KR20220030896A - Method for correcting magnetic resonance imaging error using heart rate interval - Google Patents

Abstract

A method for correcting a magnetic resonance imaging error using a heart rate interval may include the steps of: measuring T1 of a stand-alone phantom for correcting an error; obtaining a T1 map generated by mapping a recovery time according to a reference recovery rate of protons in heart tissues of a subject inverted by a radio frequency (RF) pulse in pixel units into a two-dimensional space; and calculating a correction function based on the measured T1 of the phantom; and correcting an error of the T1 map based on the calculated correction function.

Description

Method for correcting magnetic resonance imaging error using heart rate interval

The present invention relates to a method for correcting an error in magnetic resonance imaging using heart rate. The present invention includes the results performed with the support of the Ministry of SMEs and Startups commercialization support project [10448495, development of an automated model for diagnosing heart disease through comprehensive cardiac magnetic resonance imaging (MRI) analysis].

Among various molecular imaging techniques, magnetic resonance imaging (MRI) is based on the interaction between the molecules surrounding the tissue lattice and hydrogen atoms (protons), and has excellent anatomical anatomy. It is considered one of the most powerful and non-invasive diagnostic tools because it can provide images.

Recently, in magnetic resonance imaging, imaging technologies have been developed to quantitatively measure biophysical quantities as well as conventional anatomical tomography images. The biophysical quantities that can be measured by MRI are representative of the self-recovery time, blood flow rate, diffusion, and perfusion of hydrogen atoms according to high-frequency pulses in human tissues, and can be safely and accurately measured non-invasively.

Among these, the contrast between tissues can be created through the characteristics of each component of self-healing, and this difference in recovery time is actively used as a biophysical quantity that can quantitatively evaluate the disease of the tissue at the molecular level.

However, errors in the results may occur depending on the installation environment of the magnetic resonance imaging apparatus and the magnetic resonance imaging conditions.

Conventionally, in order to correct this error, an attachable phantom is attached to the patient, the patient and the patient are simultaneously photographed in the MRI, and the measurement error of the T1 value measured in the myocardium is corrected using the T1 value measured in the phantom. method (patent application number: 10-2018-0077181, 10-2019-0025102) was used.

The conventional error correction method has a weakness in that it is necessary to accurately know the position of the patient's heart in order to photograph the patient and the phantom together, and accurate error correction is possible only when the position of the patient's heart is located on the same imaging plane as the attachable phantom.

For this reason, the conventional T1 correction method of the myocardium using an attached phantom has a problem in that the success rate is lower than expected when applied to an actual clinical environment.

In order to solve the above problem, an object of the present invention is to propose a method of correcting the T1 measurement error of an MRI system using a general type of stand-alone phantom instead of a method of correcting the T1 of the myocardium using an attached phantom.

Another object of the present invention is to propose a magnetic resonance imaging error correction method using a heartbeat interval.

The magnetic resonance imaging error correction method using a heartbeat interval according to an embodiment of the present invention for solving the above technical problem includes the steps of measuring T1 of an independent phantom for the error correction, and converting the subject to an RF (Radio Frequency) pulse Obtaining a T1 map generated by mapping the recovery time according to the reference recovery rate of protons in the inverted cardiac tissue in pixel units in a two-dimensional space, calculating a correction function based on the measured T1 of the phantom, the calculated correction The method may include correcting an error of the T1 map based on the function.

In addition, in the measuring step, the first T1 of the phantom is measured using a modified look-locker inversion recovery (MOLLI) sequence, and the phantom using an inversion recovery turbo spin echo and a MOLLI sequence can measure the second T1 of

In addition, in the calculating of the correction function, a first correction function is calculated through multiple polynomial regression analysis based on the reference T1 and the second T1 of the phantom, and the reference T1 is the previously measured reference of T1 of the phantom. It may be a ground-truth value.

In addition, the calculating of the correction function may include calculating a second correction function through multiple polynomial regression analysis based on the phantom reference T1 and the first T1.

In addition, the calculating of the correction function may include calculating a third correction function through multiple polynomial regression analysis based on the first T1 and the second T1.

In addition, the calculating of the correction function may include calculating the second correction function and the third correction function by dividing the correction coefficients according to the heart rate interval (RRI).

Also, the correcting may include correcting the T1 map in a pixel-by-pixel manner based on the correction function.

In addition, the correcting may include correcting the error of the T1 map by using at least one of the first correction function, a second correction function in which a correction coefficient is determined according to the heartbeat interval of the subject, and a third correction function.

