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WO2016127295A1 - 一种磁共振系统中获得感兴趣区域位置信息的方法及装置 - Google Patents

一种磁共振系统中获得感兴趣区域位置信息的方法及装置 Download PDF

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Publication number
WO2016127295A1
WO2016127295A1 PCT/CN2015/072567 CN2015072567W WO2016127295A1 WO 2016127295 A1 WO2016127295 A1 WO 2016127295A1 CN 2015072567 W CN2015072567 W CN 2015072567W WO 2016127295 A1 WO2016127295 A1 WO 2016127295A1
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region
interest
excitation
magnetic resonance
roi
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PCT/CN2015/072567
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English (en)
French (fr)
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陈瑞松
牟晓勇
叶迪
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北京汇影互联科技有限公司
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Priority to PCT/CN2015/072567 priority Critical patent/WO2016127295A1/zh
Publication of WO2016127295A1 publication Critical patent/WO2016127295A1/zh

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves 
    • A61B5/055—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging

Definitions

  • the present invention relates to the field of magnetic resonance technology, and in particular to a method and apparatus for obtaining location information of a region of interest in a magnetic resonance system.
  • the magnetic resonance system uses magnetic resonance principles to obtain tomographic images of the human body through radio frequency pulse excitation, gradient layer selection, and magnetic resonance signal acquisition and reconstruction.
  • MRI magnetic resonance system
  • Gray-scale tomographic images of objects obtained after magnetic resonance system scanning different in objects Due to the different magnetic resonance properties, the tissue appears as a distinct area in the MR image.
  • the tissue containing water will have a certain signal (brighter) in the MR image, while the solid tends to be weak (dark).
  • the tip of an interventional instrument in interventional surgery applications, we focus on the actual position of the tip of the interventional instrument, then the tip is the ROI in the application, where the interventional instrument is usually a hollow needle, guided by an optical/electromagnetic tracking device , gradually penetrate the body until it is accurately penetrated into the predetermined lesion area. Then, probes of various treatment devices are placed in the needle to perform interventional treatment on the lesion area.
  • ROI Region of Interest
  • the tracking device and the ROI are connected by a rigid connecting material.
  • the connecting material may be curved. When the rigidity of the material is destroyed, it means that the geometric relationship between the device and the ROI changes, and the ROI coordinate information calculated by the tracking coordinates deviates from the actual coordinate of the ROI.
  • the magnetic resonance scan obtains the MR image, and the position of the ROI is manually or automatically recognized in the MR image. Due to the limitation of magnetic resonance imaging characteristics, in order to obtain an MR image, it is necessary to perform periodic tens or even thousands of signal acquisitions with different parameters, and then reconstruct a large number of signals (generally two-dimensional or three-dimensional Fourier transform). After getting the image. The entire scan time is long, about tens of seconds to a few minutes, limiting the scope of application of this method. For subsequent identification, manual identification can cause the entire application process to not run automatically. The automatic recognition of ROI has great difficulties in complex images.
  • Embodiments of the present invention provide a method for obtaining location information of a region of interest in a magnetic resonance system, and determining a shape and a projection direction of at least one excitation region according to a region of interest (ROI).
  • the excitation region is excited by selecting a corresponding radio frequency pulse and scanning imaging parameters based on the shape of the excitation region and the imaging characteristics of the ROI.
  • a signal is acquired in a readout direction perpendicular to the projection direction. Identifying the acquired signal results in actual coordinates of the region of interest (ROI).
  • An embodiment of the present invention further provides a device for obtaining a region of interest location information in a magnetic resonance system, comprising an excitation region determining unit configured to determine a shape and a projection direction of at least one excitation region according to a region of interest (ROI). And an excitation unit, configured to excite the excitation region by using a corresponding radio frequency pulse and scanning imaging parameters according to the shape of the excitation region and the ROI imaging characteristic.
  • a reading unit for acquiring signals in a readout direction perpendicular to the projection direction.
  • An identification unit configured to identify the actual coordinate of the region of interest (ROI) obtained by the acquisition signal.
  • the above technical solution of the embodiment of the invention has the advantages that the magnetic resonance device and the magnetic resonance signal itself are directly used to measure the actual coordinates of each point on the device in real time, which is more direct and more accurate, and reduces the risk of surgery; the operation is simple, and no additional operation is required.
  • the tracking device basically relies on the magnetic resonance device itself to complete the instrument tracking.
  • FIG. 1 is a flow chart showing a method for obtaining location information of a region of interest in a magnetic resonance system according to an embodiment of the present invention
  • FIG. 2 is a schematic structural diagram of a device for obtaining location information of a region of interest in a magnetic resonance system according to an embodiment of the present invention
  • FIG. 3 is a detailed flowchart of a method for obtaining location information of a region of interest in a magnetic resonance system according to an embodiment of the present invention
  • 4A is a schematic view showing a stripe region excited by 2D RF according to an embodiment of the present invention.
  • FIG. 4B is a schematic diagram of the corresponding signal strength of FIG. 4A according to an embodiment of the present invention.
  • FIG. 5 is a detailed flowchart of a method for obtaining position information of a point region in a magnetic resonance system according to an embodiment of the present invention
  • FIG. 6A is a schematic view showing a projection direction and a readout direction when a strip-shaped region is excited by a strip-shaped ROI according to an embodiment of the present invention
  • 6B is a schematic view showing a projection direction and a readout direction when a strip-shaped region is excited by a dot-shaped ROI according to an embodiment of the present invention
  • Figure 7 is a schematic illustration of projection along a needle in accordance with an embodiment of the present invention.
  • the magnetic resonance system performs RF excitation, gradient layer selection, phase modulation according to a certain timing, and finally collects data. This whole process becomes the acquisition cycle.
  • TR repetition time
  • a TR is implemented according to the timing, and the time is between 1ms and 10s.
  • the acquisition of MR images often requires dozens or even thousands of TRs to complete.
  • Interventional instruments usually hollow needles, guided by optical/electromagnetic tracking devices, gradually penetrate the body until they are accurately penetrated into the predetermined lesion area. Then, probes of various treatment devices are placed in the needle to perform interventional treatment on the lesion area.
  • Magnetic resonance imaging pulse sequence setting of parameters such as radio frequency pulse, gradient field and signal acquisition time and their arrangement in time series.
  • Excitation region The region within the object excited by the magnetic resonance imaging sequence.
  • Commonly used imaging sequences generally use one-dimensional RF pulses (1D RF) that excite the slice regions in a standard object.
  • Multidimensional RF Pulses Commonly used 1D RF pulses (1D RF) are a layer of excitation within an object. Multidimensional RF pulses (Bottomley and Hardy 1987; Hardy and Cline 1989) can narrow the excitation range to a specific shape. Two-dimensional pulses (2D RF) excite only strip or cylindrical regions, and three-dimensional pulses (3D RF) only excite a point or globular region. In addition to the standard multi-dimensional RF pulses, there are some special pulses equivalent to multi-dimensional pulses, such as the orthogonal surface intersection excitation pulses equivalent to 2D RF (Feinberg et al. 1985). These similar special pulses are treated equivalently to equivalent multidimensional pulses in the present invention.
  • FIG. 1 is a flow chart showing a method for obtaining location information of a region of interest in a magnetic resonance system according to an embodiment of the present invention.
  • the shape and projection direction of at least one excitation region are determined according to a region of interest (ROI).
  • ROI region of interest
  • Step 102 Select a corresponding radio frequency pulse and scan imaging parameters to excite the excitation region according to the shape of the excitation region and the imaging characteristic of the ROI.
