JP7724648B2 - Myocardial blood flow dynamics analysis method, myocardial blood flow dynamics analysis device, and myocardial blood flow dynamics analysis program - Google Patents

Description

The present invention relates to a myocardial hemodynamic analysis method, a myocardial hemodynamic analysis device, and a myocardial hemodynamic analysis program.

Myocardial hemodynamic analysis is a method for examining cardiac health by analyzing myocardial blood flow and energy metabolism. This analysis often uses nuclear medicine techniques such as PET and SPECT. One example is a method for creating a time activity curve (TAC) in a region of interest set in the left ventricular cavity and left ventricular myocardium to evaluate how blood is taken up into the myocardium. A TAC is a curve that shows the change over time in the count values obtained by measuring the amount of radiation emitted from a radiopharmaceutical administered to the body over a specified time interval.

A radiopharmaceutical administered to a subject travels through the right and left ventricular cavities of the heart and into the left ventricular myocardium. At this time, due primarily to the influence of cardiac pulsation, the TAC of the left ventricular myocardium overlaps with the radioactivity counts as the drug passes through the right and left ventricular cavities, particularly in the early phase of administration, resulting in an overestimation of the count value. This phenomenon is called spillover. To accurately quantify myocardial blood flow, it is necessary to correct for the effects of spillover.

Patent Document 1 describes a technology that corrects for the effects of spillover by calculating an approximate curve that approximates the bulging portion of the TAC in the left ventricular cavity using a normal distribution, and an approximate straight line that approximates the equilibrium section of the TAC in the left ventricular myocardium, and then connecting the rising point of the approximate curve with the intersection point of the approximate curve and the approximate straight line using a theoretical formula.

Japanese Patent Application Laid-Open No. 2019-207183

The objective of the present invention is to provide technology for more accurately quantifying myocardial blood flow in nuclear medicine examinations.

One embodiment of the present invention is a method for correcting a time activity curve (TAC) of the left ventricular myocardium in myocardial hemodynamic analysis, which includes determining a correction start time index for starting the correction based on the right ventricular lumen TAC. In particular, determining the correction start time index includes determining the correction start time index based on the time index at which the right ventricular lumen TAC peaks.

In some embodiments, the correction may be a spillover correction.

In myocardial hemodynamic analysis, a radiopharmaceutical administered to a subject travels through the right and left ventricular cavities of the heart and then migrates to the left ventricular myocardium. Therefore, it is expected that the radiopharmaceutical will begin to migrate to the left ventricular myocardium at the earliest around the time when the right ventricular cavity TAC peaks. Therefore, by determining the correction start time index for starting spillover correction of the left ventricular myocardium TAC based on the time index when the right ventricular cavity TAC peaks, it is possible to appropriately set this correction start time index.

The term "time index" refers to the value on the time axis of a TAC. A TAC is a curve that represents the change in radiation count values over time, and various methods can be used to determine the value on the time axis. For example, the time axis value can be the number of seconds from the time the radioactive drug was administered, the number of seconds from the start of radiation collection, or the actual time. The measurement event number of the radiation count value can also be used; for example, a time axis value of 5 for a data point in a TAC can indicate that this data point was obtained in the fifth measurement. As such, there are various ways to determine the value on the time axis of a TAC, but in this specification, the values on the time axis of a TAC are collectively referred to as the "time index."

[0008] In some embodiments, determining the corrected start time index comprises:
determining the time T between the time index at which the right ventricle lumen TAC peaks and the time index at which a curve obtained by fitting at least a portion of the left ventricle lumen TAC to a normal distribution peaks;
determining a first correction amount based on the time T;
determining the corrected start time index based on a time index obtained by delaying the time index at which the right ventricular lumen TAC peaks by the first correction amount;
may include:

As mentioned above, the start of radiopharmaceutical transfer to the left ventricular myocardium is expected to occur at the earliest when the right ventricular lumen TAC peaks, but more accurately, later than the time when the right ventricular lumen TAC peaks. Therefore, by using the above correction to delay the corrected start time index beyond the time index when the right ventricular lumen TAC peaks, it becomes possible to more appropriately set the corrected start time index. Furthermore, the inventors have discovered that by calculating the first correction amount based on the time T, it becomes possible to appropriately set the corrected start time index.