On the other hand, the magnetic resonance imaging error correction device using the heartbeat interval is a T1 measuring unit that measures the T1 of the independent phantom for the error correction, and the test object is inverted with an RF (Radio Frequency) pulse according to the standard recovery rate of protons in the heart tissue. A T1 map acquisition unit that obtains a T1 map generated by mapping the recovery time in pixel units in a two-dimensional space, a correction function calculation unit that calculates a correction function based on the measured T1 of the phantom, and the calculated correction function. An error correction unit for correcting an error of the T1 map may be included.

In addition, the T1 measurement unit measures the first T1 of the phantom using a Modified Look-Locker Inversion Recovery (MOLLI) sequence, and uses an Inversion Recovery turbo spin echo and a MOLLI sequence of the phantom. A second T1 may be measured.

In addition, the correction function calculation unit calculates a first correction function through multiple polynomial regression analysis based on the reference T1 of the phantom and the second T1 of the phantom, and the reference T1 is a pre-measured actual value serving as a reference for the T1 of the phantom. (ground-truth).

Also, the correction function calculator may calculate a second correction function through multiple polynomial regression analysis based on the phantom reference T1 and the first T1.

Also, the correction function calculator may calculate a third correction function through multiple polynomial regression analysis based on the first T1 and the second T1.

In addition, the correction function calculator may calculate the second correction function and the third correction function by dividing the correction coefficients according to the heart rate interval (RRI).

Also, the error correcting unit may correct the T1 map in a pixel-by-pixel manner based on the correction function.

The error correcting unit may correct the error of the T1 map by using one of the first correction function, a second correction function in which a correction coefficient is determined according to the heartbeat interval of the subject, and a third correction function.

According to the present invention, accurate error correction is possible by using an independent phantom instead of an attached phantom.

In addition, the present invention can have a high correction success rate in an actual clinical environment by subdividing the correction function in consideration of the heartbeat interval.

1 is a diagram schematically illustrating an apparatus for correcting an MR image error using a heartbeat interval according to an embodiment of the present invention.
2 is a flowchart illustrating a magnetic resonance image error correction method according to an embodiment of the present invention.
3 and 4 are exemplary views illustrating a method of measuring a first T1 of a phantom using a MOLLI sequence according to an embodiment of the present invention.
5 is a block diagram illustrating a configuration of an error correction apparatus according to an embodiment of the present invention.

The following is merely illustrative of the principles of the invention. Therefore, those skilled in the art can devise various devices that, although not explicitly described or shown herein, embody the principles of the invention and are included in the spirit and scope of the invention. In addition, it should be understood that all conditional terms and examples listed herein are, in principle, expressly intended only for the purpose of understanding the inventive concept, and are not limited to the specifically enumerated embodiments and states. .

The above objects, features and advantages will become more apparent through the following detailed description in relation to the accompanying drawings, and accordingly, those of ordinary skill in the art to which the invention pertains will be able to easily practice the technical idea of the invention. .

In addition, in the description of the invention, if it is determined that a detailed description of a known technology related to the invention may unnecessarily obscure the gist of the invention, the detailed description thereof will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Magnetic resonance imaging (MRI), that is, MRI uses an inversion recovery RF pulse to reverse the longitudinally magnetized atoms by a magnetic field, and then classifies the components in the recovery process that are recovered in the form of an exponential curve, and the recovery time according to the components can be calculated. An MRI signal is acquired by scanning a signal generated from the subject in k-space, and an MRI image is acquired by converting the acquired MRI signal.

Specifically, the characteristics of each component of self-healing can be emphasized by adjusting, for example, TR (Time to repetition) and TE (Time to echo) as variables for an applied RF (Radio Frequency) pulse.

In this case, TR refers to the repetition time of the RF pulse. TR refers to a time interval for generating an RF pulse used to obtain a resonance signal, and mainly determines the amount of longitudinal relaxation (Spin-Lattice Interaction).

TE is the signal generation time and refers to the time until the echo signal is obtained after outputting the RF pulse. TE determines the degree of dispersion (out-of-phase) of the spins recovered onto the transverse plane (Spin-Spin Interaction).

In this case, T1 is defined as the time until the average magnetization of 63% of the initial state is recovered in the longitudinal direction after the RF pulse is injected and reversed in the vertical axis direction as the T1 relaxation time.

T2 is defined as the time it takes for the average magnetization in the abscissa plane to decrease by 37% of the initial phase by dephasing.

That is, by measuring the above time by varying the TR and TE of the RF pulse, a T1-weighted image or a T2-weighted image can be generated.

Specifically, a method of correcting an error of a T1 map generated as a T1-weighted image using a heart rate will be described in the present invention.

Hereinafter, it will be described in more detail with reference to FIG. 1 .

1 is a diagram schematically illustrating a magnetic resonance imaging error correction system using a heartbeat interval according to an embodiment of the present invention.