  • the scan imaging parameters include a layer thickness of an excitation region, an echo time, an imaging parameter of the T1 image, and an imaging parameter of the T2 image, and the scanning imaging parameter should maximize a difference in magnetic resonance signals between the ROI region and the ROI surrounding region.
  • Step 103 acquiring a signal in a readout direction perpendicular to the projection direction.
  • Step 104 Identify the acquired signal to obtain actual coordinates of the region of interest (ROI).
  • determining the shape and the projection direction of the at least one excitation region according to the region of interest (ROI) further includes: calculating, in a certain direction, the cumulative change of the magnetic resonance signal intensity in the excitation region including the ROI The direction is the projection direction.
  • the shape of the excitation region includes a layered region, a strip region, and a dot region.
  • exciting the excitation region by using a corresponding radio frequency pulse according to the shape of the excitation region further includes exciting the excitation by using a one-dimensional radio frequency pulse when the shape of the excitation region is a layered region. a region; when the shape of the excitation region is a strip region, the excitation region is excited by a two-dimensional radio frequency pulse or an equivalent pulse; when the shape of the excitation region is a dot region, a three-dimensional radio frequency pulse or equivalent is used.
  • the excitation region is pulsed.
  • acquiring the signal in the readout direction perpendicular to the projection direction further includes adjusting the phase (usually the phase is zero) such that when the acquired echo signal is strongest, perpendicular to the projection direction The signal is read in the read direction.
  • the projection direction is the long-axis direction of the strip-shaped ROI in the region, and the readout direction is perpendicular to the projection direction;
  • the projection direction is the short-axis direction of the strip-shaped excitation region, and the readout direction is long perpendicular to the short-axis direction.
  • a signal is collected multiple times for the shape of the excitation region and the imaging characteristic of the ROI, and weights are assigned to the multiple acquired signals, and the multiple acquisition signals of the attached weight are integrated to obtain a comprehensive acquisition. signal.
  • determining the shape and the projection direction of the at least one excitation region according to the region of interest further includes determining a shape and a projection direction of the plurality of excitation regions according to the degree of freedom of the region of interest.
  • the plurality of excitation regions are not parallel (eg, may be intersecting) in the region of interest.
  • the plurality of excitation regions are perpendicular to the region of interest.
  • the method further includes comparing the actual coordinates with ideal coordinates, when the actual coordinates and the ideal coordinates If the difference exceeds the predetermined threshold, a deviation alarm is issued.
  • the actual coordinates of the plurality of regions of interest are collected along the interventional instrument, and the plurality of actual coordinates are converted into the actual shape of the interventional instrument to determine whether the interventional instrument is deformed.
  • the magnetic resonance signal itself is directly used to measure the actual coordinates of each point on the instrument in real time, which is more direct and more accurate, and reduces the risk of surgery; the operation is simple, no additional tracking equipment is needed, and basically relies on magnetic resonance
  • the device itself completes the instrument tracking.
  • FIG. 2 is a schematic structural diagram of a device for obtaining location information of a region of interest in a magnetic resonance system according to an embodiment of the present invention.
  • the excitation region determining unit 201 is configured to determine a shape and a projection direction of the at least one excitation region according to the region of interest (ROI).
  • ROI region of interest
  • the excitation unit 202 is configured to excite the excitation region by using a corresponding radio frequency pulse and scanning imaging parameters according to the shape of the excitation region and the ROI imaging characteristic.
  • the scan imaging parameters include a layer thickness of an excitation region, an echo time, an imaging parameter of the T1 image, and an imaging parameter of the T2 image, and the scanning imaging parameter should maximize a difference in magnetic resonance signals between the ROI region and the ROI surrounding region.
  • the reading unit 203 is configured to collect signals in a readout direction perpendicular to the projection direction.
  • the identifying unit 204 is configured to identify the actual coordinates of the region of interest (ROI) obtained by the acquired signal.
  • ROI region of interest
  • the excitation region determining unit 201 further accumulates, in a certain direction, a direction in which the change in the intensity of the magnetic resonance signal is most apparent as the projection direction in the excitation region including the region of interest.
  • the shape of the excitation region includes a layered region, a strip region, and a dot region.
  • the excitation unit 202 further excites the excitation region by using a one-dimensional radio frequency pulse when the shape of the excitation region is a layered region; when the shape of the excitation region is a strip region The excitation region is excited by a two-dimensional radio frequency pulse or an equivalent pulse; when the shape of the excitation region is a point region, the excitation region is excited by a three-dimensional radio frequency pulse or an equivalent pulse.
  • the reading unit 203 acquires a signal in a readout direction perpendicular to the projection direction by adjusting the phase (usually the phase is zero) such that the acquired echo signal is strongest.
  • the excitation region determining unit 201 is further configured to: when the layered excitation region containing the strip-shaped ROI is excited by using a one-dimensional radio frequency pulse, the projection direction is a long-axis direction of the strip-shaped ROI in the region.
  • the readout direction of the reading unit 203 is perpendicular to the projection direction; when the point R is excited using a two-dimensional radio frequency pulse or other equivalent sequence In the strip-shaped excitation region of the OI, the projection direction is the short-axis direction of the strip-shaped excitation region, and the readout direction of the reading unit 203 is the long-axis direction perpendicular to the short-axis direction; when using a three-dimensional radio frequency pulse or the like
  • the projection direction may be any direction, and the readout direction of the reading unit 203 is perpendicular to the selected projection direction.
  • the reading unit 203 is further configured to acquire a signal multiple times for the shape of the excitation region and the imaging characteristic of the ROI, and perform weight assignment on the multiple acquired signals to integrate the weighted The signal is acquired multiple times to obtain a comprehensive acquisition signal.
  • the excitation region determining unit 201 is further configured to determine a shape and a projection direction of the plurality of excitation regions according to the degree of freedom of the region of interest.
  • the plurality of excitation regions are not parallel to the region of interest, such as intersecting.
  • the plurality of excitation regions are perpendicular to the region of interest.
  • a comparison unit 205 is further included for comparing the actual coordinates with the ideal coordinates, and when the difference between the actual coordinates and the ideal coordinates exceeds a predetermined threshold, a deviation alarm is performed.
  • the conversion unit 206 is further configured to collect the actual coordinates of the plurality of regions of interest along the interventional instrument, convert the plurality of actual coordinates into the actual shape of the interventional instrument, and determine whether the interventional instrument occurs. Deformation.
  • the actual measurement of the actual coordinates of each point on the instrument is directly utilized by the signal itself, which is more direct and more accurate, and reduces the risk of surgery; the operation is simple, no additional tracking equipment is needed, and basically relies on the magnetic resonance device itself. Complete instrument tracking.
  • FIG. 3 is a detailed flowchart of a method for obtaining location information of a region of interest in a magnetic resonance system according to an embodiment of the present invention.
  • the shape, projection direction and scanning imaging parameters of the excitation region are determined according to the imaging characteristics and shape characteristics of the ROI. For example, when considering the imaging characteristics of the ROI, it is necessary to consider the number of hydrogen atoms, the longitudinal and transverse relaxation time factors of the ROI, so that it is possible to determine the use of the corresponding scanning imaging parameters to maximize the difference in magnetic resonance signals between the ROI and the area around the ROI.
  • the determining the scan imaging parameter may be completed in step 301 or may be completed in step 302.
  • the embodiment of the present invention does not limit the specific step in which the process is performed.
  • Step 302 Select a corresponding radio frequency pulse according to the shape of the excitation region.
  • the layered region selects one-dimensional (1D) RF
  • the strip region selects two-dimensional (2D) RF or equivalent RF
  • the dotted region selects three-dimensional (3D) RF or equivalent RF.
