JP2005198708A - Vascular stenosis rate analyzing apparatus and vascular stenosis rate analyzing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blood vessel stenosis rate analyzing apparatus and a blood vessel stenosis rate analyzing method capable of accurately and objectively measuring a stenosis rate regardless of a projection direction or an operator's experience.
A blood vessel shape data generation unit 13 generates three-dimensional blood vessel shape data based on the three-dimensional image data obtained by a volume rendering image data generation unit 12 or a plurality of two-dimensional image data. The diameter detection unit 14 detects the minimum blood vessel diameter in the projection direction perpendicular to the blood vessel axis from the blood vessel shape data. Next, the stenosis part detection unit 15 generates a minimum diameter curve by combining a plurality of minimum blood vessel diameters detected along the blood vessel axis direction, and detects a stenosis part based on the minimum diameter curve. The stenosis rate calculating unit 17 calculates the stenosis rate based on the data of the temporary normal blood vessel generated by the temporary normal blood vessel setting unit 16 using the blood vessel shape data and the data of the minimum blood vessel diameter at the stenosis site.
[Selection] Figure 1

Description

  The present invention relates to a blood vessel stenosis rate analyzing apparatus and a blood vessel stenosis rate analyzing method for analyzing a stenosis portion of a blood vessel based on medical image data of a blood vessel obtained using an image diagnostic apparatus or the like.

  Medical image diagnostic technology has made rapid progress with X-ray CT apparatuses and MRI apparatuses that have been put into practical use with the development of computer technology in the 1970s, and is indispensable in today's medical care. In particular, in recent X-ray CT apparatuses and MRI apparatuses, real-time display of image data is possible with the increase in speed and performance of biological information detection apparatuses and arithmetic processing apparatuses, and further, generation and display of three-dimensional image data. Became easy to do.

  For example, in an X-ray CT apparatus, an X-ray tube for irradiating X-rays and an X-ray detector for detecting the irradiated X-rays are arranged opposite to the periphery of the subject, and the subject is further placed on the X-ray CT. By relatively moving in the body axis direction (slice direction) with respect to the X-ray tube and the X-ray detector, X-ray projection data in a plurality of slice sections of the subject is collected, and a plurality of sheets are obtained based on these X-ray projection data 2D image data or 3D image data (volume data) is generated.

  On the other hand, a method for calculating a range of a stenosis site and a stenosis rate using morphological data inside a blood vessel has been developed. As a method based on two-dimensional image data obtained by X-ray imaging of a subject in which a contrast medium is injected into a blood vessel, a provisional normal blood vessel diameter in a stenosis portion of the two-dimensional image data is estimated based on the blood vessel diameter of the normal portion. A method of calculating the stenosis rate by comparing the estimated temporary normal blood vessel diameter with the actual stenotic blood vessel diameter has been proposed (for example, see Patent Document 1).

  In this method, the contrast agent concentration in the cross section indicated by the marker 502 perpendicular to the blood vessel axis 501 of the blood vessel 500 in FIG. 16A is plotted on the vertical axis in FIG. The horizontal axis of FIG. 16 (b) is taken and the contrast agent distribution curve 503 is obtained. A blood vessel diameter 504 is measured by applying an entropy filter to the distribution curve 503. Such measurement is performed on a plurality of positions in the blood vessel axis direction, and a blood vessel diameter change curve 505 in the blood vessel axis direction as shown in FIG. 16C is obtained using the obtained plurality of blood vessel diameter data. . Next, the change curve 505 is subjected to Hough transform to estimate a change curve 506 of the temporary normal blood vessel diameter, and a portion having a blood vessel diameter equal to or less than the estimated temporary normal blood vessel diameter is detected as a stenosis portion. Then, the stenosis rate is calculated based on the stenotic blood vessel diameter at the stenotic site and the estimated temporary normal blood vessel diameter.

On the other hand, as a method for calculating a stenosis rate using three-dimensional image data by an X-ray CT apparatus, an MRI apparatus, or the like, blood vessels in a stenosis part and a normal part which are manually set with respect to blood vessel shape data obtained in three dimensions A method of comparing diameters has been performed. In this method, the stenosis rate is calculated based on the vascular diameter or the vascular cross-sectional area obtained in the cross section perpendicular to the vascular axis of the stenosis site and the normal site.
JP-A-11-164833 (page 10, FIGS. 18-21)

  In the above-described method using two-dimensional image data, the size of the blood vessel diameter depends on the X-ray projection direction. For example, the projection direction in X-ray imaging is not necessarily the projection direction in which the clinically important minimum blood vessel diameter is obtained. It does not match. For this reason, it has been difficult to obtain an accurate stenosis rate.

  On the other hand, in the method using three-dimensional image data, the blood vessel shape can be evaluated from an arbitrary direction, so there is no problem of dependency on the projection direction as described above. Since the blood vessel diameter and the cross-sectional area of the blood vessel at the stenosis site and the normal site are used for calculation of the stenosis rate, the accuracy of the stenosis rate depends on the operator's experience and skill. That is, the method for specifying a normal site or a stenosis site varies depending on the operator, and even if the same operator is used, the reproducibility is poor. For this reason, the value of the obtained stenosis rate was lacking in objectivity.

  The present invention has been made in view of the above problems, and its purpose is to measure the stenosis rate of blood vessels using three-dimensional image data, so that it does not depend on the projection direction or the experience of the operator. Another object of the present invention is to provide a blood vessel stenosis rate analyzing apparatus and a blood vessel stenosis rate analyzing method capable of always accurately and objectively measuring a stenosis rate.

  In order to solve the above problem, the blood vessel stenosis rate analyzing apparatus according to the present invention according to claim 1 generates blood vessel shape data for generating three-dimensional blood vessel shape data based on three-dimensional image information obtained by a medical image diagnostic apparatus. In a cross-section substantially perpendicular to the blood vessel axis of the generated blood vessel shape data, the generation means detects the minimum diameter projection direction in which the projection diameter of the blood vessel inner wall is minimum, and the projection diameter in the minimum diameter projection direction is detected as the minimum blood vessel diameter. A stenosis part for detecting a normal part and a stenosis part of a blood vessel based on a minimum blood vessel diameter detected by the minimum blood vessel diameter detection means in a plurality of cross sections within a predetermined analysis range along the blood vessel axis; Detection means, provisional normal blood vessel setting means for setting three-dimensional provisional normal blood vessel shape data in the stenotic region based on the blood vessel shape data in the normal region, and the stenosis Wherein the blood vessel shape data based on the preliminary normal vascular shape data is characterized by having a stenosis ratio calculating means for calculating a stenosis rate in position.

  According to a second aspect of the present invention, there is provided a blood vessel stenosis rate analyzing apparatus according to the present invention, and blood vessel shape data generating means for generating three-dimensional blood vessel shape data based on three-dimensional image information obtained by a medical image diagnostic apparatus. The cross-sectional area measuring means for measuring the cross-sectional area of the blood vessel in a cross section substantially perpendicular to the blood vessel axis of the blood vessel shape data, and the cross-sectional area measuring means in the plurality of cross sections within a predetermined analysis range along the blood vessel axis. A stenosis part detecting means for detecting a normal part and a stenosis part of a blood vessel based on a blood vessel cross-sectional area, and a provisional normality for setting three-dimensional provisional normal blood vessel shape data in the stenosis part based on the blood vessel shape data in the normal part Blood vessel setting means; and stenosis rate calculating means for calculating a stenosis rate based on the blood vessel shape data and the provisional normal blood vessel shape data at the stenosis site. It is.