In the above embodiment, the reason why the peak of the left ventricular lumen TAC is not used directly but rather the peak of the curve obtained by normal distribution fitting of a portion of the left ventricular lumen TAC is used is because the left ventricular lumen TAC has a gentle slope near its apex, making it difficult to clearly identify the peak. In some embodiments, if the peak of the left ventricular lumen TAC can be clearly identified, the time T may be determined using the peak of the left ventricular lumen TAC directly rather than the peak of the curve obtained by normal distribution fitting.

Another example of an embodiment of the present invention is a method for correcting a time activity curve (TAC) of the left ventricular myocardium in myocardial hemodynamic analysis, which includes determining a correction start time index for starting the correction based on the left ventricular cavity TAC. In particular, determining the correction start time index includes determining the correction start time index based on the rising edge of the left ventricular cavity TAC.

The rise of the left ventricular lumen TAC may be defined based on the count value of the left ventricular lumen TAC. For example, it may be defined as the time index at which the count value of the left ventricular lumen TAC first exceeds a predetermined count value, or as a time index a predetermined time earlier than the time index.

In some embodiments, the correction may be a spillover correction.

[0008] In some embodiments, determining the corrected start time index comprises:
determining the time T between the time index at which the left ventricular lumen TAC rises and the time index at which the left ventricular lumen TAC peaks;
determining a first correction amount based on the time T;
determining the corrected start time index based on a time index obtained by delaying the time index at which the left ventricular lumen TAC rises by the first correction amount;
may include:

In some embodiments, one or both of the onset time index and the peak time index may be determined using a curve obtained by fitting at least a portion of the time activity curve of the left ventricular cavity to a normal distribution.

An example of an embodiment of the present invention may further include determining a correction end time index for ending spillover correction of the left ventricular myocardium TAC based on the left ventricular lumen TAC. In particular, determining the correction end time index may include:
determining a second correction amount based on the time T;
determining the corrected end time index based on a time index obtained by delaying by the second correction amount a time index at which a curve obtained by fitting at least a portion of the left ventricular lumen TAC to a normal distribution reaches a peak;
may include:

As mentioned above, in myocardial hemodynamic analysis, the radiopharmaceutical administered to the subject migrates from the left ventricular cavity to the left ventricular myocardium. Therefore, it is believed that spillover of radiation originating from the left ventricular cavity into the left ventricular myocardium TAC continues for a certain period of time after the left ventricular cavity TAC peaks. Therefore, the inventors of the present application discovered that by setting the correction end time index for ending the spillover correction of the left ventricular myocardium TAC based on the time index at which the curve obtained by fitting at least a portion of the left ventricular cavity TAC to a normal distribution peaks, delayed by the second correction amount, it is possible to appropriately set the correction end time index.

Another example of an embodiment of the present invention is a method for performing spillover correction of left ventricular myocardial TAC in myocardial hemodynamic analysis, which includes estimating at least a portion of the spillover-corrected left ventricular myocardial TAC using a logarithmic function based on the value of the left ventricular myocardial TAC at the correction start time index at which the spillover correction begins and the value of the left ventricular myocardial TAC at the correction end time index at which the spillover correction ends.

Logarithmic functions generally have a shape that has a steep rise but quickly levels off. This shape is useful for approximating the shape of the left ventricular myocardial TAC.

An example of the estimation is, at each time index between the corrected start time index and the time index at which a curve obtained by fitting at least a part of the left ventricular cavity TAC to a normal distribution reaches a peak,
Comparing the count value of the left ventricular myocardium TAC after Spillover's correction with the count value of a curve obtained by fitting at least a portion of the left ventricular cavity TAC to a normal distribution;
If the count value of the left ventricular myocardium TAC after Spillover's correction is greater than the count value of the curve obtained by normal distribution fitting to at least a portion of the left ventricular cavity TAC, replacing the count value of the left ventricular myocardium TAC after Spillover's correction with the count value of the curve obtained by normal distribution fitting to at least a portion of the left ventricular cavity TAC;
may include:

Theoretically, due to the order of radiopharmaceutical accumulation, the value of the left ventricular myocardial TAC will never exceed the value of the left ventricular lumen TAC before the peak of the left ventricular lumen TAC after normal distribution fitting. If it did, the estimate of the left ventricular myocardial TAC would be invalid. Therefore, by performing the above comparison and replacement process, the validity of the estimate of the left ventricular myocardial TAC can be confirmed, and if it is invalid, the invalidity can be resolved.

