JP7243973B2 - Simulator, Injection Device or Imaging System Equipped with Simulator, and Simulation Program - Google Patents

Description

TECHNICAL FIELD The present invention relates to a simulator for simulating temporal changes in signal intensity to be obtained using nuclear magnetic resonance imaging, an injection device or an imaging system equipped with the simulator, and a simulation program.

Patent Document 1 discloses a simulator equipped with a prediction unit that predicts temporal changes in pixel values of each of a plurality of compartments obtained by dividing a tissue along the blood flow direction, based on subject information, an injection protocol, and tissue information. is described.

WO2016/084373

In CT (Computed Tomography) as described in Patent Document 1, the X-ray attenuation is approximately linearly correlated with the volume or injection rate of the contrast agent. On the other hand, in MRI (Magnetic Resonance Imaging) using nuclear magnetic resonance imaging, the signal intensity increases as the volume of the contrast agent or the injection speed increases. The rate of increase in strength is small. As such, signal intensity does not increase linearly with increasing volume of contrast agent or injection rate. Therefore, the signal intensity that should be obtained by imaging the subject's tissue using the nuclear magnetic resonance imaging method could not be simulated using the proportionality factor.

A simulator according to an aspect of the present invention includes a drug solution information acquisition unit that acquires drug solution information; a protocol acquisition unit that acquires an injection protocol of a contrast medium; A predicting unit for simulating a change in agent concentration over time, wherein the conversion data in which the contrast agent concentration and the signal intensity to be obtained using the nuclear magnetic resonance imaging method are associated with each other are referred to, and are obtained by the simulation. and a predicting unit for simulating the time course of the signal intensity of the tissue from the time course of the contrast medium concentration.

Further features of the invention will become apparent from the following description of an exemplary embodiment, given by way of example with reference to the accompanying drawings.

Schematic block diagram of the simulator. Transformed data in which contrast agent concentration and signal intensity are related. FIG. 4 is a schematic perspective view of a sample support used for imaging a sample; Main screen displayed on the display of the simulator. Automatic optimization screen displayed on the display of the simulator. Automatic optimization flow chart. Schematic of an injection device and imaging system.

Exemplary embodiments for carrying out the present invention will now be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the following embodiments are arbitrary and can be changed according to the configuration of the device to which the present invention is applied or various conditions. Also, unless otherwise stated, the scope of the invention is not limited to the embodiments specifically described below. Unless otherwise specified, the term contrast agent includes both a contrast agent alone and a drug solution containing other solvents and additives in addition to the contrast agent.

[First embodiment]
A simulator (perfusion simulator) 20 shown in FIG. 1 predicts temporal changes in signal intensity of a subject's tissue to be obtained using nuclear magnetic resonance imaging. Therefore, the simulator 20 includes a control section 25 including a CPU and the like and a storage section 24 . The control unit 25 controls each unit of the simulator 20 according to control programs stored in the storage unit 24 . Each part is logically realized as various functions by the control part 25 executing various processes corresponding to the control program installed in the storage part 24 . Furthermore, the control unit 25 also functions as a display control unit that controls the display unit 26 .

The storage unit 24 includes a RAM (Random Access Memory) that is a system work memory for the control unit 25 to operate, a ROM (Read Only Memory) that stores programs or system software, an HD (Hard-disk Drive), and an SSD ( (Solid State Drive), etc. The storage unit 24 also includes a simulation program 29 as a control program that causes the control unit 25 as a computer to function as a prediction unit 16 that predicts changes over time in the signal intensity of the tissue of the subject to be obtained using nuclear magnetic resonance imaging. Remember. Alternatively, the control unit 25 can be stored in a portable recording medium such as a CD (Compact Disc), a DVD (Digital Versatile Disc), a CF (Compact Flash) card, or an external storage medium such as a server on the Internet. Various processes can also be controlled according to the program and the simulation program 29 .

The control unit 25 includes a subject information acquiring unit 11 that acquires subject information about a subject who is a subject. The subject information acquisition unit 11 acquires subject information input from the input unit 27 of the simulator 20 by the operator of the simulator 20 . This subject information includes, for example, weight, height, heart function, and heart rate. Other examples of subject information include hemoglobin amount, body surface area, stroke volume, cardiac output, estimated glomerular filtration rate (eGFR), creatinine level, age, sex, lean body mass, and body mass index. , circulating blood volume, subject number (subject ID), history of subject illness and side effects, subject name, date of birth, blood volume, and blood flow velocity.

Alternatively, the subject information acquisition unit 11 may acquire subject information from the storage unit 24 of the simulator 20 or an external storage device (server). Such servers include, for example, RIS (Radiology Information System), PACS (Picture Archiving and Communication System), HIS (Hospital Information System), imaging systems, and imaging workstations. Furthermore, the subject information acquisition unit 11 may acquire subject information from the MR device 3 or the injection device 2 shown in FIG.

The control unit 25 also includes a protocol acquisition unit 12 that acquires a contrast agent injection protocol. The protocol acquisition unit 12 acquires an injection protocol stored in the storage unit 24 by the operator via the input unit 27 . The injection protocol includes, for example, the injection time and injection rate of the drug solution. In addition, the injection protocol includes, as another example, an injection method, a contrast medium injection site, an injection amount, an injection timing, a contrast medium concentration, an injection pressure, an injection rate acceleration, a contrast medium injection time and injection rate, and a physiological saline solution. Information such as injection time and injection speed, presence/absence of boost injection of contrast medium, increase/decrease of injection speed, presence/absence of cross injection, presence/absence of link speed setting, volume of injection tube, and the like may be included.

Cross-injection in the injection protocol refers to injecting the contrast agent at a higher injection rate than the saline solution until the set time has elapsed from the start of the injection, and then injecting the contrast agent so that the injection rate gradually decreases. At the same time, it is an injection method in which physiological saline is injected so that the injection rate increases gradually. The link speed setting in the injection protocol is a setting that links the injection speeds of the contrast medium and the physiological saline so that the injection speeds of both are the same. Alternatively, the protocol acquisition unit 12 may acquire the injection protocol from an external storage device or the injection device 2 (Fig. 7).

Furthermore, the control unit 25 includes a tissue information acquisition unit 13 that acquires tissue information of the subject. The tissue information acquisition unit 13 acquires tissue information stored in the storage unit 24 by the operator via the input unit 27 . The tissue information includes, for example, the number of compartments in the tissue (the number of divided compartments of blood vessels and organs), the volume of the tissue (volume of vascular lumen), the volume of capillaries, the volume of extracellular fluid lumen, the blood flow rate per unit tissue ( blood flow velocity), contrast agent penetration rate in tissue (capillary permeability surface area), contrast agent penetration back rate in tissue (capillary permeability surface area), and tissue-native signal intensity. The number of compartments in tissue information can be set such that there are more tissues with large volumes than tissues with small volumes. Tissues include the heart (right and left ventricles), blood vessels, kidneys, ureters, other organs and muscles. Alternatively, the tissue information acquisition unit 13 may acquire tissue information from an external storage device or the injection device 2 (FIG. 7).

The control unit 25 also includes a drug solution information acquisition unit 14 that acquires a contrast medium amount as an example of drug solution information. The medicinal solution information acquisition unit 14 acquires medicinal solution information stored in the storage unit 24 by the operator via the input unit 27 . This medicinal liquid information includes, as other examples, viscosity, osmotic pressure ratio, amount of physiological saline, product ID, product name, chemical classification, contained ingredients, concentration, expiry date, syringe capacity, syringe pressure resistance, cylinder inner diameter, piston stroke, and lot number. A case will be described below in which the product name, contrast medium concentration, osmotic pressure ratio, viscosity, and contrast medium amount of a gadolinium contrast medium are acquired as drug solution information. As an example, the product names are Gadovist (Gd-BT-DO3A) and Primovist (Gd-EOB-DTPA) sold by Bayer Yakuhin Co., Ltd., Prohanth (Gd-HP-DO3A) sold by Eisai Co., Ltd., Fuji Pharma Includes Magnescope (Gd-DOTA) sold by Co., Ltd.

Alternatively, the liquid medicine information acquisition unit 14 may acquire liquid medicine information from an external storage device or the injection device 2 . Furthermore, the liquid medicine information acquisition unit 14 may acquire liquid medicine information from a reading unit built into the injection device 2 (FIG. 7). This reading unit reads liquid medicine information from a data carrier attached to a syringe mounted on the injection head 21 . This data carrier is, for example, an RFID chip, an IC tag or a bar code.