  On the other hand, the blood vessel stenosis rate analyzing method of the present invention according to claim 21 includes a step of generating three-dimensional blood vessel shape data based on the three-dimensional image information obtained by the medical image diagnostic apparatus, and the generated blood vessel shape. In a cross-section substantially perpendicular to the blood vessel axis of the data, a step of detecting a minimum diameter projection direction in which the projection diameter of the blood vessel inner wall is minimum, a projection diameter in the minimum diameter projection direction as a minimum blood vessel diameter, and a predetermined along the blood vessel axis Generating a minimum diameter curve based on the minimum blood vessel diameter in the plurality of cross sections within the analysis range; detecting a normal site and a stenosis site of the blood vessel based on the minimum diameter curve; and Setting three-dimensional provisional normal blood vessel shape data at the stenotic site based on blood vessel shape data; and the blood vessel shape data at the stenotic site. It is characterized by the step of calculating a stenosis rate based the on preliminary normal vascular shape data with.

  Furthermore, the blood vessel stenosis rate analyzing method of the present invention according to claim 22 includes a step of generating three-dimensional blood vessel shape data based on the three-dimensional image information obtained by the medical image diagnostic apparatus, and the generated blood vessel shape. Measuring a blood vessel cross-sectional area in a cross section substantially perpendicular to the blood vessel axis of data; generating a cross-sectional area curve based on the blood vessel cross-sectional area in a plurality of the cross-sections within a predetermined analysis range along the blood vessel axis; Detecting a normal blood vessel region and a stenosis region based on the generated cross-sectional area curve; and setting three-dimensional provisional normal blood vessel shape data in the stenosis region based on the blood vessel shape data in the normal region. And calculating a stenosis rate based on the blood vessel shape data and the provisional normal blood vessel shape data at the stenosis site. It is set to.

  According to the present invention, the blood vessel diameter or blood vessel cross-sectional area at the stenotic site based on the 3D blood vessel shape data generated from the 3D image data, and the blood vessel diameter or blood vessel cross-sectional area of the temporary normal blood vessel estimated at the stenotic site. Therefore, it is possible to always obtain an objective and accurate stenosis rate without depending on the projection direction or the operator.

  Embodiments of the present invention will be described below with reference to the drawings.

  The feature of the present embodiment is that the tentative portion in the stenosis part estimated from the minimum vascular diameter of the stenosis part measured based on the three-dimensional vascular data by the image diagnostic apparatus and the vascular diameter of the normal part around the stenosis part. The purpose is to automatically measure the stenosis rate from the diameter of a normal blood vessel.

(Device configuration)
Hereinafter, the configuration of the blood vessel stenosis rate analyzing apparatus according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a functional block diagram showing the overall configuration of the blood vessel stenosis rate analyzing apparatus according to the present embodiment.

  The blood vessel stenosis rate analyzing apparatus 100 shown in FIG. 1 temporarily stores a plurality of adjacent two-dimensional image data or volume data supplied from a separately installed medical image diagnostic apparatus 21 via a network or a storage medium. 3D image data storage unit 11, rendering image data generation unit 12 that generates volume rendering image data of blood vessels using stored 3D image data, and 3D from a plurality of 2D image data or volume data The blood vessel shape data generation unit 13 for generating the blood vessel shape data is provided.

  Further, the blood vessel stenosis rate analyzing apparatus 100 detects the minimum value of the blood vessel inner diameter (hereinafter referred to as the minimum blood vessel diameter) in a predetermined section based on the three-dimensional blood vessel shape data and changes the minimum blood vessel diameter with respect to the blood vessel axis direction. A minimum blood vessel diameter detection unit 14 that generates a curve (hereinafter referred to as a minimum diameter curve), a stenosis site detection unit 15 that detects a range of a stenosis site based on the minimum diameter curve, and a periphery of the detected stenosis region Based on the three-dimensional blood vessel shape data of the normal blood vessel, the temporary normal blood vessel setting unit 16 that estimates the shape of the normal blood vessel (provisional normal blood vessel) in the stenosis part, the minimum blood vessel diameter in the stenosis part, and the minimum blood vessel diameter A stenosis rate calculation unit 17 that calculates the stenosis rate of the blood vessel based on the blood vessel diameter (hereinafter referred to as the projection diameter) of the temporary normal blood vessel in the same direction as the measured direction (hereinafter referred to as the minimum diameter projection direction). It is provided.

  Furthermore, the blood vessel stenosis rate analyzing apparatus 100 displays the calculated stenosis rate and the like, and the central axis of the blood vessel with respect to the two-dimensional image data or the volume rendering image data (hereinafter referred to as a blood vessel core line). And an input unit 18 for inputting various command signals, and a system control unit 20 for comprehensively controlling each unit.

  The three-dimensional image data storage unit 11 of the vascular stenosis rate analyzing apparatus 100 includes a large-capacity storage circuit, and is collected using a medical image diagnostic apparatus 21 such as an X-ray CT apparatus or an MRI apparatus for a vascular stenosis part of a subject. A plurality of two-dimensional image data or three-dimensional volume data is stored. That is, the medical image data of the subject requested to the medical image diagnostic apparatus 21 or an image data server (not shown) by a doctor in charge of the subject or an examination engineer (hereinafter referred to as an operator) via a network or a storage medium. And is stored in the three-dimensional image data storage unit 11.

  The rendering image data generation unit 12 reads out three-dimensional data (volume data) stored in the three-dimensional image data storage unit 11, generates volume rendering image data based on the image data, and stores it in an internal storage circuit. At the same time, it is displayed on the display unit 19. However, when the image data supplied from the three-dimensional image data storage circuit 11 is a plurality of pieces of image data, interpolation processing is performed on these image data as necessary, and the volume data is generated. . Then, opacity and color tone are set for each voxel value of the generated volume data, and volume rendering image data is generated.

  The blood vessel shape data generation unit 13 generates two-dimensional image data (MPR (Multi-Planar-Reconstruction)) in a plurality of sections substantially perpendicular to the blood vessel running set by the operator with respect to the volume rendering image data displayed on the display unit 19. A function for generating (image data) and displaying it on the display unit 19, and a function for setting a blood vessel core line based on a start point, a passing point, and an end point set by the operator in the blood vessel cross section of the MPR image data. By using the points on the blood vessel core line as a reference, the inner wall contour point (hereinafter referred to as the blood vessel contour point) of the blood vessel cross section perpendicular to the blood vessel core line is synthesized to form a blood vessel contour line. A function for generating three-dimensional blood vessel shape data by compositing in the direction of the blood vessel axis, and a torsion correction for correcting the data twist when there is data twist in the obtained three-dimensional blood vessel shape data It has the ability. The starting point, passing point, and end point can be set not only in volume data but also in an MRP image generated from a plurality of two-dimensional image data.

  As the method for detecting the blood vessel contour point, here, the blood vessel contour point and the blood vessel contour line are extracted by automatically tracking the inside of the blood vessel from a point arbitrarily designated in the blood vessel (for example, a point on the blood vessel core line). The so-called Bessel tracking method (see, for example, Onno Wink, Wiro J. Niessen, “Fast Delineation and Visualization of Vessel in 3-D Angiographic Images”, IEEE Trans. Med. Imag. Vol. 19, No. 4, 2000). Although suitable for use, a method of thinning the internal region of a luminal organ (eg, GD Rubin, DS Paik, PC Johnston, S. Napel, “Measurement of the Aorta and Its Branches with Helical CT,” Radiology, Vol. 206, No. 3, pp. 823-9, Mar., 1998.) may be used.