  • step 303 the selected region is excited with the selected radio frequency pulse.
  • 2D RF is used to excite strips, such as In the region A shown in FIG. 4A, the short-axis direction of the region A in FIG. 4A is the projection direction, and the long-axis direction is the readout direction, and FIG. 4B is a schematic diagram of the corresponding signal strength of FIG. 4A.
  • step 304 the phase is adjusted (usually the phase is zero), so that when the collected echo signal is the strongest, the vertical projection direction is the readout direction, and the signal acquisition is performed, and the required time is 1 TR (pulse sequence repetition time).
  • step 305 the acquired signal is processed (usually a Fourier transform) to obtain a projection line.
  • Step 306 according to the imaging characteristics of the ROI, for example, in the magnetic resonance T1 image, the ROI of the interventional needle appears as a weak signal (dark), and the human tissue around the needle appears as a strong signal (brighter), which can be projected
  • the projection coordinates corresponding to the ROI can be identified.
  • step 307 it is determined whether the degrees of freedom of the projected coordinates of the ROI have been identified.
  • strip ROI in the slice such as the diaphragm on the sagittal plane, it is sufficient to determine this degree of freedom in the up and down direction.
  • interventional device ROI needle tip 401
  • Step 308 according to the degree of freedom of the ROI deficiency, select another independent area that intersects the region of interest in the last excitation region, and step 303 is performed.
  • step 309 all the projection coordinates of the ROI obtained in the above step and the spatial coordinates of the scan area are integrated, and the actual coordinates of the ROI can be solved.
  • n is generally less than or equal to 3
  • n TR times ranging from 1ms to 10s
  • FIG. 5 is a detailed flowchart of a method for obtaining position information of a point region in a magnetic resonance system according to an embodiment of the present invention.
  • the shape of the ROI region is point-like, and its imaging feature is that its signal is much weaker than the surrounding area.
  • a strip-shaped area A (as shown in Fig. 4A) is selected, and the area A width and thickness are similar to the ROI. This strip area A should contain the ROI, and the projection direction is perpendicular to the long axis direction of the area A.
  • a two-dimensional RF pulse or equivalent pulse and appropriate imaging parameters are selected (to make the difference in magnetic resonance signals between the ROI and surrounding tissue as large as possible).
  • step 503 the excitation region A is excited by a 2D RF pulse.
  • the reading direction is the long axis direction of the excitation region A, which is collected only once in this example.
  • Step 505 performing Fourier transform on the obtained signal to obtain a projection line.
  • Step 506 since the imaging feature of the ROI is that the signal is significantly lower than the surrounding area, the projection line we obtain will have a distinct "bright-dark-light" feature (as shown in Figure 4B), wherein the dark line segment is in the middle.
  • the point is the projection coordinate a of the center of the ROI in the direction of the long axis A.
  • step 507 the ROI area has two degrees of freedom, and step 508 needs to be performed to perform another acquisition.
  • step 508 the remaining degrees of freedom of the ROI are related to the excitation regions in the above steps, and an excitation region B is selected in the non-parallel direction of the A-axis direction, and A and B should intersect at the ROI.
  • the excitation region B shape feature is similar to the excitation region A and is also a strip-shaped region including the ROI, but the long-axis direction of the excitation region B is not parallel to the long-axis direction of the excitation region A.
  • the excitation region B The long axis direction is perpendicular to the long axis direction of the excitation region A.
  • steps 503-506 are re-executed to obtain a projection coordinate b of the ROI center in the longitudinal direction of the excitation region B.
  • Step 509 integrating the projected coordinates a and b, and the coordinate information of the excitation regions A and B in the magnetic resonance system, the actual coordinates of the ROI center can be obtained.
  • the optimal condition is determined according to a priori conditions, such as percutaneous point coordinates, depth, direction, rigidity of the instrument, and the like.
  • the search path determines the search pitch according to the size of the excitation region, and determines an excitation region every other search interval; obtains a projection line according to the predicted position of the ROI, and finds the actual ROI according to the ROI imaging characteristics (eg, imaging parameters, light and dark, etc.) Position; scan obtains a number of MR images containing ROI, and compares the actual coordinates obtained by the search to confirm the correctness of the results.
  • the ideal position information of the ROI has been obtained or inferred by various tracking means, such as the prior art in the background art. It is necessary to verify whether the actual position of the ROI is consistent with it. The deviation is to verify the difference between the ideal position and the actual position, and it is searched around the ideal position. If the preset distance is exceeded, an alarm is issued. Taking the P point as the starting point, select the appropriate excitation area, and finally obtain the projection lines of the respective degrees. If there is no line segment in the one or more projection lines that meets the ROI imaging characteristics, the actual position of the ROI has deviated from the ideal position in the corresponding direction.
  • a starting point and a rough search direction are specified manually or automatically, starting to search for the ROI, confirming the ROI shape characteristics and position information.
  • FIG. 6A is a schematic diagram showing a projection direction and a readout direction of a layered excitation region according to an embodiment of the present invention, wherein the black region is a region of interest, and the outer frame is Excitation region, when the region of interest is a strip region, the excitation region is a slice region (using 1D RF excitation), the projection direction is along the long axis direction of the region of interest, and the readout direction is perpendicular to the region of interest, The projection direction is the signal accumulation direction, the region of interest is a low signal, and the other regions are high signals.
  • the high and low signals of the region of interest and the excitation region can be determined as appropriate, and the scanning imaging parameters are selected such that the signal difference between the region of interest and the surrounding tissue is as large as possible.
  • FIG. 6B is a schematic view showing a projection direction and a readout direction of a strip-shaped excitation region according to an embodiment of the present invention, wherein the region of interest is a dot (black region in the figure), such as a puncture needle, and the excitation region is a strip region (FIG. 6B) In the outer frame), using 2D RF or equivalent pulse excitation.
  • the region of interest is a dot (black region in the figure), such as a puncture needle
  • the excitation region is a strip region (FIG. 6B) In the outer frame), using 2D RF or equivalent pulse excitation.
  • Figure 7 is a schematic illustration of projection along the long axis of the interventional instrument in accordance with an embodiment of the present invention.
  • the strip-shaped excitation region A along the long axis direction of the needle body is selected, and the region should include a part of the needle body, the needle tip (ROI) and the tissue in front of the needle tip.
  • the outer frame in Fig. 7 indicates the selected strip-shaped area, the black area in the frame is the included needle body, and the rightmost side is the needle tip ROI (at the dotted line).
  • the remaining white areas within the frame represent the tissue outside the puncture needle. According to FIG.
  • the long axis direction of the strip-shaped region is selected as the readout direction, and the short-axis direction is the projection direction, and 2D RF or equivalent pulse excitation, acquisition echo, Fourier transform, and 1 are performed on the region.
  • a projection line is obtained in the TR.
  • the projection line the accumulated signal in the left region of the needle containing the low signal (accumulated in the projection direction) is compared with the needle-free body.
  • the right side area is obviously lower, and the strong and weak junction is the actual position of the needle tip ROI.
  • the needle body has been bent, leaving the excitation area ahead of time. You can continue to select other similar strip-like excitation areas that intersect with area A (the needle is at the intersection) along the long axis of the needle. Repeat the appeal step to obtain the bending of the needle in all directions, so that the needle can be analyzed. Bending direction.
  • the method of selecting a region along the long axis of the needle shown in Figure 7 can be combined with the method of selecting the region perpendicular to the long axis of the needle shown in Figure 4A to determine more quickly whether the needle is between the known (or assumed) ideal position. Deviation, bending and other information.
