navigated in art.Opening Extent of Syetem, security and convenience needed for structures and methods guarantee Minimally Invasive Surgery of the invention；Especially, in order to improve resonance image quality and real-time and ensure that operating theater instruments precise positioning and operation route are precisely controlled.

Description

One kind is used for minimally invasive operation navigating system and method

Technical field

It is used for minimally invasive operation navigating system and method the present invention relates to magnetic resonance arts, more particularly to one kind.

Background technology

Accurate minimally-invasive treatment technology is conducive to improving curative effect and mitigating patient suffering, obtains more and more in clinical treatment Application.The radiotherapy technologies such as laser, X-ray, gamma ray, high intensity focused ultrasound technology and heating ablation and cryoablation etc. Interventional therapeutic technique and other various Minimally Invasive Surgeries are required for being accurately positioned focus and in therapeutic process by image-guided technology In the sphere of action and curative effect of accurate monitoring electromagnetic wave, ultrasonic wave or operating theater instruments on target in real time.With ultrasound and the shadow such as CT As technology is compared, nuclear magnetic resonance image (MRI) technology not only has high-resolution and multi-faceted multi-parameter imaging advantages, moreover it is possible to clear Show border, nerve and the blood vessel of anatomical structure, or even monitor in real time human physiological activity and detection metabolite and target The temperature in region, to human body without any infringement and radiation injury, therefore is particularly suitable for image navigation.

The PCI systems such as the stereotaxis cranial surgery of modern MRI guiding are generally by Minimally Invasive Surgery apparatus (or surgical engine Device people), optical tracking positioning subsystem and MRI image guiding and navigation subsystem constitute.For being navigated in MRI arts, magnet is opened Degree of putting, sweep speed and image artifacts are mostly important technical indicators, and signal noise ratio (snr) of image and resolution requirement can accurately show Target position and medical instrument locations, it is accurate reliable that Temperature Distribution monitoring freezes this kind of PCI requirement of ablation for hot/cold.By In above-mentioned technical requirements, the MRI image navigation product into clinical practice so far is few in number, with open middle low field Based on MRI system.For example, the Signa SP (0.5T) of GE are midfield superconduction open systems, by niobium Two superconducting coils that tin alloy material makes are disposed vertically generation horizontal magnetic field, increased the width of accessible area；Germany The Proview0.23T Open of the Magnetom Open 0.2T of Siemens Company and Dutch PHILIPS Co. are that low field is often led out Formula system is put, vertical magnetic field is produced by upper and lower two impedance type magnets, it is allowed to from side close to patient, and opened in nearly 280 ° of scopes Exhibition intervention operation technique.Requirement of such image-guidance system to magnetic compatible surgical apparatus is relatively low, and image quality and speed energy General clinical intervention Treatment need is met, for example, the biopsy of prostate cancer, fibroid and joint disease or Minimally Invasive Surgery are controlled Treat.Although the MRI system of high field intensity or superelevation field intensity is required for the application of many important imaging methods and technology is provided High s/n ratio or high-resolution condition, but the cylindrical hermetic structure of superconducting magnet and high cost seriously limit MRI technique Application in PCI and Minimally Invasive Surgery.For a long time, superconducting MRI PCI system is mainly used in pre-operative surgical route Planning and postoperative curative effect assessment, and Time share scanning scheme is frequently used in being navigated in art, for example, the IntraOp Signa of GE HD 3T systems need to be carried back and forth between screened room and operating room by slide rail in scanning and operation technique, in addition it is also necessary to borrow Help stereotaxic technique (such as optical tracking technology) and device is realized in the conversion by physical space and logical space (i.e. image area) Tool mark tracking, or even need to develop displacement in very complicated and the necessary efficiently art of the correcting algorithm amendment histoorgan of computing Error, this causes that application of this kind of high-field MRI systems in PCI is severely limited.Comparatively, radiation is controlled The less enclosed construction for being limited by superconducting magnet is treated, during this may allow superconducting MRI system and linear accelerator combination to realize art Navigation PCI, but require that the dosage and targeting precision of tumor radiotherapy can be controlled safely and effectively.In any case, it is modern MR imaging apparatus are trends of the times to Open architecture development, and this can not only improve for patient (particularly claustrophobia patient) The comfort level of inspection, especially can in art MRI image direct application open up broad space.

China has also had since the nineties in last century a small amount of Permanent Magnet MRI system to face for the PCI of medical research institute Bed experiment, but be essentially all the simple combination of existing diagnosis type permanent magnetism imaging system and general optical tracking position indicator, also The imaging method of the special navigation system and suitable navigation of not developing unique MRI technique advantage is widely used in minimally invasive hand Art and PCI.

The content of the invention

In order to the openness for overcoming existing imager magnet and loop construction is limited, and for the work of cranium brain and joint disease Inspection and Minimally Invasive Surgery (such as drug injection and puncture drainage) treat needs, and the present invention is proposed a kind of high for openness and positioned The accurately image magnet structure of special magnetic resonance image-guidance system.

It is used for minimally invasive operation navigating system the invention provides one kind, including：Yoke, magnet steel, pole plate, shielded coil, ladder Degree coil, radio-frequency coil, scanning bed, heating rod, heating plate, temperature sensor, shell, T/R sending and receiving switch, gradient power amplifier, penetrate Frequency power amplifier, preamplifier, temperature conditioning unit, optical tracking alignment system, coil tuning control unit, scanning bed control unit, Navigation imaging control unit, system control interface, main frame, display, it is characterised in that magnet is open U-shape structure, magnet Gap is more than 500mm, and pole plate radius is 350mm to 400mm；The pole plate radius is 380mm；Magnet field intensity is in 0.2T to 0.7T Between；The radio-frequency coil of magnet is biplane circular polarisation structure, sets some without magnetoelectricity between outer conductor loop and inner wire ring Hold；Radio-frequency receiving-transmitting coil switchs the conversion realized transmitting and receive by T/R；Described is more than 100 without magnetocapacitance quantity；X, Y Respectively there are two groups with Z axis plane gradient coil, one group is placed in a magnetic pole inner side, and another group is placed in another magnetic pole inner side, coil Plane is separated by eddy plate each parallel to polar board surface with pole plate；Wherein, Z axis gradient coil is by main gradient coil Constituted with axial shield coil, belong to MAXWELL coils, coiling is concentric circles pattern, the circle of main gradient coil 13, axial shield line 14 circles are enclosed, two groups of gradient coils are connected to gradient power amplifier by 6 gradient cables through gradient power wave filter；Main gradient coil and Axial shield coil is made using printed-board technology；Axial shield coil is placed in main gradient coil outside and near pole The gradient current of plate, axial shield coil and main gradient coil is in opposite direction, and magnetic field gradient is limited in axial shield coil circumference It is interior, it is cancelled the thrust that current impulse is produced with magnetostatic field interactions in coil；Main gradient coil, axial shield coil it Between insulating barrier is set；Main gradient coil, axial shield coil and insulating barrier radius are preferably 350mm, and each coil thickness is 4mm To 5mm, main gradient coil and axial shield coil-span are 2mm to 3mm.

The present invention separately provides a kind of Minimally Invasive Surgery air navigation aid, using claim 1 for minimally invasive operation navigating system, Specific method is as follows：

Step 100：Magnetic susceptibility artifact or metal artifacts without magnetic medicine equipment are detected according to operating process in advance With optimization navigation sequence parameter, and the collection three-dimensional high definition T1 weighted graphs on navigation imager or High-Field imager before surgery Picture, adds sweep enhancing scanning, angiogram or functional imaging etc. if necessary, then carries out operation route planning, including target spot sets, enters Pin path planning and operation plan are worked out.

Step 200：Then exist:In navigation imaging system by scanned position by calibration scan bed elevation of water and by The straight line laser of laser orientation instru-ment is guided and is placed in isocenter point region, shimming is carried out from Dynamic Local shimming technique, by three The three-dimensional space selectivity radio-frequency pulse of individual slice selective gradient and three sinc waveform pulses compositions excites the matter in a small size Son or other magnetic atom cores, then gather free induction decay signal FID, and the sequence reruns, while constantly passing through line Property gradient or shimming gradient regulation magnetic field homogeneity until spectrum integration area it is maximum, so as to realize the uniformity of magnetic field of imaging area Optimize.

Step 300：Then flow of navigation is set up internal reference coordinate system and is controlled by navigation module and with navigation interface The operation of local quick navigation sequence, three tomography signals of orthogonal direction are gathered according to operation route repeatedly, and each direction can be with Collection individual layer can also synchronous acquisition multilayer, or use real-time route tracing mode, first pass through navigation software scanning and obtain big The visual field positions picture, in positioning as upper first positioning scanning aspect center is in surgical portal position, and is planned towards target position Several groups of scanning aspects, every group of aspect can be arranged on different azimuth to avoid nerve or blood vessel, being set between aspect The half of slice thickness；Positional parameter and waveform parameter are constantly updated in procedure and real time scan is fixed so as to continuously track Position surgical instrument position.

The quick navigation sequence design essential characteristic of described local is that radio-frequency pulse has three-dimensional space selectivity, right The slice selective gradient of first radio frequency excitation pulse, first radio frequency reunion pulse and second radio frequency reunion pulse is answered to be arranged on not Same orientation, and using the SLR impulse waveforms for exciting profile elevations h to optimize, may be selected and meanwhile it is uniform excite it is multiple close to frequency band, The scope and spacing of each frequency band can carry out accurate adjustment as in positioning by thickness and interlamellar spacing, and pulse excitation profile amplitude can Integral area correction according to each frequency band is consistent, repeatedly gathers a part of k-space line and goes forward side by side horizontal pulse phase loop, and May be selected to apply frequency encoding gradient and slice selective gradient simultaneously during data acquisition, receiver bandwidth is set to 100kHz or more Height, then carries out k-space data and adds up and part Fourier image reconstruction.It is equal that this navigation imaging method can not only improve image Evenness, resolution ratio and signal to noise ratio, may also suppress magnetic susceptibility artifact and metal artifacts, and shorten sweep time；

Step 400：After guided therapy terminates, local high resolution scanning is carried out on navigation imager or High-Field imager Scan to confirm curative effect with enhancing.Compared with scanning of being navigated in art, the acquisition matrix of frequency coding and phase-encoding direction here Double further to improve image resolution ratio.

Preferably, the step of flow of navigation includes Dynamic Local shimming：Scanned position is flat by calibration scan bed Straight line laser guide of the face highly and by laser orientation instru-ment is placed in isocenter point region, is carried out from Dynamic Local shimming technique Shimming, the proton or other magnetic in a small size are excited using sequence with three slice selective gradients and sinc or SLR radio-frequency pulses Property atomic nucleus, then gather free induction decay signal, rerun the sequence, while being adjusted by linear gradient or shimming gradient Section magnetic field homogeneity is maximum until spectrum integration area, so as to the uniformity of magnetic field for realizing imaging area is optimized.

Preferably, track and localization surgical instrument position is tested by metal artifacts and calibration steps is realized：It is primarily based on sulphur Standard water mould and gradin-echo the test Distribution of Magnetic Field figure of sour copper liquor, then add in the central area of standard water mould Bar shaped or intersecting parallels test Distribution of Magnetic Field figure without magnetic metal material and by gradin-echo, calculate the two Distribution of Magnetic Field figures Difference, from difference it is minimum make operating theater instruments without magnetic metal material or composite, finally surveyed on gradient echo image Amount dead space size simultaneously carries out consistency checking with bonding jumper actual size, in this, as the accurate of operating theater instruments self-position Mark.

