KR102382199B1 - Apparatus and method for processing magnetic resonance imaging using artificial standard index - Google Patents

Abstract

The present invention relates to a magnetic resonance image processing technique using an artificial reference index, and the magnetic resonance image processing method is a quantitative unit that constitutes image particles with an MRI contrast agent having a preset concentration so as to express damage to an abnormal tissue. An artificial reference index of the T1 value is set, and an MRI signal simultaneously measured from the subject is set together with an artificial reference index prepared using an MRI contrast agent of a preset concentration, and the artificial reference index included in the input MRI signal is obtained. By referring to the signal intensity and comparing it with the MRI signal intensity of the subject, the location of the abnormal tissue and the degree of damage are specified.

Description

Apparatus and method for processing magnetic resonance imaging using artificial standard index

The present invention relates to a technology for processing a medical image, and in particular, an image processing apparatus, method, and method for standardizing a magnetic resonance signal using an artificial reference index in processing a magnetic resonance image, which is the basis for diagnosis of myocardial fibrosis It relates to recording media.

Magnetic Resonance Imaging (MRI) is a technique for acquiring an image of a subject by measuring a signal generated from a hydrogen nucleus using a gradient magnetic field and a high-frequency electromagnetic wave that excites hydrogen nuclei with respect to the subject.

On the other hand, atrial fibrillation (AF) is known as the most common arrhythmia in the world and is associated with a distinct incidence and mortality. Although the electrophysiological mechanisms that induce and persist atrial fibrillation have not been fully understood, atrial fibrillation is characterized by focal firing activity and re-entry facilitated by left atrial (LA) fibrosis. ) is hypothesized to be a combination of

Left atrial fibrosis has been considered an irreversible form of left atrial remodeling that occurs in response to inflammation, stretch, or overload. In addition, electrophysiological studies have shown that left atrial fibrosis is associated with the development and progression of atrial fibrillation. Electrical isolation of left atrial fibrosis by catheter ablation as an arrhythmia-inducing matrix has been widely accepted as an effective strategy for the management of drug-refractory atrial fibrillation. Some studies have shown that left atrial fibrosis is mainly observed in the posterior left atrial wall near the pulmonary vein ostia, and that the distribution of left atrial fibrosis varies with the chronicity of atrial fibrillation. The distribution and extent of left atrial fibrosis may be related to the prognosis and therapeutic outcome of atrial fibrillation after catheter ablation.

(Reference 1.) Calkins H, Kuck KH, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design. Heart Rhythm 2012;9(4):632-696.e21. (Reference 2.) January CT, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol 2014;64(21):e1-76. (Reference 3.) Calkins H, Hindricks G, Cappato R, et al. 2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation. Heart Rhythm 2012;9(4):632-696.e21.

The technical problem to be solved by the present invention is that, in the conventional MRI analysis, an inaccurate reference of an image signal is set by setting a signal intensity standard of a normal tissue and a signal intensity increase standard of an abnormal tissue from a magnetic resonance signal in the body of a subject. ) is selected, and to solve the problem of incorrect MRI interpretation of left atrial fibrosis along with an evaluation error of the relative difference of magnetic resonance signals due to improper selection of criteria.

In order to solve the above technical problem, a magnetic resonance image processing method according to an embodiment of the present invention includes (a) MRI of a preset concentration so that a magnetic resonance imaging (MRI) processing apparatus can express damage to abnormal tissue. setting an artificial reference index of a T1 value, which is a quantitative unit constituting an image particle with a contrast medium; (b) receiving, by the MRI processing apparatus, an MRI signal simultaneously measured from the subject together with an artificial reference index manufactured using the MRI contrast medium of the preset concentration; and (c) specifying the position of the abnormal tissue and the degree of damage by comparing it with the MRI signal strength of the subject with reference to the signal strength of the artificial reference indicator included in the MRI signal input by the MRI processing device; includes

In the magnetic resonance image processing method according to an embodiment, the step (a) of setting the artificial reference index includes a plurality of physiological saline packs having different gadolinium concentrations using gadolinium selected as an MRI contrast agent through a pack. Individual artificial reference indicators corresponding to the T1 values of MRI may be matched for each concentration. In addition, since half of the maximum signal intensity of the MRI is allocated as a threshold value of the signal strength, it may be set so that late gadolinium enhancement (LGE) appears in a region having a signal strength exceeding the allocated threshold. Furthermore, by adjusting the gadolinium concentration of the plurality of physiological heart saline packs, it is possible to set the abnormal signal intensity standard step by step.

In the magnetic resonance image processing method according to an embodiment, the step (b) of receiving an MRI signal may include positioning a plurality of artificial reference indicators prepared using a plurality of preset concentrations of an MRI contrast agent adjacent to the subject. After performing the measurement, the MRI signal may be measured, and the measured MRI signal may be input.

In the magnetic resonance image processing method according to an embodiment, the step (c) of visualizing the location of the abnormal tissue and the degree of damage may include: (c1) calculating the relation between the T1 value and the magnetic resonance signal intensity from the input MRI signal. calculating; and (c2) converting the MRI signal into an image signal based on a T1 value using the calculated relational expression.

In the magnetic resonance image processing method according to an embodiment, in the step (c1), a correlation in which the concentration of the MRI contrast agent is proportional to the severity of the abnormal tissue and inversely proportional to the T1 value is used, but a preset concentration of the MRI contrast agent is used. A relational expression between the T1 value and the magnetic resonance signal intensity may be calculated from the MRI signal with reference to . Also, in the magnetic resonance image processing method according to an embodiment, in step (c2), an area showing a signal intensity exceeding the threshold value may be marked as an abnormal tissue by using a pre-allocated threshold value of the signal strength. . Furthermore, the abnormal tissue is a tissue in which myocardial fibrosis occurs, and the location and damage degree of myocardial fibrosis can be visualized and quantified by referring to the concentration of the MRI contrast agent.

On the other hand, below, a computer-readable recording medium in which a program for executing the above-described magnetic resonance image processing method in a computer is recorded is provided.

In order to solve the above technical problem, an apparatus for processing a magnetic resonance image according to an embodiment of the present invention is an artificial manufactured using a magnetic resonance imaging (MRI) contrast agent of a preset concentration to express damage to an abnormal tissue. an input unit receiving an MRI signal simultaneously measured from a subject together with a reference index; a memory storing a program for processing the measured MRI signal; and at least one processor for driving the program, wherein the program stored in the memory sets an artificial reference index of the T1 value, which is a quantitative unit constituting image particles with the MRI contrast medium of the preset concentration, and a command for specifying the position of the abnormal tissue and the degree of damage by comparing it with the MRI signal strength of the subject with reference to the signal strength of the artificial reference indicator included in the inputted MRI signal.