An example of the estimation may include setting the count value of the left ventricular myocardium TAC after spillover correction to 0 before the correction start time index. In other words, it may be assumed that the radiopharmaceutical has not been taken up into the left ventricular myocardium before the correction start time index.

Another embodiment of the present invention includes a system comprising a processing means and a storage means, the system storing program instructions that, when executed by the processing means, are configured to cause the system to perform the method.

Another example of an embodiment of the present invention includes a computer program comprising program instructions configured, when executed by a processing means of a system, to cause the system to perform the method.

FIG. 1 is a diagram illustrating a hardware configuration of a system capable of implementing the present invention. 10 is a flowchart illustrating an example of a process for setting a correction start time index for starting spillover correction of left ventricular myocardial TAC and a correction end time index for ending spillover correction according to the present invention. 10 is an example of graphs showing right ventricle lumen TAC data 130 and left ventricle lumen TAC data 132 used to explain the embodiment. 10A and 10B are diagrams for explaining peak detection processing of the right ventricle lumen TAC and the left ventricle lumen TAC. 10A and 10B are diagrams illustrating examples of corrected start time indexes and corrected end time indexes determined in an embodiment. 1 is a flowchart illustrating an example of spillover correction disclosed in the present application. 10 illustrates the original left ventricular myocardial TAC and the left ventricular myocardial TAC after spillover correction in this example. 1 is a flowchart for introducing an example of the use of spillover correction disclosed in the present application.

Below, examples of preferred embodiments of the technical concepts disclosed in this specification will be described with reference to the accompanying drawings.

Figure 1 is a diagram illustrating the hardware configuration of a system 100 in which the present invention can be implemented. As depicted in Figure 1, system 100 is similar in hardware to a typical computer and may include a CPU 102, a main memory 104, a mass storage device 106, a display interface 107, a peripheral device interface 108, and a network interface 109. As with a typical computer, high-speed RAM (random access memory) can be used for the main memory 104, and inexpensive, high-capacity hard disks or SSDs can be used for the mass storage device 106. A display for displaying information can be connected to system 100 via display interface 107. User interfaces such as a keyboard, mouse, and touch panel can also be connected to system 100 via peripheral device interface 108. The network interface 109 can be used to connect to other computers or the Internet via a network.

The mass storage device 106 stores an operating system (OS) 110 that controls the most basic functions of the system 100. The mass storage device 106 may also store a program 120 for determining a corrected start time index and a corrected end time index used for spillover correction of left ventricular myocardial TAC in myocardial hemodynamic analysis. When executed by the CPU 102, the corrected start/end time index determination program 120 is configured to determine the corrected start time index and the corrected end time index based on the right ventricular lumen TAC data 130 and the left ventricular lumen TAC data 132. The program 120 may also be configured to save the determined corrected start time index and corrected end time index as corrected start/end time index data 140. The right ventricular lumen TAC data 130, the left ventricular lumen TAC data 132, and the corrected start/end time index data 140 may be data stored in the mass storage device 106.

The mass storage device 106 may also store a left ventricular myocardial TAC estimation program 122. When executed by the CPU 102, the program 122 is configured to estimate at least a portion of the left ventricular myocardial TAC after spillover correction based on the correction start and end time index data 140. The left ventricular myocardial TAC estimation program 122 may be configured to use the original left ventricular myocardial TAC data 134 to create the left ventricular myocardial TAC after spillover correction. The program 122 may also be configured to save the entire corrected left ventricular myocardial TAC as left ventricular myocardial TAC data 142. The original left ventricular myocardial TAC data 134 and the corrected left ventricular myocardial TAC data 142 may also be data stored in the mass storage device 106.

The mass storage device 106 may also store an information output program 124. When executed by the CPU 102, the information output program 124 is configured to display the TAC data 130, 132, 134, 142 and the corrected start and end time index data 140 on an external display via the display interface 107 in a format that is easy for the user to view.