  • the actual coordinates of the interventional device are continuously monitored in real time, and the ratio is continuously compared with the ideal coordinate.
  • the interventional device automatically warns after deviating from the ideal position to a certain extent;
  • the actual coordinates of points (such as equal interval points), based on the coordinates of these points, the actual position of the interventional instrument is derived, and whether the interventional instrument is bent or deformed; the optical/electromagnetic tracking system is discarded, and only the actual coordinates of the interventional instrument are tracked.
  • the structure and material composition within the ROI can be designed, the difference in characteristics between the ROI and the surrounding tissue is increased, and the recognizability of the ROI is improved.
  • the magnetic resonance signal of the surrounding tissue is weak (dark)
  • a substance with a strong signal under magnetic resonance such as a copper sulfate solution
  • the ROI exhibits a strong magnetic resonance in the obtained projection line.
  • Signal (bright).
  • a general purpose processor may be a microprocessor.
  • the general purpose processor may be any conventional processor, controller, microcontroller, or state machine.
  • the processor may also be implemented by a combination of computing devices, such as a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other similar configuration. achieve.
  • the steps of the method or algorithm described in the embodiments of the present invention may be directly embedded in hardware, a software module executed by a processor, or a combination of the two.
  • the software modules can be stored in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium in the art.
  • the storage medium can be coupled to the processor such that the processor can read information from the storage medium and can write information to the storage medium.
  • the storage medium can also be integrated into the processor.
  • the processor and the storage medium may be disposed in an ASIC, and the ASIC may be disposed in the user terminal. Alternatively, the processor and the storage medium may also be disposed in different components in the user terminal.
  • Computer readable media includes computer storage media and communication media that facilitates the transfer of computer programs from one place to another.
  • the storage medium can be any available media that any general purpose or special computer can access.
  • such computer-readable media can include, but is not limited to, RAM, R OM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other device or device that can be used for carrying or storing instructions or data structures.
  • any connection can be appropriately defined as a computer readable medium, for example, if the software is from a website site, server or other remote resource through a coaxial cable, fiber optic computer, twisted pair, digital user Lines (DSL) or wirelessly transmitted in, for example, infrared, wireless, and microwave are also included in the defined computer readable medium.
  • the disks and discs include compact disks, laser disks, optical disks, DVDs, floppy disks, and Blu-ray disks. Disks typically replicate data magnetically, while disks typically optically replicate data with a laser. Combinations of the above may also be included in a computer readable medium.