Preferably, excited in a small size with the radio-frequency pulse for exciting profile elevations h to optimize using multi-faceted slice selective gradient Proton magnetic resonance signal, first 90 ° of radio frequency excitation pulse and first 180 ° of reunion pulse here is using uniformly exciting SLR impulse waveforms, and the corresponding slice selective gradient amplitude of first radio-frequency pulse of setting is G in navigation sequence_s1=2 π Δ f/ γ/ FOV_x, the corresponding slice selective gradient amplitude of second radio-frequency pulse of setting is G_s2=2 π Δs f/ γ/FOV_y, the 3rd RF pulse-to-pulse is set Corresponding slice selective gradient amplitude is rushed for G_s3=2 π Δs f/ γ/THK, wherein FOV_x、FOV_yCan be on sequential parameter table directly with THK Regulation.

Preferably, radio-frequency pulse is preferably SLR pulses, and its waveform feature parameter sets as follows：When band product TBP be 4 or 8, With outer ripple factor and with interior ripple factor no more than 0.5%, excitation pulse flip angle be pi/2, slice selective gradient intensity according to Required thickness is set, for example, be here 0.7G/cm；Or when band product TBP be 16, with outer ripple factor and with interior ripple factor not More than 0.5%, reunion pulse flip angle is π, and slice selective gradient intensity is 0.5G/cm；And be based in the case of synchronous multilayer is excited The optimization of synchronous scanning calibrating sequence excites profile, and the sequence is characterized in that radio-frequency pulse selects simultaneous shot impulse waveform, selects layer Gradient and frequency encoding gradient are arranged on same orientation, and k-space data is gathered in the echo time, then calibration is excited in the following manner Profile and magnitude image：

A. signal is gathered with the synchronous scanning calibrating sequence shown in Figure 22 and from the SLR impulse waveforms of each phase code And Fourier transform obtains exciting profile to frequency domain, is expressed as C₁、C₂And C₃；

B. C is calculated₁、C₂And C₃Integral area, k is expressed as here₁=∫ ∫ C₁dxdy、k₂=∫ ∫ C₂Dxdy and k₃=∫ ∫C₃Dxdy, here ∫ ∫ represent two-dimensional integration, x and y represent two-dimensional coordinate；

C. alignment profiles figure is C₁、With

D. same, the two dimensional image obtained to three scanning is in above-mentioned integral area ratio k₁、k₂And k₃Carry out

Calibrate and carry out each tomographic image decomposition by formula (4)；

Although aforesaid way may be directly applied to three layers of simultaneous shot situation, it is clear that can be generalized to it by similar fashion The calibration of its Multi-layer synchronous shot images.

Preferably, receiver bandwidth is preferably more than 100kHz, the bandwidth of radio-frequency pulse under metal artifacts disturbed condition Δ f needs optimization in advance, can operating process setting Δ f be different value according to Fig. 7, therefrom searches magnetic susceptibility artifact or gold Δ f when category artifact is minimum, applies frequency encoding gradient and slice selective gradient simultaneously during data acquisition, then Δ f optimal values connect Single echo acquirement time span is bordering on, otherwise Δ f is preferably 2kHz or much higher value.

Preferably, from navigation sequence Local-SE-NV, the navigation imaging sequence is adopted on the basis of spin-echo sequence Local excition is realized with the slice selective gradient and SLR pulses in three orientation, or selects navigation sequence Local-ME-NV, this is navigated into As sequence is using magnetic resonance signal in three slice selective gradients and SLR pulse excitation low coverages in orientation, then in both positive and negative polarity sexual intercourse The frequency encoding gradient for replacing gathers multiple gtadient echos during applying, by minimizing echo time and preferred phase code step number For 32 or 64 or other can quickly realize T1 weighted imagings compared with small integer.Here, slice selective gradient G_s1、G_S2And G_S3Orientation fixed Position is as being above set to orthogonal direction, G_s1, G_s2And G_s3Represent different azimuth slice selective gradient, wherein the first two perpendicular or parallel to Operation route, another is parallel or perpendicular to operation route, the orientation and amplitude and G of other slice selective gradients_s3It is identical, signal acquisition Since after the 3rd radio-frequency pulse, k-space filling and image reconstruction use partial Fourier mode；Local imaging sequence The essential characteristic of Local-ME-NV is, when sweep speed is paid the utmost attention to, one is applied gradient positive-negative polarity switching instant is read G_blipGradient, such part of data acquisition be equivalent to echo wave plane collection, the number of echoes in dotted line frame may be configured as 32 or its Its less integer, the data of collection are processed according to the conventional phasing of echo-planar imaging and image reconstruction mode.

Preferably, from navigation sequence Local-HASTE-NV, the navigation imaging sequence is returned in single-shot FAST SPIN Slice selective gradient and SLR pulses on the basis of wave train using three orientation realize local excition, and use half-fourier acquisition Mode quickly realizes T2 weighted imagings；Here, the echo time be arranged on 80ms to 140ms scopes, slice selective gradient G_s1、G_S2And G_S3 Orientation in positioning as being above set to orthogonal direction, wherein the first two vertical (or parallel) in operation route, another it is parallel or Perpendicular to operation route, the orientation and G of other slice selective gradients_s3It is identical；Also, selecting layer direction additionally to apply to compensate gradient here G_sc1、G_sc2、G_sc3…G_scn, its gradient amplitude is and G_S3Identical, its gradient width is and G_r1It is identical；First impulse waveform spy Levy parameter：Minimum phase SLR, when band product TBP be 8, with interior ripple factor be 0.5%, with outer ripple factor be 0.1%, pulse Flip angle is pi/2, and slice selective gradient intensity thickness according to needed for is set, such as 0.7G/cm；Second impulse waveform characteristic parameter： Minimum phase SLR, when band product TBP be 16, with interior ripple factor be 0.5%, with outer ripple factor be 0.1%, pulse flip angle It is π, slice selective gradient intensity thickness according to needed for is set, such as 0.5G/cm；3rd pulse and succeeding impulse wave character are joined Number：Minimum phase SLR, when band product TBP be 16, with interior ripple factor be 0.5%, with outer ripple factor be 0.1%, pulse upset Angle is π, and slice selective gradient intensity is 0.5G/cm, or (needing description Figure 26 impulse waveforms parameter herein), linear phase SLR, when Band product TBP is 16, and ripple factor is 0.1% inside and outside band, and pulse flip angle is π, and slice selective gradient intensity is 0.5G/cm.

Since after the 3rd radio-frequency pulse, k-space filling and image reconstruction use partial Fourier side to signal acquisition Formula.

Preferably, radio-frequency pulse has spatial selectivity, can uniformly excite simultaneously it is multiple close to frequency band, optional position The radio-frequency pulse shape of Multi-layer synchronous imaging meets following formula：

SLR (t) represents linear phase SLR pulses in above formula, and γ represents gyromagnetic ratio,WithRepresent respectively Pulse code phase, G_sRepresent slice selective gradient, r_i(i=0-n) one group of space vector of simultaneous shot aspect at equal intervals is represented；It is logical User interface is crossed in positioning as the corresponding position line of upper setting And transmit each layer orientation ginseng The impulse waveform calculation procedure of navigation module is counted to, the impulse waveform of renewal is exported and is loaded into navigation imaging control unit, so Navigation sequence Local-MSME-NV, the impulse waveform realization office that the sequence is defined using three slice selective gradients and above formula are run afterwards Domain is uniformly excited, and many echo-signals are gathered under the alternate frequency encoding gradient effect of positive-negative polarity, then carries out realtime graphic Rebuild；For three layers of simultaneous shot situation, radio frequency excitation pulse waveform is calculated as follows and obtains：

R in above formula₀The space vector of simultaneous shot aspect is represented, Δ S represents the spacing of simultaneous shot aspect, by regulation In above formula waveform parameter can optimize excite profile three close to frequency band range realize that the magnetic resonance signal of three aspects is uniform Excite, for example, G here_s1.5G/cm is set to based on required thickness, the bandwidth of SLR pulses is set to 1kHz, when band product TBP set 4 are set to, band and out-of-band ripple factor is no more than 0.5%, during three scanningWithIt is respectively set to With Reunion pulse is preferably 180 ° of minimum phase SLR pulses or linear phase SLR pulses, G under spin echo acquisition pattern_sValue No more than greatest gradient amplitude, 2.0G/cm is set to here, the bandwidth requirement of SLR pulses is not less than (3THK+2 Δ S) γ·G_s/ (2 π), is set to 4kHz here, and wherein THK represents the thickness of the aspect corresponding to each frequency band, SLR pulses when Band product TBP is set to 8 or 16, and 0.1% is set to interior ripple factor, and 0.1% is set to outer ripple factor；Scanning every time is adopted Collect a part of k-space line, three scanning obtains image S₁, image S₂With image S₃, picture breakdown is finally carried out as the following formula to be obtained respectively Tomographic image：

S ' in formula (4)₁,S'₂With S '₃Represent the image corresponding to three aspects of simultaneous shot.

When sweep speed is paid the utmost attention to, a G is applied gradient positive-negative polarity switching instant is read_blipGradient, so number Echo wave plane is equivalent to according to collecting part to gather, the number of echoes in dotted line frame may be configured as 32 or other less integers, adopt The phasing and image reconstruction mode that the data of collection are first commonly used according to echo-planar imaging are processed, and right back-pushed-type (4) is entered Row picture breakdown obtains each tomographic image.

Beneficial effect：Opening Extent of Syetem, security and convenience needed for structure guarantee Minimally Invasive Surgery of the invention；Especially It is, in order to improve resonance image quality and real-time and ensure that operating theater instruments precise positioning and operation route are precisely controlled.

Brief description of the drawings

Fig. 1 is provided in an embodiment of the present invention for minimally invasive operation navigating system structure chart.

Fig. 2 be Fig. 1 in A-A to sectional view.

Fig. 3 is planar radio frequency coils structure chart provided in an embodiment of the present invention.

Fig. 4 is gradient coil structures figure provided in an embodiment of the present invention.

Fig. 5 is the winding mode schematic diagram of main coil provided in an embodiment of the present invention and axial shield coil.

The information-based operating room schematic diagram that Fig. 6 navigates for the MRI image of the embodiment of the present invention.

Fig. 7 is the apparatus testing process of the embodiment of the present invention.

Fig. 8 is the local dynamic shimming sequence of the embodiment of the present invention：G_s1, G_s2, G_s3The logical gradients of different azimuth are represented, Can be by positioning as setting its orientation.

Fig. 9 is the navigation workflow of the embodiment of the present invention.

Figure 10 is the navigation software functional block diagram of the embodiment of the present invention.

Navigation sections and parameter of the Figure 11 for the embodiment of the present invention：Left figure is navigation interface, including " operation assessment ", " road Plan in footpath " and " navigation scanning " sub-interface, correspond respectively to 1031,1032 and 1033 functional modules in Figure 10.Right figure is to lead Boat parameter list, using floating window shape formula, for changing sequential parameter and reconstruction parameter.

Figure 12 is the real-time route tracing mode schematic diagram of the embodiment of the present invention.Rectangle frame represents scanning aspect, circle Represent scanning aspect center.

Figure 13 is local spin echo navigation sequence (Local-SE-NV) of the embodiment of the present invention：G_s1, G_s2And G_s3Represent The slice selective gradient of different azimuth, the slice selective gradient G shown in dotted line_s4It is option, Δ t represents the echo time.

Figure 14 is (left side) minimum phase SLR excitation pulse waveforms of the embodiment of the present invention, and (right side) minimum phase SLR excites arteries and veins Impulse sends out profile.Waveform feature parameter：When band product TBP be 8, with interior ripple factor be 0.5%, with outer ripple factor be 0.1%, Pulse flip angle is pi/2, and slice selective gradient intensity is 0.7G/cm.