Referring to FIG. 1 , the error correction apparatus 100 for performing the magnetic resonance imaging error correction method using a heart rate according to the present embodiment is configured in conjunction with the MRI apparatus 1000 or is configured as a part of the MRI apparatus 1000 . can be

As described above, the MRI apparatus 1000 applies a magnetic field and an RF pulse to the subject (or a photographer) 10 , and extracts features in a recovery process after magnetization and inversion of hydrogen atoms in a specific axial direction. By generating an MRI image using the signal received during the recovery process, non-invasive image acquisition and diagnosis are possible.

Specifically, the MRI apparatus 1000 calculates the T1 recovery time according to the recovery rate in the spin-lattice recovery process, which is recovered to an exponential curve shape after inverting the longitudinally magnetized atoms according to the direction of the magnetic field using an inversion recovery RF pulse. can In addition, a T1 value generated from the heart of the subject 10 may be scanned in k-space to be acquired as an MRI signal, and the acquired MRI signal may be mapped in units of pixels to generate a T1 map.

The error correction apparatus 100 is an apparatus for correcting the error of the T1 map. The MRI apparatus 1000 measures T1 of a stand-alone phantom of a general form, and a correction function can be calculated based on the T1 of the phantom. there is. Here, the stand-alone phantom is a composition in which NiCl2 and Agarose are mixed at various concentrations so that the T1 and T2 value ranges in the myocardium are obtained. Unlike the phantom, only the phantom is positioned in the MRI apparatus 1000 to measure T1. In the present invention, the T1MES phantom of 'T1 mapping performance and measurement repeatability: results from the multi-national T1 mapping standardization phantom program (T1MES))' published in the JCMR journal in 2016 is used.

Also, the error correcting apparatus 100 may correct an error of the T1 map of the subject 10 based on the calculated correction function.

Hereinafter, a method for correcting an MR image error using a heart rate according to the present embodiment will be described in more detail with reference to FIG. 2 .

The error correction apparatus 100 may measure T1 of an independent phantom for error correction through the MRI apparatus 1000 ( S100 ).

Specifically, the error correcting apparatus 100 may measure the first T1 of the phantom according to the heartbeat interval using a modified look-locker inversion recovery (MOLLI) sequence.

Hereinafter, a method of measuring the first T1 of the phantom using the MOLLI sequence will be described with reference to FIGS. 3 and 4 .

Referring to FIG. 3 , the error correcting apparatus 100 may acquire a plurality of images according to heartbeat interval and RF pulse synchronization. In this case, in the case of the heart, the heartbeat interval may be measured by measuring an electrical signal generated from the heart called an electrocardiogram (ECG). For example, the beating cycle may be determined based on a specific waveform among the ECG signals. Specifically, by using the R wave representing the highest point among the QRS group, the intermediate map is obtained in units of the RR interval, which is defined as the interval between the R wave and the R wave of the next signal, thereby minimizing the effect of the heart rate to obtain an image. can do.

Specifically, as shown in FIG. 3 , a plurality of signals may be measured at a specific time point of the RR interval after the RF pulse is applied.

When the first inversion occurs after the first RF pulse is applied, a plurality of partial images may be acquired by repeatedly measuring the recovery signals in the longitudinal direction of atoms in the cardiac tissue according to the RR interval.

At this time, the number of images (five) to be acquired may be predetermined, and a second RF pulse is applied on the premise that atoms are recovered through a recovery period after image acquisition, and when a second inversion occurs, a plurality of partial images according to the RR interval (3) can be obtained as an intermediate map for T1 generation.

In addition, the error correction apparatus 100 maps the recovery time of the heart tissues in the eight partial images (A to E) 42 obtained in plurality as shown in FIG. 4 in units of pixels, and sets the recovery time to a normalized curve ( 44) can be fitted.

Using an inversion recovery (IR) pulse, the hydrogen atoms are rotated 180 degrees from the equilibrium state of +M0 to -M0. Thereafter, the TI (inversion time) is adjusted at the time interval for starting image acquisition after imaging, and the degree of recovery of inverted hydrogen atoms to +M0 varies according to the TI time, and the contrast of MRI images varies.

That is, the amount of recovery of the longitudinal axis after inversion of hydrogen atoms in the heart tissue may be measured in units of pixels in a plurality of partial images, and this may be fitted in the form of an exponential function.

A curve for curve fitting can be defined by a three-parameter (A, B, T1) model. The curve has a time value t according to T1* as an input of an exponential function, and a signal intensity y(t) according to time t is defined by Equation 1 below.

[Equation 1]

Also, T1 may be calculated by applying Equation 2 below.

[Equation 2]

With the above equation, the error correcting apparatus 100 may measure the first T1 of the phantom according to the heartbeat interval.

In addition, in the measuring step (S100), the error correction device 100 measures the second T1 of the phantom according to the heartbeat interval using the inversion recovery turbo spin echo (IR-TSE) and the MOLLI sequence. can Here, the inversion recovery turbo spin echo is a method of filling different k-spaces by obtaining echoes having a plurality of different phase codes during one TR.