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Abstract

一种磁共振系统中获得感兴趣区域位置信息的方法及装置。其中方法包括根据感兴趣区域ROI确定至少一激发区域的形状和投影方向(101)；根据所述激发区域的形状和ROI成像特性，利用相应的射频脉冲和扫描成像参数激发所述激发区域(102)；以垂直于所述投影方向的读出方向采集信号(103)；识别所述采集信号得到所述感兴趣区域ROI的实际坐标(104)。上述技术方案的优点在于：直接利用信号本身，实时对器械上各点实际坐标的测量，更直接，更准确，降低手术风险；操作简单，不需要额外的跟踪设备，基本上依靠磁共振设备本身完成器械跟踪。

Description

一种磁共振系统中获得感兴趣区域位置信息的方法及装置 技术领域
本发明涉及磁共振技术领域，具体地涉及一种磁共振系统中获得感兴趣区域位置信息的方法及装置。
背景技术
磁共振系统(MRI)利用磁共振原理，通过射频脉冲激发，梯度选层，磁共振信号采集及重建，获得人体的断层影像。通常包括磁体、梯度线圈、射频发射线圈、接收线圈、射频功放、梯度功放、谱仪、成像序列、扫描控制和重建软件等，磁共振系统扫描后得到的物体的灰度断层影像，物体内不同的组织由于不同的磁共振特性，在MR影像中表现为明暗有别的区域，一般含水的组织在MR影像中都会有一定的信号(较亮)，而固体往往信号弱(暗)。
在具体应用中，使用者往往比较关注物体内的部分区域(Region of Interest，以下简称ROI)。常见如介入器械的尖端，在介入手术应用中，我们关注介入器械尖端的实际位置，那么尖端就是该应用中的ROI，其中介入器械通常为中空的穿刺针，在光学/电磁跟踪设备的引导下，逐步刺入人体，直至准确刺入预定的病灶区。然后在针内放入各种治疗设备的探针，对病灶区开展介入治疗。
在磁共振技术的应用领域中，用户十分关注ROI的位置信息，包括该ROI区域的具体坐标、相对位置关系、运动变化规律、变化轨迹、变化特征。只有获得这些位置信息，后续操作(如介入式治疗)才能展开。目前获得位置信息的方法一般分三种：
1.在ROI内部直接放置电磁或光学跟踪设备，通过获取跟踪装置的坐标，从而获得ROI位置信息。但ROI往往处于物体的内部，不容易置入。即使成功置入，ROI通常会被刺入人体内部，光线会被遮挡，无法实现光学跟踪。而电磁跟踪装置的电磁信号会干扰磁共振系统的运行，形成伪影。因此这种方法应用起来面临很多问题，成本也较高。
2.保持跟踪设备与ROI的相对几何关系，将跟踪设备放置在物体外部，用光学跟踪来获得装置的坐标。然后根据确定的几何关系去推算ROI的位置信息。这种方法的问题在于很难保持设备与ROI间的相对几何关系不变。比如，通过刚性的连接材料来连接跟踪设备和ROI。但实际应用中，连接材料是可能出现弯曲的。当材料的刚性被破坏，也就意味着设备与ROI之间的几何关系发生变化，通过跟踪坐标推算出来的ROI坐标信息也就偏离了ROI的实际坐标。
3.磁共振扫描得到MR影像，在MR影像中人工或自动识别出ROI的位置。由于磁共振成像特性的限制，为了得到一幅MR影像，需要以不同参数执行周期性的几十甚至上千次信号采集，然后对大量信号进行重建(一般是二维或三维傅里叶变换)后得到影像。整个扫描时间较长，约数十秒到几分钟，限制这种方式的应用范围。对于后续的识别，人工识别会导致整个应用流程无法自动运行。而ROI的自动识别在复杂影像中存在较大的困难。
发明内容
本发明的目的是提供一种一种磁共振系统中获得感兴趣区域位置信息的方法及装置，用于解决现有技术中获取感兴趣区域不方便，而且不准确的问题。
本发明实施例提供了一种磁共振系统中获得感兴趣区域位置信息的方法，根据感兴趣区域(ROI)确定至少一激发区域的形状和投影方向。根据所述激发区域的形状和ROI的成像特性，选择对应的射频脉冲和扫描成像参数激发所述激发区域。以垂直于所述投影方向的读出方向采集信号。识别所述采集信号得到所述感兴趣区域(ROI)的实际坐标。
本发明实施例还提供了一种磁共振系统中获得感兴趣区域位置信息装置，包括激发区域确定单元，用于根据感兴趣区域(ROI)确定至少一激发区域的形状和投影方向。激发单元，用于根据所述激发区域的形状和ROI成像特性，利用相应的射频脉冲和扫描成像参数激发所述激发区域。读取单元，用于以垂直于所述投影方向的读出方向采集信号。识别单元，用于识别所述采集信号得到所述感兴趣区域(ROI)的实际坐标。
本发明实施例的上述技术方案的优点在于：直接利用磁共振设备和磁共振信号本身，实时对器械上各点实际坐标的测量，更直接，更准确，降低手术风险；操作简单，不需要额外的跟踪设备，基本上依靠磁共振设备本身完成器械跟踪。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图做一简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1所示为本发明实施例一种磁共振系统中获得感兴趣区域位置信息的方法流程图；
图2所示为本发明实施例一种磁共振系统中获得感兴趣区域位置信息装置的结构示意图；
图3所示为本发明实施例一种磁共振系统中获得感兴趣区域位置信息的方法详细流程图；
图4A所示为本发明实施例利用2D RF激发条状区域的示意图；
图4B为本发明实施例图4A相应的信号强弱示意图；
图5所示为本发明实施例一种磁共振系统中获得点状区域位置信息的方法详细流程图；
图6A所示为本发明实施例对条带状ROI进行层状区域激发时的投影方向和读出方向示意图；
图6B所示为本发明实施例对点状ROI进行条带状区域激发时的投影方向和读出方向示意图；
图7所示为本发明实施例沿针投影的示意图。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
在本发明的磁共振系统中有一些名词需作如下定义：
采集周期：磁共振系统在扫描过程，按照一定时序执行射频激发、梯度选层、相位调制，最后采集到数据，这个整个流程成为采集周期。
重复时间：磁共振系统的每次采集周期所花时间称为重复时间，简称TR。一个TR根据时序实现的不同，时间在1ms-10s间。MR影像的获取往往需要几十甚至上千个TR才能完成。
介入器械：通常为中空的穿刺针，在光学/电磁跟踪设备的引导下，逐步刺入人体，直至准确刺入预定的病灶区。然后在针内放入各种治疗设备的探针，对病灶区开展介入治疗。
磁共振成像脉冲序列(成像序列)：射频脉冲、梯度场和信号采集时刻等参数的设置及其在时序上的排列。
激发区域：磁共振成像序列所激发的物体内的区域。常用的成像序列一般用的都是一维射频脉冲(1D RF)，所激发的是标准的物体体内的片层区域。
多维射频脉冲：常用的一维射频脉冲(1D RF)都是激发物体内的一层区域。而多维射频脉冲(Bottomley and Hardy 1987；Hardy and Cline 1989)能将激发范围缩小至特定形状。二维脉冲(2D RF)只激发条状或圆柱状的区域，三维脉冲(3D RF)只激发一个点状或球状区域。除了标准的多维射频脉冲，还有一些等效于多维脉冲的特殊脉冲，如等效于2D RF的正交面相交激发脉冲(Feinberg et al.1985)。在本发明中这些类似的特殊脉冲与等效的多维脉冲等同对待。
如图1所示为本发明实施例一种磁共振系统中获得感兴趣区域位置信息的方法流程图。
包括步骤101，根据感兴趣区域(ROI)确定至少一激发区域的形状和投影方向。
步骤102，根据所述激发区域的形状和ROI的成像特性，选择对应的射频脉冲和扫描成像参数激发所述激发区域。
其中，所述扫描成像参数包括激发区域的层厚、回波时间、T1像的成像参数和T2像的成像参数，所述扫描成像参数应使ROI的区域和ROI周围区域的磁共振信号差异最大化。
步骤103，以垂直于所述投影方向的读出方向采集信号。
步骤104，识别所述采集信号得到所述感兴趣区域(ROI)的实际坐标。
作为本发明的一个实施例，所述根据感兴趣区域(ROI)确定至少一激发区域的形状和投影方向进一步包括，以包含ROI的激发区域沿某一方向累计计算磁共振信号强弱变化最明显的方向作为投影方向。
作为本发明的一个实施例，所述激发区域的形状包括，层状区域、条状区域和点状区域。