In addition to the elements depicted in FIG. 1, system 100 may also include components similar to those found in typical computer systems, such as power supplies and cooling systems. Computer systems can be implemented in a variety of forms using a variety of technologies, including distributed, redundant, and virtualized storage devices, the use of multiple CPUs, CPU virtualization, the use of processors specialized for specific processes such as DSPs, and hardware-based decision-making processes combined with a CPU. The inventions disclosed herein may be implemented on any type of computer system, and their scope is not limited by the type of computer system. The technical concepts disclosed herein can generally be embodied as: (1) a program including instructions configured to cause a device or system including the processing means to perform various processes described herein when executed by the processing means; (2) a method of operating a device or system realized by the processing means executing the program; or (3) a device or system including the program and processing means configured to execute the program. As noted above, some software processing may be implemented in hardware.

It should also be noted that when the system 100 is manufactured, sold, or started up, the TAC data 130, 132, 134, and 142 and the corrected start and end time index 140 may not be stored in the mass storage device 106. The TACs 130, 132, and 134 may be data transferred to the system 100 from an external device, for example, via the peripheral device interface 108 or the network interface 109. The corrected start and end time index 140 and the corrected left ventricular myocardial TAC 142 may be data generated by executing the corrected start and end time index determination program 120 or the left ventricular myocardial TAC estimation program 122. It should be noted that the scope of the invention disclosed herein is not limited by whether or not these data are stored in a storage device.

Next, with reference to the flowchart in Figure 2 and Figures 3A-3C, an example of a process for setting a correction start time index for starting spillover correction of left ventricular myocardial TAC and a correction end time index for ending spillover correction according to the present invention will be described. Depending on the embodiment, this exemplary process 200 may be a process executed by the system 100 as a result of the CPU 102 executing the correction start/end time index determination program 120.

Step 202 indicates the start of processing. In step 204, right ventricular lumen TAC data 130 and left ventricular lumen TAC data 132 are loaded from the mass storage device 106. The right ventricular lumen TAC data 130 and left ventricular lumen TAC data 132 are data obtained by myocardial hemodynamic measurements using an external SPECT device or PET device.

Figure 3A shows an example of a graph displaying the loaded right ventricular lumen TAC data 130 and left ventricular lumen TAC data 132. The values on the horizontal axis of the graph are time-related values, representing the number of seconds from the start of radiation collection. That is, the time index in this example represents the number of seconds from the time of administration of the radiopharmaceutical. The vertical axis represents the radiation count value. In the figure, curve 302 is a curve connecting each data point of the right ventricular lumen TAC data 130, and curve 304 is a curve connecting each data point of the left ventricular lumen TAC data 132. Curve 306 is a curve obtained by normal distribution fitting of a portion of the left ventricular lumen TAC data 132.

In step 206, the peak of the right ventricular lumen TAC is detected. In this example, the data point where the count value is maximum in the right ventricular lumen TAC data 130 is taken as the peak of the right ventricular lumen TAC. In some embodiments, at least a portion of the right ventricular lumen TAC data 130 may be fitted with a normal distribution or the like, and the peak point of this fitting may be taken as the peak of the right ventricular lumen TAC.

In step 208, the peak of the left ventricular lumen TAC is detected. In this example, the peak of the left ventricular lumen TAC is determined as the point where the curve 306 obtained by normal distribution fitting of a portion of the left ventricular lumen TAC data 132 reaches its peak.

The reason for using the peak of a curve obtained by normal distribution fitting a portion of the left ventricular lumen TAC data 132 rather than using the peak of the left ventricular lumen TAC data 132 directly is that the original left ventricular lumen TAC has a gentle slope near its apex, making it difficult to clearly identify the peak. The range of the left ventricular lumen TAC data 132 for normal distribution fitting may be set manually or automatically. When set automatically, for example, a predetermined range around the time index at which the count value in the left ventricular lumen TAC data 132 reaches its maximum may be set as the range for normal distribution fitting. For example, the standard deviation (S.D.) may be calculated within a range of 10 seconds around the time index at which the count value reaches its maximum in the left ventricular lumen TAC data 132, and normal distribution fitting may be performed within a range of 3 S.D. around the time index at which the count value reaches its maximum. Of course, these seconds and ranges are merely examples, and other values may be used. In software implementation, these seconds and ranges may be manually adjustable. In some embodiments, the data point at which the count value in the left ventricular cavity TAC data 132 is maximum may be taken as the peak of the left ventricular cavity TAC.

