JP2007330413A - Image diagnostic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image diagnostic device to display tissue affinity of a contrast medium by measuring a contrast medium luminance change of an object aimed at and pharmacokinetically analyzing a contrast medium concentration change in accordance with its result. <P>SOLUTION: This image diagnostic device has an ultrasonic probe to acquire a reflection signal from the object aimed at by transmitting an ultrasonic wave to the object aimed at, a contrast medium luminance measuring part to constitute a two-dimensional ultrasonic image by using the reflection signal acquired by the ultrasonic probe, to set a plural number of measuring regions to carry out contrast medium luminance measurement of the object aimed at within an image surface and to measure contrast medium luminance within the measuring regions, a pharmacokinetics analyzing part to pharmacokinetically analyze the contrast medium concentration change measured in the contrast medium luminance measuring part and to pharmacokinetically compute the tissue affinity of an attended tissue and an image display part to image and display information to show the tissue of the object aimed at and the affinity of the contrast medium acquired in the pharmacokinetics analyzing part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention measures the contrast agent concentration change of the target tissue over time using ultrasound, analyzes the blood-tissue affinity of the target tissue pharmacokinetically, and images the affinity between the tissue and the contrast agent. The present invention relates to a diagnostic imaging apparatus that displays images in an integrated manner.

  A normal ultrasonic echo image visualizes a difference in tissue structure caused by a difference in acoustic impedance of a tissue, and is widely used as a non-invasive diagnostic tool for grasping the form of a living tissue. Furthermore, in recent years, an ultrasound contrast agent composed of a microbubble preparation having a diameter of about several μm or less has appeared and has been clinically used. The ultrasound contrast agent becomes a strong reflection source when irradiated with ultrasound. As a result, an enhanced high-contrast image can be obtained at the site where the contrast agent is present. In addition, it is also known that a strong nonlinear signal for the transmission wave is generated due to the characteristics of the bubbles. For example, by imaging only the frequency component twice the transmission wave, it is separated from the tissue image, and from the contrast agent. Only the signal can be enhanced and imaged.

  Contrast agents are usually administered from the limb veins. The intravenously administered contrast agent is transmitted to each tissue together with arterial blood by the left heart system via the right heart system and pulmonary circulation.

  For example, consider the case where there is normal liver tissue and an adjacent liver tumor. If liver tissue and tumor tissue have similar acoustic impedance in normal echo images, it is difficult to distinguish them. Here, when an ultrasound contrast agent is administered, there is a difference in the distribution of blood flow between the liver tissue and the tumor tissue, and thus there is a difference in the distribution of the contrast agent. Conventionally, the surgeon has memorized the difference visually to assist in the diagnosis of tissue characteristics.

  Part of the contrast medium that has reached the peripheral tissue is filtered out of the blood vessel and present in the tissue gap due to the structure of the peripheral blood vessel and the surrounding tissue. Here, a part of the contrast agent binds to the tissue according to a specific affinity with the tissue. Most ultrasound contrast agents are composed of proteins such as albumin or lipid components such as phospholipids around microbubbles, so the main factor that determines the affinity between tissue and contrast agent is contrast Proteins or lipids around the drug.

  The affinity with which the contrast agent binds differs depending on the tissue type. Alternatively, even in the same tissue, the tissue may be thermally denatured by a therapeutic action such as tissue heating coagulation treatment using high-intensity ultrasonic waves or coagulation treatment by radio waves. In general, a protein constituting a tissue or a protein existing on the surface of a tissue is denatured and loses its function when exposed to a high temperature of 60 ° C. or more for a certain period of time. As a result, a change occurs in the binding affinity with a drug such as a contrast agent. However, in the conventional diagnostic imaging apparatus, the operator cannot display the affinity between the tissue and the contrast medium only by visually grasping the temporal change in the distribution of the contrast medium to the tissue.

  Therefore, an object of the present invention is to measure the contrast agent concentration change over time of the target tissue using ultrasound and to calculate the tissue affinity of the target tissue pharmacokinetically, and to contrast the target tissue with the contrast medium. To provide an image diagnostic apparatus for extracting and imaging information indicating the affinity of an agent.