作为本发明的一个实施例，根据所述激发区域的形状利用对应的射频脉冲激发所述激发区域进一步包括，当所述激发区域的形状为层状区域时，采用一维射频脉冲激发所述激发区域；当所述激发区域的形状为条状区域时，采用二维射频脉冲或等效脉冲激发所述激发区域；当所述激发区域的形状为点状区域时，采用三维射频脉冲或等效脉冲激发所述激发区域。
作为本发明的一个实施例，以垂直于所述投影方向的读出方向采集信号中进一步包括，调节相位(通常是相位为零)使得采集回波信号最强时以垂直于所述投影方向的读出方向采集信号。
作为本发明的一个实施例，当使用一维射频脉冲激发所述含有条状ROI的层状激发区域时，投影方向为区域内条状ROI的长轴方向，读出方向为垂直于投影方向；当使用二维射频脉冲或其他等效序列激发所述经过点状ROI的条状激发区域时，投影方向为条状激发区域的短轴方向，读出方向为垂直于所述短轴方向的长轴方向；当使用三维射频脉冲或其他等效序列激发所述经过点状ROI的点状激发区域时，投影方向可为任意方向，读出方向垂直于所选的投影方向。
作为本发明的一个实施例，针对所述激发区域的形状和ROI的成像特性多次采集信号，对所述多次采集信号进行权重赋值，综合所述附有权重的多次采集信号得到综合采集信号。
作为本发明的一个实施例，根据感兴趣区域(ROI)确定至少一激发区域的形状和投影方向中还进一步包括，根据感兴趣区域的自由度确定多个激发区域的形状和投影方向。
作为本发明的一个实施例，所述多个激发区域于感兴趣区域不平行(例如可以为相交)。
作为本发明的一个实施例，所述多个激发区域于感兴趣区域垂直。
作为本发明的一个实施例，在识别所述采集信号得到所述感兴趣区域(ROI)的实际坐标之后还包括，将所述实际坐标与理想坐标比较，当所述实际坐标与所述理想坐标的差值超出预定阀值，则进行偏离报警。
作为本发明的一个实施例，沿介入器械采集多个感兴趣区域的实际坐标，将多个实际坐标转换为所述介入器械的实际形状，判断所述介入器械是否发生变形。
通过上述本发明的方法，直接利用磁共振信号本身，实时对器械上各点实际坐标的测量，更直接，更准确，降低手术风险；操作简单，不需要额外的跟踪设备，基本上依靠磁共振设备本身完成器械跟踪。
如图2所示为本发明实施例一种磁共振系统中获得感兴趣区域位置信息装置的结构示意图。
包括激发区域确定单元201，用于根据感兴趣区域(ROI)确定至少一激发区域的形状和投影方向。
激发单元202，用于根据所述激发区域的形状和ROI成像特性，利用相应的射频脉冲和扫描成像参数激发所述激发区域。
其中，所述扫描成像参数包括激发区域的层厚、回波时间、T1像的成像参数和T2像的成像参数，所述扫描成像参数应使ROI的区域和ROI周围区域的磁共振信号差异最大化。
读取单元203，用于以垂直于所述投影方向的读出方向采集信号。
识别单元204，用于识别所述采集信号得到所述感兴趣区域(ROI)的实际坐标。
作为本发明的一个实施例，所述激发区域确定单元201进一步以包含感兴趣区域的激发区域沿某一方向累计计算磁共振信号强弱变化最明显的方向作为投影方向。
作为本发明的一个实施例，所述激发区域的形状包括，层状区域、条状区域和点状区域。
作为本发明的一个实施例，所述激发单元202进一步当所述激发区域的形状为层状区域时，采用一维射频脉冲激发所述激发区域；当所述激发区域的形状为条状区域时，采用二维射频脉冲或等效脉冲激发所述激发区域；当所述激发区域的形状为点状区域时，采用三维射频脉冲或等效脉冲激发所述激发区域。
作为本发明的一个实施例，所述读取单元203通过调节相位(通常是相位为零)使得采集回波信号最强时以垂直于所述投影方向的读出方向采集信号。
作为本发明的一个实施例，所述激发区域确定单元201还用于当使用一维射频脉冲激发所述含有条状ROI的层状激发区域时，投影方向为区域内条状ROI的长轴方向，所述读取单元203的读出方向为垂直于投影方向；当使用二维射频脉冲或其他等效序列激发所述经过点状R  OI的条状激发区域时，投影方向为条状激发区域的短轴方向，所述读取单元203的读出方向为垂直于所述短轴方向的长轴方向；当使用三维射频脉冲或其他等效序列激发所述经过点状R OI的点状激发区域时，投影方向可为任意方向，所述读取单元203的读出方向垂直于所选的投影方向。
作为本发明的一个实施例，读取单元203还用于针对所述激发区域的形状和ROI的成像特性多次采集信号，对所述多次采集信号进行权重赋值，综合所述附有权重的多次采集信号得到综合采集信号。
作为本发明的一个实施例，所述激发区域确定单元201还用于根据感兴趣区域的自由度确定多个激发区域的形状和投影方向。
作为本发明的一个实施例，所述多个激发区域于感兴趣区域不平行，例如相交。
作为本发明的一个实施例，所述多个激发区域于感兴趣区域垂直。
作为本发明的一个实施例，还包括比较单元205，用于将所述实际坐标与理想坐标比较，当所述实际坐标与所述理想坐标的差值超出预定阀值，则进行偏离报警。
作为本发明的一个实施例，还包括转换单元206用于沿介入器械采集多个感兴趣区域的实际坐标，将多个实际坐标转换为所述介入器械的实际形状，判断所述介入器械是否发生变形。
通过上述本发明的装置，直接利用信号本身，实时对器械上各点实际坐标的测量，更直接，更准确，降低手术风险；操作简单，不需要额外的跟踪设备，基本上依靠磁共振设备本身完成器械跟踪。
如图3所示为本发明实施例一种磁共振系统中获得感兴趣区域位置信息的方法详细流程图。
包括步骤301，根据ROI的成像特性和形状特点，确定激发区域的形状、投影方向和扫描成像参数。例如，在考虑ROI的成像特性时，需要考虑ROI的氢原子数量、纵向和横向弛豫时间因素，从而可以确定使用相应的扫描成像参数，使得ROI和ROI周围区域的磁共振信号差异最大化。
其中所述确定扫描成像参数可以在步骤301完成，也可以在步骤302中完成，本发明的实施例并不限定具体在哪一步骤执行该处理。
步骤302，根据激发区域形状，来选择对应的射频脉冲。层状区域选择一维(1D)的RF，条状区域选择二维(2D)RF或等效RF，而点状区域选择三维(3D)RF或等效RF。
步骤303，用选定的射频脉冲激发选定区域。在本例中，采用2D RF去激发条状区域，如 图4A所示的区域A，在图4A中区域A的短轴方向为投影方向，长轴方向为读出方向，图4B为图4A相应的信号强弱示意图。
步骤304，调节相位(通常是相位为零)使得采集回波信号最强时，以垂直投影方向为读出方向，进行信号采集，所需时间为1个TR(脉冲序列重复时间)。
在进一步的实施例中，为了更准确的进行信号采集，可以做多次激发和采集，对每次的结果进行累加后取平均值，得到最终的采集信号，可以有效提高信噪比和排除运动、系统造成的偏差。
步骤305，对采集的信号进行处理(通常为傅里叶变换)，得到一条投影线。
步骤306，根据ROI的成像特性，例如在磁共振T1图像中，介入穿刺针的ROI表现为弱信号(暗)，而穿刺针周围的人体组织表现为较强信号(较亮)，可以在投影线上做一维识别，就能识别出ROI所对应的投影坐标。
步骤307，判断ROI的投影坐标的自由度是否都已经识别。对于片层内的条状ROI，如矢状面上的横膈膜，确定上下方向的这一个自由度就足够了。而对于介入器械ROI(针尖401)则是上下、左右两个自由度，需确定两个投影坐标才能确定介入器械的实际坐标。如果判断结果为是，则进入步骤309，否则进入步骤308。
步骤308，根据ROI欠缺的自由度，选择与上一次激发区域在感兴趣区域相交的另一个独立区域进行步骤303。
步骤309，将上述步骤中得到的ROI所有投影坐标和扫描区域的空间坐标综合起来，可以解出ROI的实际坐标。
基于上述流程，假设ROI的自由度为n(n一般小于等于3)，那么我们只需要n个TR时间(范围从1ms-10s)就可以快速的计算出ROI的实际坐标位置信息。而且本方法只对一维投影线进行识别，识别难度远小于从影像中识别，健壮性更好，使用范围也更广。
如图5所示为本发明实施例一种磁共振系统中获得点状区域位置信息的方法详细流程图。
步骤501，ROI区域的形状为点状，它的成像特征是它的信号和周围区域对比要弱很多。选择一个条状的区域A(如图4A所示)，区域A宽度和厚度与ROI相仿。这个条状区域A应将ROI包含在内，投影方向垂直于区域A的长轴方向。