Figure 15 is (left side) minimum phase SLR reunion impulse waveforms of the embodiment of the present invention；(right side) minimum phase SLR reunion arteries and veins Impulse sends out profile.Waveform feature parameter：When band product TBP be 16, with interior ripple factor be 0.5%, be with outer ripple factor 0.1%, pulse flip angle is π, and slice selective gradient intensity is 0.5G/cm.

Figure 16 is navigation sequence (many echo sequences of local, Local-ME-NV) in the art of the embodiment of the present invention：G_s1, G_s2, G_s3Represent the slice selective gradient of different azimuth, G_s4, G_s5, G_s6......G_snThe choosing layer ladder that sampling period applies is represented as option Degree, G_pRepresent phase encoding gradient, G_preRepresent that gradient, G are read in preparation_r1, G_r2, G_r3......G_rnRepresent that first to n is read ladder Degree, gradient area is equal but opposite polarity for adjacent reading, and 90 ° of radio-frequency pulses are preferably the minimum phase SLR pulses shown in Figure 14, 180 ° of radio-frequency pulses are preferably the minimum phase SLR pulses shown in Figure 15.

Figure 17 is navigation sequence (three layers of many echo sequences of synchronous local, Local-MEEPI- in the art of the embodiment of the present invention NV)：G_blipIt is phase encoding gradient, is applied to frequency encoding gradient positive-negative polarity switching instant, the same Figure 16 of other parameters.

Figure 18 is navigation sequence (three layers of many echo sequences of synchronous local, Local-MSME- in the art of the embodiment of the present invention NV)：G_s1, G_s2, G_s3Represent the slice selective gradient of different azimuth, G_s4, G_s5, G_s6......G_snRepresent that sampling period is applied as option Plus slice selective gradient, G_pRepresent phase encoding gradient, G_preRepresent that gradient, G are read in preparation_r1, G_r2, G_r3......G_rnRepresent first To n reading gradient, adjacent reading gradient area is equal but opposite polarity, and be preferably shown in Figure 15 three layers of first radio-frequency pulse are same Step excites SLR pulses, and second and the 3rd radio-frequency pulse select 180 ° of reunion SLR pulses shown in Figure 15 or Figure 26, and root Slice selective gradient amplitude is adjusted according to required thickness is appropriate in imaging sequence.

Figure 19 is navigation sequence (three layers of many echo sequences of synchronous local, Local-MSEPI- in the art of the embodiment of the present invention NV)：G_blipIt is phase encoding gradient, is applied to frequency encoding gradient positive-negative polarity switching instant, the same Figure 18 of other parameters.

Figure 20 is three layers of simultaneous shot radio-frequency pulse shape (left side) of the embodiment of the present invention and excites profile (right side).In right figure Dotted line represents C₁', asterisk line represents C₂', solid line represents C₃’。

Figure 21 is the calibration three first layers simultaneous shot pulse excitation profile of the embodiment of the present invention.Dotted line represents C in figure₁', it is long Short dash line represents C₂', solid line represents C₃’。

Figure 22 is the Multi-layer synchronous scan calibration sequence of the embodiment of the present invention：Radio-frequency pulse is Multi-layer synchronous excitation pulse, G_s1、G_s2And G_s3Represent slice selective gradient.

Figure 23 is three layers of simultaneous shot pulse excitation profile after the calibration of the embodiment of the present invention.Dotted line represents C in figure₁', it is long Short dash line represents C₂', solid line represents C₃’。

Figure 24 is (left side) five layers of simultaneous shot impulse waveform of the embodiment of the present invention, and solid line represents waveform real part, dotted line table Oscillography shape imaginary part；(right side) five layers of simultaneous shot profile, different types of curve corresponds to the different aspects of simultaneous shot respectively in figure.

Figure 25 is (left side) nine layers of simultaneous shot impulse waveform of the embodiment of the present invention, and solid line represents waveform real part, dotted line table Oscillography shape imaginary part；(right side) nine layers of simultaneous shot profile, different types of curve corresponds to the different aspects of simultaneous shot respectively in figure.

Figure 26 is linear phase SLR reunions radio-frequency pulse shape (left side) of the embodiment of the present invention and excites profile (right side).Ripple Shape characteristic parameter：When band product TBP be 16, be 0.1% with interior ripple factor, be 0.1% with outer ripple factor, pulse flip angle is π, slice selective gradient intensity is 0.5G/cm.

Figure 27 is navigation sequence (local fast acquisition interleaved spin echo, Local-HASTE- in the art of the embodiment of the present invention NV)：First 90 ° of radio frequency excitation pulse and first 180 ° of reunion pulse are respectively from shown in Figure 14 (left side) and Figure 15 (left side) SLR pulses, second and follow-up 180 ° of reunion pulses are from the SLR pulses shown in Figure 15 (left side) or Figure 26 (left side).90 ° of radio frequencies swash Time interval between hair pulse and 180 ° of reunion pulses is TE/2, and the time interval between 180 ° of reunion pulses is TE.G_s1、 G_s2、G_s3…G_snRepresent the slice selective gradient of different azimuth, G_preRepresent that gradient, G are read in preparation_r1、G_r2、G_r3…G_rnRepresent and read gradient, G_sc1、G_sc2、G_sc3…G_scnExpression is applied to the compensation gradient for selecting layer direction, ± G_P1、±G_P2、±G_p3…±G_pnRepresent both positive and negative polarity The phase encoding gradient of property.Part repeats N in dotted line frame_PE/ 4 times, signal acquisition is since after the 3rd SLR pulse.

Specific embodiment

For make present invention solves the technical problem that, the technical scheme that uses and the technique effect that reaches it is clearer, below The present invention is described in further detail in conjunction with the accompanying drawings and embodiments.It is understood that specific implementation described herein Example is used only for explaining the present invention, rather than limitation of the invention.It also should be noted that, for the ease of description, accompanying drawing In illustrate only part rather than full content related to the present invention.

First, principle and structure

It is of the invention for minimally invasive operation navigating system and method, its basic boom is as shown in figure 1, be different from routine diagnosis The technical characteristic of MRI system and other MRI navigation system is described as follows：

(1) magnet design is the open U-shape structure shown in Fig. 1, and magnet field intensity is preferably in 0.2T~0.7T scopes 0.3T aggravates the magnetic susceptibility artifact or metal artifacts of image to avoid high field intensity.Important technology different from conventional magnet designs refers to Mark is that magnet gap is more than 500mm, and pole plate diameter reduces 1/3 to 1/2,360mm is preferably, to increase than routine diagnosis type The convenience of operation technique.(2) radio-frequency receiving-transmitting coil design is biplane circular polarisation type, as shown in Figure 2.Swept different from diagnosis The flat board radio-frequency coil retouched, switchs here by T/R and realizes transmitting and receive capabilities simultaneously, it is to avoid individual reception coil is to micro- It is uniform that the space limitation of invasive procedures, particularly electric capacity quantity at least more than 100, fully improvement radio frequency Flied emission and signal are received Property.(3), for biplane main coil and in the additional biplane axial shield coil in outside, its winding mode is as schemed for gradient coil design Shown in 3, installation site as shown in figure 1, each coil and shielding board diameter are preferably 360mm, main coil and axial shield coil it Between added with high permeability high resistivity eddy-current screen plate, fully weaken the vortex that produces when gradient switches and disturb and limit gradient Coil thickness increases.

Above-mentioned technical characteristic is mainly Opening Extent of Syetem, security and convenience needed for ensureing Minimally Invasive Surgery；Especially, In order to improve resonance image quality and real-time and ensure that operating theater instruments precise positioning and operation route are precisely controlled, the present invention Propose airmanship scheme and imaging method in following arts：

First, magnetic susceptibility artifact or metal artifacts without magnetic medicine equipment are entered according to the operating process shown in Fig. 7 in advance Row detection and optimization navigation sequence parameter (for example, RF pulse width and echo acquirement time), and navigating into before surgery As gathering three-dimensional high definition t1 weighted image on instrument or High-Field imager, add sweep enhancing scanning, angiogram or function if necessary Imaging etc., then operation route planning is carried out, including target spot is set, inserting needle path planning and operation plan are worked out.

Secondly, then in the navigation imaging system shown in Fig. 1 by scanned position by calibration scan bed elevation of water And the straight line laser guide by laser orientation instru-ment is placed in isocenter point region, and shimming is carried out from Dynamic Local shimming technique, Its technical characteristic is that the proton or other magnetic in a small size are excited using the three-dimensional space selectivity radio-frequency pulse shown in Fig. 8 Property atomic nucleus, collection free induction decay signal (FID) adjusts magnetic field homogeneity until frequency by linear gradient or shimming gradient Spectral integral area is maximum, so as to the uniformity of magnetic field for realizing imaging area is optimized.

Then, according to the flow of navigation shown in Fig. 9 by the navigation module shown in Figure 10 and with navigation circle shown in Figure 11 Face sets up internal reference coordinate system and controls the quick navigation sequence of local to run, and three orthogonal sides are gathered repeatedly according to operation route To tomography signal, each direction can gather individual layer can also synchronous acquisition multilayer, or using the real-time road shown in Figure 12 Footpath tracing mode constantly updates positional parameter and waveform parameter in procedure and real time scan is so as to continuous track and localization hand Art instrument positions.

As shown in Figure 13-Figure 27, its essential characteristic is RF pulse-to-pulse to the quick navigation sequence design of local described here Punching has three-dimensional space selectivity, correspondence first radio frequency excitation pulse, first radio frequency reunion pulse and second radio frequency weight The slice selective gradient of poly- pulse is arranged on different azimuth, and using the SLR impulse waveforms for exciting profile elevations h to optimize, may be selected simultaneously It is uniform excite it is multiple close to frequency band, the scope and spacing of each frequency band can be carried out accurately as in positioning by thickness and interlamellar spacing Regulation, pulse excitation profile amplitude can be consistent according to the correction of the integral area of each frequency band, repeatedly gathers a part of k-space line Go forward side by side horizontal pulse phase loop, and may be selected to apply frequency encoding gradient and slice selective gradient simultaneously during data acquisition, receive Machine bandwidth is set to 100kHz or higher, then carries out k-space data and adds up and part Fourier image reconstruction.It is this to navigate into Image space method can not only improve uniformity degree of image, resolution ratio and signal to noise ratio, may also suppress magnetic susceptibility artifact and metal artifacts, and shorten Sweep time.

After guided therapy terminates, carry out local high resolution scanning on navigation imager or High-Field imager and enhancing is swept Retouch to confirm curative effect.Compared with scanning of being navigated in art, the acquisition matrix of frequency coding and phase-encoding direction is doubled here Above further to improve image resolution ratio.

As shown in figure 1, this magnet structure is used for into minimally invasive operation navigating system, the minimally invasive operation navigating system includes： Yoke 1, magnet steel 2, pole plate 3, shielded coil 4, gradient coil 5, radio-frequency coil 6, scanning bed 7, heating rod 8, heating plate 9, temperature Sensor 10, shell 11, T/R sending and receiving switch 12, gradient power amplifier 13, RF power amplification 14, preamplifier 15, temperature conditioning unit 16, Optical tracking alignment system 17, coil tuning control unit 18, scanning bed control unit 19, navigation are imaged control unit 20, are System control interface 21, main frame 22, display 23.