Next, the principle of the twist correction function will be described with reference to FIG. As shown in FIG. 2, for example, when setting a blood vessel contour point centering on a blood vessel core line in each of a plurality of cross sections S1 to S3 substantially perpendicular to the blood vessel axis, the setting start position of the blood vessel contour point in the circumferential direction is arbitrary. Therefore, it is necessary to form a blood vessel contour surface (blood vessel surface) by associating the blood vessel contour points P21 to P2N of the cross section S2 adjacent to the blood vessel contour points P11 to P1N of the cross section S1. Similarly, the blood vessel contour points are also associated with the cross section S2 and the cross section S3. Specifically, the contour point Cmn is in the same direction as the blood vessel contour point Pmn (m = 1 to 3, n = 1 to N) with a constant radius R with respect to the blood vessel cross section Sm (m = 1 to 3 in FIG. 2). A circle Tm (m = 1 to 3) for twist correction processing having (θ) is set. Then, as shown in the following formula (1), the position information of the contour point C1n (θ0) of the circle T1 and the contour of T2 measured by shifting the contour point C1n (θ0) in the circumferential direction by the angle θ. Based on the position information of the point C2n (θ0 + θ), the distances [C1n (θ0), C2n (θ0 + θ)] between the respective contour points are integrated for n = 1 to N, and the total distance B (θ) (θ = -180 ° to 180 °), and θ = θ ′ at which this value is minimum is detected as the amount of twist of the data.

  Next, data correction is performed based on the detected twist amount. For example, the blood vessel contour point P2n (θ0) adjacent to the blood vessel contour point P1n (θ0) is changed to position information of P2n (θ0 + θ ′) = P2n ′ obtained by rotating the torsion amount θ ′, and the corresponding point is determined again. . Similarly, for the blood vessel contour point P3n (θ) of the cross section S3, the circle T2 after twist correction is fixed, and the minimum sum of the distances between the contour points when T3 is shifted in the same direction by the angle θ Is detected as a twist amount, and data correction is performed based on the twist amount. Correction is performed for all cross sections in the direction of the blood vessel axis, and a blood vessel contour line and further a blood vessel contour surface (three-dimensional blood vessel shape data) are generated based on the blood vessel contour points of each corrected cross section.

  By the above-described twist correction of the blood vessel contour point, the distortion of the three-dimensional blood vessel shape data due to the twist is greatly reduced as in the conventional case, so that the calculation accuracy of the blood vessel diameter, the blood vessel cross-sectional area, and further the stenosis rate is improved.

  Next, the minimum blood vessel diameter detection unit 14 measures the projection diameter by a projection process around the blood vessel axis (0 degrees to 180 degrees) of the three-dimensional blood vessel shape data obtained by the blood vessel shape data generation unit 13. The minimum diameter projection direction in which the minimum value of the projection diameter (minimum blood vessel diameter) is measured, the function of measuring the value of the minimum blood vessel diameter at that time, and the measurement of the minimum blood vessel diameter described above are performed along the blood vessel axis. And a function of generating a minimum diameter curve indicating a change in the minimum blood vessel diameter with respect to the blood vessel axis direction based on a plurality of minimum blood vessel diameter values.

  If the projection angle interval is set finely in order to increase the measurement accuracy of the projection diameter in the above-described projection processing, the time required for measurement increases. For this reason, for example, a method of estimating the minimum diameter projection direction by applying an optimization method such as the Brent method to projection diameter data obtained at a coarse projection angle interval (Δθ) is desirable.

  Hereinafter, the principle of the minimum diameter projection direction estimation by the Brent method will be described with reference to FIG. The Brent method is a method for calculating the extreme value by performing a convergence operation by parabolic interpolation using any three points of the function d (θ) of the obtained measurement value. For example, a predetermined cross section perpendicular to the blood vessel axis is used. The projection diameter d (θ) of the blood vessel is measured while sequentially changing the projection direction θ in Δθ steps. Then, as shown in FIG. 3, d (θ2) indicating the minimum value among the projection diameters d (θ) obtained discretely, and projection diameters d (θ1) and d (θ3) before and after the extraction are extracted. Then, the projection diameter d (θ4) of the three-dimensional blood vessel shape data in the projection direction θ4 having the extreme value (minimum value) dx (θ4) of the parabola g1 (θ) determined by these three values is measured. Next, it has a minimum value dx (θ5) of the parabola g2 (θ) determined by the newly obtained projection diameter d (θ4) and three values d (θ1) and d (θ2) close to this value. The projection diameter d (θ5) of the three-dimensional blood vessel shape data in the projection direction θ5 is measured. The minimum diameter projection direction θmin and the minimum blood vessel diameter d (θmin) are obtained by repeating such processing until the difference between the nth projection direction and the (n + 1) th projection direction is equal to or less than a preset value.

  On the other hand, the stenosis site detection unit 15 analyzes the analysis range for calculating the stenosis rate based on the analysis start point and analysis end point specified by the operator from the input unit 18 with respect to the minimum diameter curve generated in the minimum blood vessel diameter detection unit 14. And a function for detecting a stenosis site and a normal site by setting a regression line for the minimum diameter curve in the analysis range and comparing the regression line with the minimum diameter curve. .

  Next, the temporary normal blood vessel setting unit 16 estimates the normal blood vessel by interpolating or extrapolating the three-dimensional blood vessel shape data in the normal region automatically set with the minimum diameter curve to the stenosis region, Three-dimensional blood vessel shape data of a temporary normal blood vessel that is continuous with the three-dimensional blood vessel shape data is set.

  In addition, the stenosis rate calculating unit 17 detects the minimum blood vessel diameter detected by the minimum blood vessel diameter detecting unit 14 at a plurality of positions in the blood vessel axis direction at the stenotic site detected by the stenotic site detector 15 and the minimum of these. The diameter stenosis rate Std is calculated based on the detection result of the projection diameter of the temporary normal blood vessel in the substantially same direction as the minimum diameter projection direction in which the blood vessel diameter is obtained. Then, the maximum value Std (max) of the diameter stenosis rate is detected from a plurality of values of the diameter stenosis rate Std obtained at different positions in the blood vessel axis direction.

  Further, the stenosis rate calculating unit 17 reads out the blood vessel contour line of the stenosis site and the blood vessel contour line of the temporary normal blood vessel at a predetermined position in the blood vessel axis direction from the three-dimensional blood vessel shape data of the stenosis site, and surrounds these contour lines. The area stenosis rate Sts is calculated based on the area of the stenosis site and the area of the temporary normal blood vessel. Further, the area stenosis rate Sts is measured for a plurality of positions in the vascular axis direction by the same procedure, and the maximum value Sts (max) of the area stenosis rate is obtained from the obtained values of the area stenosis rates Sts. To detect.

  The display unit 19 includes a display data generation circuit and a monitor (not shown). The volume rendering image data generated by the rendering image data generation unit 12, the three-dimensional blood vessel shape data generated by the blood vessel shape data generation unit 13, and the minimum Image data such as a minimum diameter curve generated by the blood vessel diameter detection unit 14 and a graph are displayed. Further, the range of the stenosis detected by the stenosis site detection unit 15 and the diameter calculated by the stenosis rate calculation unit 17 are displayed. Numerical values of the maximum value Std (max) of the stenosis rate and the maximum value Sts (max) of the area stenosis rate are displayed. At this time, the display data generation circuit generates display data by combining the image data, the graph, and various measurement values, and displays the display data on the monitor.

  On the other hand, the input unit 18 is an interactive interface including an input device such as a keyboard, a trackball, and a mouse on a control panel and a display panel, and inputs patient information and various command signals, and MPR image data for volume rendering image data. Position designation, setting of the blood vessel core line in the MPR image data, and further setting of an analysis range for detecting a stenosis site and calculating a stenosis rate.