  In order to achieve the above object, in the diagnostic imaging apparatus of the present invention, the contrast agent luminance change over time of the target tissue is measured using ultrasound, and the blood-tissue affinity of the target tissue is pharmacokinetically determined. Analysis processing is performed, and information indicating the affinity between the target tissue and the contrast agent is imaged and displayed.

  Hereinafter, typical configuration examples of the diagnostic imaging apparatus of the present invention will be listed.

  (1) An ultrasonic probe for transmitting an ultrasonic wave to the target object and acquiring a reflection signal from the target object, and a two-dimensional super-wave using the reflection signal acquired by the ultrasonic probe Contrast agent luminance measurement unit configured to measure a contrast agent luminance in the measurement region by configuring a sound wave image, setting a measurement region for measuring the contrast agent luminance of the target object in the image plane, and measuring the contrast agent luminance Pharmacokinetic analysis of contrast agent luminance change measured in the region, and pharmacokinetic analysis unit for calculating the tissue affinity of the tissue of interest pharmacokinetically, and the tissue of interest obtained in the pharmacokinetic analysis unit and And an image display unit that images and displays information indicating the affinity of the contrast agent.

  (2) In the diagnostic imaging apparatus according to (1), the contrast medium luminance measurement unit sets a plurality of regions for calculating tissue affinity within a plane of a two-dimensional ultrasonic image obtained by transmitting and receiving ultrasonic waves. The ratio of the calculated values is obtained.

  (3) In the diagnostic imaging apparatus of (1), the ultrasonic probe for transmitting and receiving ultrasonic signals is an ultrasonic probe in which a plurality of piezoelectric elements are arranged in a one-dimensional or two-dimensional array. It is characterized by being.

  (4) The diagnostic imaging apparatus according to (1), wherein information indicating an affinity relationship between a tissue of a region of interest and a contrast agent calculated pharmacokinetically from a change in contrast agent concentration of the tissue of interest is imaged. To do.

  (5) In the diagnostic imaging apparatus according to (4), the image for pharmacokinetic analysis of contrast agent luminance change is a functional image using a contrast agent such as an ultrasound image, a PET image, an MRI image, or an X-ray image. It is characterized by being.

  (6) Ultrasound probe that transmits / receives ultrasonic waves to / from the target object and obtains a two-dimensional tomographic image of the target object, and contrast imaging of the target object from an ultrasonic image acquired by the ultrasonic probe A means for measuring the agent brightness, a pharmacokinetic analysis of the measured contrast agent concentration change, and a pharmacokinetic calculation of the tissue affinity of the tissue of interest; And an image display unit for imaging and displaying information indicating the affinity between the target tissue and the contrast medium.

  According to the present invention, it is possible to display the contrast agent binding affinity in accordance with a change in tissue properties that cannot be reflected in the echo image of the prior art, which is useful for tissue discrimination and treatment effect determination.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of an image diagnostic apparatus according to an embodiment of the present invention.

  First, an apparatus configuration from acquisition of an ultrasound image of a target object to display of the affinity of a tissue and contrast medium analyzed from pharmacokinetic analysis from contrast medium luminance change will be described with reference to the block diagram of FIG. To do.

  An ultrasonic probe (hereinafter referred to as a probe) 2 has a structure in which a plurality of piezoelectric elements are arranged. An analog transmission signal is sent to each piezoelectric element from the transmission beamformer 3 via the D / A converter 4 and irradiates the target object 1 with ultrasonic waves. The ultrasonic wave transmitted from each piezoelectric element is electronically delayed by the transmission beam former 3 and is focused at a predetermined depth. The transmitted wave signal is reflected within the object of interest 1 and received again by each piezoelectric element of the probe. The reflected echo received by each piezoelectric element is corrected by the TGC (Time Gain Control) unit 5 for attenuation due to the arrival depth of the transmission wave, then converted to a digital signal by the A / D converter 6, and received beamformer. 7 is sent.