The control unit 25 also includes a target value acquisition unit 15 that acquires the target duration of the target signal strength. The operator can input at least one of the target signal strength and the target duration from the input section 27 . Then, the target value acquisition unit 15 acquires the target signal strength and the target duration stored in the storage unit 24 by the operator via the input unit 27 . This target duration means the time during which a signal strength greater than the target signal strength is maintained. Alternatively, controller 25 may obtain the target signal strength and target duration from an external storage device or injection device 2 .

The control unit 25 also includes an examination information acquisition unit 17 that acquires an echo time (TE) or a flip angle (FA) as an example of examination information. The examination information acquisition unit 17 can acquire examination information stored in the storage unit 24 by the operator via the input unit 27 . This examination information includes, as another example, imaging parameters such as repetition time (TR), examination number (examination ID), examination site, examination date and time, chemical liquid type, chemical liquid name, and site information related to the site to be imaged. good too. This part information is information that can specify a part (range) selected as an imaging target. For example, the site information includes the name of the imaging site, the name of the imaging method, and the distance from the injection site of the drug solution to the imaging site. Alternatively, the control unit 25 may acquire examination information from an external storage device or the MR apparatus 3 .

The control unit 25 also includes a prediction unit 16 that simulates temporal changes in the concentration of the contrast agent in the subject's tissue based on the injection protocol and the drug solution information, for example. The prediction unit 16 refers to conversion data 28 such as a conversion table or a conversion map in which contrast agent concentrations and signal intensities to be obtained using nuclear magnetic resonance imaging are associated. Thereby, the prediction unit 16 simulates the time-dependent change in tissue signal intensity based on the time-dependent change in contrast agent concentration obtained by simulation. For example, the prediction unit 16 receives the injection protocol from the protocol acquisition unit 12 as injection time (sec) and injection rate (mL/sec) of contrast medium, injection time (sec) and injection rate (mL/sec) of physiological saline, ), the presence or absence of cross injection, and the presence or absence of link speed setting. Further, the prediction unit 16 can acquire the contrast agent concentration (mol/L), the osmotic pressure ratio, the viscosity (mPs.s), and the amount of the contrast agent (mL) as the drug solution information from the drug solution information acquisition unit 14 .

Further, the prediction unit 16 obtains the hemoglobin amount (g/dL), weight (kg), height (cm), heart function (%), heart rate (bpm), body surface area, and body surface area from the subject information acquisition unit 11 as subject information. (m ² ), cardiac output (L/min), and eGFR may be obtained. Here, when the average cardiac function is taken as 100%, if the cardiac function is superior to the average cardiac function, it will increase (e.g., 120%), and if it is inferior, it will decrease (e.g., 80%). , is the value set by the operator. Alternatively, the prediction unit 16 may calculate at least one of body surface area, cardiac output, and estimated glomerular filtration rate. For example, the body surface area can be calculated by the Fujimoto formula, the Dubois formula, or the Shintani formula based on the weight and height. Cardiac output can also be calculated based on body surface area, cardiac function and heart rate. Also, eGFR can be calculated based on creatinine level, age and gender. Measured cardiac output (L/min) or the ratio of measured cardiac output to average cardiac output may also be used as a parameter that substitutes for cardiac function.

Furthermore, the prediction unit 16 obtains the tissue information from the tissue information acquisition unit 13 as the number of compartments in the tissue, the volume of the tissue, the volume of the capillary, the volume of the extracellular fluid cavity, the blood flow velocity, the capillary permeability surface area, the capillary Vascular permeability surface area and tissue native signal intensity may be obtained. Thereby, the prediction unit 16 can simulate changes in signal intensity over time in the tissue of the subject in each of a plurality of compartments obtained by dividing the tissue of the subject along the blood flow direction. This simulation is performed based on subject information, injection protocol, and tissue information. After that, the prediction unit 16 causes the storage unit 24 to store the signal intensity of each compartment for each time in association with each tissue.

Also, the prediction unit 16 may acquire the echo time (TE) and the flip angle (FA) from the inspection information acquisition unit 17 as inspection information. Thereby, the prediction unit 16 can refer to the imaging parameters such as the echo time (TE) and the flip angle (FA) to acquire signal intensities associated with a plurality of contrast agent concentrations having different imaging parameters. Furthermore, the prediction unit 16 can acquire additional information such as the analysis time (sec) input by the operator from the input unit 27 . This analysis time is the length of time to be predicted, and corresponds to the length of the X-axis (FIG. 4) of the time signal intensity curve. Thereby, the prediction unit 16 can match the length of the X-axis with the analysis time desired by the operator.

The simulator 20 also includes a display section 26 that displays each tissue compartment in a color having a density corresponding to the signal intensity. Then, the control unit 25 changes the density of each tissue compartment in the predicted image 41 (FIG. 4) displayed on the display unit 26 according to the change in signal intensity over time. Therefore, the control unit 25 reads out the signal intensity of the compartment at the selected time from the storage unit 24 and changes the shade of the compartment. The display unit 26 displays operation screens such as a main screen and an automatic optimization screen, which will be described later. The display 26 may also display the injection protocol, device input status, setting status, and injection results.

The simulator 20 also includes an input unit 27 connected to the subject information acquisition unit 11, the protocol acquisition unit 12, the tissue information acquisition unit 13, the drug solution information acquisition unit 14, the target value acquisition unit 15, and the examination information acquisition unit 17. ing. As this input unit 27, for example, a numeric keypad or a keyboard can be used. Alternatively, a touch panel that serves both as the input unit 27 and the display unit 26 may be used.

[Prediction of changes over time in signal intensity]
The prediction unit 16 performs a simulation for predicting temporal changes in the concentration of the contrast medium in the tissue of the subject. The tissues of this subject include, for example, the right ventricle, aorta, veins (cephalic vein, pulmonary vein, ascending vena cava, descending vena cava, hepatic vein, and renal vein), arteries (cephalic artery, pulmonary artery, ascending aorta, descending aorta, abdominal aorta, lower abdominal aorta, pancreatic artery, hepatic artery, and renal vein), brain (head), upper extremities, myocardium (myocardium dominated by right coronary artery, myocardium dominated by anterior descending artery, circumflex artery) myocardium), lungs, liver, stomach, spleen, pancreas, intestine, kidneys, ureters, lower extremities, left ventricle and portal vein. Each tissue of the subject is divided into a plurality of compartments along the blood flow direction according to the number of divided compartments of the tissue acquired from the tissue information acquisition unit 13 . However, if a highly accurate simulation is not required, the number of compartments in each tissue may be singular.

The prediction unit 16 divides the volume of the tissue including the compartment to be predicted, the capillary volume of the tissue, and the extracellular fluid cavity volume of the tissue by the number of divided compartments to obtain the contrast agent concentration for each compartment. Predict changes over time. For example, when the number of divided compartments is 15, the prediction unit 16 divides each of the tissue volume, the capillary volume, and the extracellular fluid cavity volume by 15. to predict. Here, the prediction unit 16 refers to the osmotic pressure and viscosity of the contrast medium to simulate diffusion of the contrast medium. This is because MRI uses a much smaller amount of contrast medium than CT. Specifically, the prediction unit 16 simulates the diffusion of the contrast agent such that the diffusion speed of the contrast agent in blood is directly proportional to the osmotic pressure of the contrast agent and inversely proportional to the viscosity of the contrast agent.

In addition, in the simulation, the contrast agent injected from the vein of the upper extremities moves to each organ via the right ventricle, lungs, left ventricle, and aorta (ascending aorta, descending aorta), and then reaches the right ventricle via the vein. do. Furthermore, in the simulation, the contrast agent injected into the body is discharged out of the body through the kidney and ureter. In the simulation, some contrast agents (for example, Primovist sold by Bayer Yakuhin, Ltd.) may be excreted from the biliary tract after being taken up by hepatocytes.

Therefore, the prediction unit 16 predicts temporal changes in the contrast agent concentration of each tissue in order from the right ventricle toward upstream and downstream in the blood flow direction. For example, the prediction unit 16 first predicts the right ventricle, then the vena cava and vein located upstream in the blood flow direction with respect to the right ventricle, and the vena cava and vein located downstream in the blood flow direction with respect to the right ventricle. Prediction of tissue groups including arteries and arteries. That is, the prediction unit 16 predicts the temporal change in contrast agent concentration of each tissue in order from the tissue closer to the injection site of the contrast agent toward the upstream and downstream in the blood flow direction.