In Figure 3B, the detected peaks of the right and left ventricular lumen TAC are shown by lines 312 and 314. The horizontal axis value indicated by line 312 is the time axis value at the peak of the right ventricular lumen TAC (i.e., the time index at which the peak of the right ventricular lumen TAC occurs), and the horizontal axis value indicated by line 314 is the time axis value at the peak of the left ventricular lumen TAC (i.e., the time index at which the peak of the left ventricular lumen TAC occurs).

In step 210, the time T between the peak of the right ventricular lumen TAC and the peak of the left ventricular lumen TAC is calculated. The time T may, for example, simply be the value on the time axis at the peak of the left ventricular lumen TAC (i.e., the time index at which the left ventricular lumen TAC peak occurs) minus the value on the time axis at the peak of the right ventricular lumen TAC (i.e., the time index at which the right ventricular lumen TAC peak occurs). An example of the time T is illustrated using the letter T in Figure 3B.

In step 212, the time index at which the spillover correction of the left ventricular myocardium TAC begins is determined. In the present application, this time index is referred to as the correction start time index. In a preferred embodiment, this correction start time index is determined by delaying the time index at which the right ventricular lumen TAC peaks by the correction amount calculated based on the time T calculated in step 210.

This correction amount CV1 can be calculated, for example, by the following formula.
Here, α>1. α is a value that should be determined for each facility depending on the radiopharmaceutical to be administered, but the inventors have found that when a thallium preparation is used as the radiopharmaceutical, an α of about 4 is appropriate.

In step 214, the time index at which the spillover correction of the left ventricular myocardial TAC ends is determined. In the present application, this time index is referred to as the correction end time index. In a preferred embodiment, this correction end time index is determined by delaying the time index at which the left ventricular lumen TAC peaks by the correction amount calculated based on the time T calculated in step 210.

This correction amount CV2 can be calculated, for example, by the following formula.
Here, β > 0. β is also a value that should be determined for each facility depending on the radiopharmaceutical to be administered, but the inventors have found that when a thallium preparation is used as the radiopharmaceutical, a value of approximately 1 is appropriate for β.

Figure 3C shows an example of correction amounts CV1 and CV2 calculated using the data in this example with α = 5 and β = 1. Therefore, the correction start time index in this example is the value on the horizontal axis indicated by line 322, and the correction end time index in this example is the value on the horizontal axis indicated by line 324.

In some embodiments, the correction start time index may be determined without correction using the correction amount CV1. In other words, the time index that gives the peak of the right ventricle lumen TAC may be used as the correction start time index.

In step 216, the calculated corrected start time index and corrected end time index are stored in the mass storage device 106 as corrected start/end time index data 140.

Step 218 is an optional step. In step 218, the calculated corrected start time index and corrected end time index are displayed on an external display as numerical values or graphs. For example, a display such as that shown in FIG. 3C may be provided. This display may be a process performed by the CPU 102 executing the information output program 124.

Step 220 marks the end of process 200.

Process 200 makes it possible to appropriately set the correction start time index for starting spillover correction of left ventricular myocardial TAC and the correction end time index for ending spillover correction in myocardial hemodynamic analysis.

Technetium and thallium preparations are known radiopharmaceuticals used in myocardial hemodynamic analysis. Of these, thallium preparations are known to be more affected by spillovers than technetium preparations. The present invention provides significant advantages over conventional techniques, as it can set an appropriate correction end time index even when thallium preparations are used as the radiopharmaceutical.

Existing methods may be used as specific methods for spillover correction of left ventricular myocardial TAC. For example, the method described in Patent Document 1 can be used. However, this application also discloses a new invention for the method of spillover correction.

Figure 4 is a flowchart illustrating a process 400, which is an example of spillover correction disclosed herein. In some embodiments, this exemplary process 400 may be performed by the system 100 as a result of the CPU 102 executing the left ventricular myocardial TAC estimation program 122.