Magnet 60 is designed as the open U-shape structure shown in Fig. 1 and Fig. 2, magnet field intensity in 0.2T to 0.7T scopes, preferentially For 0.3T with avoid high field intensity aggravate image magnetic susceptibility artifact or metal artifacts.Different from the important technology of conventional magnet designs Index is that magnet gap is more than 450mm, and the radius ratio routine diagnosis type of pole plate 3 reduces 1/5 to 1/4, to increase operation technique Convenience.Radio-frequency coil 6 is designed as biplane circular polarisation type, and some nothings are set between outer conductor loop 50 and inner wire ring 52 Magnetocapacitance 51, as shown in figure 3, different from the flat board radio-frequency coil of diagnostic scan, hair is realized simultaneously here by T/R switches 12 Penetrate and receive capabilities, it is to avoid individual reception coil is limited the space of Minimally Invasive Surgery, particularly without the quantity of magnetocapacitance 51 at least 100 More than, fully improve the uniformity that radio frequency Flied emission and signal are received, supporting RF power amplification have 15kW or more power with The need for meeting supper-fast navigation imaging sequence.

As shown in figure 4, biplane gradient coil 5 is designed as three groups of biplane main gradient coils 101, every group of two difference positions In imaging area up and down and near the position of pole plate 3, linear magnetic field gradient is produced in X-axis, Y-axis and Z-direction respectively, and in axially main ladder The additional biplane axial shield coil 102 in outside of degree coil 101, the main gradient line of axial biplane is calculated with target field method The coiling form of circle 101 and axial shield coil 102, is concentric circles pattern as shown in Figure 5, using printed-board technology system Form, the mode of connection of axial shield coil 102 is similar with the gradient cable connection mode shown in Fig. 4, but gradient current direction Conversely, main gradient coil installation site is as depicted in figs. 1 and 2；In addition, in biplane axial direction main gradient coil and axial shield line Add insulating barrier 103 between circle and closely connect, install the whirlpool of high permeability high resistivity between main gradient coil 101 and pole plate 3 additional Stream barricade, the vortex produced when fully decrease gradient switches and thrust simultaneously limit the increase of gradient coil thickness.

Other specification is as follows：The field intensity of magnet 60 is preferably 0.3T, and air gap is preferably 500mm, and the radius of magnet pole 3 is less than A laser orientation instru-ment 1 is installed in 380mm, the top of magnet 60, using 12V direct current supplys, a wordline light spot shape, and output wavelength is 635nm to 650nm scopes, position coordinates is accurate to 0.1mm.Gradient coil greatest gradient intensity is 15mT/m, and switching rate is 50mT/m/ms or higher, main gradient coil 101 and the radius of axial shield coil 102 are preferably 350mm, thickness 4mm to 5mm, Generally constrained within 5% away from 2mm to 3mm, and gradient linearity degree, effective imaging area DSV not less than 250mm × 250mm × 300mm, and confirmation is designed according to Biot-Savart theorems calculating gradient linearity area size.

Package unit constitutes an information-based operating room for suitable MRI image navigation, as shown in fig. 6, including：Magnet 60, Laser orientation instru-ment 61, scanning bed 7, bayonet socket 63, ultra-large type LCDs 64, keyboard 66, rack 67 (inside has main frame and magnetic field Alarm), operation table 68, auxiliary positioning graticule 69.Console uses movable small computer desk, transfers main frame and installation one Magnetic field alarm, for preventing computer desk to be disturbed by high-intensity magnetic field into 10 gauss ranges.Imaging data uses Optical Fiber Transmission side Formula and shuangping san mode, small liquid crystal display 65 (medical touch-screen display) are fixed on the desktop of computer desk, super large Type LCDs 64 is arranged on the wall of the imager back side.Operation table 68 is docked by bayonet socket 63 with scanning bed 7, and patient can push away Enter imaging area, performed the operation while scanning, need removal imaging area to carry out some special operations also dependent on operation and grasp Make.Clinical scanning and operation during, main frame load navigation sequence to navigation be imaged control unit, the latter according to navigation sequence with Navigational parameter control radio-frequency sending coil produces required radio-frequency pulse, and controls gradient coil to produce required gradient current arteries and veins Punching, the magnetic resonance signal of three dimensions coding is produced at human body imaging position, and then, magnetic resonance signal connects through RF receiving coil Upload to main frame and data processing carried out by navigation and control software in real time and image shows by imaging control unit of navigating after receipts, Thus doctor can in time obtain operating theater instruments and target position information.

It is of the invention for minimally invasive operation navigating system and method be a kind of structure height open and with navigation calibration and The diagnosis of Real-time High Resolution scan function and the dual-purpose magnetic resonance navigation system of PCI and technical scheme, in particular, provide and lead The special local imaging technique of boat and can pinpoint Multi-layer synchronous excitation technique.

The system architecture of described high opening reaches the U-shaped magnet of more than 500mm including opening, and is equipped with transmitting reception Type biplane radio-frequency coil and private mask gradient coil are used to improve the convenience of operation technique.

Described transmitting reception type biplane radio-frequency coil is switched by T/R and realizes transmitting and receive capabilities simultaneously, it is to avoid Individual reception coil is limited the space of Minimally Invasive Surgery, particularly electric capacity quantity at least more than 100, fully improves radio frequency Flied emission The uniformity received with signal.

Private mask gradient coil is X/Y/Z axle biplane gradient coils, and the diameter than routine diagnosis type coil reduces 1/3 To 1/2, preferably 360mmm, gradient linearity degree is constrained within 10%, and additional biplane shielding on the outside of Z axis main gradient coil Gradient, its coiling form is as shown in Figure 5.

The implementation of navigation calibration function includes Dynamic Local shimming, and scanned position is high by calibration scan bed plane Spend and the straight line laser guide by laser orientation instru-ment is placed in isocenter point region, carried out from Dynamic Local shimming technique even , it is characterized in that exciting proton or other magnetic in a small size former using the spatial selectivity radio-frequency pulse shown in Fig. 8 Daughter nucleus, gathers free induction decay signal, and magnetic field homogeneity is adjusted until spectrum integration face by linear gradient or shimming gradient Product is maximum, so as to the uniformity of magnetic field for realizing imaging area is optimized.

The implementation of navigation calibration function includes that metal artifacts are tested and calibrated, and is primarily based on the mark of copper sulfate solution Quasi- water mould and gradin-echo test Distribution of Magnetic Field figure, then the central area of standard water mould add bar shaped or intersecting parallels without Magnetic metal material simultaneously tests Distribution of Magnetic Field figure by gradin-echo, the difference of the two Distribution of Magnetic Field figures is calculated, from difference Minimum makes operating theater instruments without magnetic metal material or composite, and dead space size is finally measured on gradient echo image And consistency checking is carried out with bonding jumper actual size, in this, as the precise marking of operating theater instruments self-position.

Being achieved in that for navigation calibration function, the navigation module shown in Figure 10 is passed through according to the flow of navigation shown in Fig. 9 Internal reference coordinate system is set up with the navigation interface shown in Figure 11 and predetermined operation route coordinates and control local quickly navigate sequence Row operation, three imaging region signals of orthogonal plane are progressively gathered along operation route, or using real-time shown in Figure 12 Path trace pattern, scanning aspect center is since surgical portal position until target position is along the operation shown in arrow Path direction Δ L/2 incremented by successively, constantly updates positional parameter and waveform parameter and real time scan is so as to even in procedure Continuous track and localization surgical instrument position.

The essential characteristic of local imaging technique is, using multi-faceted slice selective gradient and the RF pulse-to-pulse for exciting profile elevations h to optimize Impulse sends out the proton signal in a small size, and first 90 ° of radio frequency excitation pulse and first 180 ° of reunion pulse here are adopted With the SLR impulse waveforms for uniformly exciting, and the corresponding slice selective gradient amplitude of first radio-frequency pulse is set in navigation sequence it is G_s1=2 π Δs f/ γ/FOV_x, the corresponding slice selective gradient amplitude of second radio-frequency pulse of setting is G_s2=2 π Δs f/ γ/FOV_yIf, It is G to put the corresponding slice selective gradient amplitude of the 3rd radio-frequency pulse_s3=2 π Δs f/ γ/THK, wherein FOV_x、FOV_yCan be in sequence with THK Directly adjusted on row parameter list.

The essential characteristic of local imaging technique is to need to optimize the band of radio-frequency pulse in advance under metal artifacts disturbed condition Δ f wide, receiver bandwidth is preferably more than 100kHz, and SLR pulses are optimized under the conditions of TBP≤8 excites profile, and its waveform is special Levy as shown in Figure 14 and Figure 15, and each frequency band obtained based on the calibrating sequence shown in Figure 22 in the case of synchronous multilayer is excited Integral area optimization excites profile or calibration image amplitude, then in frequency coding direction and choosing during k-space data is gathered Layer direction applies gradient pulse simultaneously.

The bandwidth deltaf f optimal ways of radio-frequency pulse are that it is different value that the operating process according to Fig. 7 sets Δ f, for example 750Hz, 1kHz, 1.25kHz, 1.5kHz etc., therefrom search magnetic susceptibility artifact or metal artifacts it is minimum when Δ f, when Apply frequency encoding gradient and slice selective gradient during data acquisition simultaneously, then Δ f optimal values are close to the single echo acquirement time Length, otherwise Δ f are preferably 2kHz or much higher value.

The essential characteristic of local imaging technique is, from the Local- shown in the Local-SE-NV or Figure 13 shown in Figure 13 ME-NV simultaneously minimizes the echo time and can quickly realize T1 weighted imagings.Here, slice selective gradient G_s1、G_S2And G_S3Orientation positioning Orthogonal direction is set on picture, in operation route, another parallel (or vertical) is in operation for wherein the first two vertical (or parallel) Route, the orientation and amplitude and G of other slice selective gradients_s3It is identical, signal acquisition since after the 3rd radio-frequency pulse, k-space Filling and image reconstruction use partial Fourier mode.

The essential characteristic of local imaging sequence Local-ME-NV is, when sweep speed is paid the utmost attention to, reading, gradient is positive and negative The polarity switching moment applies a G_blipGradient, as shown in figure 17, such part of data acquisition is equivalent to echo wave plane collection, Number of echoes in dotted line frame may be configured as 32 or other less integers, and the data of collection are according to the conventional phase of echo-planar imaging Bit correction and image reconstruction mode are processed.

The essential characteristic of local imaging technique is can quickly to realize T2 from the Local-HASTE-NV sequences shown in Figure 27 Weighted imaging.Here, the echo time be arranged on 80ms to 140ms scopes, slice selective gradient G_s1、G_S2And G_S3Orientation positioning picture On be set to orthogonal direction, in operation route, another parallel (or vertical) is in operation road for wherein the first two vertical (or parallel) Line, the orientation and G of other slice selective gradients_s3It is identical；Also, selecting layer direction additionally to apply to compensate gradient G here_sc1、G_sc2、 G_sc3…G_scn, its gradient amplitude is and G_S3Identical, its gradient width is and G_r1It is identical；First pulse and second pulse are adopted Used similar to the ripple shown in Figure 15 or Figure 26 with similar to the waveform shown in Figure 14 and Figure 15, the 3rd pulse and succeeding impulse Shape, waveform parameter optimal way is same as above, and signal acquisition since after the 3rd radio-frequency pulse, fill and image by k-space Rebuild and use partial Fourier mode.

Can the essential characteristic of pinpoint Multi-layer synchronous excitation technique be that radio-frequency pulse has spatial selectivity, can be same When uniformly excite it is multiple close to frequency band, for example, for three layers of simultaneous shot situation from the navigation sequence shown in Figure 18 Local-MSME-NV, wherein radio frequency excitation pulse waveform are calculated as follows and obtain：

Its wave character and excite profile as shown in Figure 20 or Figure 23, reunion pulse is preferred under spin echo acquisition pattern Be 180 ° of minimum phase SLR pulses or linear phase SLR pulses, as shown in Figure 15 and Figure 26, and pulse of meeting again radio frequency band Width requires to be not less than (3THK+2 Δ S) γ G_s/(2π).Equally, other Multi-layer synchronous excite situation to use and are similar to Mode realizes, as shown in figures 24 and 25.