Also, the prediction unit 16 uses a differential equation such as Equation 1 below, for example, in order to obtain the change in contrast agent concentration in each tissue (blood vessel and organ) as a time function. Here, the concentration of the contrast agent flowing into the compartment is _C1 , the concentration of the contrast agent flowing out of the compartment is _C2 , the volume of the compartment is V, and the blood flow rate (blood velocity) per unit tissue in the compartment is Q.

Furthermore, the prediction unit 16 calculates the seepage speed when the contrast agent permeates from the capillaries into the extracellular fluid space and the cell Consider the permeation back speed when permeating from the external fluid cavity to the capillaries. Therefore, the prediction unit 16 uses, for example, differential equations such as Equations 2 and 3 below. Here, the volume of the extracellular fluid space is Vec, the contrast agent concentration in the extracellular fluid space is Cec, the volume of the capillary is Viv, the contrast agent concentration in the capillary is Civ, and the seepage speed is _PS1 . , and the stain return speed is _PS2 .

By solving the above differential equation, the elapsed time from the start of injection and the change in contrast medium concentration are obtained as functions of time. Examples of parameters used for this prediction are: tissue volume of 120 mL to 160 mL, capillary volume of 2 mL to 5 mL, extracellular fluid cavity volume of 12 mL to 18 mL, and 120 mL/min to 180 mL/min for the stomach. of blood flow per unit tissue (arterial blood flow velocity), a seepage speed of 15 or more and 25 or less, and a seepage return speed of 15 or more and 25 or less are used. The seepage speed and the seepage-back speed can be calculated from the product of capillary area and permeability. For example, assuming that the total area of capillaries in the human body is 800m ² , the capillary area is assigned to each organ according to its weight. Then, assuming that the permeability of all organs is 1 ml/min/g, the seepage rate and the seepage return rate can be calculated.

Furthermore, the predictor 16 takes into account the diffusion of contrast agents between adjacent compartments. That is, the prediction unit 16 predicts the time-dependent change in contrast agent concentration such that the contrast agent concentration in the high-concentration compartment is decreased and the contrast agent concentration in the low-concentration compartment is increased between adjacent compartments. Here, when the density difference is large, the prediction unit 16 increases the amount of decrease and the amount of increase of the contrast agent density.

Also, when the osmotic pressure ratio of the contrast agent is large, the prediction unit 16 increases the amount of decrease and the amount of increase in the concentration of the contrast agent. Furthermore, the prediction unit 16 increases the amount of decrease and the amount of increase of the contrast agent concentration when the contact area between the compartments is large. Specifically, when compartments of different tissues are adjacent to each other, the prediction unit 16 reduces the amount of decrease and the amount of increase in contrast agent concentration because the contact area is small. Then, when the compartments of the same tissue are adjacent to each other, the contact area becomes large, so the prediction unit 16 increases the amount of decrease and the amount of increase of the contrast medium concentration.

[Discharge of contrast medium]
A portion of the contrast medium actually injected into the body does not recirculate as it exits the body via the kidneys and ureters. Therefore, the prediction unit 16 calculates the discharge amount of the contrast medium based on the predetermined discharge rate, and performs simulation by subtracting the discharge amount from the contrast medium in the capillaries of the kidney. As a result, a portion of the contrast that reaches the kidneys is subtracted from the total body (in plasma) contrast. Specifically, the prediction unit 16 allocates the contrast agent that has reached the kidney to capillaries, extracellular fluid spaces, and cellular parenchyma. After that, the prediction unit 16 divides the contrast agent assigned to the renal capillaries into three and assigns them to the renal arteries, renal extracellular fluid spaces, and ureters. That is, the prediction unit 16 performs a simulation to move the excreted amount of the contrast agent from the capillaries of the kidney to the ureter. Since the contrast agent that has moved to the ureters does not return to the body, it is subtracted from the total amount of contrast agent for the entire body.

More of the contrast agent moves into the ureters in proportion to the concentration of the contrast agent in the capillaries of the kidney. That is, the discharge rate (mL/sec) of the contrast medium increases in proportion to the concentration of the contrast medium in the capillaries. This contrast agent concentration is the ratio of the contrast agent to the contrast agent in the tissue (compartment) and the blood per unit time (for example, 10 msec). In addition, the amount of contrast medium actually injected into the body increases in proportion to the eGFR. Therefore, the prediction unit 16 further multiplies the value obtained by multiplying the eGFR by the adjustment coefficient by the contrast medium concentration to obtain the contrast medium discharge rate. This adjustment coefficient is a value larger than 0 and smaller than 5 as an example. By simulating the discharge of the contrast agent, the total amount of the contrast agent for the entire body decreases over time, so a more accurate simulation can be performed.

Furthermore, the prediction unit 16 may simulate that a liver-specific contrast agent (for example, Primovist sold by Bayer Yakuhin, Ltd.) taken into hepatocytes in the liver is discharged through the biliary tract. In addition, the prediction unit 16 may subtract the contrast agent in the ureter after a predetermined period of time so as to simulate that the contrast agent in the ureter is pushed by urine and moved to the bladder.

[Create conversion data]
As noted above, in MRI, the rate of increase in signal intensity is small relative to the rate of increase in contrast volume or injection rate. As such, signal intensity does not increase linearly with increasing volume of contrast agent or injection rate. As a result, even if the contrast agent concentration in tissue is predicted, the signal intensity cannot be derived from the contrast agent concentration using a proportionality factor. Therefore, the prediction unit 16 refers to the conversion data 28 stored in the storage unit 24 and acquires the signal intensity corresponding to the predicted contrast agent concentration. Specifically, the prediction unit 16 calculates the contrast medium concentration over time of the contrast medium in the body of the subject, and predicts the contrast medium concentration by referring to the conversion data 28 in which the contrast medium concentration and the signal intensity are associated. Get the signal strength corresponding to . This conversion data 28 is prepared in advance by imaging a plurality of samples of contrast agents prepared by diluting them to various densities with a plurality of patterns of imaging parameters for each model of MR apparatus and obtaining signal intensities. can.

For example, the storage unit 24 stores conversion data 28 as shown in FIG. In this conversion data 28, the signal intensity of an image actually captured by an MR device (“Vantage Titan (3.0T)” sold by Canon Medical Systems Inc.) is associated with the contrast agent concentration. Also, the signal intensity of the transformed data 28 is associated with a plurality of contrast agent concentrations that differ from each other. For this purpose, the conversion data 28 is created based on signal intensities obtained by preparing a plurality of contrast agent samples diluted to various concentrations and imaging the prepared plurality of samples using nuclear magnetic resonance imaging. ing. Examples include 0.000001%, 0.000002%, 0.000005%, 0.00001%, 0.00002%, 0.00005%, 0.0001%, 0.0002%, 0.0005%, 0.001%, 0.002%, 0.005%, 0.01%%, 0.02%, 0.05%, 0.05% %, 0.2%, 0.5%, 1%, 2% and 5% diluted samples can be used. That is, samples obtained by diluting the contrast agent in 21 steps in the molar concentration range of 5×10 ⁻⁹ mol/L to 0.5 mol/L can be used. As a result, in the converted data 28 in which the contrast agent concentration is plotted on the logarithmic axis, the measurement points can be spaced at approximately equal intervals.

These samples can be obtained by diluting the contrast medium with human blood (for example, "Human blood O Type 450 ml" sold by Cosmo Bio Co., Ltd.). Specifically, 2 ml of an aqueous contrast agent solution obtained by diluting a contrast agent with distilled water is mixed with 8 ml of blood to prepare a sample having a desired diluted concentration. As an example, first, 0.5 ml of contrast agent and 999.5 ml of distilled water are mixed to prepare a 2000-fold diluted contrast agent aqueous solution. Then, 8 ml of blood and 2 ml of 2000-fold diluted contrast agent aqueous solution are mixed. This makes it possible to prepare a 10000-fold diluted sample of 10 ml.

By using the aqueous contrast agent solution in this way, the amount of blood to be used can be reduced without lowering the dilution accuracy. That is, when preparing a low-concentration sample, the amount of contrast medium to be put in is extremely small, and even a slight measurement error can result in a large error. For example, when preparing 10 ml of a 10,000-fold diluted sample, 0.001 ml of contrast medium must be accurately weighed and added. On the other hand, if the amount of blood to be diluted is increased while the amount of contrast medium to be injected is set to a certain amount, a large amount of blood is required. For example, 9999 ml of blood is required to prepare a 10000-fold diluted sample from 1 ml of contrast agent. Therefore, the amount of blood to be used can be reduced by using the contrast agent aqueous solution.