  The reception beamformer 7 outputs the addition result by multiplying a delay time according to the distance from the focal position to each piezoelectric element. By performing two-dimensional scanning with this focused ultrasonic wave, a two-dimensional reflected echo distribution of the subject of interest 1 is obtained. An RF signal divided into a real part and an imaginary part is output from the reception beamformer 7 and sent to the envelope detection unit 8 and the measurement region setting unit 11. The signal sent to the envelope detection unit 8 is converted into a video signal, and then interpolated between scan lines by the scan converter 9 and reconstructed into two-dimensional image data, and then displayed on the image display unit 10. Is done. In the measurement region setting unit 11, a measurement region for measuring contrast agent luminance is arbitrarily set to an optimum size according to the tissue form, and is sent to the contrast agent luminance measurement unit 12. The contrast agent luminance measurement unit 12 measures a change in contrast agent luminance within the measurement region. The pharmacokinetic analysis unit 13 calculates the affinity of the tissue and the contrast agent analyzed pharmacokinetically from the contrast agent luminance change of the region of interest measured by the contrast agent luminance measurement unit, that is, the contrast agent concentration change, and displays it. Displayed on the unit 10.

  FIG. 2 is a schematic diagram showing the observed two-dimensional ultrasonic image 14. There is a blood vessel 16 inside the liver 15 in the figure, and the surgeon can set the region of interest region 18 and 19 on a portion of the blood vessel on the region of interest 17 and the tissue outside the vessel.

  Next, specific steps of the present invention will be described with reference to a flowchart (FIG. 3) and a block diagram (FIG. 4) showing an embodiment of a device configuration related to blood tissue affinity calculation. The surgeon designates a two-dimensional ultrasonic image 14 that is an area to be observed from the displayed image (step S1). A blood vessel 16 is observed inside the liver 15 in the designated image. Here, on the image to be observed, the operator designates the blood vessel region 17 of interest in a part of the blood vessel by the input unit 26 (S2), and subsequently designates the first tissue region of interest 18 (S3). Two interested tissue regions 19 can be designated (S4). The designated blood vessel region 17 of interest and tissue regions 18 and 19 of interest are set in the measurement region setting unit 11 installed in the computer 27 controlled by the control unit 20. The surgeon can also designate the third and fourth tissue regions of interest as necessary.

  Subsequently, the contrast medium brightness measurement unit 12 acquires the intravascular contrast medium brightness in the blood vessel region of interest designated in S2 over time (S5). A plurality of temporal contrast agent luminance data can be stored in the memory unit 25 (S6). At this time, using the contrast agent time luminance data acquired over time, the contrast agent concentration time curve creating unit 21 can also curve the change in contrast agent luminance in the blood and display it on the display unit 10. Is also possible.

S7 is a step of calculating a contrast medium intravascular disappearance rate parameter. In the calculation method, the blood flow contrast agent luminance time actual data acquired in S5 and accumulated in the memory unit 25 is fitted by the following equation in the arithmetic unit 22 by the least square method, and in the contrast agent disappearance rate parameter calculation unit 23, A parameter α indicating the distribution speed of the contrast medium and a parameter β indicating the disappearance speed of the contrast medium from the blood are calculated.
C _P (t) = A exp (-αt) + B exp (-βt)
Similarly, the contrast medium brightness measurement unit 12 acquires the contrast medium brightness in the first tissue region of interest designated in S3 over time (S9). The contrast agent luminance data acquired over time is accumulated in the memory unit 25 (S10). The intra-tissue contrast agent luminance time actual data accumulated in S10 is subjected to the least square fitting to the following expression in the calculation unit 22, and the contrast agent disappearance rate parameter calculation unit 23 can calculate the intra-tissue disappearance rate parameter ( S11). At this time, using the contrast agent time luminance data in the tissue acquired over time, the contrast agent concentration time curve creation unit 21 can also curve the contrast agent luminance change in the tissue of interest. Can also be displayed.

+ B{exp(-β t)- exp(-K_2n t) } / (K_2n - β) ].
実際には、上記式は、次式に書き換えることができる。
C_T (t) = R_B [ K₁ A {exp(-α t) - exp(-K₂ t) } / (K₂ -α) + K₁ B {exp(-β t)- exp(-K₂ t) } / (K₂ -β)+ K₃ A {exp(-α t)- exp(-K₄ t) } / (K₄ -α) + K₃ B {exp(-β t) - exp(-K₄ t) } / (K₄ -β) ],
同様にして、第二の関心組織領域における造影剤組織消失速度パラメータの算出は工程S12からS14にて算出することができる。
ここで、工程S8にて、上記にて算出された各パラメータから、第一の関心組織の造影剤親和度を示す値Dnを造影剤血液組織親和度算出部２４において、次式を使い算出する。言い換えると、Dnは、血液と組織の間での、造影剤の親和性を示す値である。