The essential characteristic of navigation sequence Local-MSME-NV is that the frequency band range and spacing of simultaneous shot pulse can be fixed Position carries out accurate adjustment as on by thickness and interlamellar spacing, during three scanningWithIt is respectively set toWith A part of k-space line of each scanning collection, three scanning obtains image S₁, S₂And S₃, picture breakdown is finally carried out as the following formula to be obtained Each tomographic image：

The essential characteristic of navigation sequence Local-MSME-NV is, when sweep speed is paid the utmost attention to, is reading gradient both positive and negative polarity Property switching instant apply a G_blipGradient, as shown in figure 19, such part of data acquisition is equivalent to echo wave plane collection, empty Number of echoes in wire frame may be configured as 32 or other less integers, and the data of collection are first according to the phase that echo-planar imaging is conventional Bit correction and image reconstruction mode are processed, and right back-pushed-type (4) carries out picture breakdown much each tomographic images.

(such as TBP in the case of picture breakdown is incomplete>8), it is multiple close to the uniform calibrating mode that excites of frequency band be

(1) with the synchronous scanning calibrating sequence shown in Figure 22 and from the SLR impulse waveforms of each phase code in formula (3) Simultaneously Fourier transform obtains exciting profile collection signal to frequency domain, is expressed as C₁、C₂And C₃；

(2) C is calculated₁、C₂And C₃Integral area, be expressed as herek₂=∫ ∫ C₂Dxdy and k₃ =∫ ∫ C₃Dxdy, wherein ∫ ∫ represent two-dimensional integration, and x and y represent two-dimensional coordinate；

(3) alignment profiles figure is C₁、WithAs shown in figure 23.

(4) same, the two dimensional image obtained to three scanning is in above-mentioned integral area ratio k₁、k₂And k₃Calibrated simultaneously Each tomographic image decomposition is carried out by formula (4).

Can the essential characteristic of pinpoint Multi-layer synchronous excitation technique be that Multi-layer synchronous exciting method can be used for any position The aspect imaging put, i.e.,

And corresponding position line is set as upper in positioning by the user interface shown in Figure 11 And the impulse waveform calculation procedure of navigation module of each layer direction parameter shown in Figure 10 is transmitted, what output updated Impulse waveform is simultaneously loaded into the imaging control unit of the navigation shown in Fig. 1, then runs scanning sequence and carries out real time image reconstruction.

2nd, instantiation

Air navigation aid of the invention and software are applied to various field intensity magnetic resonance imaging systems, are particularly suited for open type magnetic Resonance imaging system, such as the magnetic resonance imaging navigation system shown in Fig. 1, Fig. 2, its basic boom and technology implementation detail explanation It is as follows：

Magnet field intensity is preferably 0.3T, and air gap is preferably 550mm, and body even field ring (or being polar ring) diameter is less than A laser orientation instru-ment 1 is installed in 360mm, magnet top, using 12V direct current supplys, a wordline light spot shape, and output wavelength is 635nm to 650nm scopes, position coordinates is accurate to 0.1mm.Radio-frequency receiving-transmitting coil is using the biplane circular polarisation class shown in Fig. 3 Type, wherein electric capacity quantity at least more than 100, and realization transmitting simultaneously and receive capabilities, supporting RF power amplification are switched by T/R With 15kW or more power.Gradient coil uses flat main coil, and greatest gradient intensity is 20mT/m, and switching rate is 60mT/m/ms, coil diameter is preferably 360mm, and gradient linearity degree is generally constrained within 10%, and according to Biot- Savart theorems calculate gradient linearity area size and are designed confirmation；In addition, in axial gradient coil in outside additional mask Coil, the coiling form of axial gradient coil and shielded coil is calculated with target field method, as shown in Figure 5.Console is adopted Movable small computer desk is used, main frame is transferred and a magnetic field alarm is installed, for preventing computer desk to enter 10 gauss ranges Disturbed by high-intensity magnetic field.Imaging data uses Optical Fiber Transmission mode and shuangping san mode, and medical touch-screen display is fixed on On the desktop of computer desk, super large LCDs is arranged on the wall of the imager back side.Operation table is right with scanning bed by bayonet socket Connect, patient can push imaging area, performed the operation while scanning, need removal imaging area to carry out some also dependent on operation special Different operation technique.So, package unit constitutes an information-based operating room for suitable MRI image navigation, as shown in Figure 6.For Realize image-guided not by the magnetic susceptibility artifact or metal artifacts severe jamming of operating theater instruments in art, the present invention is according to Fig. 7 Shown testing process is detected and calibrated to the metal artifacts of operating theater instruments, wherein with reference to used by water mould is daily quality inspection Standard water mould comprising copper sulfate solution, target water mould is added comprising strip or derrick in the central area of standard water mould The water mould that shape is made without magnetic metal material, is primarily based on reference to water mould and gradin-echo test Distribution of Magnetic Field figure, Ran Houji In target water mould and gradin-echo test Distribution of Magnetic Field figure, the difference of the two Distribution of Magnetic Field figures is calculated, it is minimum from difference Without magnetic metal material (such as titanium alloy and ceramic composite) make operating theater instruments, and obtain optimal pulse width and return The parameters such as ripple acquisition time, the corresponding dead space size of bonding jumper are finally measured on image and are entered with bonding jumper actual size Row consistency checking.

On the other hand, the various air navigation aids and imaging method of magnetic resonance imaging navigation system by navigation software realize, Navigation software includes 1031,1032 and 1033 functional modules shown in Figure 10, for controlling hardware system 100,101 and 102 works Make.Wherein, the control function of module 1031 includes：Carry out image measurement and analysis；Generation assessment report.The control of module 1032 Function includes：Set up magnetic resonance navigation scanning sequence, agreement and parameter list；Selection navigation scheme and pattern；Carry out system in real time Calibration, scanning and image reconstruction.The control function of module 1033 includes：Set up image area internal reference coordinate system；Definition simultaneously can Depending on changing operation route；Many planes show target spot and instrument trajectories in real time；Operation path deviation is analyzed in real time and is alerted.Navigation software Operational platform design mode as shown in figure 11, S11 to S31 represents the image of different azimuth or aspect in figure, and image passes through mouse Mark is double-clicked and switched between individual display pattern and multiple display patterns.Wherein, system calibration sequence includes local shimming and ladder Degree gamma correction, for improving uniformity of magnetic field and compensation gradient non-linear error, T1 navigation sequences refer to T1 weighted imagings Quick navigation sequence, the sequence such as including universe and local SE-NV, ME-NV and MSME-NV, T2 navigation sequences refer to T2 weighted imagings Quick navigation sequence, the sequence such as including universe and local HASTE-NV, FISP-NV, T2* navigation sequences refer to T2* weighted imagings Quick navigation sequence, the sequence such as including universe and local EPI-NV.Sequential parameter table and reconstruction parameter table use floating window shape Parameter value can be changed and stored to formula, each sequence names respective parameter list page of correspondence, such as Figure 11 (under) shown in." opened in figure Slice selective gradient direction parameter of the beginning " key after mouse click in parameter list updates impulse waveform and performs scanning and real-time figure As rebuilding.

Above-mentioned MRI navigation system realizes clinical navigation operation according to the flow of navigation shown in Fig. 9, is described as follows：

First, three-dimensional isotropic high-resolution t1 weighted image is obtained on High-Field imager, is navigated for operations on cranium and brain Plus enhancing scanning is swept, add sweep diffusion tensor and angiogram to show focus, blood vessel and nerve fibre if necessary.Connect , operation route planning is carried out based on internal reference coordinate system.For operations on cranium and brain navigation, internal reference establishment of coordinate system mode It is that encephalic commissura anterior trailing edge midpoint to the line at postcommissure leading edge midpoint is set to footpath, the horizontal plane made by it between joint It is set to HO planes, FO planes is set to by the coronal-plane in footpath between joint, add the median sagittal plane SO planes of brain, it is fixed just to constitute Three datum planes of position picture.The intersection point of these three datum planes is set to origin.Axle by origin fore-and-aft direction is sagittal axis (footpath overlaps between joint), it is determined as Y-axis；Z axis are set to by the above-below direction of the origin vertical axis vertical with Y-axis；With by original The frontal axis put left and right directions and intersected vertically with Y-axis is set to X-axis.Using these planes and axis, you can draw out intracerebral each The three dimensional space coordinate of individual structure.Route canonical form is, many along carrying out to three-dimensional full brain high-resolution T1 weightings k-space data Reconstruction image plane, optimal operation route is determined and labeled as a series of nodes position on image according to internal reference coordinate system Put, read corresponding gradient direction parameter, then, according to High-Field imager and the respective greatest gradient intensity of imager of navigating The above-mentioned gradient direction parameter of ratiometric correction is simultaneously stored in each navigation sequence parameter list of navigation imager as navigation orientation Parameter default.

Then, service chart 10 and the navigation software shown in Figure 11 on MRI navigation imagers, selection navigation sequence are simultaneously circulated Run, described in specific design mode and characteristic parameter setting requirements following article embodiment 1-6 on each navigation sequence.It is right In each navigation sequence, navigation direction parameter and scan image are read using varied angle scan pattern, while incidentally scanning other Two images of orthogonal direction, every time obtain three groups of faultage images, every group can be single image or simultaneous shot collection it is many Image is opened, the anatomical structure and medical instrument locations of imaging area are shown on medical display.Or, it is non-linear in gradient system The real-time continuous tracking of probe location, Tu12Zhong are realized in the case of error is larger using the real-time route tracing mode shown in Figure 12 Spacing between adjacent aspect is Δ L, and scanning aspect center is along the operation pathway direction Δ incremented by successively shown in arrow L/2, real time scan can suspend Current Scan since surgical portal position and join until target position terminates, during real time scan The positioning of next node position is reset on the image for having scanned according to predetermined operation route and internal reference coordinate system Line, then starts scan image or updates impulse waveform according to positional parameter and start synchronous scanning.Due to operating theater instruments (such as without Magnetic metal probe) no signal character shape is shown as on MRI image, this inherently provides the contrast with surrounding tissue, Can be used as the precise marking of operating theater instruments self-position, and can be by the operating process optimization parameter and magnetic shown in Fig. 7 Rate artifact is so as to increase the contrast of operating theater instruments and surrounding tissue, and above-mentioned navigation pattern causes surgical instrument position Positioning precision is not influenceed by extraneous factor；Conversely, in Fig. 1 optical tracking alignment system (including infrared navigation camera, positioning show Track device, the puncture needle equipped with navigation photosphere, magnetic compatibility power supply and communication cable and navigation feature module etc.) as conventional alternate item Azimuth information for real-time tracking operating theater instruments is, it is necessary to set up MRI scan system coordinate system and optical positioning system coordinate system Relativeness, then the positioning-system coordinate of operating theater instruments is converted into scanning system coordinate and jointly real with patient's MRI image When be displayed on screen, but setting accuracy is prone to position in patient's art and changes or histoorgan displacement influence and apparatus Bent at its tip deformation effect.

Finally, local high resolution scanning and increasing are carried out on navigation imager or High-Field imager after guided therapy terminates It is strong to scan to confirm curative effect.Compared with scanning of being navigated in art, the acquisition matrix of frequency coding and phase-encoding direction increases here More than one times further to improve image resolution ratio.