In addition, since the signal intensity to be obtained differs depending on the imaging parameters, the contrast medium concentration of the conversion data 28 is associated with a plurality of signal intensities with mutually different imaging parameters. Specifically, the contrast agent concentration of the transformed data 28 is associated with the signal intensity to be obtained under the condition that the echo time is set to 1.2ms, 1.6ms, 2.0ms and 2.4ms. Furthermore, the contrast medium concentration of the conversion data 28 is associated with the signal intensity that should be obtained under the condition that the flip angles are set to 10 degrees, 15 degrees, 20 degrees, and 25 degrees. Therefore, the conversion data 28 is created based on signal intensities obtained by imaging multiple samples with different imaging parameters. That is, four patterns of flip angles are set for each of the four patterns of echo time to image the sample, and a total of 16 images are captured for one sample. In addition to the echo time and the flip angle, the sample may be further imaged under each condition in which the repetition time (TR) is set in a plurality of ranges as an imaging parameter.

Furthermore, since the signal strength to be obtained differs for each MR apparatus, the conversion data 28 corresponds to a plurality of different MR apparatuses. That is, the conversion data 28 is for each model of MR apparatus (for example, "Ingenia CX (3.0T)" sold by Philips Japan, "Trilium Oval (3.0T)" sold by Hitachi, Ltd., and Canon It contains multiple data created in "Vantage Titan (3.0T)" sold by Medical Systems Co., Ltd. Therefore, the conversion data 28 is created based on signal intensities obtained by imaging a plurality of samples for each model of MR apparatus.

An example of imaging a sample will be described with reference to FIG. When imaging a sample, after preparing 10 ml of each sample with a desired dilution concentration, the sample is enclosed in a 10-ml syringe 51 . Then, the syringe 51 is inserted into the substantially cylindrical sample support 50, the sample support 50 is placed in the bore of the MR apparatus (not shown), and the signal intensity is measured. For this purpose, a hole 52 into which a syringe 51 enclosing a sample is inserted is formed in the center of the sample support 50 . As an example, the diameter of hole 52 is 10 mm. As an example, the sample support 50 has an outer diameter of 120 mm and a length of 60 mm. Such a sample support 50 can be formed from acrylic resin using a 3D printer.

In addition, an internal space 53 is formed around the hole 52 in which a liquid that serves as a reference material for MRI can be enclosed. In addition, a filling port (not shown) for a substance that can be sealed with a screw cap 54 as an example of a sealing device is formed on the rear surface of the sample support 50 . By opening the screw cap 54, the internal space 53 of the sample support 50 can be filled with liquid. Further, the screw cap 54 is formed with a bubble escape portion for releasing bubbles in the internal space 53 . This bubble escape section communicates with the internal space 53, and allows bubbles mixed in the liquid to escape from the imaging range into the bubble escape section.

The liquid in the sample support 50 is a substance that provides a sufficient contrast ratio with respect to the sample in both T1-weighted images and T2-weighted images. In MRI, for example, the signal strength fluctuates depending on the receiver gain at the time of imaging. Therefore, the reference material is imaged simultaneously with the sample, and the signal intensity of the sample is normalized by the signal intensity of the reference material. As an example, a copper sulfate aqueous solution ( _CuSO4 aqueous solution) with a concentration of 0.5 w/v% to 1 w/v% can be used as the reference substance. Furthermore, a thickening agent such as a polyvinyl alcohol aqueous solution (PVA aqueous solution) having a concentration of 5 w/v% to 10 w/v% may be added to the reference substance. Specifically, the sample support 50 is filled with a 10 w/v % polyvinyl alcohol aqueous solution, and a copper sulfate aqueous solution is added to the sample support 50 so that the concentration becomes 1 w/v %. This can prevent artifacts due to convection of the reference material.

The imaging sequence can be T1-weighted images of the gradient echo system used in typical dynamic contrast-enhanced MRI examinations. As an example, a routine imaging sequence for MRI angiography is used to take axial cross-sectional images of the sample support 50 and the sample by the 3D-FFE (Fast Field Echo 3D) method. When imaging with "Vantage Titan (3.0T)" sold by Canon Medical Systems Inc., imaging parameters other than echo time and flip angle are, for example, repetition time (3.6), number of acquisition (number of acquisition) : 1.0, reduction factor: 2.0, fat saturation pulse: ON, matrix: 224 × 256, field of view: 360 mm, slice thickness: 4.0 mm, slice gap: 0 mm , Scan time: set to 20sec.

Then, the signal intensities of the sample region and the reference substance region are measured, respectively, and normalized by dividing the signal intensity of the sample by the signal intensity of the reference substance. That is, the signal intensity of the sample is normalized so that the signal intensity of the reference substance becomes 1000. The signal intensity of the sample obtained by this normalization is a real number of about 0.0 to 1.0. Then, the obtained signal intensity of the sample is associated with the contrast agent concentration of the sample to create conversion data 28 . That is, contrast agent concentration is plotted on the horizontal axis and signal intensity is plotted on the vertical axis to create a semi-logarithmic graph. Also, since the obtained signal intensity is discrete data, it is interpolated using a spline function. Alternatively, it may be interpolated using the Lagrangian function or other interpolation methods such as the method of least squares.

In the transform data 28 of FIG. 2, the signal intensity is related to the contrast agent concentration for multiple samples when the echo time is set to 2.0 ms and the flip angle is set to 10 degrees, 15 degrees, 20 degrees, or 25 degrees. ing. The rightmost plot in FIG. 2 shows the signal intensity corresponding to a contrast agent concentration of 5%. Also, the leftmost plot in FIG. 2 shows the signal intensity corresponding to a contrast agent concentration of 0.000001%. As shown in FIG. 2, contrast agent concentration and signal intensity are not proportional. That is, as the injection rate of the contrast agent increases, the contrast agent concentration in a given tissue increases, but the signal intensity does not increase linearly in that tissue. Therefore, a large increase in contrast agent concentration may result in a small increase in signal intensity or a decrease in signal intensity.

Also, in the converted data 28 of FIG. 2, when the flip angle is set to 10 degrees, the signal intensity of the peak associated with the contrast medium concentration of 0.5% is 0.812. However, the signal intensity associated with the higher contrast agent concentration of 5% is 0.179, a significant decrease from the peak signal intensity. In other words, with respect to the contrast agent concentration corresponding to the peak of signal intensity, the signal intensity decreases at higher contrast agent concentrations. Therefore, even if the contrast agent concentration in tissue is predicted, the signal intensity cannot be derived from the contrast agent concentration.

In this respect, the prediction unit 16 can predict the signal strength by referring to the transform data 28 created in advance. For example, when the echo time is set to 2.0 ms and the flip angle is set to 10 degrees, the prediction unit 16 can obtain a signal strength of 0.179 when the predicted contrast agent concentration is 5%. Under the same conditions, if the predicted contrast agent concentration is 0.5%, the prediction unit 16 can obtain 0.812 as the signal intensity. When this simulation ends, the prediction unit 16 causes the storage unit 24 to sequentially store the simulation results. The simulation results contain time-dependent signal strength information associated with the tissue.

[Main screen]
A main screen as an example displayed on the display unit 26 will be described with reference to FIG. The main screen is an operation screen for inputting various numerical values, and a predicted image 41 is arranged on the upper right of the main screen. A condition setting column 42 is arranged on the upper left of the main screen, and a graph column 43 showing a time signal intensity curve is arranged on the upper center of the main screen. In addition, a display button 44 is arranged at the lower center of the main screen, and a patient setting field 45 is arranged at the lower right of the main screen.

In graph column 43, the X-axis corresponds to elapsed time (sec) from the start of injection, and the Y-axis corresponds to signal intensity. In this graph field 43, curves showing changes in signal intensity of a plurality of tissues with respect to time can be superimposed and displayed. In this case, the controller 25 displays each curve in a different color. In addition, in FIG. 4, a curve showing changes in the signal intensity of the hepatic artery is displayed. When displaying the total amount of contrast medium, the X axis corresponds to the elapsed time (sec) from the start of injection, and the Y axis corresponds to the amount of contrast medium (mL). In addition, a Y-axis fixing check box 435 is provided on the upper right of the graph column 43 . The operator can select the Fixed Y-axis check box 435 to fix the maximum value of the Y-axis (the Fixed Y-axis setting is not selected in FIG. 4). For example, if the maximum value of the Y-axis is fixed at 50, the maximum value of the Y-axis is maintained at 50 even when only the total contrast medium volume (eg, maximum 15.0 mL) is displayed. On the other hand, if the fixed Y-axis setting is not selected, the maximum value of the Y-axis is changed to 15, for example, if only a maximum total contrast volume of 15.0 mL is to be displayed.