In the magnetic resonance image processing apparatus according to an embodiment, the program stored in the memory uses gadolinium selected as an MRI contrast agent and uses a plurality of physiological saline packs having different gadolinium concentrations to obtain T1 values of MRI for each concentration. It is possible to match individual artificial reference indicators corresponding to . In addition, in the program stored in the memory, half of the maximum signal intensity of the MRI is allocated as a threshold value of the signal strength, so that late gadolinium enhancement (LGE) appears in a region having a signal strength exceeding the allocated threshold. It is possible to set the abnormal signal intensity standard step by step by adjusting the gadolinium concentration of the plurality of physiological heart saline packs.

In the magnetic resonance image processing apparatus according to an embodiment, the program stored in the memory places a plurality of artificial reference indicators prepared using a plurality of preset concentrations of an MRI contrast agent adjacent to the subject, and then receives the MRI signal. It may measure and receive the measured MRI signal.

In the magnetic resonance image processing apparatus according to an embodiment, the program stored in the memory calculates a relational expression between the T1 value and the magnetic resonance signal intensity from the inputted MRI signal, and uses the calculated relational expression to calculate the MRI signal can be converted into an image signal based on the T1 value. In addition, the program stored in the memory uses a correlation in which the concentration of the MRI contrast agent is proportional to the severity of the abnormal tissue and inversely proportional to the T1 value, and the T1 value and the T1 value from the MRI signal with reference to a preset concentration for the MRI contrast agent A relational expression of the magnetic resonance signal intensity is calculated, and an area showing a signal intensity exceeding the threshold value is marked as an abnormal tissue using a threshold value of a previously assigned signal intensity, wherein the abnormal tissue is a tissue in which myocardial fibrosis occurs, and an MRI contrast agent By referring to the concentration of , the location of myocardial fibrosis and the degree of damage can be visualized and quantified.

In the embodiments of the present invention, by normalizing the magnetic resonance signal of the MRI to the T1 value through the artificial reference index for each concentration of the MRI contrast agent, the evaluation error of the relative difference of the magnetic resonance signal due to improper selection of the reference (reference) of the image signal Together with this, it is possible to fundamentally prevent the problem of erroneous MRI interpretation of left atrial fibrosis and provide images that lead to reliable and efficient diagnosis of myocardial fibrosis.

1 is a flowchart illustrating a method of processing a magnetic resonance image using an artificial reference indicator according to an embodiment of the present invention.
2A and 2B are diagrams for explaining artificial reference indicators proposed by embodiments of the present invention.
FIG. 3 is a flowchart illustrating in more detail a process of specifying the location of an abnormal tissue and a degree of damage in the magnetic resonance image processing method of FIG. 1 according to an embodiment of the present invention.
4 is a diagram for explaining a relationship between cardiac MRI and an artificial reference index.
5 is a block diagram illustrating an apparatus for processing a magnetic resonance image using an artificial reference indicator according to an embodiment of the present invention.
6 is an exemplary diagram comparing a standardized image based on a T1 value proposed by embodiments of the present invention with a conventional cardiac MRI.
7 is an exemplary diagram comparing MRI fusion image information with an invasive electrophysiology test.
8 is a diagram illustrating a process for determining left atrial fibrosis by delayed gadolinium-enhanced MRI and a three-dimensional left atrium (3D-LA) model.
9 is a diagram illustrating the frequency of occurrence of MRI delayed gadolinium enhancement in nine left atrium segments.
10 is a diagram illustrating delayed gadolinium-enhanced MRI of a 45-year-old male with PAF.
11 is a diagram illustrating delayed gadolinium-enhanced MRI of a 65-year-old male with PeAF.

Before describing the embodiments of the present invention in detail, the technical limitations and problems pointed out in the environment in which the present invention is implemented will be briefly introduced.

Through electrophysiological studies, researchers have found that left atrial late gadolinium enhancement (LGE) is associated with the chronicity of atrial fibrillation (AF). However, conventional cardiac MRI (magnetic resonance imaging) was used to evaluate the degree of atrial delayed gadolinium enhancement, not a distribution pattern of delayed gadolinium enhancement in the left atrium.

Basically, MRI implements image information based on the relative difference in magnetic resonance signals between body tissues without a prescribed unit of image signal. At this time, it was pointed out as a problem that improper selection of a reference for the image signal could lead to an erroneous MRI interpretation of left atrial fibrosis along with an error in the evaluation of the relative difference between the magnetic resonance signals. In this regard, T1 map MRI, which converts magnetic resonance imaging signals of left atrial fibrosis into a reference unit called T1 relaxation time, has been introduced. However, the image acquisition time was too long to image the entire heart through T1 map MRI for quantification, and technical limitations were pointed out as shown in the following comparison table.

Therefore, it was noted that if the left atrial fibrosis model was implemented based on the T1 relaxation time, it could be used as a standard for diagnosing left atrial fibrosis in the existing MRI.

On the other hand, myocardial fibrosis can be visualized through delayed gadolinium-enhanced MRI (LGE MRI). Recently, delayed gadolinium-enhanced MRI has been used to evaluate left atrial fibrosis in patients with atrial fibrillation. In general, atrial fibrillation can be more difficult to treat with left atrial hypertrophy, aging, and development of left atrial fibrosis. Accordingly, in the process of devising the embodiments of the present invention, the regional distribution of left atrial fibrillation as well as left atrial hypertrophy is related to chronic atrial fibrillation, and as determined by delayed gadolinium-enhanced MRI, the distribution of left atrial fibrillation was determined by atrial fibrillation. We hypothesized that it could be assessed whether it depends on the chronicity of

In this regard, the T1 value of MRI is a quantitative unit constituting imaging particles. During cardiac MRI, the concentration of the MRI contrast agent in the myocardial tissue is proportional to the severity of myocardial fibrosis, whereas the concentration and the T1 value of the MRI contrast agent are proportional to the severity of myocardial fibrosis. has an inversely proportional relationship. However, up to now, in the conventional MRI technique using the T1 value, the time and cost required for examination have been pointed out as problems.