The quick local spin echographic of embodiment 1

Based on above-mentioned MRI navigation system and flow of navigation, quick navigation sequence is from the local spin echo shown in Figure 13 Sequence Local-SE-NV, wherein, 90 ° of radio-frequency pulses are preferably the minimum phase SLR pulses shown in Figure 14, two 180 ° of reunions Radio-frequency pulse can select the minimum phase SLR pulses shown in Figure 15 or the linear phase SLR pulses shown in Figure 26.In radio-frequency power When not enough, band product TBP is constant and accordingly adjust SLR pulse widths when can reduce radio frequency bandwidth and keep, and according to required SLR arteries and veins The data point interval time of width adjusting wave file is rushed, while gradient amplitude layer needed for obtaining in regulatory sequence parameter list It is thick.Under metal artifacts disturbed condition, receiver bandwidth is preferably 100kHz or higher, and the echo time is optimized for minimum value, It is G to apply frequency encoding gradient and amplitude during data acquisition simultaneously_s3Slice selective gradient, and operating process sets according to Fig. 7 Radio-frequency pulse bandwidth deltaf f is put for different value, such as 750Hz, 1kHz, 1.25kHz, 1.5kHz etc. therefrom search magnetic susceptibility Δ f when artifact or minimum metal artifacts.When slice selective gradient is applied simultaneously during data acquisition, then TBP/ Δs f optimal values connect Single echo acquirement time span is bordering on, otherwise Δ f is generally preferred to 2kHz or much higher value.Under real-time route tracing mode, The position line as upper setting navigation sequence is positioned in many planes (such as three planes) and adjust its thickness, spacing and orientation, in imaging The corresponding gradient intensity of first radio-frequency pulse of setting is G in sequence_s1=2 π Δs f/ γ/FOV_x, second radio-frequency pulse correspondence Gradient intensity be G_s2=2 π Δs f/ γ/FOV_y, the 3rd corresponding gradient intensity of radio-frequency pulse is G_s3=2 π Δs f/ γ/THK, Wherein Δ f is radio-frequency pulse bandwidth, FOV_xAnd FOV_yRepresent the visual field in x-axis and y-axis direction respectively, may be configured as 32mm, 64mm or 128mm, thickness THK are set to 8mm, and set sequence repetition time TR=300ms, phase code step number N_pe=32,64 or 128, sequence repetition number NEX=1.K-space data uses part Fourier acquisition mode, and within the remaining time of each TR By other adjacent aspects of the same manner selective excitation, scanning aspect is set in real time according to navigation pattern hangs down with operation route direction It is straight or parallel.Then, navigation sequence is run, one group of k-space line of each phase code circle collection or fills at data acquisition interpolation Zero, and carry out part Fourier reconstruction acquisition t1 weighted image.Sweep time is calculated as

T_ACQ=55%NEXN_PETR=0.355%132=5.3 (s)

Because TR is not less than 300ms, the proton magnetization vector of tissue can largely recover, so it is avoided that The overlapping artifact of interlayer.Compared with the spin-echo sequence (SE) of routine diagnosis, the scan method is remarkably improved scanning effect Rate, and image has high-resolution.In high field intensity imaging system, quick navigation sequence of the invention and parallel acquisition technique knot Conjunction can further shorten several times of sweep time.

The many echographics of quick local of embodiment 2

Based on above-mentioned MRI navigation system and flow of navigation, quick navigation sequence is returned from many gradients of local shown in Figure 16 Wave train Local-ME-NV, wherein, 90 ° of radio-frequency pulses are preferably the minimum phase SLR pulses shown in Figure 14, first and Two 180 ° of reunion radio-frequency pulses are from the minimum phase SLR pulses shown in Figure 15 or the linear phase SLR pulses shown in Figure 26. When radio-frequency power is not enough, band product TBP is constant and accordingly adjust SLR pulse widths when can reduce radio frequency bandwidth and keep, and root According to the data point interval time of required SLR pulse width modulations wave file, while gradient amplitude is arrived in regulatory sequence parameter list Required thickness.Under metal artifacts disturbed condition, receiver bandwidth is preferably 100kHz or higher, and the echo time is optimized for minimum Value, it is G to apply frequency encoding gradient and amplitude simultaneously during data acquisition_s3Slice selective gradient, and the operation stream according to Fig. 7 Cheng Youhua Δs f.Under real-time route tracing mode, in many planes (such as three planes) positioning as the positioning of upper setting navigation sequence Line simultaneously adjusts its thickness, spacing and orientation, and the corresponding gradient intensity of first radio-frequency pulse of setting is G in imaging sequence_s1=2 πΔf/γ/FOV_x, the corresponding gradient intensity of second radio-frequency pulse is G_s2=2 π Δs f/ γ/FOV_y, the 3rd radio-frequency pulse pair The gradient intensity answered is G_s3=2 π Δs f/ γ/THK, set FOV_xAnd FOV_yIt is 32mm, 64mm or 128mm, THK is 8mm, and is set Put sequence repetition time TR=300ms, phase code step number N_pe=32,64 or 128, sequence repetition number NEX=1 or 2.K is empty Between data acquisition use part Fourier acquisition mode, and press the same manner selective excitation in the remaining free time of each TR Other adjacent aspects, scanning aspect sets perpendicular or parallel with operation route direction in real time according to navigation pattern.As NEX=2, The polarity of each reading gradient of alternating inversion is scanned every time, and each phase code circulation is incremented by successively or successively decreases phase encoding gradient simultaneously Collection k-space data, data acquisition carries out complex signal and adds up to strengthen signal to noise ratio and eliminate phase error after terminating, then adopt T1 weighted image is obtained with partial Fourier reconstruction mode.Sweep time T_ACQCan be calculated as

T_ACQ=55%NEXN_PETR=0.355%232=10.6 (s)

As NEX=1, sweep time T_ACQCan be calculated as

T_ACQ=55%NEXN_PETR=0.355%132=5.3 (s)

The imaging method is based on local scan mode under conditions of focal area high-resolution and signal to noise ratio is ensured significantly Degree improves scan efficiency, and can suppress metal artifacts.In the bar of gradient switching rate quite fast (such as 100mT/m/ms) Echo quantity under part in Figure 16 dotted line frames can further increase, so as to further improve figure while contrast needed for ensureing As signal to noise ratio.

In addition, when sweep speed will give special priority for, G can be chosen in sequential parameter table_blipGradient option, is reading Gradient positive-negative polarity switching instant applies a G_blipGradient, as shown in figure 17.Number of echoes N in figure in dotted line frame_peIt is settable It is 32 or 64, phase encoding gradient intensity meets G_pe=G_blip·N_pe/ 2 conditions, sweep time is

T_ACQ=55%NEXN_PETR=0.355%2=0.33 (s)

Real time scan is thus fully achieved, and due to applying using short echo train and during data acquisition simultaneously Frequency encoding gradient and slice selective gradient, common Nyquist artifact and magnetic susceptibility artifact can be substantially reduced, in conjunction with using back The conventional prescan of ripple planar imaging and phase correction scheme fully can eliminate image artifacts in the navigation system shown in Fig. 1 Interference.

The three layers of synchronous scanning of quick local of embodiment 3

Based on above-mentioned MRI navigation system and flow of navigation, quick navigation sequence is excited from the Multi-layer synchronous shown in Figure 18 Local-MSME-NV sequences.In order to increase radio-frequency drive uniformity, the waveform of first radio-frequency pulse of imaging sequence is using figure Linear phase SLR impulse waveforms shown in 20；Also, in order to while exciting human many levels, radio-frequency pulse shape is by following Mode carries out phase code：

Here, SLR (t) represents linear phase SLR pulses, G_sExpression selects the layer direction to beGradient intensity,It is in representing The vector of central layer locus, can here be set as isocenter point directly in positioning as upper setting, and the position of adjacent layer is by choosing Thickness THK and interlamellar spacing Δ the S setting in layer direction, Δ S is by G_SWith bandwidth deltaf f according to Δ S=2 π Δs f/ γ/G_sSetting,WithIt is initial phase, and Δ S>THK.In order to realize that each layer is uniformly excited, it is to avoid interlayer overlaps artifact, and Can realize being accurately positioned in clinical navigation application, the bandwidth of first radio-frequency pulse is set as 1kHz when individual layer is excited here, When band product TBP be set as 4, band and out-of-band ripple factor is respectively set as 0.5% and 0.1%, slice selective gradient be 0.7 Gauss/ Centimetre (G/cm), then obtains the impulse waveform that multiple adjacent aspects are uniformly excited simultaneously by formula (3), often walks phase loop and produces A kind of waveform, corresponding to a wherein step phase loop three layers of impulse waveform of simultaneous shot and excite profile to be displayed in Figure 20 In.Second of Local-MSME-NV sequences and the 3rd radio-frequency pulse can use the 180 ° of sinc pulses of Hamming adding windows, this In be preferably 180 ° of minimum phase SLR pulses (see Figure 15) or linear phase SLR pulses (see Figure 26), and adjust with a width of (3 THK+2·ΔS)·γ·G_s/(2π).In order to decode many levels while exciting from the magnetic resonance signal of phase code Signal simultaneously reduces peak radio-frequency power, for example, for three layers of simultaneous shot situation, during three scanningWithWith following Mode carries out phase loop, i.e. With

Three scanning obtains image S₁, S₂And S₃, then carry out picture breakdown as the following formula and obtain each tomographic image：

Middle low field imaging clinically generally requires cumulative three times or four times, the institute under the conditions of other sweep parameter identicals State simultaneous shot acquisition mode excites acquisition mode to improve signal noise ratio (snr) of image about 40% than conventional individual layer.

When band product TBP it is larger when or magnetic field homogeneity it is poor when, the signal amplitude of synchronous scanning may be inconsistent, causes Not exclusively, at this moment the situation of TBP=16 as shown in Figure 21 needs to carry out range error calibration in the steps below for picture breakdown：

(2) C is calculated₁、C₂And C₃Integral area, k is expressed as here₁=∫ ∫ C₁dxdy、k₂=∫ ∫ C₂Dxdy and k₃= ∫∫C₃Dxdy, wherein ∫ ∫ represent two-dimensional integration, and x and y represent two-dimensional coordinate；

(3) alignment profiles figure is C₁、WithAs shown in figure 23.

In addition, under metal artifacts disturbed condition, receiver bandwidth is preferably 100kHz or higher, the echo time is optimized for Minimum value, it is G to apply frequency encoding gradient and amplitude simultaneously during data acquisition_s3Slice selective gradient, and according to Fig. 4 grasp Make process optimization Δ f.

In addition, when sweep speed will give special priority for, G can be chosen in sequential parameter table_blipGradient option, is reading Gradient positive-negative polarity switching instant applies a G_blipGradient, as shown in figure 19, the number of echoes N in figure in dotted line frame_peIt is settable It is 32 or 64, phase encoding gradient intensity meets G_pe=G_blip·N_pe/ 2 conditions, sweep time is calculated as

T_ACQ=55%NEXN_PETR3=55%20.33 ≈ 1 (s)

Then, the conventional prescan of echo-planar imaging, phasing and image reconstruction scheme are used in combination shown in Fig. 1 Navigation system on obtain without artifact interference MRI image.

Embodiment 4：Quick any Multi-layer synchronous scanning of local：

Multi-layer synchronous exciting method described in embodiment 3 can also be combined with SLR pulse techniques and is generalized to ordinary circumstance, I.e.