A scroll bar 431 is arranged below the graph column 43 . The operator can operate this scroll bar 431 to move the current time point bar 432 in the horizontal direction of the graph column 43 . When the operator operates the scroll bar 431 , the control section 25 reads from the storage section 24 the signal strength of each compartment at the selected time. Then, the control unit 25 causes the predicted image 41 to reflect the read out signal strength and causes the display unit 26 to display it. For example, in FIG. 4, a time point of 72.5 seconds after the start of injection is selected, and the predicted image 41 at that time point is displayed. In the initial setting, the predicted image 41 at the start of injection, that is, at the time when 0 sec has elapsed, is displayed. 4 shows a horizontal section of the body as the predicted image 41, but the predicted image 41 may be an image showing an arbitrary section including a transverse plane, a coronal plane, and a sagittal plane, a volume rendering method, or Three-dimensional images displayed by surface rendering methods, as well as other images such as angiographic views, may be displayed. Further, in FIG. 4, an image simulating the upper body of a human body is displayed as the predicted image 41 . However, the display unit 26 may arrange the compartments so that each tissue is displayed independently, and display each compartment in a color with a density corresponding to the signal intensity. Moreover, the display unit 26 may display each compartment in color.

A plurality of display buttons 44 for selecting tissues to be displayed are arranged below the graph column 43 . The operator can select the tissue to be displayed in the graph column 43 from the display buttons 44 . In FIG. 4, the hepatic artery button 442 is selected. Further, when the operator selects the total contrast medium amount button 441, a total contrast medium amount bar (not shown) is displayed in the graph field 43, and a curve showing changes in the total amount of contrast medium remaining in the body is displayed in the graph field 43. be done. In this case, the operator can operate the scroll bar 433 to move the displayed total contrast medium amount bar vertically in the graph column 43 . In addition, the control unit 25 displays the contrast agent amount at the position selected by the operator by operating the scroll bar 433 below the scroll bar 433 . Furthermore, a save button 443 is arranged on the display button 44 . The operator can select this save button 443 to save the contrast medium concentration and the curve displayed in the graph field 43 in CSV (comma-separated values) format.

Furthermore, operation buttons 411 for operating the image are arranged below the predicted image 41 . The operation buttons 411 include a stop button, a play button, a 3x speed play button, a 10x speed play button, a 30x speed play button, and a reset button in order from the left of the main screen. When the operator selects the play button, the predicted image 41 is played continuously as a moving image along the elapsed time. When the operator selects the 3x speed play button, the 10x speed play button, and the 30x speed play button, the video playback speed increases. This allows the operator to visually recognize the position of the contrast agent within each tissue at the desired time. Also, the current time point bar 432 in the graph column 43 moves along the X-axis corresponding to the elapsed time when the predicted image 41 is continuously reproduced. Playback is paused when the operator selects the stop button. When the operator selects the reset button, the reproduction ends, and the predicted image 41 returns to the initial setting (when 0 sec has elapsed).

A display condition change button 412 for the predicted image 41 is arranged on the right side of the predicted image 41 on the main screen. When the operator presses this display condition change button 412, the display condition of the predicted image 41, that is, WL (Window Level) or WW (Window Width) is changed according to the pressed button, and the brightness or contrast is changed. Buttons A1 to A3 are automatic buttons, extracting the maximum and minimum values of signal intensity from the time signal intensity curves of all tissues, and determining display conditions that are optimal display conditions. Specifically, when the button A3 is selected, the contrast is changed to high, and when the button A1 is selected, the contrast is changed to low. Selecting button A2 changes to medium contrast. Further, buttons T1 to T3 calculate the maximum and minimum signal intensity values from the time signal intensity curve of only the tissue selected by the display button 44, and determine display conditions that will be the optimum display conditions. Specifically, when the button T3 is selected, the contrast is changed to high, and when the button T1 is selected, the contrast is changed to low. Selecting button T2 changes to medium contrast.

In the condition setting field 42 displayed on the upper left of the main screen, drug information, injection protocol, imaging parameters, analysis time, etc. can be set. Specifically, the operator can operate the drug pull-down menu 421 to select one of a plurality of drug names. For example, contrast agents that may be selected include gadovist, primovist, magnescope and prohance. When the operator selects a drug, the drug solution information acquisition unit 14 (FIG. 1) acquires drug solution information such as contrast medium concentration (gadolinium concentration), viscosity, osmotic pressure ratio, and contrast medium amount corresponding to the drug name selected by the operator. to get These chemical information are stored in advance in the storage unit 24 .

Alternatively, the drug solution information acquisition unit 14 can also acquire the gadolinium concentration, the viscosity, the osmotic pressure ratio, and the amount of contrast medium that are input by the operator from the input unit 27 . For example, a gadolinium concentration button may be provided, and when the operator selects the gadolinium concentration button, the control unit 25 can cause the display unit 26 to display a gadolinium concentration input screen. The operator can input the desired gadolinium concentration from the input screen. Similarly, buttons for inputting the viscosity, osmotic pressure ratio, and contrast medium amount may be provided, and the operator may input drug solution information. The control unit 25 displays the amount of contrast medium and the like acquired by the drug solution information acquisition unit 14 in the condition setting field 42 according to the input.

The operator can select the injection time button 422 in the contrast medium setting field to enter the injection time of the contrast medium in the injection protocol. When the operator selects the injection time button 422 , the control unit 25 displays an injection time input screen on the display unit 26 . The operator can then input the desired injection time from the input screen. Similarly, the operator can select injection rate button 423 to enter the injection rate of the contrast agent in the injection protocol. Furthermore, a contrast agent amount button per body weight may be arranged in the contrast agent setting field so that the contrast agent amount per body weight can be input. In this case, when the amount of contrast medium per body weight is input, the prediction unit 16 multiplies the amount of contrast medium per body weight by the body weight to automatically change the amount of contrast medium.

In addition, the operator can select link speed setting check box 426 to enable or disable link speed setting. When the link speed setting is selected, the contrast agent injection speed and the physiological saline injection speed are set to be the same. For example, when the contrast medium injection rate is changed from 1.0 mL/sec to 2.0 mL/sec, the saline injection rate is automatically set to 2.0 mL/sec. In this case, the input of the infusion rate of saline may be prohibited. Further, when the injection speed of the physiological saline is changed, the injection speed of the contrast medium may be automatically set. Note that the link speed setting is selected in FIG.

In the saline setting field (saline setting field), the operator can select the injection time button 422 to enter the saline injection time in the injection protocol. When the operator selects the injection time button 422 , the control unit 25 displays an injection time input screen on the display unit 26 . The operator can then input the desired injection time from the input screen. Similarly, the operator can select infusion rate button 423 and saline volume button 424 to enter the saline infusion rate and volume, respectively, in the infusion protocol.

An injection amount display screen 427 is arranged below the physiological saline setting field. In the injection amount display screen 427, the X axis is the elapsed time from the start of injection, and the Y axis is the injection rate. In the injection amount display screen 427, the area representing the injection amount of the contrast agent and the area representing the injection amount of the physiological saline are displayed in different colors. The control unit 25 displays the injection amount in the injection protocol acquired by the protocol acquisition unit 12 ( FIG. 1 ) on the injection amount display screen 427 .

An imaging parameter pull-down menu 425 is arranged below the injection amount display screen 427 . The operator can manipulate the imaging parameter pull-down menu 425 to change the echo time and flip angle as imaging parameters. When the echo time and flip angle are changed, the control unit 25 changes the data displayed in the graph column 43 and the image displayed in the predicted image 41 . On the other hand, the contrast agent concentration distribution of each tissue is unaffected by changes in echo time and flip angle.