  The system control unit 20 includes a CPU and a storage circuit (not shown), and controls each unit and the entire system based on a command signal from the input unit 18.

(Stenosis rate calculation procedure)
Next, a procedure for calculating a stenosis rate by the vascular stenosis rate analyzing apparatus 100 according to the present embodiment will be described with reference to FIGS. FIG. 4 is a flowchart showing the procedure for calculating the stenosis rate.

(Saving 3D image data)
First, the operator of the vascular stenosis rate analyzing apparatus 100 uses the input unit 18 as subject information and examination information as subject ID, subject name, date of birth, date of image data collection, diagnostic device name, imaging. Enter the target blood vessel name.

  The system control unit 20 that has received these pieces of information requests the three-dimensional image data corresponding to the input data to the medical image diagnostic device 21 having the name of the diagnostic device input at the input unit 18. Here, the three-dimensional image data is assumed to be volume data obtained by helical scanning of an X-ray CT apparatus, but other medical devices such as a multi-slice method of an X-ray CT apparatus, an MRI apparatus, and an ultrasonic diagnostic apparatus. Volume data obtained by an image diagnostic apparatus or a plurality of adjacent two-dimensional image data may be used.

  Then, the desired volume data supplied from the medical image diagnostic apparatus 21 is stored in the three-dimensional image data storage unit 11 of the vascular stenosis rate analyzing apparatus 100. The volume data is normally supplied from the medical image diagnostic apparatus 21 via a network or the like, but may be supplied by a large-capacity storage medium such as a magneto-optical desk (step S1 in FIG. 4).

(Generation of volume rendering image data)
On the other hand, the rendering image data generation unit 12 reads the volume data stored in the three-dimensional image data storage unit 11, and sets the opacity and color tone (including black and white) corresponding to each voxel value of the volume data. Volume rendering image data is generated and temporarily stored in an internal storage circuit (step S2 in FIG. 4).

(Generation of 3D blood vessel shape data)
Next, the blood vessel shape data generation unit 13 applies the Bessel tracking method to the volume rendering image data obtained by the rendering image data generation unit 12 to generate three-dimensional blood vessel shape data related to the inner diameter of the blood vessel.

  That is, the blood vessel shape data generation unit 13 first reads out the volume rendering image data stored in the storage circuit of the rendering image data generation unit 12 and displays it on the display unit 19. Next, based on the position information of the blood vessel cross section set by the operator in the displayed volume rendering image data, a plurality of two-dimensional image data are read from the volume data stored in the rendering image data generation unit 12. MPR image data is generated and displayed on the display unit 19.

  FIG. 5 shows the blood volume rendering image data 31 displayed on the monitor of the display unit 19 at this time, and the MPR image data 32 to 34 at the MPR image generation positions 35 to 37 set in the volume rendering image data 31. ing. The MPR image generation position 35 set in the volume rendering image data 31 indicates a cross-sectional position for designating the start point Ps of the blood vessel core line when generating the three-dimensional blood vessel shape data, and the MPR image generation position 36 is The cross-sectional position for designating the passage point Pb of the blood vessel core line, and the MPR image generation position 37 indicate the cross-sectional position for designating the end point Pe of the blood vessel core line.

  When the operator changes the MPR image generation positions 35 to 37 by using the input device of the input unit 18, the blood vessel shape data generation unit 13 newly sets the MPR image data at the updated position. Generated and displayed on the display unit 19. The MPR image generation position 36 for designating the passage point Pb of the blood vessel core line may be set at a plurality of locations.

  The start point Ps, passage point Pb, and end point Pe of the blood vessel core line are designated by the operator for the MPR image data displayed on the display unit 19 by the above-described method. Next, the blood vessel shape data generation unit 13 that has received the start command for generating the three-dimensional blood vessel shape data from the system control unit 20 automatically sets the blood vessel core line based on the position information of the start point Ps, the passage point Pb, and the end point Pe. . Furthermore, the blood vessel inner wall is detected in a plurality of cross sections perpendicular to the blood vessel core line, the blood vessel contour point and the blood vessel contour line are set, and the blood vessel contour line is synthesized in the direction of the blood vessel axis to thereby obtain the three-dimensional blood vessel shape data. Is generated.

  Next, the torsional correction already described in FIG. 2 is performed on the obtained three-dimensional blood vessel shape data, and the corrected three-dimensional blood vessel shape data is stored in the internal storage circuit and displayed on the display unit 19 (FIG. 4). Step S3).

  FIG. 6 shows the three-dimensional blood vessel shape data displayed at this time. The three-dimensional blood vessel shape data includes a blood vessel core line 41 and a blood vessel contour surface (blood vessel surface) 43. The blood vessel contour surface 43 is a blood vessel contour line on a plurality of planes 45-1 to 45-N orthogonal to the blood vessel core line 41. 42 is synthesized and formed in the blood vessel axis direction 44.

(Detection of minimum blood vessel diameter and generation of minimum diameter curve)
Next, the minimum blood vessel diameter detecting unit 14 measures the projection diameter of the blood vessel by a projection process from a predetermined direction perpendicular to the blood vessel axis at a predetermined position in the blood vessel axis direction in the three-dimensional blood vessel shape data. The minimum diameter projection direction in which the projection diameter is the smallest among the plurality of projection diameter data obtained by performing such projection processing around the blood vessel axis (in the range of 0 to 180 degrees), and the minimum diameter projection direction The value of the minimum blood vessel diameter obtained in step 1 is obtained (step S4 in FIG. 4).

  In the above projection processing, the projection diameter d (θ) of the blood vessel obtained in the projection direction θ is, as shown in FIG. 7, two projection optical axes 46-1 that are in contact with the blood vessel contour 42 and parallel to the projection direction θ. And the distance between the lines of 46-2. In this case, an X axis 48 perpendicular to the projection direction θ is set with the reference point 47 arbitrarily set inside the blood vessel outline 42 as the origin, and each point of the blood vessel outline 42 on the axis of the X axis 48 is set. (Vessel contour points) P1 to PM are projected. Next, by adding the maximum projection length d (+) in the positive direction of the X axis extracted from the projection lengths d1 to dM obtained at this time and the maximum projection length d (−) in the negative direction of the X axis. The projected diameter d (θ) can be obtained.

  In addition, when obtaining the accurate minimum blood vessel diameter and minimum diameter projection direction only by the above-described method, it is necessary to increase the number of projection directions and the number of points on the blood vessel contour line. The problem is that the processing time also increases. For this reason, the previously described Brent method is applied to the projection diameter data obtained with a small number of projection directions (for example, a rough projection angle interval of about 15 degrees) or the number of blood vessel contour points, and the minimum blood vessel diameter and the minimum diameter projection direction are determined. Ask.

  Next, the measurement of the minimum blood vessel diameter and the minimum diameter projection direction is repeated along the blood vessel axis direction, and the minimum diameter curve indicating the change of the minimum blood vessel diameter with respect to the blood vessel axis direction using the obtained plurality of minimum blood vessel diameter data. Is generated. Then, the generated minimum diameter curve is displayed on the display unit 19 together with the already obtained three-dimensional blood vessel shape data (step S5 in FIG. 4).

  FIG. 8 shows three-dimensional blood vessel shape data 51, a minimum diameter curve 52, and two-dimensional image data (MPR image data) 53 extracted from the volume data, which are displayed on the monitor of the display unit 19 at this time. The minimum diameter curve 52 is a distance along the blood vessel core line 41 from the start point Ps of the blood vessel core line 41 set in the three-dimensional blood vessel shape data 51 on the vertical axis, and the minimum blood vessel diameter at an arbitrary distance on the blood vessel core line 41. A change curve 56 of the minimum blood vessel diameter with respect to the blood vessel axis direction is shown with the value as the horizontal axis.