The embodiments of the present invention devised from recognizing this problem suggest a technical means for interpreting an MRI signal based on the T1 relaxation time, and introduce the accompanying experiments. Embodiments of the present invention described below relate to image processing technology for diagnosing myocardial fibrosis through cardiac magnetic resonance imaging (MRI), and in particular, cardiac MRI through artificial reference indicators for each concentration of gadolinium MRI contrast agent. By standardizing the magnetic resonance signal to the T1 value, a reliable and efficient diagnosis of myocardial fibrosis was promoted.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, detailed descriptions of well-known functions or configurations that may obscure the gist of the present invention in the following description and accompanying drawings will be omitted. In addition, throughout the specification, 'including' a certain component does not exclude other components unless otherwise stated, but means that other components may be further included.

The terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as "comprises" or "comprises" are intended to designate that the described feature, number, step, operation, component, part, or combination thereof exists, but is one or more other features or It should be understood that the existence or addition of numbers, steps, operations, components, parts, or combinations thereof does not preclude the possibility of addition.

Unless specifically defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted to have meanings consistent with the context of the related art, and are not to be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. .

1 is a flowchart illustrating a method of processing a magnetic resonance image using an artificial reference indicator according to an embodiment of the present invention.

In step S110 , the magnetic resonance imaging (MRI) processing apparatus sets an artificial reference index of a T1 value, which is a quantitative unit constituting image particles with an MRI contrast agent having a preset concentration to express damage to an abnormal tissue. In this process, a specific MRI contrast agent concentration (a high concentration is preferable considering that the T1 value and the contrast agent concentration are inversely proportional) is used to select the damaged tissue (for example, , an artificial reference indicator designed to express the T1 value of myocardial fibrosis) is prepared. T1 set here serves as a criterion or evaluation index for judging the severity of tissue damage based on the concentration of the contrast medium.

In particular, using gadolinium selected as the MRI contrast agent, individual artificial reference indicators corresponding to the T1 values of MRI may be matched for each concentration through a plurality of saline packs having different gadolinium concentrations. In addition, since half of the maximum signal intensity of the MRI is allocated as a threshold value of the signal strength, it may be set so that late gadolinium enhancement (LGE) appears in a region having a signal strength exceeding the allocated threshold. At this time, it is preferable to set the abnormal signal intensity standard step by step by adjusting the gadolinium concentration of the plurality of physiological heart saline packs. The process of configuring the physiological saline pack will be described in more detail later with reference to FIGS. 2A and 2B.

In step S120 , the MRI processing apparatus receives the simultaneously measured MRI signal from the subject together with the artificial reference index manufactured using the MRI contrast medium of a preset concentration in step S110 . In this process, the magnetic resonance signal of the artificial reference index in cardiac MRI is measured, but the subject and the artificial reference index are simultaneously examined. More specifically, a plurality of artificial reference indicators prepared using a plurality of preset concentrations of an MRI contrast agent are positioned adjacent to a subject, and then an MRI signal is measured, and the measured MRI signal is received. That is, the artificial reference index produced according to the standard set in step S110 is placed on the subject (the patient's chest) and the examination is performed, thereby inducing simultaneous comparison of the left atrium and the artificial reference index in the MRI obtained thereafter.

In step S130, the MRI processing device compares the MRI signal strength of the subject with reference to the signal strength of the artificial reference indicator included in the MRI signal input through the step S120, thereby determining the position of the abnormal tissue and the degree of damage. specify In this process, the left atrial fibrosis model was implemented based on the T1 relaxation time, rather than image information based on the relative difference between the conventional magnetic resonance signals between body tissues. Therefore, the fibrosis is evaluated by simultaneously comparing the left atrium and the artificial reference index included in the MRI signal, but the MRI can be induced to determine the fibrosis of the left atrium by imaging the presence of a contrast agent in the myocardial tissue.

2A and 2B are diagrams for explaining an artificial reference index proposed by embodiments of the present invention, and propose a process of manufacturing an artificial reference index (or phantom).

First, to introduce the gadolinium phantom (Gadolinium phantom) proposed by the embodiments of the present invention. In order to obtain a high signal threshold of delayed gadolinium contrast enhancement (LGE), a gadolinium phantom was fabricated by injecting a high concentration of gadolinium contrast agent into a small saline pack. Then, the T1 relaxation time of the gadolinium phantom is evaluated using a cardiac magnetic resonance (MR) T1 map. The phantom with 0.1 mM gadolinium shows a short T1 relaxation time of 330 msec on the MRI T1 map.

The T1 relaxation time is a quantified unit of the magnetic resonance signal emitted by hydrogen atoms, and the MRI contrast agent gadolinium can shorten the T1 relaxation time. Basically, gadolinium remains in the fibrous tissue, shortening the T1 relaxation time. In the artificial reference index proposed by the embodiments of the present invention, a short T1 relaxation time (<400 msec) of the fibrous tissue by injecting a gadolinium contrast agent in 0.1 ml units into a physiological saline pack artificial phantom pack, that is, a left atrial fibrosis model has been implemented.

Referring to FIG. 2A , a phantom pack (arrow) that implements an average T1 relaxation time of 400 msec or less, equivalent to myocardial fibrosis, was manufactured by injecting an MRI contrast agent into a saline pack with a micropipette. As shown, the MRI T1 map shows that the T1 relaxation time (330 msec) was significantly shortened in the gadolinium phantom (white arrow).

Referring to FIG. 2B , an artificial reference indicator pack 10 including five units is illustrated. One reference index unit 15 is composed of a mixture of MRI contrast medium and physiological saline, and by connecting reference index units for each contrast medium concentration corresponding to a specific T1 value, for example, an artificial reference including five artificial reference index units. The indicator pack 10 may be configured. One unit of the artificial reference indicator is manufactured to accommodate, for example, a contrast medium and physiological saline solution having a volume of at least 20 ml. Therefore, it is possible to set the abnormal signal intensity criterion step by step by adjusting the gadolinium concentration of the five exemplified physiological heart saline packs. To this end, from the point of view of implementation, it is necessary to secure experimental data on the concentration of the MRI contrast agent for each significant T1 value.

On the other hand, the artificial reference indicator pack 10 should be small enough so that the subject (patient) does not feel discomfort during the MRI process, but at the same time secure the minimum size to obtain the necessary signal strength through the MRI contrast medium. shall. Therefore, it is possible to manufacture a small phantom pack of an appropriate size based on experience and experiments in the clinical field.

FIG. 3 is a flowchart illustrating in more detail a process (step S130 ) of visualizing the position and degree of damage of an abnormal tissue in the magnetic resonance image processing method of FIG. 1 according to an embodiment of the present invention.