A graph setting check box 428 , an analysis time button 429 , and an update button 420 are arranged below the imaging parameter pull-down menu 425 . The operator can select either contrast agent concentration or signal intensity in the graph settings checkboxes 428 . When the operator selects the signal intensity, the data displayed in the graph column 43 and the image displayed in the predicted image 41 are changed to the signal intensity of each tissue. Further, when the operator selects the contrast agent concentration, the data displayed in the graph column 43 and the image displayed in the predicted image 41 are changed to the contrast agent concentration distribution of each tissue. Also, the operator can select the analysis time button 429 to input the analysis time corresponding to the length of the X-axis of the graph column 43 . Note that the update button 420 will be described later.

A patient setting field 45 is arranged at the lower right of the main screen. In the patient setting field 45, weight, height, cardiac function, and heart rate can be entered. Based on the subject information acquired by the subject information acquisition section 11 (FIG. 1), the control section 25 displays the weight, height, cardiac function, and heart rate in the patient setting field 45 in advance. Specifically, when the operator selects the weight button 451 , the control unit 25 displays a weight input screen on the display unit 26 . Then, the operator can input the weight of the subject from the input screen. Similarly, the operator can select height button 452, heart function button 453, and heart rate button 454 to enter the subject's height, heart function, and heart rate, respectively. Note that when the operator inputs weight or the like from the input unit 27, the subject information obtaining unit 11 obtains the input value.

The patient setting field 45 also includes a body surface area field and a cardiac output field. The prediction unit 16 calculates the body surface area based on the weight and height acquired by the subject information acquisition unit 11 . Then, the control unit 25 displays the calculated body surface area in the body surface area field. Similarly, the prediction unit 16 calculates the cardiac output based on the subject's body surface area, cardiac function, and heart rate acquired by the subject information acquisition unit 11 . The control unit 25 displays the calculated cardiac output in the cardiac output field. Note that when the operator inputs the weight of the subject, the subject information obtaining unit 11 obtains the input value.

Furthermore, an eGFR field, a creatinine value button, an age button, and a sex button may be arranged in the patient setting field 45 . In this case, the operator can select the creatinine value button, the age button, and the gender button to input the subject's creatinine value, age, and gender, respectively. The subject information acquisition unit 11 acquires the input creatinine value and the like. The prediction unit 16 calculates eGFR based on the obtained creatinine value, age, and sex of the subject. The control unit 25 displays the calculated eGFR in the eGFR column. Alternatively, the subject information acquiring section 11 may acquire the heart rate from an external measuring device. Furthermore, the subject information acquiring unit 11 may acquire the stroke volume or the cardiac output from an external measuring device. When the stroke volume is acquired, the prediction unit 16 calculates the cardiac output by multiplying the stroke volume by the heart rate.

After completing the settings, the operator selects the update button 420 located at the lower left of the main screen. As a result, the input various information is acquired, and the prediction unit 16 performs a simulation according to the acquired various information, and stores the simulation result in the storage unit 24 . After that, the control unit 25 reads the simulation result from the storage unit 24 . Then, the control unit 25 displays the predicted image 41 of the tissue corresponding to the display button 44 selected by the operator. Furthermore, the control unit 25 displays the time signal intensity curve of the tissue corresponding to the display button 44 selected by the operator in the graph field 43 .

In the upper left of FIG. 4, an automatic optimization tab 46 and an organization setting tab 47 are arranged to the right of the main screen tabs. When the operator selects the automatic optimization tab 46, the control unit 25 displays the automatic optimization screen (FIG. 5) on the display unit 26. FIG. The operator can then automatically perform injection protocol optimization from the auto-optimization screen. Also, when the operator selects the organization setting tab 47 , the control section 25 displays an organization setting screen (not shown) on the display section 26 . Then, the operator selects tissue information (for example, tissue volume, capillary volume, extracellular fluid cavity volume, blood flow rate per unit tissue, contrast agent exudation rate in tissue, and contrast agent in tissue) from the tissue setting screen. agent stain return speed) can be input.

[Automatic optimization screen]
FIG. 5 shows an auto-optimization screen for automatically optimizing injection protocols. An optimization setting column is arranged on the upper side of the automatic optimization screen, and a preset button 461 and a load button 462 are arranged on the lower side of the automatic optimization screen. When the operator selects the optimize button 467 on the auto-optimize screen, the predictor 16 automatically optimizes the injection protocol.

A target pull-down menu 463, a target signal strength button 464, a target duration button 465, a maximum contrast agent amount button 466, an optimization button 467, a fixed time check box 468, and a fixed speed check box 469 are arranged in the optimization setting column. It is The operator can operate the target pull-down menu 463 to select one of multiple organizations. When the operator selects a target organization, the organization information acquisition unit 13 acquires organization information corresponding to the target organization selected by the operator.

The operator can also select target signal strength button 464 to enter a target signal strength. When the operator selects the target signal strength button 464 , the control section 25 displays an input screen for the target signal strength on the display section 26 . Then, the operator can input a desired target signal strength from the input screen. Similarly, the operator can select a target duration button 465 and a maximum contrast volume button 466 to enter a target duration and maximum contrast volume, respectively. The target value acquisition unit 15 acquires the input target signal strength and target duration. In addition, the medicinal solution information acquiring unit 14 acquires the input maximum amount of contrast medium. Alternatively, the drug solution information acquisition unit 14 may acquire the amount of contrast medium filled in the syringe as the maximum amount of contrast medium based on the drug name selected by the operator.

In addition, the operator can select a fixed time or fixed speed check box 468 or a fixed speed check box 469 to select a fixed time or fixed speed condition. In FIG. 5, the fixed speed condition is selected. When the fixed rate condition is selected, the prediction unit 16 performs re-simulation (FIG. 6) without changing the injection rate. When the fixed time condition is selected, the prediction unit 16 performs re-simulation without changing the injection time.

The operator can select the preset button 461 and save the settings entered in the optimization setting column as preset 1 to preset 4 when the button is selected. When the preset button 461 is selected, the prediction unit 16 causes the storage unit 24 to store the settings input as preset 1 to preset 4 according to the selected button. The operator can also select load button 462 to retrieve settings saved as preset 1 through preset 4. FIG. When the load button 462 is selected, the prediction unit 16 reads one of the settings stored as preset 1 to preset 4 from the storage unit 24 according to the selected button. Then, the prediction unit 16 reflects the read settings on the target signal strength and the like.

[Automatic optimization]
The optimization will be described below with reference to the flow chart of FIG. When the operator selects the optimization button 467 (FIG. 5) (S101), the prediction unit 16 acquires various information (S102). Specifically, the prediction unit 16 acquires a contrast agent injection protocol from the protocol acquisition unit 12 . Furthermore, the prediction unit 16 acquires the maximum amount of contrast agent from the drug solution information acquisition unit 14 and acquires the target signal intensity and the target duration from the target value acquisition unit 15 . The prediction unit 16 also acquires test information from the test information acquisition unit 17 . After that, based on the obtained maximum contrast agent amount, the prediction unit 16 simulates the temporal change in the concentration of the contrast agent in the tissue of the subject when half the maximum contrast agent amount is injected as the used contrast agent amount according to the obtained injection protocol. . Then, the prediction unit 16 refers to the conversion data 28 and simulates changes in signal strength over time. Subsequently, the prediction unit 16 obtains the predicted duration from the simulation result (S103).

Next, the prediction unit 16 compares the calculated predicted duration with the target duration (S104). Then, if the predicted duration is shorter than the target duration (YES in S105), the prediction unit 16 determines the signal intensity of the tissue of the subject when injecting a larger amount of contrast agent than the amount of contrast agent used in the previous simulation. Re-simulate the change over time of Therefore, the prediction unit 16 performs re-simulation by changing at least one of the injection speed and the injection time of the contrast agent. That is, the prediction unit 16 increases the amount of contrast agent used (S106).

Specifically, when the fixed rate condition is selected, the prediction unit 16 lengthens the injection time without changing the injection rate in the injection protocol. This increases the amount of contrast agent used as a result of longer injection times. When the fixed time condition is selected, the prediction unit 16 increases the injection rate without changing the injection time in the injection protocol. This increases the injection rate per unit time and, as a result, increases the amount of contrast agent used.

If the predicted duration is longer than the target duration (YES in S107), the prediction unit 16 calculates the time course of the signal intensity of the subject's tissue when injecting a smaller amount of contrast medium than the amount of contrast medium used in the previous simulation. Resimulate changes. Therefore, the prediction unit 16 performs re-simulation by changing at least one of the injection speed and the injection time of the contrast medium. That is, the prediction unit 16 reduces the amount of contrast agent used (S108).