  Then, if the marker 55-1 is set on the narrowed portion 54 of the minimum diameter curve 52 displayed on the display unit 19 by the input device of the input unit 18, the marker 55-2 is set on the same part of the three-dimensional blood vessel shape data. Is automatically set, and the MPR image data 53 in the cross section where the marker 55-1 or the marker 55-2 is set is displayed. Further, in this MPR image data, the minimum diameter projection direction in the narrowed portion 54 is displayed by an arrow 57.

  On the other hand, the operator can observe the MPR image data of the blood vessel cross section at a desired position by dragging the marker 55-1 on the change curve 56 of the minimum blood vessel diameter. Can be easily grasped.

(Analysis range setting)
Next, the analysis range is set and the stenosis site is detected using the minimum diameter curve 52 obtained by the minimum blood vessel diameter detection unit 14. First, the operator uses the input unit 18 input device to input the start point marker Qs and end point marker Qe of the minimum diameter curve 52 corresponding to the start point Ps and end point Pe in the three-dimensional blood vessel shape data 51 displayed on the display unit 19 of FIG. Use to select. Next, a duplicate marker (analysis start point marker) Qxs of the start point marker Qs or a duplicate marker (analysis end point marker) Qxe of the end point marker Qe that is newly displayed when the marker is selected is displayed on the change curve 56 in the minimum diameter curve. Drag to the desired position and set the area between these two markers as the analysis range. At this time, the analysis start point marker Qxs and the analysis end point marker Qxe are also displayed at the corresponding positions of the three-dimensional blood vessel shape data (step S6 in FIG. 4).

  The analysis range set by the analysis start point marker Qxs and the analysis end point marker Qxe may be set in the three-dimensional blood vessel shape data 51. The analysis start point marker Qxs and the analysis end point marker Qxe set at this time are the minimum diameter curve. 52 is also displayed. When the start point marker Qxs and the end point marker Qxe are not specified, the range specified by the start point Ps and the end point Pe is set as the analysis range in stenosis site detection as it is.

(Detection of normal and stenotic sites)
Next, the stenosis part detection unit 15 automatically detects a normal part and a stenosis part in the blood vessel using the minimum diameter curve obtained by the minimum blood vessel diameter detection unit 14. In this case, since the minimum diameter curve is generated based on the projected diameters in a plurality of directions perpendicular to the blood vessel axis, it can be considered as an index indicating the three-dimensional unevenness of the blood vessel. A procedure for detecting a stenosis site and a normal site will be described with reference to the flowchart shown in FIG.

  The stenosis site detection unit 15 sets a regression line 61 for the minimum blood vessel diameter change curve 56 in the minimum diameter curve in which the analysis range is set as shown in FIG. 10A (step S21 in FIG. 9). Next, the change curve 56 is compared with the straight line 62 obtained by multiplying the linear function of the regression line 61 by the coefficient (1-α), and the minimum blood vessel diameter data in the region 63 showing a value smaller than the straight line 62 is deleted (FIG. 9). Step S24). Note that α is an allowable ratio when deleting the minimum blood vessel diameter data in the stenosis portion, and is set in advance, for example, 10%.

  After deleting the minimum blood vessel diameter data indicating a value smaller than the straight line 62, a regression line is set again using only the minimum blood vessel diameter data of the remaining region 64, and the reset regression line and the region 64 are set again. Are compared with each other, and the minimum blood vessel diameter data having a value smaller than the regression line is deleted. Such a procedure is repeated (step S25 and step S26 in FIG. 9). For example, in FIG. 10B, when the ratio of the number of remaining minimum blood vessel diameter data becomes a preset remaining ratio β%, or When the position of the regression line 65 that has been repeatedly reset does not change, the region 66 in which the minimum blood vessel diameter data remains is detected as a normal region, and the deleted region 67 is detected as a stenosis region (step S25 in FIG. 9 and Step S27).

  However, when the slope of the regression line set at the first time is γ (for example, γ = 0.1) or more, and the ratio of the minimum diameter B / A at the two points where the regression line set at the first time and the minimum diameter curve intersect Is equal to or less than ω (for example, ω = 0.4), the end of the analysis range is regarded as a stenosis site, and an average value straight line without an inclination is set instead of the regression line (step S22 and step S22 in FIG. 9). S23). Then, the minimum blood vessel diameter data having a value smaller than this average value straight line is deleted (step S24 in FIG. 9), and the regression line is repeatedly set in the same manner as described in FIG. 10 after the second time (FIG. 9). In steps S24 to S26), the stenosis part and the normal part are detected (step S27 in FIG. 9).

  That is, as shown in FIG. 11A, when the end of the analysis range is stenosis (end stenosis), the minimum blood vessel diameter data of the normal part is compared with the straight line 72 based on the regression line 71. a1 is deleted, and therefore the normal site and the stenosis site cannot be accurately detected. In order to deal with such a problem, in the present embodiment, whether or not the end stenosis is based on the value of the slope γ of the regression line 71 and the value ω of the minimum diameter ratio of the two points where the regression line intersects the minimum diameter curve. In the case of end stenosis, as shown in FIG. 11 (b), the minimum blood vessel diameter data at the end stenosis site is deleted by comparison with a straight line 74 based on the average value straight line 73, and then FIG. The normal part 75 and the stenosis part 76 are detected by the same regression line method (step S7 in FIG. 4).

(Generation of temporary normal blood vessel data)
If the stenosis part is automatically detected by the above-described procedure, the three-dimensional normal blood vessel data (provisional normal blood vessel data) in the stenosis part can be obtained by interpolating or extrapolating the three-dimensional blood vessel shape data in the normal part to the stenosis part. Set up. In this case, temporary normal blood vessel data may be generated by setting a regression line in the three-dimensional blood vessel shape data in the normal region (step S8 in FIG. 4).

(Calculation of stenosis rate)
If the provisional normal blood vessel data is set, the stenosis rate calculation unit 17 calculates the stenosis rate in the analysis range based on the provisional normal blood vessel data and the minimum blood vessel diameter data of the minimum diameter curve. FIG. 12 shows a blood vessel contour 81 of the temporary normal blood vessel at a predetermined position in the blood vessel axis direction and a blood vessel contour 82 of the stenosis portion in the same portion obtained from the three-dimensional blood vessel shape data, and the minimum blood vessel diameter d (θmin ) Is calculated as the projection diameter Fr (θmin) of the temporary normal blood vessel in the same projection direction as the minimum diameter projection direction θmin in which the projection is performed. The diameter stenosis rate Std is calculated by substituting these values into the following equation (2).

Further, the area Ar surrounded by the blood vessel contour 81 of the provisional normal blood vessel and the area A surrounded by the blood vessel contour 82 of the stenosis site are calculated, and the area stenosis rate Sts is calculated by the following equation (3). (Step S9 in FIG. 4).

  Next, after calculating the diameter stenosis rate Std and the area stenosis rate Sts at all positions within the analysis range in the blood vessel axis direction, the maximum value (maximum diameter stenosis rate) Std (max) and the area stenosis rate Sts are calculated. The maximum value (maximum area stenosis rate) Sts (max), the position in the blood vessel axis direction indicating these maximum stenosis rates, and the like are automatically detected, and the detection result is stored in an internal storage circuit.