+ B {exp (-β t)-exp (-K _2n t)} / (K _2n -β)].
In practice, the above equation can be rewritten as:
C _T (t) = R _B [K ₁ A {exp (-α t)-exp (-K ₂ t)} / (K ₂ -α) + K ₁ B {exp (-β t)-exp (- K ₂ t)} / (K ₂ -β) + K ₃ A (exp (-α t)-exp (-K ₄ t)} / (K ₄ -α) + K ₃ B (exp (-β t) -exp (-K ₄ t)} / (K ₄ -β)],
Similarly, the calculation of the contrast medium tissue disappearance rate parameter in the second region of interest can be performed in steps S12 to S14.
Here, in step S8, a value Dn indicating the contrast agent affinity of the first tissue of interest is calculated from the parameters calculated above using the following formula in the contrast agent blood tissue affinity calculation unit 24. . In other words, Dn is a value indicating the affinity of the contrast agent between blood and tissue.

Dn = C _T (t) / C _P (t)
Actually, it can be rewritten as:
Dn = K ₁ / K ₂ + K ₃ / K ₄ .
Similarly, the tissue affinity of the second tissue of interest is calculated (S15).

  As described above, the tissue affinity comparison unit 28 can also compare the tissue affinity between the first and second tissues of interest in S16. The comparison result can be superimposed and displayed on the corresponding area on the arbitrary echo image on the display unit 10. Alternatively, the threshold setting unit 29 can superimpose and display on an arbitrary echo image by color identification in which the affinity for each region of interest is compared with the threshold according to the threshold set in step S18.

1 is a block diagram showing the configuration of an image diagnostic apparatus that is Embodiment 1 of the present invention. The schematic diagram of the observed ultrasonic tomogram. The flowchart figure explaining the operation | movement from the contrast agent brightness | luminance data acquisition to the tissue affinity calculation of a contrast agent in the diagnostic imaging apparatus of Example 1. FIG. The block diagram which shows one form of the apparatus structure in connection with blood tissue affinity calculation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Target object, 2 ... Ultrasonic probe, 3 ... Transmission beam former, 4 ... D / A converter, 5 ... TGC, 6 ... A / D converter, 7 ... Reception beam former, 8 ... Envelope detection 9, a scan converter, 10 a display unit, 11 a measurement region setting unit, 12 a contrast medium luminance measurement unit, 13 a pharmacokinetic analysis unit, 14 a two-dimensional ultrasound image, 15 a liver, 16 a blood vessel, DESCRIPTION OF SYMBOLS 17 ... Blood vessel region of interest, 18 ... First interest tissue region, 19 ... Second interest tissue region, 20 ... Control unit, 21 ... Contrast medium concentration time curve creation unit, 22 ... Calculation unit, 23 ... Contrast agent disappearance rate Parameter calculation unit, 24: Contrast medium blood tissue affinity calculation unit, 25 ... Memory unit, 26 ... Input unit, 27 ... Computer, 28 ... Tissue affinity comparison unit, 29 ... Threshold setting unit.

Claims (3)

  A measurement region setting unit for setting a measurement region used for measuring the contrast agent luminance of a target object in the medical image plane, and a contrast agent luminance change measurement for detecting a contrast agent luminance change in the measurement region set by the measurement region setting unit A contrast medium brightness time curve measured by the contrast medium brightness change measuring section, a pharmacokinetic analysis section for calculating contrast medium affinity of a set tissue, and an image processed by the pharmacokinetic analysis section And an image display unit that performs image diagnosis.   The measurement area setting unit sets a plurality of measurement areas to be used for measuring the contrast agent luminance of the target object in the presence image, and the pharmacokinetic analysis unit calculates a ratio of the contrast medium affinity in the plurality of measurement areas. The image diagnostic apparatus according to claim 1, wherein the image diagnostic apparatus calculates and displays the result on the image display unit. The image diagnostic apparatus according to claim 1, wherein the measurement region setting unit performs region setting according to a structure of a target object.

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