Specifically, when the fixed rate condition is selected, the prediction unit 16 shortens the injection time without changing the injection rate in the injection protocol. This reduces the amount of contrast agent used as a result of shorter injection times. If the fixed time condition is selected, the prediction unit 16 reduces the injection rate without changing the injection time in the injection protocol. This reduces the injection rate per unit time and, as a result, the amount of contrast agent used.

The prediction unit 16 re-simulates changes over time in the signal intensity of the tissue of the subject when injecting the amount of contrast agent to be used calculated according to the changed injection protocol (S109). Then, the prediction unit 16 obtains the predicted duration again from the re-simulation result. After that, the prediction unit 16 stores the re-simulation result and the injection protocol used in the re-simulation in the storage unit 24 . Here, if the end condition is satisfied (YES in S110), the re-simulation ends. This end condition is when the predicted duration matches the target duration, when re-simulation is performed a predetermined number of times (e.g. 40 times), when a predetermined time (e.g. 10 seconds) has elapsed since the start of re-simulation, or when the fluctuation reaches a predetermined threshold This is the case when: The condition that this variation is equal to or less than a predetermined threshold is a condition that the difference between the predicted duration during re-simulation and the predicted duration during previous re-simulation is equal to or less than a predetermined threshold (0.01 sec, for example).

If the termination condition is not satisfied (NO in S110), the prediction unit 16 compares the calculated predicted duration with the target duration again (S104). Then, if the predicted duration is shorter than the target duration, the prediction unit 16 re-simulates changes over time in the signal intensity of the subject's tissue when a larger amount of contrast agent is injected. In addition, when the predicted duration is longer than the target duration, the prediction unit 16 re-simulates changes over time in the signal intensity of the subject's tissue when a smaller amount of contrast agent is injected. Then, the prediction unit 16 obtains the predicted duration again from the re-simulation result.

After completing the re-simulation, the prediction unit 16 refers to the results obtained by the re-simulation to determine the optimum injection protocol. For example, the prediction unit 16 selects, among the stored re-simulation results, the injection protocol corresponding to the simulation result in which the length of the predicted duration is equal to or greater than the target duration and the amount of contrast agent used is the smallest as the optimum injection protocol. It is determined and stored in the storage unit 24 . Alternatively, the prediction unit 16 selects, from among the stored re-simulation results, the injection protocol corresponding to the simulation result having the predicted duration equal to or longer than the target duration and the maximum signal strength being the highest as the optimum injection protocol. may be stored in the storage unit 24 as .

Subsequently, the control unit 25 closes the automatic optimization screen and opens the main screen. At the same time, the prediction unit 16 reflects the optimum injection protocol conditions (amount of contrast medium, injection time and injection rate of contrast medium, amount of saline, and injection time and injection rate of saline) in the contrast medium setting field. . Then, the control unit 25 replaces the pre-optimized injection protocol with the optimal injection protocol and displays it. Furthermore, the control unit 25 reads the time-signal intensity curve from the simulation results corresponding to the optimum injection protocol and displays it in the graph column 43 . Similarly, the control unit 25 reads and displays the predicted image 41, and the automatic optimization ends.

According to the simulator 20 for simulating the change in signal intensity over time in MRI described above, it is possible to convert the contrast agent concentration into signal intensity and simulate the change over time in the signal intensity in the tissue of the subject.

The simulation program 29 executed in the simulator 20 is a simulation program 29 that predicts changes over time in the signal intensity of the subject's tissue to be obtained using nuclear magnetic resonance imaging, and the control unit 25 as a computer is controlled by the drug solution. A drug solution information acquisition unit 14 that acquires information, a protocol acquisition unit 12 that acquires a contrast agent injection protocol, and a prediction unit 16 that simulates temporal changes in contrast agent concentration in the tissue of a subject based on the injection protocol and drug solution information. The tissue signal is obtained from the time-dependent change in the contrast agent concentration obtained by simulation with reference to conversion data 28 in which the contrast agent concentration and the signal intensity to be obtained using the nuclear magnetic resonance imaging method are associated. It functions as a prediction unit 16 that simulates the change in intensity over time. This simulation program 29 can be stored in a computer-readable recording medium.

Next, an imaging system 100 including the simulator 20 (FIG. 1) will be described with reference to FIG. In this imaging system 100 , the simulator 20 is mounted on at least one of the MR device 3 and the injection device 2 .

As shown in FIG. 7, the imaging system 100 includes an injection device 2 that injects a contrast agent, and an MR device 3 that is wired or wirelessly connected to the injection device 2 and that images an object. The MR apparatus 3 has an imaging section (gantry) 31 which has a substantially tunnel-shaped bore and which images an object on the bed. The MR apparatus 3 also includes a control device 32 that controls the MR apparatus 3 as a whole. Furthermore, the MR apparatus 3 has a display 33 as an example of a display unit and a user interface such as a keyboard as an example of an input unit 34 .

The control device 32 controls the imaging section 31 so as to capture an image of the subject according to the imaging parameters set by the operator. The imaging parameters include, for example, echo time, flip angle and repetition time. Furthermore, the control device 32 also functions as the simulator 20 . In addition, the control device 32 can communicate with the imaging unit 31, the injection device 2, and an external storage device (external storage device) by wire or wirelessly.

The imaging unit 31 has a bed, a static magnetic field generator, a gradient magnetic field generator, a transmitter/receiver, and a sequencer (imaging control unit). The imaging unit 31 irradiates a subject placed in a static magnetic field with a high-frequency magnetic field, collects nuclear magnetic resonance signals emitted from the subject by the high-frequency magnetic field, and reconstructs an image.

The display 33 is connected to the control device 32 and displays the input state, setting state, imaging result, and various information of the device. Alternatively, the control device 32 and the display 33 can be constructed integrally. Also, the operator can input drug solution information, injection protocol, tissue information, subject information, and target values to the MR apparatus 3 via the input unit 34 .

The injection device 2 comprises an injection head 21 for injecting contrast medium according to an injection protocol. Then, the injection device 2 injects a medical solution filled in a syringe, such as physiological saline and various contrast media, into the subject. The injection device 2 also includes a stand 22 that holds the injection head 21 and a console 23 that is connected to the injection head 21 by wire or wirelessly.

The console 23 functions as a control device that controls the injection head 21 . Furthermore, this console 23 may function as the simulator 20 . The console 23 has a touch panel 26 functioning as an input display unit, and can communicate with the injection head 21 and the MR apparatus 3 by wire or wirelessly. This touch panel 26 can display the injection protocol, input status of the device, setting status, injection results, and various information. The injection device 2 may be provided with a display as a display section and a keyboard as an input section instead of the touch panel 26 . If the controller 32 of the MR apparatus 3 also functions as the simulator 20, the console 23 does not have to function as the simulator 20. FIG.

Alternatively, instead of the console 23, the injection device 2 includes a control device connected to the injection head 21, and a display unit (for example, a touch panel display) connected to the control device and displaying the injection status of the liquid medicine. may have. This control device also functions as the simulator 20 . Also, the injection head 21 and the control device can be configured integrally with the stand 22 . Furthermore, a suspension member may be provided in place of the stand 22, and the injection head 21 may be suspended from the ceiling via the suspension member.

The injection device 2 may also have a remote control device (for example, hand switch or foot switch) for remotely controlling the injection head 21 . This remote control device can remotely control the injection head 21 to start or stop injection. Additionally, the injection device 2 may have a power source or battery. This power supply or battery can be provided either in the injection head 21 or the controller, or it can be provided separately therefrom.

The injection head 21 includes a syringe holder on which a syringe filled with a liquid medicine is mounted, and a driving mechanism for pushing out the liquid medicine in the syringe according to an injection protocol. The injection head 21 also has an operation section 212 for inputting the operation of the drive mechanism. The operation unit 212 is provided with, for example, a drive mechanism forward button, a drive mechanism reverse button, and a final confirmation button. Furthermore, the injection head 21 may be provided with a head display for displaying injection conditions, injection status, device input status, setting status, and various injection results.

When the contrast medium is injected, an accessory such as an extension tube is connected to the tip of the syringe mounted on the injection head 21 . Then, when preparation for injection is completed, the operator presses the final confirmation button of the operation unit 212 . Thereby, the injection head 21 waits in a state in which injection can be started. When the injection is started, the contrast agent pushed out from the syringe is injected into the subject's body through the extension tube.