(Display of stenosis rate)
The length of the stenosis part (Z2-Z1), the maximum diameter stenosis rate Std (max), the maximum area stenosis rate Sts (max), and the minimum value of the minimum blood vessel diameter data (minimum blood vessel diameter (min)) are automatically determined by the above procedure. If detected, these results are displayed on the display unit 19. FIG. 13 shows a specific example of the display screen at this time, in which three-dimensional blood vessel shape data 51 to which provisional normal blood vessel data (not shown) is added and a minimum diameter curve 52 are displayed. MPR image data 53 corresponding to the position of the marker 55 set in the data 51 or the minimum diameter curve 52 is displayed. In addition, the MPR image data 53 shows the blood vessel contour 81 of the temporary normal blood vessel generated from the three-dimensional blood vessel shape data 51, the blood vessel contour 82 of the stenosis, and the direction arrow 57 of the minimum blood vessel diameter. ing.

  The three-dimensional blood vessel shape data 51 is displayed as a color map on the basis of the diameter stenosis rate Std and the area stenosis rate Sts, and the provisional normal blood vessel data changes the transparency and the blood vessel data of the stenosis portion in the three-dimensional blood vessel shape data 51. Is superimposed on the screen. Further, the stenosis range Z1 to Z2, the maximum stenosis rate position 91, the minimum vascular diameter (min) position 92, and the like are superimposed on the three-dimensional blood vessel shape data 51 and the minimum diameter curve 52, and the maximum stenosis rate Std ( Max) and Sts (max), the length of the stenosis site, the minimum blood vessel diameter (min), and the like are displayed (step S10 in FIG. 4). However, in the three-dimensional blood vessel shape data 51 of FIG. 13, descriptions of the stenosis ranges Z1 to Z2, the maximum stenosis rate position 91, and the minimum blood vessel diameter (min) position 92 are omitted.

  According to the present embodiment described above, since the minimum blood vessel diameter is measured using the three-dimensional blood vessel shape data, an accurate minimum blood vessel diameter that does not depend on the projection direction can be obtained. In addition, since the minimum blood vessel diameter of the stenosis site and the projection diameter of the temporary normal blood vessel used for calculating the stenosis rate are obtained in the same projection direction at the same position in the vascular axis direction, an accurate stenosis rate can be obtained.

  Furthermore, since the stenosis part is automatically detected based on the minimum diameter curve indicating the change of the minimum blood vessel diameter in the vascular axis direction, the position of the stenosis part can always be set objectively, and the reproducible stenosis rate can be increased. Calculation is possible.

  Further, since the minimum diameter curve used in this embodiment is generated based on the three-dimensional information of the blood vessel, it can be regarded as an index indicating the three-dimensional blood vessel unevenness, and the target range for calculating the stenosis rate is It becomes possible to set accurately and easily.

  Furthermore, in the detection of the minimum diameter projection direction, the number of calculation processes can be reduced by applying the Brent method, and therefore the time required for detecting the minimum blood vessel diameter can be greatly reduced.

  On the other hand, it is possible to easily display an MPR image at a desired blood vessel cross section by arbitrarily moving a marker set perpendicular to the blood vessel axis of the three-dimensional blood vessel shape data or the minimum diameter curve, and the intravascular state of the stenotic site can be displayed. Accurate grasp and analysis range can be confirmed. Further, the progress of the stenosis site can be quantified by displaying numerical values such as the stenosis rate simultaneously with the display of the three-dimensional blood vessel shape data, minimum diameter curve, and MPR image data.

  Next, a second embodiment of the present invention will be described. The feature of the present embodiment is that the blood vessel cross-sectional area of the stenosis part measured based on the three-dimensional blood vessel data by the medical image diagnostic apparatus and the normal normal in the stenosis part estimated from the normal blood vessel data around the stenosis part. The purpose is to automatically measure the stenosis rate from the cross-sectional area of the blood vessel.

(Device configuration)
The configuration of the vascular stenosis rate analyzing apparatus in the second embodiment of the present invention will be described below with reference to the functional block diagram of FIG. However, units having the same functions as those in the first embodiment shown in FIG.

  The vascular stenosis rate analyzing apparatus 100 shown in FIG. 14 includes a 3D image data storage unit 11 that stores a plurality of 2D image data and volume data, and a rendering that generates volume rendering image data, as in the first embodiment. An image data generation unit 12 and a blood vessel shape data generation unit 13 that generates three-dimensional blood vessel shape data are provided.

  The blood vessel stenosis rate analyzing apparatus 100 measures the blood vessel cross-sectional area in a predetermined cross section based on the three-dimensional blood vessel shape data and changes the blood vessel cross-sectional area with respect to the blood vessel axis direction (hereinafter referred to as a cross-sectional area curve). Based on the three-dimensional blood vessel shape data of the normal blood vessel around the detected stenosis part, and the stenosis part detection part 26 for detecting the range of the stenosis part based on the cross-sectional area curve. The temporary normal blood vessel setting unit 16 that estimates the shape of the temporary normal blood vessel in the stenosis site, the blood vessel cross-sectional area in the stenosis site, and the blood vessel of the temporary normal blood vessel in the same cross section where the blood vessel cross-sectional area was measured A stenosis rate calculating unit 27 is provided for calculating the stenosis rate of the blood vessel based on the cross-sectional area.

  Further, the vascular stenosis rate analyzing apparatus 100 includes a display unit 19 for displaying a stenosis rate and the like, an input unit 18 for setting a vascular core line and inputting various command signals, and a system for comprehensively controlling the above units. A control unit 20 is provided.

  The blood vessel cross-sectional area measuring unit 25 measures the blood vessel cross-sectional area in a cross section perpendicular to the blood vessel axis of the three-dimensional blood vessel shape data obtained by the blood vessel shape data generating unit 13, and measures the blood vessel cross-sectional area as described above. A function is performed at a plurality of positions along the axis, and a cross-sectional area curve indicating a change in the blood vessel cross-sectional area with respect to the blood vessel axial direction is generated based on the obtained values of the plurality of blood vessel cross-sectional areas.

  On the other hand, the stenosis site detection unit 26 analyzes the stenosis rate calculation range based on the analysis start point and analysis end point specified by the operator from the input unit 18 with respect to the cross-sectional area curve generated in the blood vessel cross-sectional area measurement unit 25. And a function of detecting a stenosis region and a normal region by setting a regression line for the cross-sectional area curve in the analysis range and comparing the regression line with the cross-sectional area curve.

  Further, the stenosis rate calculating unit 27 calculates the blood vessel contour line of the stenosis site at a predetermined position in the blood vessel axis direction and the blood vessel contour of the temporary normal blood vessel from the three-dimensional blood vessel shape data in the range of the stenosis site detected by the stenosis site detector 26. The line is read out, and the stenosis rate is calculated based on the area of the stenosis site surrounded by these contour lines and the area of the temporary normal blood vessel. Further, the stenosis rate is measured at a plurality of positions in the vascular axis direction by the same procedure, and the maximum stenosis rate is detected from the obtained values of the stenosis rate.

(Stenosis rate calculation procedure)
Next, the procedure for calculating the stenosis rate by the vascular stenosis rate analyzing apparatus 100 according to this embodiment will be described with reference to the flowchart of FIG. However, the same steps as those in the first embodiment shown in FIG.

(Generation of blood vessel shape data)
First, the vascular stenosis rate analyzing apparatus 100 stores desired volume data or a plurality of two-dimensional image data supplied from the medical image diagnostic apparatus 21 in the three-dimensional data storage unit 11, and the rendering image data generation unit 12 includes: Volume rendering image data is generated using the volume data. Next, the blood vessel shape data generation unit 13 applies the Bessel tracking method to the two-dimensional image data or volume data to generate three-dimensional blood vessel shape data relating to the inner diameter of the blood vessel (steps S1 to S3 in FIG. 15).