In step S131 , a relational expression between the T1 value expressed by Equation 1 and the magnetic resonance signal intensity may be calculated from the input MRI signal. In this process, the concentration of the MRI contrast agent is proportional to the severity of the abnormal tissue and inversely proportional to the T1 value, but the correlation between the T1 value and the magnetic resonance signal intensity is obtained from the MRI signal with reference to a preset concentration for the MRI contrast agent. Relational expressions can be calculated.
[Equation 1]
Y=-11.259x+1494.396
(In Equation 1, Y is a T1 value, and X is an MRI signal.)

FIG. 4 is a diagram for explaining the relationship between cardiac MRI and an artificial reference index, and MRI was performed while the subject held the artificial reference index (arrow) on her chest. Referring to FIG. 4 , it can be seen that the five artificial reference indicators are displayed in different stages in the MRI image due to different concentrations of the contrast medium, respectively. That is, the T1 value of myocardial fibrosis may be determined based on the preset concentration of the MRI contrast agent.

In step S132, the MRI signal is converted into an image signal based on the T1 value using the relation expressed by Equation 1 above. In this process, a region showing a signal strength exceeding the threshold may be marked as an abnormal tissue by using a threshold value of the signal strength allocated in advance. Here, the abnormal tissue is, for example, a tissue in which myocardial fibrosis appears, and the location of myocardial fibrosis and the degree of damage may be visualized and quantified by referring to the concentration of the MRI contrast agent.

5 is a block diagram illustrating an apparatus 20 for processing a magnetic resonance image using the artificial reference indicator 10 according to an embodiment of the present invention. It is reconstructed from the point of view of composition. Therefore, in order to avoid duplication of description, each element will be outlined with a focus on its function. First, it is assumed that the subject receives an MRI signal measured by performing MRI together with the artificial reference indicator 10 .

The input unit 21 receives an MRI signal simultaneously measured from the subject together with the artificial reference indicator 10 manufactured using a magnetic resonance imaging (MRI) contrast agent having a preset concentration to express damage to abnormal tissue. is the composition

The memory 23 is a component that stores a program for processing the measured MRI signal, and the processor 25 is a means for driving the program and may be composed of at least one device. At this time, the program stored in the memory 23 sets an artificial reference index of the T1 value, which is a quantitative unit constituting image particles with the MRI contrast medium of the preset concentration, so as to express damage to the abnormal tissue, and a command for specifying the position of the abnormal tissue and the degree of damage by comparing it with the MRI signal strength of the subject with reference to the signal strength of the artificial reference indicator included in the inputted MRI signal.

The program stored in the memory 23 uses gadolinium selected as the MRI contrast agent to match individual artificial reference indicators corresponding to the T1 values of MRI by concentration through a plurality of physiological saline packs having different gadolinium concentrations. there is. In addition, the program stored in the memory 23 is configured as a late gadolinium enhancement (LGE) in a region having a signal strength exceeding the allocated threshold by assigning half of the maximum signal strength of the MRI as a threshold value of the signal strength. ) to appear, and by adjusting the gadolinium concentration of the plurality of physiological heart saline packs, the abnormal signal intensity standard can be set step by step.

The program stored in the memory 23 may measure an MRI signal and receive the measured MRI signal after positioning a plurality of artificial reference indicators prepared using a plurality of preset concentrations of an MRI contrast agent to be adjacent to the subject. there is.

The program stored in the memory 23 calculates a relational expression between the T1 value and the magnetic resonance signal intensity expressed by Equation 1 below from the input MRI signal, and converts the MRI signal to the T1 value using the calculated relational expression. It can be converted into a video signal based on In particular, the program stored in the memory 23 uses a correlation in which the concentration of the MRI contrast agent is proportional to the severity of the abnormal tissue and is inversely proportional to the T1 value, and the concentration of the MRI contrast agent is obtained from the MRI signal by referring to a preset concentration for the MRI contrast agent. A relational expression between the T1 value and the magnetic resonance signal intensity is calculated, and an area showing a signal intensity exceeding the threshold is indicated as an abnormal tissue using a threshold of a previously assigned signal intensity, wherein the abnormal tissue is a tissue in which myocardial fibrosis occurs. , it is possible to visualize and quantify the location of myocardial fibrosis and the extent of damage by referring to the concentration of the MRI contrast agent.
[Equation 1]
Y=-11.259x+1494.396
(In Equation 1, Y is a T1 value, and X is an MRI signal.)

6 is an exemplary view comparing a conventional cardiac MRI and a standardized image based on a T1 value proposed by embodiments of the present invention. This is a standardized image.

Referring to FIG. 6 , when cardiac MRI is standardized with a T1 value using an artificial reference index, it is possible to provide quantitative evaluation images for various types of myocardial disease without additional MRI imaging. Furthermore, cardiac MRI standardized based on the T1 value is reconstructed into a three-dimensional image to support cardiac surgery, or it is possible to provide quantitative numerical information of cardiac MRI standardized based on the T1 value for learning and analysis of artificial intelligence. .

On the other hand, left atrial fibrosis induces electrical dissociation and local conduction, thereby promoting the occurrence and worsening of atrial fibrillation. Catheter ablation, which electrically separates the region of left atrial fibrosis, the cause of cardiac arrhythmias, has recently been used for the treatment of patients with atrial fibrillation. become a major factor in determining However, in general, left atrial fibrosis has been diagnosed through an invasive electrophysiologic study of the catheter resection process, and if it can be replaced with MRI fusion image information, it is expected to improve the patient's prognosis by shortening the procedure time.

7 is an exemplary diagram comparing MRI fusion image information with an invasive electrophysiology test, and shows a clinical case of MRI fusion image information. Referring to FIG. 7 , fibrosis (orange, arrow) was suspected in the front of the left atrial three-dimensional model reconstructed from the MRI fusion image information, and this was confirmed as left atrial fibrosis in the same location through electrophysiological examination.

Hereinafter, experiments and research procedures performed in the process of deriving the embodiments of the present invention will be sequentially introduced.

Electrophysiological studies have shown that left atrial late gadolinium enhancement (LGE) is associated with the chronicity of atrial fibrillation (AF). So far, cardiac magnetic resonance imaging (MRI) has been used to evaluate the degree of atrial delayed gadolinium enhancement, not the distribution pattern of delayed gadolinium enhancement in the left atrium. Therefore, the purpose of this experiment was to investigate whether the left atrial MRI pattern is related to chronic atrial fibrillation.