Step 402 marks the start of the process. In step 404, left ventricular cavity TAC data 132 and left ventricular myocardial TAC data 134 are loaded from the mass storage device 106. Like the left ventricular cavity TAC data 132, the left ventricular myocardial TAC data 134 is data obtained by myocardial hemodynamic measurement using an external SPECT device or PET device. In step 406, corrected start and end time index data 140 is loaded from the mass storage device 106. The corrected start and end time index data 140 is the data stored in the mass storage device 106 in step 216 of the above-mentioned process 200. In some embodiments, processes 200 and 400 may be performed consecutively and integrally, in which case the left ventricular cavity TAC data 132 and the corrected start and end time index data 140 will already be in the main memory device 104. In this case, it goes without saying that there is no need to load these data again.

In step 408, the value of the estimated left ventricular myocardial TAC before the corrected start time index is determined to be 0. In other words, the value of the estimated left ventricular myocardial TAC is set to 0 at the corrected start time index and any time indexes earlier than the corrected start time index.

In step 410, the left ventricular myocardial TAC between the corrected start time index and the corrected end time index is estimated using a logarithmic function. In this embodiment, this is approximated by the following formula:

Estimated left ventricular myocardial count value (corrected start time index + n)
= base value + log ₁₀ (1.0 + ((n/(number of interpolation points) + 1) x 9.0)) x value range

In the above formula:
The number of interpolation points is the correction end time index - the correction start time index - 1.
n is an integer that varies from 1 to the number of interpolation points.
The baseline value is the count value of the left ventricular myocardial TAC at the corrected start time index. In this example, this value is set to 0 in step 408. In some embodiments, the count value of the left ventricular myocardial TAC data 134 at the corrected start time index may be used. In some embodiments, the baseline value may be set to 0 regardless of the actual count value of the TAC data 134.
The value range is calculated by subtracting the count value of the left ventricular myocardial TAC at the corrected start time index from the count value of the left ventricular myocardial TAC at the corrected end time index. In this example, the count value of the left ventricular myocardial TAC data 134 at the corrected end time index is used as the count value of the left ventricular myocardial TAC at the corrected end time index. As described above, in this example, the count value of the left ventricular myocardial TAC at the corrected start time index is set to 0.

In step 412, the validity of the left ventricular myocardial TAC estimated in step 410 is checked. The validity is checked as follows at each time index between the correction start time index and the time index at which the curve obtained by fitting a portion of the left ventricular cavity TAC data 132 to a normal distribution reaches its peak.
The count value of the left ventricular myocardial TAC after spillover correction estimated in step 410 is compared with the count value of the curve.
If the count value of the left ventricular myocardial TAC after Spillover's correction is greater than the count value of the curve, the count value of the left ventricular myocardial TAC after Spillover's correction is replaced with the count value of the curve.

Note that the above curve, i.e., the curve obtained by fitting a portion of the left ventricular cavity TAC data 132 to a normal distribution, may be the curve 306 described in relation to Figure 3A. Therefore, if process 200 and process 400 are performed continuously and integrally, there will be no need to calculate this curve again in step 410.

In step 414, the count value before the corrected start time index is set to 0, the count value between the corrected start time index and the corrected end time index is set to the count value calculated in steps 410 and 412, and the count value after the corrected end time index is set to the count value of the left ventricular myocardial TAC data 134, thereby determining the overall left ventricular myocardial TAC after spillover correction.

In some embodiments, the determined left ventricular myocardial TAC is stored as data 142 in the mass storage device 106 or displayed on an external display (step 416).

Figure 5 graphically displays the original left ventricular myocardial TAC and the left ventricular myocardial TAC after spillover correction in this embodiment. Curve 502 is a graph of left ventricular myocardial TAC data 134, and curve 504 is a graph of left ventricular myocardial TAC data 142 after spillover correction obtained in process 400. Lines 322 and 324 are the same as lines 322 and 324 shown in Figure 3C, and the values on the horizontal axes indicate the corrected start time index and corrected end time index, respectively. Referring to Figure 5, a bulge can be seen in curve 502 between the corrected start time index and the corrected end time index. This is due to the spillover phenomenon, which is a bulge caused by radiation from the right and left ventricular cavities being mixed into the left ventricular myocardial count value. It can be seen that this bulge has been neatly corrected in curve 504.