Here, SLR (t) impulse waveforms are to design linear phase digital filter simultaneously based on Parks-McClellan algorithms Become scaling method with reference to Shinnar-Le-Roux to obtain.For example, Figure 24 (left side) and five layers of simultaneous shot impulse waveform shown in (right side) With excite profile, wherein SLR (t) is linear phase SLR pulses, when band product TBP be 4, be 0.5% with interior ripple factor, band is outer Ripple factor is 0.5%, and pulse flip angle is pi/2, and slice selective gradient intensity is 1.5G/cm, and pulse bandwidth is 1kHz.Figure 25 (left side) Nine layers of simultaneous shot impulse waveform shown in (right side) and excite profile, wherein SLR (t) is linear phase SLR pulses, when band product TBP is 4, is 0.5% with interior ripple factor, is 0.5% with outer ripple factor, and pulse flip angle is pi/2, and slice selective gradient intensity is 1.5G/cm, pulse bandwidth is 1kHz.When scanning sequence is spin-echo type, reunion pulse is from linear shown in Figure 26 Phase SLR pulses, its characteristic parameter is：When band product TBP be 16, pulse bandwidth is 4kHz, with interior ripple factor be 0.1%, band Outer ripple factor is 0.1%, and pulse flip angle is π, and slice selective gradient intensity can adjust according to required thickness, for example, here for Five layers of simultaneous shot situation are set to 2.0G/cm.In the case of image is not clear enough, testing process can be obtained according to Fig. 7 The optimal pulse width of required radio-frequency pulse simultaneously adjusts the data point interval time of wave file until pulse width is optimal Value, while gradient amplitude thickness needed for obtaining in regulatory sequence parameter list.In synchronous acquisition 2n+1 layers of k-space data, RF pulses defined in formula (5) can meet uniform exciting and the requirement of adjacent aspect no overlap artifact.In clinical navigation application Being accurately positioned for imaging region is realized according to the flow of navigation shown in Fig. 9.Based on five layers or more layer simultaneous shot radio-frequency pulse Imaging sequence can significantly improve signal to noise ratio by repeatedly cumulative under the conditions of middle low field, and the increase of sweep time is relative to non- Simultaneous shot situation is substantially less.

Embodiment 5：Quick local five layers of any position synchronous scanning：

Multi-layer synchronous exciting method described in embodiment 4 can also be used for the aspect imaging of optional position, i.e.,

Specific positioning method is, by the user interface shown in Figure 11 in positioning as the corresponding position line of upper settingAnd transmit the SLR waveshapes of navigation module of each layer direction parameter shown in Figure 10 Program, exports the SLR impulse waveforms of renewal and is loaded into the imaging control unit of the navigation shown in Fig. 1, then runs scanning sequence And carry out real time image reconstruction.When scanning sequence is spin-echo type, reunion pulse is from the linear phase shown in Figure 26 SLR pulses, its characteristic parameter is：When band product TBP be 16, pulse bandwidth is 4kHz, with interior ripple factor be 0.1%, with outer line Wave system number is 0.1%, and pulse flip angle is π, and slice selective gradient intensity can be adjusted according to required thickness, and 2.0G/cm is set to here.

The local single-shot T2 weighted scannings of embodiment 6

Based on above-mentioned MRI navigation system and flow of navigation, quick navigation sequence is from the Local-HASTE- shown in Figure 27 NV sequences, first 90 ° of radio frequency excitation pulse of the sequence and 180 ° of reunion pulses in Figure 14 and Figure 15 respectively from exciting wheel The SLR pulses of wide height optimization.The waveform feature parameter of the minimum phase SLR excitation pulses shown in Figure 14 is, when band product TBP be 8, it is 0.5% with interior ripple factor, it is 0.1% with outer ripple factor, pulse flip angle is pi/2, and slice selective gradient intensity is 0.7G/ cm；The waveform feature parameter of the minimum phase SLR reunion pulses shown in Figure 15 is, when band product TBP be 16, be with interior ripple factor 0.5%, it is 0.1% with outer ripple factor, pulse flip angle is π, and slice selective gradient intensity is 0.5G/cm.It is not enough in radio-frequency power In the case of, the SLR pulses shown in second and the optional Figure 26 of follow-up 180 ° of reunion pulses, and it is pseudo- in magnetic susceptibility artifact or metal Under shadow more serious conditions can the testing process according to Fig. 7 obtain optimal SLR pulse widths and adjust the data of wave file Point interval time is optimal until image definition, while gradient amplitude thickness needed for obtaining in regulatory sequence parameter list. In Figure 27, the time interval between 90 ° of radio frequency excitation pulses and first 180 ° of reunion pulse is TE/2, follow-up 180 ° of reunion arteries and veins Time interval between punching is TE, and, generally in 80ms to 140ms scope values, signal acquisition is from after the 3rd SLR pulse for TE Start, part repeats N in dotted line frame_PE/ 4 times, N_PECan use compared with small integer, such as 32 or 64.G_s1、G_s2、G_s3、G_s4、G_s5…G_sn Slice selective gradient is represented, gradient amplitude is determined that gradient pulse length is all higher than radio frequency pulse length, wherein G by thickness_s1、G_S2And G_S3 The orientation of gradient can be in positioning as being above set to orthogonal direction, the orientation and G of other slice selective gradients_s3It is identical.G_preRepresent that preparation is read Gradient, G_r1、G_r2、G_r3…G_rnRepresent and G_preOpposite polarity and integral area are the reading gradient of its twice, G_sc1、G_sc2、G_sc3… G_scnRepresent to be applied to as option and select layer direction and G_S3Amplitude is identical and and G_r1Width identical compensates gradient.±G_P1、± G_P2、±G_p3…±G_pnRepresent positive-negative polarity and amplitude is incremented by successively or the phase encoding gradient that successively decreases, the corresponding phase of effective echo Position coding gradient is set to zero, and remaining echo sets corresponding phase encoding gradient amplitude and pole by following k-space filling modes Property.Odd number echo before effective echo is sequentially filled the top half of k-space central area, and it is empty that even number echo is sequentially filled k Between central area the latter half, the top and the bottom that the odd even echo behind effective echo fills k-space central area respectively are straight To the latter half (accounting for the 1/10 of whole k-space) of central area is filled up, then remaining odd even echo is from inside to outside gradually The blank parts of filling upper half k-space (or lower half k-space), carry out real-time partial Fourier's reconstruction after the end of scan.Due to this In N_PESmaller several times than echo train length in the HASTE sequences of routine diagnosis, the influence of noise and clutter can obviously reduce, so that Ensure that navigation picture has compared with high s/n ratio and resolution ratio.

Finally it should be noted that：Various embodiments above is merely illustrative of the technical solution of the present invention, rather than its limitations；To the greatest extent Pipe has been described in detail with reference to foregoing embodiments to the present invention, it will be understood by those within the art that：Its is right Technical scheme described in foregoing embodiments is modified, or which part or all technical characteristic are equally replaced Change, do not make the scope of the essence disengaging various embodiments of the present invention technical scheme of appropriate technical solution.

Claims

1. a kind of for minimally invasive operation navigating system, including：Yoke (1), magnet steel (2), pole plate (3), shielded coil (4), gradient Coil (5), radio-frequency coil (6), scanning bed (7), heating rod (8), heating plate (9), temperature sensor (10), shell (11), T/R Sending and receiving switch (12), gradient power amplifier (13), RF power amplification (14), preamplifier (15), temperature conditioning unit (16), optical tracking are fixed Position system (17), coil tuning control unit (18), scanning bed control unit (19), navigation imaging control unit (20), system Control interface (21), main frame (22), display (23), it is characterised in that magnet (60) is open U-shape structure, magnet gap More than 500mm, pole plate (3) radius is 350mm to 400mm；Pole plate (3) radius is 380mm；Magnet (60) field intensity is in 0.2T To between 0.7T；The radio-frequency coil (6) of magnet (60) is biplane circular polarisation structure, in outer conductor loop (50) and inner wire ring (52) set some without magnetocapacitance (51) between；Radio-frequency receiving-transmitting coil (6) switchs the conversion realized transmitting and receive by T/R； Described is more than 100 without magnetocapacitance (51) quantity；X, Y and Z axis plane gradient coil respectively have two groups, and one group is placed in a magnetic pole Side, another group is placed in another magnetic pole inner side, coil plane each parallel to pole plate (3) surface, and by eddy plate and pole plate (3) separate；Wherein, Z axis gradient coil is constituted by main gradient coil (101) and axial shield coil (102), is belonged to MAXWELL coils, coiling is concentric circles pattern, the circle of main gradient coil (101) 13, the circle of axial shield coil (102) 14, two groups of ladders Degree coil is connected to gradient power amplifier (13) by 6 gradient cables (104) through gradient power wave filter；Main gradient coil (101) It is made using printed-board technology with axial shield coil (102)；Axial shield coil (102) is placed in main gradient coil (101) gradient current of outside and close pole plate (3), axial shield coil (102) and main gradient coil (101) is in opposite direction, Magnetic field gradient is limited in axial shield coil (102) circumference, makes what current impulse and magnetostatic field interactions in coil were produced Thrust is cancelled；Insulating barrier (103) is set between main gradient coil (101), axial shield coil (102)；Main gradient coil (101), axial shield coil (102) and insulating barrier (103) radius are preferably 350mm, and each coil thickness is 4mm to 5mm, main Gradient coil (101) and axial shield coil (102) spacing are 2mm to 3mm.

2. a kind of Minimally Invasive Surgery air navigation aid, it is characterised in that using claim 1 for minimally invasive operation navigating system, tool Body method is as follows：

Step 100：Magnetic susceptibility artifact or metal artifacts without magnetic medicine equipment are carried out according to operating process in advance to detect and excellent Change navigation sequence parameter, and gather three-dimensional high definition t1 weighted image on navigation imager or High-Field imager before surgery, If necessary plus sweep enhancing scanning, angiogram or functional imaging etc., then carry out operation route planning, including target spot set, inserting needle Path planning and operation plan are worked out；

Step 200：Then navigating scanned position in imaging system by calibration scan bed elevation of water and by laser The straight line laser of position indicator is guided and is placed in isocenter point region, and shimming is carried out from Dynamic Local shimming technique, by three choosings The three-dimensional space selectivity radio-frequency pulse that layer gradient and three sinc waveform pulses are constituted excite proton in a small size or Other magnetic atom cores, then gather free induction decay signal FID, and the sequence reruns, while constantly by linear ladder Degree or shimming gradient adjust magnetic field homogeneity until spectrum integration area is maximum, so as to the uniformity of magnetic field for realizing imaging area is optimal Change；

Step 300：Then flow of navigation sets up internal reference coordinate system and controls local by navigation module and with navigation interface Quick navigation sequence operation, three tomography signals of orthogonal direction are gathered according to operation route repeatedly, and each direction can gather Individual layer can also synchronous acquisition multilayer, or use real-time route tracing mode, first pass through navigation software scanning and obtain the big visual field Positioning picture, in positioning as upper first positioning scanning aspect center is in surgical portal position, and plans several groups towards target position Scanning aspect, every group of aspect can be arranged on different azimuth to avoid nerve or blood vessel, and aspect is set between aspect The half of thickness；Positional parameter and waveform parameter are constantly updated in procedure and real time scan is so as to continuous track and localization hand Art instrument positions；

The quick navigation sequence design essential characteristic of described local is that radio-frequency pulse has a three-dimensional space selectivity, correspondence the The slice selective gradient of one radio frequency excitation pulse, first radio frequency reunion pulse and second radio frequency reunion pulse is arranged on not Tongfang Position, and using the SLR impulse waveforms for exciting profile elevations h to optimize, may be selected and meanwhile it is uniform excite it is multiple close to frequency band, each frequency The scope and spacing of band can carry out accurate adjustment as in positioning by thickness and interlamellar spacing, and pulse excitation profile amplitude can basis The integral area correction of each frequency band is consistent, repeatedly gathers a part of k-space line and goes forward side by side horizontal pulse phase loop, and data May be selected to apply frequency encoding gradient and slice selective gradient simultaneously during collection, receiver bandwidth is set to 100kHz or higher, so After carry out that k-space data is cumulative and part Fourier image reconstruction；It is this navigation imaging method can not only improve uniformity degree of image, Resolution ratio and signal to noise ratio, may also suppress magnetic susceptibility artifact and metal artifacts, and shorten sweep time；

Step 400：After guided therapy terminates, local high resolution scanning and increasing are carried out on navigation imager or High-Field imager It is strong to scan to confirm curative effect；Compared with scanning of being navigated in art, the acquisition matrix of frequency coding and phase-encoding direction increases here One times further to improve image resolution ratio.