This study includes delayed gadolinium-enhanced MRI performed on patients with atrial fibrillation from June 2017 to May 2018. The presence of left atrial delayed gadolinium enhancement was assessed in nine left atrial segments, the extent of which can be determined by the number of segments involved. Depending on the chronicity of atrial fibrillation, patients can be classified into paroxysmal atrial fibrillation (PAF) and persistent atrial fibrillation (PeAF). The location and degree of left atrial delayed gadolinium enhancement can be compared to PAF and PeAF using chi-square test and logistic regression analysis.

Previously, we found that the regional distribution of left atrial fibrillation as well as left atrial hypertrophy is related to the chronicity of atrial fibrillation, and it can be evaluated whether the distribution of left atrial fibrillation depends on the chronicity of atrial fibrillation as determined by delayed gadolinium-enhanced MRI. A hypothesis was established, and the verification process will be introduced below.

Research Materials and Methods

Study population

421 patients (mean age, 55 ± 11 years old; range 21-86) were referred for management of drug-refractory atrial fibrillation from June 2017 to May 2018 through the medical record system of Korea University Anam Hospital. age; 343 males [mean age, 55 ± 11 years; range, 21-83 years] and 78 females [mean age, 58 ± 12 years; range, 22-86 years]) were identified. The inclusion criteria were: (a) delayed gadolinium-enhanced MRI for evaluation of new left atrial fibrosis; (b) not cardiomyopathy by echocardiography; (c) not heart valve disease by echocardiography; (d) A case in which the left ventricular ejection fraction (LVEF) in echocardiography is greater than 50%. According to the inclusion criteria described above, 215 patients were retrospectively selected. Then, 20 patients with an indistinct contour of the left atrial wall on delayed gadolinium-enhanced MRI (n = 17) and those with a history of major chest surgery (n = 3) were excluded. Ultimately, 195 patients were included in the study.

Patients were divided into two groups according to atrial fibrillation type: (a) paroxysmal atrial fibrillation (PAF) (n = 121) if atrial fibrillation episode self-terminating within 7 days, and (b) atrial fibrillation episode If the episode lasts more than 7 days, it is in persistent atrial fibrillation (PeAF).

MRI protocol

LGE MRI was performed on a 3T MRI scanner (MAGNETOM Skyra, Siemens Healthineers, Erlangen, Germany) with a phased array 18-channel body matrix coil and a 12-channel spine matrix coil.

8 is a diagram illustrating a process for determining left atrial fibrosis by delayed gadolinium-enhanced MRI and a three-dimensional left atrium (3D-LA) model.

During delayed gadolinium-enhanced MRI, a gadolinium phantom (arrow) was placed on the anterior chest wall. A full width at half maximum (FWHM) technique was employed to determine the gadolinium phantom signal strength threshold used to define delayed gadolinium-enhanced voxels. Finally, because the maximum length of the clustered delayed gadolinium-enhanced voxels was greater than 1 cm, the clustered delayed gadolinium-enhanced voxels were defined as left atrial fibrosis (LAF). To localize left atrial fibrosis by delayed gadolinium-enhanced MRI, all nine segments from the three-dimensional left atrial model were preselected in the anterior and posterior left atrial margins.

Referring to FIG. 8 , for delayed gadolinium contrast-enhanced MRI, a gadolinium phantom having 10 ml volume saline packs was designed. Each pack has a different gadolinium concentration ranging from 0.01 to 0.1 mM, which shows different T1 relaxation times at 3T (200 - 3,000 msec). Patients place a gadolinium phantom in front of the chest and perform delayed gadolinium-enhanced MRI. Because shortening of the T1 relaxation time due to myocardial accumulation of gadolinium is a hallmark of myocardial fibrosis, a gadolinium phantom with a short T1 relaxation time (330 msec) is used as a delayed gadolinium-enhanced reference to define myocardial fibrosis.

Gadoterate at 0.2 mmol/kg using a three-dimensional (3D) inversion recovery gradient echo pulse sequence with respiratory navigation and electrocardiogram (ECG)-gated pulses. 15 min after intravenous injection of meglumine (Gd-DOTA marketed as Dotarem, Guerbet S.A., Paris, France), LGE MRI data are acquired. Look-Locker sequences with different reversal times are used to specify the optimal nulling time for normal myocardium on delayed gadolinium-enhanced MRI. Typical parameters for delayed gadolinium-enhanced MRI are: a voxel of size 1.5 × 1.5 × 1.5 mm, a repetition time (TR) of 487.2 ms / 1.3 ms / echo time (TE) of 300-330 ms Reversal time, flip angle of 15˚, bandwidth of 491 Hz/pixel, and parallel acquisition technique (PAT) factor 2. For image analysis, delayed gadolinium-enhanced MRI data were transferred to a workstation (Aquarius 3D Workstation). , TeraRecon, San Mateo, CA, USA).

Analysis of MRI scans

All delayed gadolinium-enhanced MRI data were independently analyzed by two reviewers with 10 and 23 years of experience in cardiac imaging, respectively, using commercial software (TerareconiNtuition; TeraRecon, San Mateo, CA, USA). Analysis of delayed gadolinium-enhanced MRI was repeated after at least 1 week. The patient's medical information and atrial fibrillation type were not disclosed to the two reviewers.

First, the contours of the left atrial endocardium were defined by manually tracking the left atrial cavity on transverse delayed gadolinium-enhanced MRI images. Left atrium size (LAV) is determined based on the contour of the left atrium endocardium. Next, the left atrial wall at a maximum distance of 2 mm from the border of the left atrial endocardium is selected as a region growing technique. Then, a hyperenhanced voxel is identified from the left atrium wall using a full width at half maximum (FWHM) technique. For this technique, a region of interest (ROI) is shown within the gadolinium phantom to evaluate the maximum signal intensity, with half of the maximum signal intensity assigned as a threshold of signal intensity. Left atrial wall voxels with signal intensities exceeding this threshold are defined as exhibiting delayed gadolinium enhancement. A left atrial region with a length of delayed gadolinium enhancement equal to or greater than 1 cm is defined as left atrial fibrosis. Finally, delayed gadolinium-enhanced MRI data are reconstructed through a color look-up table mask for better visualization of left atrial fibrosis in a 3D model of the left atrium. In this experiment, nine preselected segments of the left atrial wall were designed to determine the location of left atrial delayed gadolinium enhancement.