(Measurement of blood vessel cross section and generation of cross section curve)
Next, the blood vessel sectional area measuring unit 25 measures the area of the blood vessel cross section perpendicular to the blood vessel axis at a predetermined position in the blood vessel axis direction in the three-dimensional blood vessel shape data obtained by the blood vessel shape data generating unit 13 ( Step S4a) in FIG. Next, the measurement of the vascular cross-sectional area described above is repeated along the vascular axis direction, and a cross-sectional area curve indicating the change in the vascular cross-sectional area with respect to the vascular axis direction is generated using the obtained data of the plurality of vascular cross-sectional areas. . Then, the generated cross-sectional area curve is displayed on the display unit 19 together with the already obtained three-dimensional blood vessel shape data (step S5a in FIG. 15).

(Set analysis range and detect stenosis)
Next, using the cross-sectional area curve obtained by the blood vessel cross-sectional area measuring unit 25, setting of an analysis range and detection of a stenosis site are performed. First, the operator sets an analysis range using the input device of the input unit 18, and then the stenosis site detection unit 26 uses the blood vessel cross-sectional area measurement unit 25 in the same procedure as in the first embodiment. A normal line and a stenosis part are automatically detected by setting a regression line in the obtained cross-sectional area curve. (Step S6a and Step S7a in FIG. 15).

(Generation of temporary normal blood vessel data)
If the stenosis part is automatically detected by the above-described procedure, three-dimensional provisional normal blood vessel data in the stenosis part is generated by interpolating or extrapolating the three-dimensional blood vessel shape data in the normal part to the stenosis part (FIG. 15 step S8).

(Calculation of stenosis rate)
If the provisional normal blood vessel data is set, the stenosis rate calculating unit 27 calculates the stenosis rate in the analysis range based on the provisional normal blood vessel data and the three-dimensional blood vessel shape data. That is, the area stenosis rate Sts is calculated based on the area surrounded by the blood vessel contour line of the temporary normal blood vessel and the area surrounded by the blood vessel contour line of the stenosis site, and further, all the areas within the analysis range in the blood vessel axis direction are calculated. After calculating the area stenosis rate Sts at the position, the maximum value Sts (max) of the area stenosis rate Sts is automatically detected, and the detection result is displayed on the display unit 19 (steps S9a and S10a in FIG. 15).

  According to the second embodiment described above, since the blood vessel cross section of the stenosis site and the blood vessel cross section of the temporary normal blood vessel at the same position in the blood vessel axis direction are measured using the three-dimensional blood vessel shape data, accurate stenosis is achieved. The rate can be calculated in a short time. In particular, since the cross-sectional area curve used to detect the stenosis can be directly generated from the three-dimensional blood vessel shape data, detection of the minimum blood vessel diameter and the minimum diameter projection direction is not required, and the analysis efficiency is greatly improved. .

  Furthermore, since the stenosis part is automatically detected based on the cross-sectional area curve indicating the change in the cross-sectional area of the blood vessel in the vascular axis direction, the position of the stenosis part can always be set objectively, and the reproducible stenosis rate Can be calculated.

  As mentioned above, although the Example of this invention was described, this invention is not limited to the above-mentioned Example, It can be implemented in various deformation | transformation. For example, in the above-described embodiment, the display of the minimum diameter curve has been described. However, the calculated diameter stenosis rate, area stenosis rate, stenosis rate curve indicating changes in the vascular axis direction of these stenosis rates, A cross-sectional area curve or a minimum diameter curve indicating a change in the area or minimum blood vessel diameter in the blood vessel axis direction may be displayed on the display unit 19.

  The three-dimensional blood vessel shape data may be generated not only by the surface rendering method but also by other methods such as a wire frame method.

  Further, color map display based on the value of the stenosis rate may be performed in the three-dimensional blood vessel shape data, or the shape data of the temporary normal blood vessel may be superimposed and displayed on the blood vessel shape data of the stenosis portion. By such a display method, it is possible to simultaneously observe information on the blood vessel shape and the degree of stenosis.

  On the other hand, the position of the start point and end point of the three-dimensional blood vessel shape data set by the operator, and the position of the analysis start point and analysis end point for determining the analysis range may be inappropriate during various measurements. When it becomes clear, the measurement may be performed again after updating the position.

1 is a functional block diagram of a blood vessel stenosis rate analyzing apparatus in a first embodiment of the present invention. The figure which shows the twist correction | amendment of the blood vessel shape in the Example. The figure which shows the principle of the minimum diameter projection direction estimation in the Example. The flowchart which shows the procedure of the stenosis rate calculation in the Example. The figure which shows the MPR image for the blood vessel axis setting in the Example. The figure which shows the three-dimensional blood vessel shape data in the Example. The figure shown about the projection direction and the projection diameter of the blood vessel in the Example. The figure which shows the three-dimensional blood vessel shape data, minimum diameter curve, and MPR image data which are displayed on the display part of the Example. The flowchart which shows the detection procedure of the stenosis site | part and the normal site | part in the Example. The figure which shows the detection method of a stenosis site | part and a normal site | part in the Example. The figure which shows the other detection methods of the stenosis site | part and the normal site | part in the Example. The figure which shows the blood vessel outline of the temporary normal blood vessel in the Example, and the blood vessel outline of a stenosis site | part. The figure which shows the three-dimensional blood vessel shape data, minimum diameter curve, MPR image data, and measured value data which are displayed on the display part of the Example. The functional block diagram of the blood vessel stenosis rate analysis apparatus in 2nd Example of this invention. The flowchart which showed the procedure of the stenosis rate calculation in the Example. The figure which shows the prior art example with respect to this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Three-dimensional image data storage part 12 ... Rendering image data generation part 13 ... Blood vessel shape data generation part 14 ... Minimum blood vessel diameter detection part 15 ... Stenosis site | part detection part 16 ... Temporary normal blood vessel setting part 17 ... Stenosis rate calculation part 18 ... Input unit 19 ... display unit 20 ... system control unit 100 ... blood vessel stenosis rate analysis device

Claims (22)