Next, we will introduce an example of how the spillover correction disclosed in this application is used, using the flowchart in Figure 6. This example 600 may be a process performed by a device as a result of program instructions being executed by the processing means of the device.

Step 602 indicates the start of the process. Step 604 loads a dynamic image of the heart captured using a radiation imaging device. This dynamic image is a three-dimensional dynamic image of the heart captured for myocardial blood flow dynamic analysis, and can be, for example, data obtained by collecting radiation using a SPECT device or a PET device after exercise or drug stress is performed on a subject administered with a myocardial blood flow agent such as ^201TlCl , or under resting conditions.

In step 606, regions of interest for the right ventricular cavity, the left ventricular cavity, and the left ventricular myocardium are set for the loaded dynamic image. Setting the regions of interest requires extracting the right ventricular cavity, the left ventricular cavity, and the left ventricular myocardium from the loaded dynamic image. Since several regions of interest extraction software programs for nuclear medicine images already exist, such software can be used to perform region extraction. Existing SPECT and PET devices may come with software for this purpose, and extraction may also be performed using this software. The method described in WO2013/047496 may also be used to extract the myocardium. The entire extracted right ventricular cavity, the left ventricular cavity, and the left ventricular myocardium may each be set as a region of interest, or only a portion of each may be set as a region of interest.

In step 608, a time activity curve for the right ventricular cavity is created from the region of interest in the right ventricular cavity, a time activity curve for the left ventricular cavity is created from the region of interest in the left ventricular cavity, and a time activity curve for the left ventricular myocardium is created from the region of interest in the left ventricular myocardium. In other words, curves showing the change in radiation dose count over time are created for each region of interest.

In step 610, the time activity curve of the left ventricular myocardium is corrected using the correction method described herein.

In step 612, an index related to radioactivity uptake into the left ventricular myocardium is calculated based on the corrected time activity curve of the left ventricular myocardium. For example, an index of radioactivity uptake into the left ventricular myocardium (K1) or an index of washout from the left ventricular myocardium (k2) may be calculated. Furthermore, from these indices, for example, the myocardial uptake rate of the radiopharmaceutical may be calculated.

In some embodiments, the calculated metrics may be saved and/or displayed (step 614). Step 616 indicates the end of the process.

While the present invention has been described in detail above using preferred embodiments, the above description and accompanying drawings are not intended to limit the scope of the present invention, but rather to fulfill legal requirements. There are various variations on the embodiments of the present invention other than those described herein. For example, in one embodiment, the correction start time index is determined based on the onset of the left ventricular lumen TAC, rather than using the time index at which the right ventricular lumen TAC peaks. The various numerical values shown in the specification or drawings are merely examples and are not intended to limit the scope of the invention. Individual features included in the various embodiments described in the specification or drawings can be used only with the embodiment in which the feature is directly described, and can also be used in combination with other embodiments described herein or various implementations not described. The specific parameter values used in the embodiments are merely examples, and other values can, of course, be used. The order of the processes shown in the flowcharts does not necessarily have to be performed in the order presented. Depending on the preferences and needs of the implementer, the order may be reversed, multiple blocks may be implemented in an inseparable manner, or multiple blocks may be implemented as an appropriate loop. All of these variations are within the scope of the invention disclosed in this specification, and the scope of the invention is not limited by the implementation form of the processes. The order of the processes defined in the claims does not determine the required order of the processes, and embodiments in which the processes are performed in a different order or in which the processes include loops are also within the scope of the claimed invention.

Furthermore, for example, embodiments of the corrected start/end time index determination program 120, the left ventricular myocardial TAC estimation program 122, and the information output program 124 may include cases in which two or three of these programs are configured as a single program, or a program group consisting of three or more independent programs. As is well known, there are various implementation forms of programs, and all of these variations are within the scope of the invention disclosed herein.