9 is a diagram illustrating the frequency of MRI delayed gadolinium enhancement in nine left atrium segments.

Patients are divided into three groups: a) non-fibrotic (total number of left atrial delayed gadolinium-enhanced segments = 0), b) focal fibrosis (total number of left atrial delayed gadolinium-enhanced segments = 1), and c) extensive fibrosis (total number of left atrial delayed gadolinium-enhanced segments ≥ 2).

Referring to FIG. 9 , the left lower pulmonary vein (LIPV) cavity most commonly shows delayed gadolinium enhancement with an incidence of 19.5%. In addition, the persistent atrial fibrillation (PeAF) group showed a higher incidence of delayed gadolinium enhancement in the septum, anterior segment, and left lower pulmonary venous cavity than the paroxysmal atrial fibrillation (PAF) group.

statistical analysis

All continuous data were expressed as mean±standard deviation (SD) and all categorical data were expressed as absolute values and percentages. Left atrial size was based on quartile cutoff points. Kappa statistics were used to evaluate intra- and inter-observer agreements that quantify segments as positive and number of segments. The strength of the agreement is interpreted by the κ value. A κ value of 0.81-1.00 indicates an excellent level of agreement; 0.61-0.80 is a good match; 0.41-0.60 is a moderate level of agreement; 0.21-0.40 is fair level agreement; Below 0.20 indicates a poor level of agreement. To compare data between different groups, students' t-test or chi-square test was appropriately used. Multivariate analysis consisted of logistic regression analysis for PeAF. In multiple logistic regression analysis, a backward stepwise selection mode with repeated input of variables based on test results was used (P value <0.05). Removal of variables was performed based on likelihood ratio statistics with a probability of 0.1.

Statistical analyzes were performed via available commercial software MedCalc (version 15.8; MedCalc, Acacialaan, Ostend, Belgium). P values less than 0.05 are considered statistically significant.

result

To summarize the results, of 195 patients (55 ± 10 years, 161 males), 74 (38%) were PAF and 121 (62%) were PeAF. Of all patients, 114 (58.4%) patients had at least one left atrial delayed gadolinium-enhanced segment. The mean number of delayed gadolinium-enhanced segments was higher in the PeAF group than in the PAF group (1.4 ± 1.1 vs. 0.6 ± 0.7, P < 0.01). The incidence of delayed gadolinium enhancement in the left lower pulmonary vein (LIPV) cavity was higher in PeAF than in PAF (39.2% (29/74) vs. 7.4% (9/121), P < 0.001). In multivariate analysis, delayed gadolinium enhancement in the left lower pulmonary vein cavity was independently associated with PeAF (odds ratio = 4.2; 95% confidence interval, 1.7 - 10.5; P < 0.001). That is, the presence of fibrosis evaluated by delayed gadolinium-enhanced MRI of the left lower pulmonary vein cavity was confirmed to be associated with persistent atrial fibrillation.

More specifically, the clinical characteristics of all 195 patients are summarized in Table 2. The mean patient age is 55 ± 10 years. Of the 195 patients, 121 (62.1%) and 74 (37.9%) were PAF and PeAF, respectively. Clinical features (eg, hypertension, diabetes mellitus, prior stroke, and congestive heart failure) were similar between the PAF and PeAF groups.

Of the 195 patients, 114 (58.5%) had at least one left atrial delayed gadolinium-enhanced segment. Of the 1,755 left atrial segments in 195 patients, 195 (10.4%) were defined as delayed gadolinium enhancement. The most common segment involved in left atrial delayed gadolinium enhancement is located in the posterior left atrium wall (FIG. 9). The incidence of left atrial delayed gadolinium enhancement in each of the subsegments and in the left lower pulmonary vein (LIPV) cavity is greater than 15%. Based on the total number of left atrial delayed gadolinium-enhanced segments, of 195 patients, 81 (41.5%), 65 (33.3%), and 49 (25.1%) had non-fibrotic, focal fibrotic (1 canine left atrial delayed gadolinium-enhanced segments), and extensive fibrosis groups (two or more delayed gadolinium-enhanced segments). The prevalence of left atrial delayed gadolinium-enhanced segments in the septum, anterior segment, posterior segment, right superior pulmonary vein (RSPV) cavity, and right inferior pulmonary vein (RIPV) cavity was higher in the extensive fibrosis group than in the focal fibrosis group. (P < 0.05, Table 4).

Table 3 shows the inter- and intra-observer agreements for the identification of left atrial segments with MRI delayed gadolinium enhancement, and Table 4 shows 114 patients in at least one left atrium showing the presence of delayed gadolinium enhancement on MRI. A comparison between one focal fibrosis group and extensive fibrosis is shown.

Leader agreements for identifying positive segments of delayed gadolinium enhancement in the left atrium are presented in Table 3. Left atrial delayed gadolinium-enhanced κ values were determined between 0.56 and 0.96, considered good or excellent agreements by delayed gadolinium-enhanced MRI. Left atrial size was significantly greater in PeAF than in PAF (106.1 ± 33.1 ml vs. 83.9 ± 30.7 ml, P <0.001). For patients with left atrial size in the upper quartile (>112 mL), PeAF was more common than PAF (41.9% (31/74) vs. 14.0% (17/121), P <0.001). The total number of positive segments of left atrial delayed gadolinium enhancement was greater in the PeAF group than in the PAF group (1.4 ± 1.1 vs. 0.6 ± 0.7, P = 0.002). The incidence of extensive (2 or more segments) left atrial delayed gadolinium enhancement was greater in the PeAF group than in the PAF group (43.2% (32/74) vs. 14.0% (17/121), P <0.001). Of the nine segments, only the septum, anterior segment, and left lower pulmonary vein cavity showed a higher incidence of left atrial delayed gadolinium enhancement in the PeAF group than in the PAF group (P < 0.05).

10 is a diagram illustrating delayed gadolinium-enhanced MRI of a 45-year-old male with PAF. Transverse delayed gadolinium-enhanced MRI shows null signal intensity in the anterior segment and septum of the anterior left atrial wall. On the other hand, the subsegment of the posterior left atrial wall consists of left atrial wall voxels of high signal intensity (arrow), which is defined as left atrial fibrosis. A 3D left atrial model from delayed gadolinium-enhanced MRI shows delayed gadolinium-enhanced enhancement involving a subsegment of the posterior left atrial wall.