Also, the injection head 21 can be equipped with a prefilled syringe having a data carrier such as an RFID chip, an IC tag, or a bar code, and various syringes. The injection head 21 may then comprise a reader (not shown) that reads the data carrier attached to the syringe. The data carrier stores liquid information about the liquid. Furthermore, injection head 21 may have more than two syringe holders, or may have only one syringe holder.

The injection device 2 can receive information from an external storage device (not shown) and can also transmit information to a server. The MR device 3 can also receive information from an external storage device and can also transmit information to an external storage device. For example, inspection orders are stored in advance in the external storage device. This inspection order includes subject information about the subject and inspection information about the inspection content. In addition, the external storage device can store information on imaging results such as image data transmitted from the MR device 3 and information on injection results transmitted from the injection device 2 . It should be noted that an external viewing system or imaging workstation can also be used to operate the injection device 2 and the MR device 3 .

According to the MR apparatus 3 described above, the operator can operate the MR apparatus 3 while confirming the predicted image 41 on the display 33 . Also, the MR apparatus 3 can change the imaging parameters according to the prediction results of the prediction unit 16 . Specifically, the MR device 3 can change, for example, the echo time or flip angle so as to reach the target signal strength or target duration in the simulation results.

Further, according to the injection device 2 described above, the operator can operate the injection device 2 while confirming the predicted image 41 on the console 23 . Furthermore, the injection device 2 can change, for example, the injection rate or the injection time to match the optimal injection protocol obtained by automatic optimization.

The simulator 20 may be installed in an external computer that is wired or wirelessly connected to at least one of the MR device 3 and the injection device 2 . In this case, the simulator 20 sends simulation results and the optimal injection protocol to the MR device 3 and the injection device 2 . Furthermore, the injection device 2 and the MR device 3 may be controlled by a common control device that also functions as the simulator 20 . Also, the simulator 20 may be on the cloud or an external storage device connected to at least one of the injection device 2 and the MR device 3 or at least one of the injection device 2 and the MR device 3 through an internet line.

Although the present invention has been described with reference to each embodiment, the present invention is not limited to the above embodiments. Inventions modified within the scope of the present invention and inventions equivalent to the present invention are also included in the present invention. Further, each embodiment and each modification can be appropriately combined within a range not contrary to the present invention.

For example, as shown in FIG. 2, the signal intensity may decrease significantly even when the contrast agent concentration increases. Therefore, in this case, the target signal intensity cannot be obtained even if the amount of contrast agent used is decreased and then increased and the simulation is performed again. Therefore, the prediction unit 16 of the simulator 20 cannot obtain the target signal strength, and the predicted signal strength obtained by the re-simulation has decreased by more than a predetermined reduction rate from the predicted signal strength obtained by the previous simulation. In some cases, the amount of contrast medium used may be reduced and re-simulation may be performed again. For example, if the predicted signal intensity obtained by the previous simulation has decreased by 10% or more, the prediction unit 16 may reduce the amount of contrast medium used and perform the simulation again. That is, the prediction unit 16 may reduce the injection speed or shorten the injection time and perform the simulation again.

If the target signal strength cannot be obtained in the re-simulation with the reduced injection rate, the prediction unit 16 sets the timing for reducing the injection rate so that the timing for reducing the injection rate precedes the timing for reducing the signal strength (timing for reducing the injection rate may approach the injection start timing) and re-simulate. In this way, by gradually bringing the timing of decreasing the injection rate closer to the injection start timing, the injection rate is decreased more quickly, so the amount of contrast agent used can be further reduced.

Alternatively, the simulator 20 may simulate temporal changes in the concentration of the contrast agent in the tissue of the subject without referring to subject information or tissue information. For example, the prediction unit 16 can perform the simulation under the condition that the rate of change in contrast medium concentration between tissues is constant. However, by referring to subject information or tissue information, the prediction unit 16 can simulate temporal changes in contrast medium concentration with higher accuracy.

Furthermore, the simulator 20 may simulate temporal changes in contrast agent concentration in the subject's tissue without referring to examination information. For example, the prediction unit 16 can perform simulations under constant echo time and flip angle conditions for each contrast agent concentration. However, by referring to the test information, the prediction unit 16 can simulate the change over time of the signal intensity with higher accuracy. Furthermore, the conversion data 28 may correspond to only one type of MR apparatus. Also, in the conversion data 28, the signal intensity may be associated with the molar concentration (mol/L) of the contrast agent as the contrast agent concentration. In this case, the prediction unit 16 predicts temporal changes in the molar concentration of the contrast agent in the tissue as the contrast agent concentration (%) instead of the contrast agent and the ratio of the contrast agent to the blood. Then, the prediction unit 16 refers to the conversion data 28 and simulates changes in signal strength over time. As an example, the molar concentration of the contrast agent can be calculated by multiplying the dilution ratio of the contrast agent in the tissue (the ratio of the contrast agent to the sum of the contrast agent and blood) by the stock concentration of the contrast agent.

Some or all of the above embodiments can also be described as the following additional remarks, but are not limited to the following.

(Appendix 1)
a hole for inserting a sample to be imaged by the MR device;
and a space formed around said holes.

(Appendix 2)
The sample support according to appendix 1, wherein the space is filled with a substance that is used as a reference in an image captured by an MR device.

(Appendix 3)
a filling port for said substance;
Further comprising a sealing tool capable of sealing the filling port,
3. The sample support according to appendix 1 or 2, wherein an air bubble escape portion communicating with the space is formed in the sealing member.

2: injection device, 3: MR device, 20: simulator, 12: protocol acquisition unit, 15: target value acquisition unit, 16: prediction unit, 21: injection head, 100: imaging system, 14: drug solution information acquisition unit, 25 : control unit, 28: conversion data, 29: simulation program

Claims (11)

a chemical information acquisition unit that acquires chemical information;
a protocol acquisition unit that acquires a contrast medium injection protocol;
A predicting unit for simulating temporal changes in contrast agent concentration in a subject's tissue based on the injection protocol and the drug solution information, wherein the contrast agent concentration is associated with a signal intensity to be obtained using nuclear magnetic resonance imaging. a prediction unit that simulates the time-dependent change in the signal intensity of the tissue from the time-dependent change in the concentration of the contrast agent obtained by simulation, with reference to the obtained conversion table. 2. The simulator of claim 1, wherein the signal intensities of the conversion table are associated with a plurality of different contrast agent concentrations. 3. The simulator according to claim 1, wherein said contrast agent concentration in said conversion table is associated with a plurality of signal intensities having mutually different imaging parameters. 4. The simulator according to any one of claims 1 to 3, wherein said conversion table corresponds to a plurality of MR apparatuses different from each other. Further comprising a target value acquisition unit that acquires a target duration of the target signal strength,
The prediction unit simulates the change in the signal intensity of the tissue over time to obtain a predicted duration, compares the predicted duration to the target duration, and compares the predicted duration to the target duration. 2. The simulator according to claim 1, wherein, if short, at least one of the injection rate and the injection time of the injection protocol is varied and re-simulated. When the predicted duration is shorter than the target duration, the prediction unit performs re-simulation under conditions in which a larger amount of contrast agent is injected than the amount of contrast agent used in the simulation, and the predicted duration is set to the target. 6. The simulator according to claim 5, wherein, if the duration is longer than the duration, re-simulation is performed under the condition of injecting a smaller amount of contrast medium than the used contrast medium amount. The simulator according to any one of claims 1 to 6, wherein the prediction unit refers to results obtained by re-simulation to determine an optimum injection protocol. The simulator according to any one of claims 1 to 7, wherein the prediction unit simulates the time course of the signal intensity in each of a plurality of compartments obtained by dividing the tissue along the blood flow direction. an injection head for injecting a contrast agent according to an injection protocol;
An injection device comprising a simulator according to any one of claims 1 to 8. an MR device that captures an image of a subject;
An imaging system comprising a simulator according to any one of claims 1 to 8. A simulation program for predicting temporal changes in signal intensity of a subject's tissue to be obtained using nuclear magnetic resonance imaging, comprising a computer comprising: a drug solution information acquisition unit for acquiring drug solution information;
a protocol acquisition unit that acquires a contrast medium injection protocol;
A prediction unit for simulating temporal changes in contrast agent concentration in the tissue of the subject based on the injection protocol and the drug solution information, wherein the contrast agent concentration and the signal intensity to be obtained using nuclear magnetic resonance imaging; A simulation program that refers to a conversion table associated with and functions as a prediction unit that simulates the time-dependent change in the signal intensity of the tissue from the time-dependent change in the contrast medium concentration obtained by simulation.

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