3. Minimally Invasive Surgery air navigation aid according to claim 2, it is characterised in that the flow of navigation includes Dynamic Local The step of shimming：It is placed in by scanned position by calibration scan bed level and by the straight line laser guide of laser orientation instru-ment Isocenter point region, shimming is carried out from Dynamic Local shimming technique, and shimming sequence is penetrated with three slice selective gradients and sinc or SLR Proton or other magnetic atom cores in one small size of frequency pulse excitation, then gather free induction decay signal, repeat to transport The row sequence, while magnetic field homogeneity is adjusted until spectrum integration area is maximum by linear gradient or shimming gradient, so that real The uniformity of magnetic field of existing imaging area is optimized.

4. Minimally Invasive Surgery air navigation aid according to claim 2, it is characterised in that track and localization surgical instrument position passes through Metal artifacts are tested and calibration steps is realized：It is primarily based on standard water mould and gradin-echo the test magnetic of copper sulfate solution Field pattern, then adds bar shaped or intersecting parallels without magnetic metal material and passes through gtadient echo sequence in the central area of standard water mould Row test Distribution of Magnetic Field figure, calculates the difference of the two Distribution of Magnetic Field figures, from difference minimum without magnetic metal material or composite wood Material makes operating theater instruments, dead space size is finally measured on gradient echo image and is carried out with bonding jumper actual size consistent Property checking, in this, as the precise marking of operating theater instruments self-position.

5. Minimally Invasive Surgery air navigation aid according to claim 2, it is characterised in that using multi-faceted slice selective gradient and excite The radio-frequency pulse of profile elevations h optimization excites proton signal in a small size, here first 90 ° of radio frequency excitation pulse and First 180 ° of reunion pulse sets first radio-frequency pulse using the SLR impulse waveforms for uniformly exciting in navigation sequence Corresponding slice selective gradient amplitude is G_s1=2 π Δs f/ γ/FOV_x, setting the corresponding slice selective gradient amplitude of second radio-frequency pulse is G_s2=2 π Δs f γ/FOV_y, the corresponding slice selective gradient amplitude of the 3rd radio-frequency pulse of setting is G_s3=2 π Δs f γ/THK, wherein FOV_x、FOV_yCan directly be adjusted on sequential parameter table with THK.

6. Minimally Invasive Surgery air navigation aid according to claim 2, it is characterised in that radio-frequency pulse is preferably SLR pulses, its Waveform feature parameter sets as follows：When band product TBP be 4 or 8, with outer ripple factor and with interior ripple factor no more than 0.5%, Excitation pulse flip angle is pi/2, and slice selective gradient intensity thickness according to needed for is set, for example, be here 0.7G/cm；Or when band product TBP is 16, and with outer ripple factor and with interior ripple factor no more than 0.5%, reunion pulse flip angle is π, and slice selective gradient is strong It is 0.5G/cm to spend；And profile is excited based on the optimization of synchronous scanning calibrating sequence in the case of synchronous multilayer is excited, the spy of the sequence It is that radio-frequency pulse selects simultaneous shot impulse waveform to levy, and slice selective gradient and frequency encoding gradient are arranged on same orientation, in echo Time gathers k-space data, then calibration excites profile and magnitude image in the following manner：

A. signal and Fu are gathered with the synchronous scanning calibrating sequence shown in Figure 22 and from the SLR impulse waveforms of each phase code Vertical leaf transformation obtains exciting profile to frequency domain, is expressed as C₁、C₂And C₃；

B. C is calculated₁、C₂And C₃Integral area, k is expressed as here₁=∫ ∫ C₁dxdy、k₂=∫ ∫ C₂Dxdy and k₃=∫ ∫ C₃Dxdy, here ∫ ∫ represent two-dimensional integration, x and y represent two-dimensional coordinate；

C. alignment profiles figure is C₁、With

D. same, the two dimensional image obtained to three scanning is in above-mentioned integral area ratio k₁、k₂And k₃Calibrated and by formula (4) each tomographic image decomposition is carried out；

Although aforesaid way may be directly applied to three layers of simultaneous shot situation, it is clear that other can be generalized to by similar fashion many The calibration of layer simultaneous shot image.

7. Minimally Invasive Surgery air navigation aid according to claim 6, it is characterised in that received under metal artifacts disturbed condition Machine bandwidth is preferably more than 100kHz, and the bandwidth deltaf f of radio-frequency pulse needs optimization in advance, operating process can be set according to Fig. 7 Δ f is put for different value, Δ f when magnetic susceptibility artifact or minimum metal artifacts is therefrom searched, applied simultaneously during data acquisition Plus frequency encoding gradient and slice selective gradient, then close to single echo acquirement time span, otherwise Δ f is preferably Δ f optimal values 2kHz or much higher value.

8. Minimally Invasive Surgery air navigation aid according to claim 2, it is characterised in that select navigation sequence Local-SE-NV, The navigation imaging sequence realizes that local swashs on the basis of spin-echo sequence using the slice selective gradient and SLR pulses in three orientation Hair, or navigation sequence Local-ME-NV is selected, the navigation imaging sequence is swashed using the slice selective gradient in three orientation and SLR pulses Magnetic resonance signal in hair low coverage, then gathers multiple gradients during the alternate frequency encoding gradient of positive-negative polarity applies and returns Ripple, by minimize echo time and preferred phase code step number be 32 or 64 or other can quickly realize that T1 is weighted compared with small integer Imaging.Here, slice selective gradient G_s1、G_S2And G_S3Orientation in positioning as being above set to orthogonal direction, G_s1, G_s2And G_s3Represent different The slice selective gradient in orientation, wherein the first two perpendicular or parallel to operation route, another parallel or perpendicular to operation route, other The orientation and amplitude and G of slice selective gradient_s3Identical, signal acquisition since after the 3rd radio-frequency pulse, fill and image by k-space Rebuild and use partial Fourier mode；The essential characteristic of local imaging sequence Local-ME-NV is, when paying the utmost attention to sweep speed When, apply a G gradient positive-negative polarity switching instant is read_blipGradient, such part of data acquisition is equivalent to echo wave plane Collection, the number of echoes in dotted line frame may be configured as 32 or other less integers, and the data of collection are normal according to echo-planar imaging With phasing and image reconstruction mode processed.

9. Minimally Invasive Surgery air navigation aid according to claim 2, it is characterised in that from navigation sequence Local-HASTE- NV, the navigation imaging sequence on the basis of Single shot fast spin echo sequence using three orientation slice selective gradients and Local excition is realized in SLR pulses, and quickly realizes T2 weighted imagings using half-fourier acquisition mode；Here, the echo time set Put in 80ms to 140ms scopes, slice selective gradient G_s1、G_S2And G_S3Orientation in positioning as being above set to orthogonal direction, wherein preceding two Individual vertical (or parallel), in operation route, another is parallel or perpendicular to operation route, the orientation and G of other slice selective gradients_s3Phase Together；Also, selecting layer direction additionally to apply to compensate gradient G here_sc1、G_sc2、G_sc3…G_scn, its gradient amplitude is and G_S3It is identical, Its gradient width is and G_r1It is identical；First impulse waveform characteristic parameter：Minimum phase SLR, when band product TBP be 8, with interior ripple Coefficient is 0.5%, is 0.1% with outer ripple factor, and pulse flip angle is pi/2, and slice selective gradient intensity is 0.7G/cm；Second Impulse waveform characteristic parameter：Minimum phase SLR, when band product TBP be 16, with interior ripple factor be 0.5%, be with outer ripple factor 0.1%, pulse flip angle is π, and slice selective gradient intensity is 0.5G/cm；3rd pulse and succeeding impulse waveform feature parameter：Most Small phase SLR, when band product TBP be 16, be 0.5% with interior ripple factor, be 0.1% with outer ripple factor, pulse flip angle is π, slice selective gradient intensity is for 0.5G/cm or uses impulse waveform, its characteristic parameter：Linear phase SLR, when band product TBP be 16, band Interior to be 0.1% with outer ripple factor, pulse flip angle is π, and slice selective gradient intensity is 0.5G/cm；

Since after the 3rd radio-frequency pulse, k-space filling and image reconstruction use partial Fourier mode to signal acquisition.

10. Minimally Invasive Surgery air navigation aid according to claim 2, it is characterised in that radio-frequency pulse has spatial selectivity, Can uniformly excite simultaneously it is multiple close to frequency band, the radio-frequency pulse shape of the Multi-layer synchronous imaging of optional position meets following formula：

SLR (t) represents linear phase SLR pulses in above formula, and γ represents gyromagnetic ratio,WithPulse is represented respectively Encoding phase, G_sRepresent slice selective gradient, r_i(i=0-n) one group of space vector of simultaneous shot aspect at equal intervals is represented；By with Family interface is in positioning as the corresponding position line of upper setting And transmit each layer direction parameter and arrive The impulse waveform calculation procedure of navigation module, exports the impulse waveform of renewal and is loaded into navigation imaging control unit, Ran Houyun Row navigation sequence Local-MSME-NV, the sequence realizes that local is equal using the impulse waveform that three slice selective gradients and above formula are defined It is even to excite, many echo-signals are gathered under the alternate frequency encoding gradient effect of positive-negative polarity, then carry out real time image reconstruction； For three layers of simultaneous shot situation, radio frequency excitation pulse waveform is calculated as follows and obtains：

In above formula r₀Represent the space vector of simultaneous shot aspect, Δ S represents the spacing of simultaneous shot aspect, by adjusting above formula in waveform parameter can be excellent Change excite profile three close to frequency band range realize that the magnetic resonance signal of three aspects is uniformly excited, for example, here, SLR arteries and veins The bandwidth of punching is set to 1kHz, when band product TBP be set to 4, band and out-of-band ripple factor is no more than 0.5%, during three scanningWithIt is respectively set to With Reunion pulse is preferably 180 ° of minimum phase SLR under spin echo acquisition pattern Pulse or linear phase SLR pulses, the bandwidth requirement of SLR pulses are not less than (3THK+2 Δ S) γ G_s/ (2 π), its Middle THK represents the thickness of the aspect corresponding to each frequency band, and the long-pending TBP of when band of SLR pulses is set to 8 or 16, band and out-of-band Ripple factor is no more than 0.5%, G_sSet according to required THK, but no more than greatest gradient amplitude；Each scanning collection one Divide k-space line, three scanning obtains image S₁, image S₂With image S₃, picture breakdown is finally carried out as the following formula obtains each layer figure Picture：

S_{1}^{'} = | \frac{(S_{2} + S_{3})}{2} |, S_{2}^{'} = | \frac{(S_{1} + S_{3})}{2} |, S_{3}^{'} = | \frac{(S_{1} + S_{2})}{2} | - - - (4);

S in formula (4)₁',S'₂And S₃' represent simultaneous shot three aspects corresponding to image；

When sweep speed is paid the utmost attention to, a G is applied gradient positive-negative polarity switching instant is read_blipGradient, such data acquisition Part is equivalent to echo wave plane collection, and the number of echoes in dotted line frame may be configured as 32 or other less integers, the number of collection The phasing and image reconstruction mode commonly used according to echo-planar imaging according to elder generation are processed, and right back-pushed-type (4) carries out image Decomposition obtains each tomographic image.