11 is a diagram illustrating delayed gadolinium-enhanced MRI of a 65-year-old male with PeAF. Transverse delayed gadolinium-enhanced MRI reveals a prominent area of high signal intensity (arrow) in the posterior left atrium wall. A 3D left atrium model from MRI shows delayed gadolinium enhancement involving the left lower pulmonary vein cavity (arrow).

Gender, age, left atrial size, left atrial delayed gadolinium enhancement degree, and presence of left atrial delayed gadolinium enhancement in the septum, anterior segment, and left lower pulmonary vein cavity were used as input variables for multivariate logistic regression analysis. In this analysis, left atrial size >112 ml, extensive fibrosis (2 or more delayed gadolinium-enhanced segments), and left atrial delayed gadolinium-enhanced in the left lower pulmonary venous cavity were independent factors of PeAF (odds ratio, 3.8 [95% CI, 1.8). -8.2]: P <0.001, 3.7 [1.5 - 9.5]: P = 0.004, and 4.2 [1.7 - 10.5]: P <0.001).

Table 5 below compares the findings of delayed gadolinium-enhanced MRI between the PAF and PeAF groups.

Argument

This study evaluated the location and extent of left atrial delayed gadolinium-enhanced (LGE) MRI in patients with atrial fibrillation. The results showed that left atrial delayed gadolinium enhancement was common in the posterior left atrial wall. In particular, the most common segment seen in left atrial delayed gadolinium enhancement was the subsegment and left lower pulmonary vein cavity of the posterior left atrial wall despite the degree of left atrial delayed gadolinium enhancement. However, a comparison of delayed gadolinium-enhanced MRI between the two types of atrial fibrillation revealed that left atrial delayed gadolinium-enhanced in the left lower pulmonary vein cavity was more common in the persistent AF group than in the paroxysmal AF group (39.2% (29/29/ 72) vs. 7.4% (9/121), P < 0.01). Multivariate analysis showed that delayed left atrial gadolinium enhancement in the left lower pulmonary vein cavity, two or more segments of the left atrium, and a left atrial size greater than 112 ml were independently associated with persistent atrial fibrillation.

The spatial resolution of delayed gadolinium-enhanced MRI with a thin slice thickness of 1-2 mm enables non-invasive evaluation of left atrial wall tissue features. Assessing ablation-induced left atrial wall wounds using delayed gadolinium-enhanced MRI is possible based on contrast enhancement as well as wall thickening. Jadidi et al. reported that a high density and large area of delayed gadolinium enhancement in the left atrial wall during left atrial wall remodeling was associated with left atrial delayed gadolinium enhancement. Nevertheless, reproducible diagnostic criteria for delayed gadolinium-enhanced MRI are needed to define left atrial delayed gadolinium-enhanced MRI. This is because diffuse fibrosis of the left atrial wall may interfere with tissue discrimination by the degree of contrast enhancement on delayed gadolinium-enhanced MRI. In this study, we attempted to achieve a reproducible evaluation of left atrial delayed gadolinium-enhanced MRI using the following criteria for defining left atrial fibrosis: a) a high signal threshold of delayed gadolinium-enhanced enhancement from a gadolinium phantom, and b) delayed gadolinium. When using the maximum length of enhancement (≥1 cm), all left atrial fibrotic segments by delayed gadolinium-enhanced MRI show a region of the left atrial wall of bipolar low voltage (<0.1 mV) within the corresponding segment on the electroanatomical map.

Left atrial fibrosis can develop through a variety of physiological mechanisms, such as aging, hemodynamic upheavals, and inappropriate contraction of the left atrium with arrhythmias. In general, the posterior left atrial wall near the pulmonary venous orifice exhibits more interstitial fibrosis than the anterior left atrial wall, even in individuals without atrial fibrillation. Tanaka et al. showed that hemodynamic disruption in the left atrial cavity during an atrial fibrillation episode can lead to the development of left atrial fibrosis in the posterior left atrial wall. Platonov et al. reported a high rate of fibrosis in the posterior left atrium wall adjacent to the left lower pulmonary vein. It was also suggested that the anatomical location could lead to left atrial fibrosis near the left lower pulmonary vein cavity. This is because the pulse of the descending aorta can damage the adjacent posterior left atrium wall. In addition, the above results showed that the left lower pulmonary venous cavity is a common segment in which left atrial fibrosis can be found, as can be determined by delayed gadolinium-enhanced MRI.

The chronicity of atrial fibrillation may be associated not only with a specific location, but also with the extent of left atrial fibrosis. With sustained atrial fibrillation, pressure stress develops near the pulmonary veins. Benito et al. reported that the left atrial delayed gadolinium-enhanced segment was preferentially located in the posterior left atrium wall near the left lower pulmonary vein in patients with atrial fibrillation aged 60 years or older. Higuchi et al. reported that left atrial wall fibrosis near the left lower pulmonary vein cavity spreads to the posterior and anterior walls with the progression of atrial fibrillation. These results suggest that the pattern of delayed gadolinium-enhanced MRI may originate in the left inferior pulmonary vein cavity, usually prior to progression to other regions of the left atrium wall, which may be associated with the development of PeAF. Interestingly, we found that delayed gadolinium enhancement in the left lower pulmonary vein cavity was itself associated with PeAF, regardless of the degree of atrial delayed gadolinium enhancement. These findings suggest that the left lower pulmonary vein cavity may be important in the mechanism of progression of both left atrial fibrosis and atrial fibrillation.

In conclusion, the cavity near the posterior left atrial wall and left lower pulmonary vein shows a high incidence of left atrial fibrosis as determined by MRI in patients with atrial fibrillation. Local delayed gadolinium enhancement located in the left lower pulmonary vein cavity, a widespread degree of delayed gadolinium enhancement, or large left atrial size are independently associated with persistent atrial fibrillation. Additional clinical studies are needed to determine the patient prognosis and outcome after catheter resection to establish a clinical application of left atrial fibrosis using MRI.

According to the above-described embodiments of the present invention, in performing image processing for diagnosing myocardial fibrosis through cardiac magnetic resonance imaging (MRI), magnetic resonance imaging of cardiac MRI is performed using artificial reference indicators for each concentration of MRI contrast agent. By standardizing the resonance signal to the T1 value, it is possible to provide an image that induces a reliable and efficient diagnosis of myocardial fibrosis, and through standardized cardiac MRI, it is expected to improve the reliability of myocardial condition evaluation and diagnosis for various types of myocardial disease. Furthermore, it is possible to increase the efficiency of medical services through automation of image analysis.