Blood vessel shape data generating means for generating three-dimensional blood vessel shape data based on the three-dimensional image information obtained by the medical image diagnostic apparatus;
Minimum blood vessel diameter detection that detects the minimum diameter projection direction in which the projection diameter of the blood vessel inner wall is minimum and the projection diameter in the minimum diameter projection direction as the minimum blood vessel diameter in a cross section substantially perpendicular to the blood vessel axis of the generated blood vessel shape data Means,
A stenosis part detection means for detecting a normal part and a stenosis part of a blood vessel based on the minimum blood vessel diameter detected by the minimum blood vessel diameter detection means in the plurality of cross sections within a predetermined analysis range along the blood vessel axis;
Provisional normal blood vessel setting means for setting three-dimensional provisional normal blood vessel shape data in the stenotic region based on the blood vessel shape data in the normal region;
An apparatus for analyzing a stenosis rate, comprising: a stenosis rate calculating means for calculating a stenosis rate based on the blood vessel shape data and the provisional normal blood vessel shape data at the stenosis site. Blood vessel shape data generating means for generating three-dimensional blood vessel shape data based on the three-dimensional image information obtained by the medical image diagnostic apparatus;
A cross-sectional area measuring means for measuring a blood vessel cross-sectional area in a cross section substantially perpendicular to the blood vessel axis of the generated blood vessel shape data;
A stenosis part detecting means for detecting a normal part and a stenosis part of a blood vessel based on a blood vessel cross-sectional area measured by the cross-sectional area measuring means in the plurality of cross sections within a predetermined analysis range along the blood vessel axis;
Provisional normal blood vessel setting means for setting three-dimensional provisional normal blood vessel shape data in the stenotic region based on the blood vessel shape data in the normal region;
An apparatus for analyzing a stenosis rate, comprising: a stenosis rate calculating means for calculating a stenosis rate based on the blood vessel shape data and the provisional normal blood vessel shape data at the stenosis site.   The blood vessel shape data generation means sets a start point, a passage point, and an end point of the blood vessel core line for MPR image data in a plurality of cross sections substantially perpendicular to the blood vessel axis of the volume rendering image data. The blood vessel stenosis rate analyzing apparatus according to claim 1 or 2.   The blood vessel shape data generation means corrects the correspondence of the blood vessel axis direction to the blood vessel contour points on the plurality of blood vessel contour lines set based on the three-dimensional image information obtained from the medical image diagnostic apparatus. The blood vessel stenosis rate analyzing apparatus according to claim 1 or 2, wherein the blood vessel shape data is generated by performing synthesis after performing.   In a cross-section substantially perpendicular to the blood vessel axis of the blood vessel shape data, there is provided means for calculating a projection diameter in a predetermined direction and means for calculating a projection direction and a projection diameter at which the calculated projection diameter is minimum by an optimization method. The blood vessel stenosis rate analyzing apparatus according to claim 1 or 2, wherein   The blood vessel stenosis rate analyzing apparatus according to claim 5, wherein the optimization method is a Brent method.   Means for generating a minimum diameter curve indicating a change in the minimum blood vessel diameter with respect to the blood vessel axis direction using a plurality of the minimum blood vessel diameters detected in a plurality of cross sections substantially perpendicular to the blood vessel axis of the blood vessel shape data. The blood vessel stenosis rate analyzing apparatus according to claim 1 or 2.   Means for generating a cross-sectional area curve indicating a change in blood vessel cross-sectional area with respect to the direction of the blood vessel axis, using a plurality of the blood vessel cross-sectional areas detected in a plurality of cross-sections substantially perpendicular to the blood vessel axis of the blood vessel shape data. The blood vessel stenosis rate analyzing apparatus according to claim 1 or 2.   The stenosis site detecting means is set for a plurality of the minimum blood vessel diameters with respect to the blood vessel axis direction generated by the minimum blood vessel diameter detecting means or a plurality of the blood vessel cross-sectional areas with respect to the blood vessel axis direction generated by the cross-sectional area measuring means. The stenosis rate analyzing apparatus according to claim 1 or 2, wherein the stenosis part is detected by comparison with a regression line.   The stenosis site detecting means is configured to determine a slope of a regression line set for a plurality of the minimum blood vessel diameters or a plurality of the blood vessel cross-sectional areas with respect to the blood vessel axis direction and blood vessel diameters or cross-sectional areas at two different points on the regression line. When the ratio is larger than a preset value, the minimum blood vessel diameter data or blood vessel cross-sectional area data smaller than the average line set based on these data is deleted, and then the remaining plurality of minimum blood vessel diameter data or The blood vessel stenosis rate analyzing apparatus according to claim 9, wherein the stenosis site is detected by comparison with a regression line set for blood vessel cross-sectional area data.   3. The blood vessel stenosis rate analyzing apparatus according to claim 1, wherein the stenosis region detecting unit detects the stenosis region in an analysis range set or updated by the input unit.   3. The provisional normal blood vessel setting means sets the provisional normal blood vessel shape data by interpolating or extrapolating blood vessel shape data at the normal site to the stenosis portion. Described blood vessel stenosis rate analysis device.   The stenosis rate calculating means includes the minimum blood vessel diameter detected in a cross section substantially perpendicular to the blood vessel axis of the blood vessel shape data, and the provisional normal blood vessel shape data in the minimum diameter projection direction of a cross section substantially the same as the cross section. The stenosis rate analyzing apparatus according to claim 1 or 2, wherein the stenosis rate is calculated based on a blood vessel diameter.   The stenosis rate calculating means includes a blood vessel cross-sectional area of the stenosis site detected in a cross section substantially perpendicular to a blood vessel axis of the blood vessel shape data, and a blood vessel cross-sectional area of the provisional normal blood vessel shape data in a cross section substantially the same as the cross section. The stenosis rate analyzing apparatus according to claim 1 or 2, wherein the stenosis rate is calculated based on the stenosis rate.   Display means, the display means, in addition to the stenosis rate calculated by the stenosis rate calculation means, the blood vessel shape showing the measurement position of the blood vessel diameter or the blood vessel area used for the calculation of the stenosis rate The blood vessel stenosis according to claim 7 or 8, wherein at least one of data, the minimum diameter curve or the cross-sectional area curve indicating the measurement position, and MPR image data at the measurement position is displayed. Rate analysis device.   9. A blood vessel stenosis rate analyzing apparatus according to claim 7, further comprising display means, wherein the display means displays the blood vessel shape data in correspondence with the minimum diameter curve or the cross-sectional area curve. .   The display unit includes a display unit, and the display unit superimposes and displays the start point marker and the end point marker on the image data based on the position information of the start point and the end point of the blood vessel shape data input by the input unit with respect to the image data. The blood vessel stenosis rate analyzing apparatus according to claim 1 or 2.   The input means moves the start point marker and end point marker superimposed on the blood vessel shape data, the minimum diameter curve, or the cross-sectional area curve to a desired position in the blood vessel axis direction by the display means. 9. The stenosis rate analyzing apparatus according to claim 7, wherein setting or updating is performed.   16. The blood vessel stenosis rate analyzing apparatus according to claim 15, wherein the display unit displays the blood vessel shape data in a color map based on the value of the stenosis rate calculated by the stenosis rate calculating unit.   The blood vessel stenosis rate analyzing apparatus according to claim 19, wherein the display means displays the normal blood vessel shape data whose transparency is changed with respect to the blood vessel shape data. Generating three-dimensional blood vessel shape data based on the three-dimensional image information obtained by the medical image diagnostic apparatus;
Detecting a minimum diameter projection direction in which a projection diameter of a blood vessel inner wall is minimum and a projection diameter in the minimum diameter projection direction as a minimum blood vessel diameter in a cross section substantially perpendicular to the blood vessel axis of the generated blood vessel shape data;
Generating a minimum diameter curve based on the minimum blood vessel diameter in a plurality of the cross sections within a predetermined analysis range along the blood vessel axis;
Detecting a normal site and a stenotic site of the blood vessel based on the minimum diameter curve;
Setting three-dimensional provisional normal blood vessel shape data in the stenotic region based on the blood vessel shape data in the normal region;
A blood vessel stenosis rate analysis method comprising calculating a stenosis rate based on the blood vessel shape data and the provisional normal blood vessel shape data at the stenosis site. Generating three-dimensional blood vessel shape data based on the three-dimensional image information obtained by the medical image diagnostic apparatus;
Measuring a blood vessel cross-sectional area in a cross section substantially perpendicular to a blood vessel axis of the generated blood vessel shape data;
Generating a cross-sectional area curve based on the blood vessel cross-sectional area in a plurality of the cross-sections within a predetermined analysis range along the blood vessel axis;
Detecting a normal site and a stenosis site of the blood vessel based on the generated cross-sectional area curve;
Setting three-dimensional provisional normal blood vessel shape data in the stenotic region based on the blood vessel shape data in the normal region;
A blood vessel stenosis rate analysis method comprising calculating a stenosis rate based on the blood vessel shape data and the provisional normal blood vessel shape data at the stenosis site.

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