步骤502，选择二维RF脉冲或等效脉冲和合适的成像参数(使ROI和周围组织的磁共振信号差异尽可能大)。
步骤503，用2D RF脉冲对激发区域A进行激发。
步骤504，读取方向就是激发区域A的长轴方向，在本例中只采集一次。
步骤505，对得到的信号进行傅里叶变换，得到投影线。
步骤506，由于ROI的成像特征是信号比周边区域明显的低，因此我们得到的投影线上会有明显的“亮-暗-亮”的特征(如图4B所示)，其中暗线段的中点就是ROI的中心在A长轴方向的投影坐标a。
步骤507，ROI区域一共有两个自由度，需要执行步骤508，再进行一次采集。
步骤508，ROI剩下的自由度与上述步骤中的激发区域相关，在A长轴方向的非平行的方向上再挑选一个激发区域B，A和B应在ROI处相交。激发区域B形状特征与激发区域A类似，也是一个包含有ROI的条带状区域，但激发区域B长轴方向与激发区域A的长轴方向不平行，在较佳的实施例中激发区域B的长轴方向与激发区域A的长轴方向垂直。对激发区域B，重新执行步骤503-506，得到ROI中心在激发区域B长轴方向的投影坐标b。
步骤509，综合投影坐标a和b，还有激发区域A和B在磁共振系统中的坐标信息，可以求出ROI中心的实际坐标。
在应用上述感兴趣区域定位方法的实施例中，例如可以在介入式治疗中从经皮点开始，根据先验条件，例如经皮点坐标、深度、方向、器械的刚性等，确定最佳的搜索路径，根据激发区域的尺寸，确定搜索间距，每隔一个搜索间距确定一个激发区域；根据ROI的预计位置得到投影线，根据ROI成像特性(例如成像参数、明、暗等)找到ROI的实际位置；扫描获得若干包含ROI的MR影像，和搜寻所获得的实际坐标进行比对，确认结果的正确性。
在另一个应用实施例中，通过各种跟踪手段(例如背景技术中的现有技术)已获得或推断出ROI的理想位置信息，如理想坐标P。需要验证ROI的实际位置是否与之一致，偏差多大验证理想位置和实际位置的差别，在理想位置周边寻找，超出预设距离则进行报警。以P点为起始点，选择合适的激发区域，最后得到各自由度的投影线。如果一条或多条投影线内没有符合ROI成像特性的线段，说明ROI的实际位置在相应方向上已经偏离理想位置。这种情况下，如果需要继续找出ROI实际坐标，可以沿偏离方向进行搜寻，直到找到ROI在各个投影线上的投影，然后计算出ROI的实际坐标。如果所有投影线都有符合ROI成像特性的线段，那么可以计算出实际坐标P’，P’和P之间的差异就是位置偏差。
在另一个应用实施例中，在磁共振的2D或者3D影像中，人工或者自动的方式指定一个起始点和大致的搜寻方向，开始搜寻ROI，确认ROI形状特性和位置信息。以所指定起始点和搜寻方向为先验条件，指定优化的搜寻路径，从而迅速找到所要的信息。如图6A所示为本发明实施例层状激发区域的投影方向和读出方向示意图，其中，黑色区域为感兴趣区域，外框为 激发区域，当感兴趣区域为条状区域，激发区域为片层区域(采用1D RF激发)，投影方向为沿着感兴趣区域的长轴方向，读出方向为垂直于感兴趣区域的方向，投影方向为信号累加方向，感兴趣区域为低信号，其他区域为高信号。感兴趣区域和激发区域的高低信号可以视情况而决定，选择扫描成像参数使得感兴趣区域和周围组织的信号差异尽可能大。
如图6B所示为本发明实施例条状激发区域的投影方向和读出方向示意图，其中，感兴趣区域为点状(图中黑色区域)，例如穿刺针，激发区域为条状区域(图中的外框)，采用2D RF或等效脉冲激发。
如图7所示为本发明实施例沿介入器械长轴投影的示意图。以穿刺针为例，根据针所在的已知的理想位置，选择沿针体长轴方向的条带状激发区域A，该区域应包括部分针体、针尖(ROI)和针尖前方部分组织。图7中外框表示所选的条带状区域，框内的黑色区域为所包含的针体，最右侧为针尖ROI(虚线处)。框内的其余白色区域代表穿刺针外面的组织。按照图7所示，选择与条带状区域长轴方向为读出方向，短轴方向为投影方向，对该区域进行2D RF或等效脉冲激发、采集回波、傅里叶变换，1个TR内获得投影线。磁共振下，由于针体呈低信号，周围组织呈高信号，所以在投影线中，包含低信号的针体的左侧区域累加后的信号(按投影方向累加)相较于不包含针体的右侧区域明显要低，其中强弱交界处就是针尖ROI实际位置。如果针尖实际位置不在预定位置(例如虚线位置)，如在虚线左侧，则说明针体已弯曲，提前离开了激发区域。可以继续沿着针体长轴方向选择与区域A相交(相交处为针体)的其他类似条带状激发区域，重复上诉步骤，可以得到在各个方向上针的弯曲情况，从而可以分析针的弯曲方向。
图7所示的沿针长轴选择区域的方法可与图4A所示的垂直于针长轴选择区域的方法结合，更快的确定针与已知(或假定)的理想位置之间的是否偏离、弯曲等信息。
通过上述实施例的方法及装置，不断实时监控介入器械实际坐标，持续与理想坐标比对，当超出设定阈值后，即介入器械偏离理想位置达到一定程度后就自动警示；沿介入器械采集多个点(如等间隔点)的实际坐标，根据这些点的坐标推算出介入器械的实际位置，判断介入器械是否弯曲变形等；抛开光学/电磁跟踪系统，仅仅靠跟踪介入器械的实际坐标来完成整个介入导航；根据ROI周围组织的成像特征，可设计ROI内的结构和物质构成，加大ROI和周围组织间的特征差异，提高ROI的可识别度。例如，如果周围组织的磁共振信号较弱(暗)，可在穿刺针内灌注磁共振下呈强信号的物质(如硫酸铜溶液)，使ROI在得到的投影线中呈现很强的磁共振信号(亮)。在复杂的周围组织中的ROI，还可以设计呈现特定规则的结构，如在穿刺针的ROI内设计硫酸铜溶液、金属交替相间的结构，使ROI在所获得投影线中呈现 与周围组织完全不同的明暗相间的规则特征，从而更易于识别。
本领域技术人员还可以了解到本发明实施例列出的各种说明性逻辑块(illustrative logical block)，单元，和步骤可以通过电子硬件、电脑软件，或两者的结合进行实现。为清楚展示硬件和软件的可替换性，上述的各种说明性部件，单元和步骤已经通用地描述了它们的功能。这样的功能是通过硬件还是软件来实现取决于特定的应用和整个系统的设计要求。本领域技术人员可以对于每种特定的应用，可以使用各种方法实现所述的功能，但这种实现不应被理解为超出本实用新型实施例保护的范围。
本发明实施例中所描述的各种说明性的逻辑块，或单元都可以通过通用处理器，数字信号处理器，专用集成电路(ASIC)，现场可编程门阵列(FPGA)或其它可编程逻辑装置，离散门或晶体管逻辑，离散硬件部件，或上述任何组合的设计来实现或操作所描述的功能。通用处理器可以为微处理器，可选地，该通用处理器也可以为任何传统的处理器、控制器、微控制器或状态机。处理器也可以通过计算装置的组合来实现，例如数字信号处理器和微处理器，多个微处理器，一个或多个微处理器联合一个数字信号处理器核，或任何其它类似的配置来实现。
本发明实施例中所描述的方法或算法的步骤可以直接嵌入硬件、处理器执行的软件模块、或者这两者的结合。软件模块可以存储于RAM存储器、闪存、ROM存储器、EPROM存储器、EEPROM存储器、寄存器、硬盘、可移动磁盘、CD-ROM或本领域中其它任意形式的存储媒介中。示例性地，存储媒介可以与处理器连接，以使得处理器可以从存储媒介中读取信息，并可以向存储媒介存写信息。可选地，存储媒介还可以集成到处理器中。处理器和存储媒介可以设置于ASIC中，ASIC可以设置于用户终端中。可选地，处理器和存储媒介也可以设置于用户终端中的不同的部件中。
在一个或多个示例性的设计中，本发明实施例所描述的上述功能可以在硬件、软件、固件或这三者的任意组合来实现。如果在软件中实现，这些功能可以存储与电脑可读的媒介上，或以一个或多个指令或代码形式传输于电脑可读的媒介上。电脑可读媒介包括电脑存储媒介和便于使得让电脑程序从一个地方转移到其它地方的通信媒介。存储媒介可以是任何通用或特殊电脑可以接入访问的可用媒体。例如，这样的电脑可读媒体可以包括但不限于RAM、R OM、EEPROM、CD-ROM或其它光盘存储、磁盘存储或其它磁性存储装置，或其它任何可以用于承载或存储以指令或数据结构和其它可被通用或特殊电脑、或通用或特殊处理器读取形式的程序代码的媒介。此外，任何连接都可以被适当地定义为电脑可读媒介，例如，如果软件是从一个网站站点、服务器或其它远程资源通过一个同轴电缆、光纤电脑、双绞线、数字用户 线(DSL)或以例如红外、无线和微波等无线方式传输的也被包含在所定义的电脑可读媒介中。所述的碟片(disk)和磁盘(disc)包括压缩磁盘、镭射盘、光盘、DVD、软盘和蓝光光盘，磁盘通常以磁性复制数据，而碟片通常以激光进行光学复制数据。上述的组合也可以包含在电脑可读媒介中。