100 System 102 CPU
104 Main memory device 106 Mass storage device 107 Display interface 108 Peripheral device interface 109 Network interface 120 Program 120 Correction start/end time index determination program 122 Left ventricular myocardial TAC estimation program 122 Program 124 Information output program 130 Right ventricular lumen TAC data 132 Left ventricular lumen TAC data 134 Left ventricular myocardial TAC data 140 Correction start/end time index data 142 Left ventricular myocardial TAC data

Claims (12)

A method for correcting a time activity curve of a left ventricular myocardium in myocardial hemodynamic analysis, comprising:
determining a correction start time index representing a value on a time axis at which correction of the time activity curve of the left ventricular myocardium is to be started based on the time activity curve of the right ventricular cavity;
wherein determining the corrected start time index includes determining the corrected start time index based on a time index at which a time activity curve of the right ventricular cavity peaks. determining a correction end time index representing a time axis value at which correction of the time activity curve of the left ventricular myocardium is to be ended based on the time activity curve of the left ventricular cavity ;
The method of claim 1 further comprising: the radioactive drug used in the myocardial hemodynamic analysis is a thallium drug;
determining the corrected start time index
determining the time T between the time index at which the time activity curve of the right ventricle cavity peaks and the time index at which the time activity curve of the left ventricle cavity peaks;
determining a first correction amount based on the time T;
determining the corrected start time index based on a time index obtained by delaying the time index at which the time activity curve of the right ventricular cavity reaches its peak by the first correction amount;
wherein the first correction amount is approximately 1/4 of the time T. The method of claim 3, further comprising determining the time T as the time between the time index at which the time activity curve of the right ventricular cavity reaches its peak and the time index at which a curve obtained by fitting at least a portion of the time activity curve of the left ventricular cavity to a normal distribution reaches its peak . determining the corrected end time index
determining a second correction amount based on the time T;
determining the corrected end time index based on a time index obtained by delaying by the second correction amount a time index at which a curve obtained by fitting at least a portion of the time activity curve of the left ventricular cavity to a normal distribution reaches a peak;
wherein the second correction amount is approximately the same as the time T. 6. The method of claim 5, further comprising estimating at least a portion of the corrected time activity curve of the left ventricular myocardium using a logarithmic function based on the value of the time activity curve of the left ventricular myocardium at the corrected start time index and the value of the time activity curve of the left ventricular myocardium at the corrected end time index . At each time index between the corrected start time index and the time index at which a curve obtained by fitting at least a part of the time activity curve of the left ventricular cavity to a normal distribution reaches a peak,
comparing the count values of the corrected time activity curve of the left ventricular myocardium with the count values of a curve obtained by fitting at least a portion of the time activity curve of the left ventricular cavity to a normal distribution;
if the count value of the time activity curve of the left ventricular myocardium after the correction is greater than the count value of a curve obtained by normal distribution fitting to at least a portion of the time activity curve of the left ventricular cavity, replacing the count value of the time activity curve of the left ventricular myocardium after the correction with the count value of a curve obtained by normal distribution fitting to at least a portion of the time activity curve of the left ventricular cavity;
The method of claim 6 , comprising: The method according to claim 6 or 7 , further comprising setting a count value of the corrected time activity curve of the left ventricular myocardium to 0 before the correction start time index. Obtaining a dynamic image of the heart using a radiation imaging device;
setting a region of interest of a right ventricular cavity, a region of interest of a left ventricular cavity, and a region of interest of the left ventricular myocardium on the dynamic image;
generating a time activity curve of the right ventricular cavity from the region of interest of the right ventricular cavity, a time activity curve of the left ventricular cavity from the region of interest of the left ventricular cavity, and a time activity curve of the left ventricular myocardium from the region of interest of the left ventricular myocardium;
Correcting the time activity curve of the left ventricular myocardium by executing the method according to any one of claims 1 to 8 ;
A method comprising: A method comprising calculating an index relating to radioactivity uptake in the left ventricular myocardium based on a time activity curve of the left ventricular myocardium corrected by performing the method according to any one of claims 1 to 8 . 11. An apparatus comprising processing means and storage means, said apparatus storing program instructions that, when executed by said processing means, are configured to cause said apparatus to perform a method according to any one of claims 1 to 10 . A computer program comprising program instructions arranged, when executed by a processing means of a system, to cause said system to perform a method according to any one of claims 1 to 10 .