Meanwhile, the embodiments of the present invention can be implemented as computer-readable codes on a computer-readable recording medium. The computer-readable recording medium includes all types of recording devices in which data readable by a computer system is stored.

Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, and the like. In addition, the computer-readable recording medium is distributed in a computer system connected to a network, so that the computer-readable code can be stored and executed in a distributed manner. And functional programs, codes, and code segments for implementing the present invention can be easily inferred by programmers in the technical field to which the present invention pertains.

In the above, various embodiments of the present invention have been mainly reviewed. Those of ordinary skill in the art to which the present invention pertains will understand that the present invention can be implemented in modified forms without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments are to be considered in an illustrative rather than a restrictive sense. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

10: artificial reference indicators
20: Magnetic resonance image processing device
21: input unit
23: memory
25: processor

Claims (16)

(a) setting an artificial reference index of the T1 value, which is a quantitative unit constituting image particles with an MRI contrast agent having a preset concentration so that the magnetic resonance imaging (MRI) processing apparatus can express damage to abnormal tissue;
(b) receiving, by the MRI processing apparatus, an MRI signal simultaneously measured from the subject together with an artificial reference indicator manufactured using the MRI contrast medium of the preset concentration; and
(c) specifying, by the MRI processing device, the location of the abnormal tissue and the degree of damage by comparing it with the MRI signal intensity of the subject with reference to the signal intensity of the artificial reference indicator included in the inputted MRI signal; Including, a method of processing a magnetic resonance image. The method of claim 1,
The step (a) is,
Using gadolinium selected as an MRI contrast agent and matching individual artificial reference indicators corresponding to T1 values of MRI by concentration through a plurality of physiological saline packs having different gadolinium concentrations, A method of processing a magnetic resonance image. 3. The method of claim 2,
Processing of magnetic resonance imaging, in which half of the maximum signal intensity of MRI is assigned as a threshold value of signal intensity, so that late gadolinium enhancement (LGE) is set to appear in a region having a signal intensity exceeding the assigned threshold Way. 3. The method of claim 2,
A method of processing a magnetic resonance image, which sets abnormal signal intensity standards step by step by adjusting the gadolinium concentration of the plurality of physiological cardiac saline packs. The method of claim 1,
The step (b) is,
A method of processing a magnetic resonance image, comprising positioning a plurality of artificial reference indicators prepared using a plurality of preset concentrations of an MRI contrast agent to be adjacent to a subject, measuring an MRI signal, and receiving the measured MRI signal. The method of claim 1,
Step (c) is,
(c1) calculating a relational expression between the T1 value and the magnetic resonance signal intensity expressed by Equation 1 below from the input MRI signal; and
(c2) converting the MRI signal into an image signal based on a T1 value using the calculated relational expression;
[Equation 1]
Y=-11.259x+1494.396
(In Equation 1, Y is a T1 value, and X is an MRI signal.) 7. The method of claim 6,
The step (c1) is,
Using a correlation in which the concentration of the MRI contrast agent is proportional to the severity of the abnormal tissue and inversely proportional to the T1 value, the relationship between the T1 value and the magnetic resonance signal intensity is calculated from the MRI signal with reference to a preset concentration for the MRI contrast agent , a method of processing magnetic resonance imaging. 7. The method of claim 6,
The step (c2) is,
A method of processing a magnetic resonance image, wherein an area showing a signal intensity exceeding the threshold is marked as an abnormal tissue by using a threshold value of a previously assigned signal intensity. 9. The method of claim 8,
The abnormal tissue is a tissue in which myocardial fibrosis occurs, and the location and damage degree of myocardial fibrosis are visualized and quantified by referring to the concentration of an MRI contrast agent. 10. A computer-readable recording medium recording a program for executing the method of any one of claims 1 to 9 on a computer. an input unit for receiving an MRI signal simultaneously measured from a subject together with an artificial reference indicator manufactured using a magnetic resonance imaging (MRI) contrast agent having a preset concentration to express damage to abnormal tissue;
a memory storing a program for processing the measured MRI signal; and
At least one processor for running the program,
The program stored in the memory is
An artificial reference index of the T1 value, which is a quantitative unit constituting image particles, is set with the MRI contrast agent of the preset concentration, and the object under test is referred to by referring to the signal intensity of the artificial reference index included in the input MRI signal. A magnetic resonance image processing apparatus, comprising instructions for specifying a position of an abnormal tissue and a degree of damage by comparing the MRI signal strength of the MR image to the same. 12. The method of claim 11,
The program stored in the memory is
A magnetic resonance image processing apparatus for matching individual artificial reference indicators corresponding to the T1 values of MRI by concentration through a plurality of physiological saline packs having different gadolinium concentrations using gadolinium selected as an MRI contrast agent. 13. The method of claim 12,
The program stored in the memory is
half of the maximum signal strength of the MRI is assigned as a threshold value of signal strength, so that late gadolinium enhancement (LGE) appears in a region having a signal strength exceeding the allocated threshold,
A magnetic resonance image processing apparatus for setting abnormal signal intensity standards step by step by adjusting the gadolinium concentration of the plurality of physiological cardiac saline packs. 12. The method of claim 11,
The program stored in the memory is
An apparatus for processing a magnetic resonance image, wherein a plurality of artificial reference indicators manufactured using a plurality of preset concentrations of an MRI contrast agent are positioned adjacent to a subject, the MRI signal is measured, and the measured MRI signal is received. 12. The method of claim 11,
The program stored in the memory is
Calculating a relation between the T1 value and the magnetic resonance signal intensity expressed by Equation 1 below from the input MRI signal, and converting the MRI signal into an image signal based on the T1 value using the calculated relational equation. image processing unit.
[Equation 1]
Y=-11.259x+1494.396
(In Equation 1, Y is a T1 value, and X is an MRI signal.) 16. The method of claim 15,
The program stored in the memory is
Using a correlation in which the concentration of the MRI contrast agent is proportional to the severity of the abnormal tissue and inversely proportional to the T1 value, the relationship between the T1 value and the magnetic resonance signal intensity is calculated from the MRI signal with reference to a preset concentration for the MRI contrast agent, ,
Marking an area showing a signal strength exceeding the threshold as an abnormal tissue by using a threshold of a pre-allocated signal strength,
The abnormal tissue is a tissue in which myocardial fibrosis appears, and the location and damage degree of myocardial fibrosis are visualized and quantified by referring to the concentration of an MRI contrast agent.

Images