以上所述的具体实施方式，对本发明的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上所述仅为本发明的具体实施方式而已，并不用于限定本实用新型的保护范围，凡在本实用新型的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本实用新型的保护范围之内。

Claims (24)

  1. 一种磁共振系统中获得感兴趣区域位置信息的方法，其特征在于，
    根据感兴趣区域(ROI)确定至少一激发区域的形状和投影方向；
    根据所述激发区域的形状和ROI的成像特性，选择对应的射频脉冲和扫描成像参数激发所述激发区域；
    以垂直于所述投影方向的读出方向采集信号；
    识别所述采集信号得到所述感兴趣区域ROI的实际坐标。
  2. 根据权利要求1所述的一种磁共振系统中获得感兴趣区域位置信息的方法，其特征在于，所述根据感兴趣区域ROI确定至少一激发区域的形状和投影方向进一步包括，以包含ROI的激发区域沿某一方向累计计算磁共振信号强弱变化最明显的方向作为投影方向。
  3. 根据权利要求2所述的一种磁共振系统中获得感兴趣区域位置信息的方法，其特征在于，所述激发区域的形状包括，层状区域、条状区域和点状区域；
    所述扫描成像参数包括激发区域的层厚、回波时间、T1像的成像参数和T2像的成像参数，所述扫描成像参数使ROI的区域和ROI周围区域的磁共振信号差异最大化。
  4. 根据权利要求3所述的一种磁共振系统中获得感兴趣区域位置信息的方法，其特征在于，根据所述激发区域的形状利用对应的射频脉冲激发所述激发区域进一步包括，当所述激发区域的形状为层状区域时，采用一维射频脉冲激发所述激发区域；当所述激发区域的形状为条状区域时，采用二维射频脉冲或等效脉冲激发所述激发区域；当所述激发区域的形状为点状区域时，采用三维射频脉冲或等效脉冲激发所述激发区域。
  5. 根据权利要求4所述的一种磁共振系统中获得感兴趣区域位置信息的方法，其特征在于，当使用一维射频脉冲激发所述含有条状ROI的层状激发区域时，投影方向为区域内条状R0I的长轴方向，读出方向为垂直于投影方向；当使用二维射频脉冲或其他等效序列激发所述经过点状ROI的条状激发区域时，投影方向为条状激发区域的短轴方向，读出方向为垂直于所述短轴方向的长轴方向；当使用三维射频脉冲或其他等效序列激发所述经过点状ROI的点状激发区域时，投影方向为任意方向，读出方向垂直于所选的投影方向。
  6. 根据权利要求1所述的一种磁共振系统中获得感兴趣区域位置信息的方法，其特征在于，以垂直于所述投影方向的读出方向采集信号中进一步包括，调节相位使得采集回波信号最强时以垂直于所述投影方向的读出方向采集信号。
  7. 根据权利要求1所述的一种磁共振系统中获得感兴趣区域位置信息的方法，其特征在于，针对所述激发区域的形状和ROI的成像特性多次采集信号，对所述多次采集信号进行权重 赋值，综合所述附有权重的多次采集信号得到综合采集信号。
  8. 根据权利要求1所述的一种磁共振系统中获得感兴趣区域位置信息的方法，其特征在于，根据感兴趣区域确定至少一激发区域的形状和投影方向中还进一步包括，根据感兴趣区域的自由度确定多个激发区域的形状和投影方向。
  9. 根据权利要求8所述的一种磁共振系统中获得感兴趣区域位置信息的方法，其特征在于，所述多个激发区域于感兴趣区域不平行。
  10. 根据权利要求9所述的一种磁共振系统中获得感兴趣区域位置信息的方法，其特征在于，所述多个激发区域于感兴趣区域垂直。
  11. 根据权利要求1所述的一种磁共振系统中获得感兴趣区域位置信息的方法，其特征在于，在识别所述采集信号得到所述感兴趣区域的实际坐标之后还包括，将所述实际坐标与理想坐标比较，当所述实际坐标与所述理想坐标的差值超出预定阀值，则进行偏离报警。
  12. 根据权利要求1所述的一种磁共振系统中获得感兴趣区域位置信息的方法，其特征在于，沿介入器械采集多个感兴趣区域的实际坐标，将多个实际坐标转换为所述介入器械的实际形状，判断所述介入器械是否发生变形。
  13. 一种磁共振系统中获得感兴趣区域位置信息装置，其特征在于，
    包括激发区域确定单元，用于根据感兴趣区域确定至少一激发区域的形状和投影方向；
    激发单元，用于根据所述激发区域的形状和ROI成像特性，利用相应的射频脉冲和扫描成像参数激发所述激发区域；
    读取单元，用于以垂直于所述投影方向的读出方向采集信号；
    识别单元，用于识别所述采集信号得到所述感兴趣区域的实际坐标。
  14. 根据权利要求13所述的一种磁共振系统中获得感兴趣区域位置信息装置，其特征在于，所述激发区域确定单元进一步以包含感兴趣区域的激发区域沿某一方向累计计算磁共振信号强弱变化最明显的方向作为投影方向。
  15. 根据权利要求14所述的一种磁共振系统中获得感兴趣区域位置信息装置，其特征在于，所述激发区域的形状包括，层状区域、条状区域和点状区域；
    所述扫描成像参数包括激发区域的层厚、回波时间、T1像的成像参数和T2像的成像参数，所述扫描成像参数使ROI的区域和ROI周围区域的磁共振信号差异最大化。
  16. 根据权利要求15所述的一种磁共振系统中获得感兴趣区域位置信息装置，其特征在于，所述激发单元进一步当所述激发区域的形状为层状区域时，采用一维射频脉冲激发所述激发区域；当所述激发区域的形状为条状区域时，采用二维射频脉冲或等效脉冲激发所述激 发区域；当所述激发区域的形状为点状区域时，采用三维射频脉冲或等效脉冲激发所述激发区域。
  17. 根据权利要求16所述的一种磁共振系统中获得感兴趣区域位置信息装置，其特征在于，所述激发区域确定单元还用于当使用一维射频脉冲激发所述含有条状ROI的层状激发区域时，投影方向为区域内条状ROI的长轴方向，所述读取单元的读出方向为垂直于投影方向；当使用二维射频脉冲或其他等效序列激发所述经过点状ROI的条状激发区域时，投影方向为条状激发区域的短轴方向，所述读取单元的读出方向为垂直于所述短轴方向的长轴方向；当使用三维射频脉冲或其他等效序列激发所述经过点状ROI的点状激发区域时，投影方向为任意方向，所述读取单元的读出方向垂直于所选的投影方向。
  18. 根据权利要求13所述的一种磁共振系统中获得感兴趣区域位置信息装置，其特征在于，所述读取单元进一步通过调节相位使得采集回波信号最强时以垂直于所述投影方向的读出方向采集信号。
  19. 根据权利要求13所述的一种磁共振系统中获得感兴趣区域位置信息装置，其特征在于，读取单元还用于针对所述激发区域的特性多次采集信号，对所述多次采集信号进行权重赋值，综合作数附有权重的多次采集信号得到综合采集信号。
  20. 根据权利要求13所述的一种磁共振系统中获得感兴趣区域位置信息装置，其特征在于，所述激发区域确定单元还用于根据感兴趣区域的自由度确定多个激发区域的形状和投影方向。
  21. 根据权利要求20所述的一种磁共振系统中获得感兴趣区域位置信息装置，其特征在于，所述多个激发区域于感兴趣区域不平行。
  22. 根据权利要求20所述的一种磁共振系统中获得感兴趣区域位置信息装置，其特征在于，所述多个激发区域于感兴趣区域垂直。
  23. 根据权利要求13所述的一种磁共振系统中获得感兴趣区域位置信息装置，其特征在于，还包括比较单元用于将所述实际坐标与理想坐标比较，当所述实际坐标与所述理想坐标的差值超出预定阀值，则进行偏离报警。
  24. 根据权利要求13所述的一种磁共振系统中获得感兴趣区域位置信息装置，其特征在于，还包括转换单元用于沿介入器械采集多个感兴趣区域的实际坐标，将多个实际坐标转换为所述介入器械的实际形状，判断所述介入器械是否发生变形。
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