That is, in the measuring step (S100), the first T1 of the phantom is measured using a Modified Look-Locker Inversion recovery (MOLLI) sequence, and the phantom using an Inversion Recovery turbo spin echo and a MOLLI sequence. The second T1 of . may be measured according to the heartbeat interval.

Next, the error correction apparatus 100 maps the recovery time according to the reference recovery rate of protons in the cardiac tissue inverted by the RF (Radio Frequency) pulse to the subject in units of pixels in the two-dimensional space to map the T1 map generated by the MRI apparatus ( 1000) can be obtained from Also, the error correction apparatus 100 may directly generate the T1 map through the MRI apparatus 1000 .

Next, the error correction apparatus 100 may calculate three correction functions based on the measured phantom T1 ( S300 ).

Specifically, the error correction apparatus 100 calculates the first correction function through multiple polynomial regression based on the phantom reference T1 and the second T1, and based on the phantom reference T1 and the first T1 A second correction function may be calculated through multiple polynomial regression analysis, and a third correction function may be calculated through multiple polynomial regression analysis based on the first T1 and the second T1. Here, the reference T1 means a ground-truth that serves as a reference for the previously measured phantom T1.

That is, in order to generate a correction function, the error correction apparatus 100 includes a first correction function as a Gold-standard T1 map based calibration method (Gold-standard T1 map based calibration (GC)), and a second correction function as a MOLLI T1 map. Based on the calibration method (MOLLI T1 map based calibration (MC)), the third calibration function may use an internal reference based calibration method (Internal Reference based calibration (IC)).

Also, the error correcting apparatus 100 may arbitrarily set a heartbeat interval of the subject, and calculate the second correction function and the third correction function, respectively, depending on whether or not the heart rate interval (RRI) is considered.

For example, the error correction apparatus 100 subdivides the second correction function and the third correction function into a case in which a heartbeat interval is considered and a case in which the heartbeat interval is not considered (static RRI, 900 ms), respectively, as shown in Table 1 below. can do.

Method RRI [ms] Input Source Calibration Model Index Gold-standard T1 map based calibration (GC) N/A

MOLLI T1 map based calibration (MC) 900

Various

Internal Reference based calibration (IC)
900

Various

In this case, the error correcting apparatus 100 may calculate the second correction function and the third correction function by using the first T1 corresponding to each heartbeat interval.

For example, when the heartbeat interval is subdivided into 100ms intervals in the range of 700 to 1100ms, the error correcting apparatus 100 uses the first T1 corresponding to each heartbeat interval to the second second having a correction coefficient as shown in Table 2 below. A correction function can be calculated.

Table 2 is a table showing the correction coefficients corresponding to the RRI of the myocardial native T1 map before contrast medium injection for the MOLLI T1 map-based correction method.

Institution Method Index RRI [ms] Coefficient of Calibration function a b c d A MC ₁ 700 0 0 1.051E+00 -3.304E+00 800 0 0 1.043E+00 1.156E+00 900 0 0 1.035E+00 5.357E+00 1000 0 0 1.029E+00 7.576E+00 1100 0 0 1.026E+00 9.989E+00 MC ₂ 700 0 -1.252E-04 1.296E+00 -8.470E+01 800 0 -1.313E-04 1.302E+00 -8.486E+01 900 0 -1.376E-04 1.308E+00 -8.543E+01 1000 0 -1.418E-04 1.312E+00 -8.678E+01 1100 0 -1.481E-04 1.322E+00 -8.903E+01 mc ₃ 700 -1.995E-07 5.045E-04 7.314E-01 4.388E+01 800 -1.881E-07 4.656E-04 7.639E-01 3.777E+01 900 -1.804E-07 4.381E-04 7.870E-01 3.356E+01 1000 -1.790E-07 4.324E-04 7.900E-01 3.280E+01 1100 -1.821E-07 4.380E-04 7.875E-01 3.350E+01 B MC ₁ 700 0 0 1.054E+00 -9.291E+00 800 0 0 1.046E+00 -4.517E+00 900 0 0 1.036E+00 9.215E-01 1000 0 0 1.032E+00 4.097E+00 1100 0 0 1.031E+00 5.195E+00 MC ₂ 700 0 -1.057E-04 1.261E+00 -7.798E+01 800 0 -1.111E-04 1.264E+00 -7.724E+01 900 0 -1.274E-04 1.289E+00 -8.356E+01 1000 0 -1.314E-04 1.293E+00 -8.317E+01 1100 0 -1.378E-04 1.305E+00 -8.657E+01 mc ₃ 700 -1.895E-07 4.900E-04 7.278E-01 4.350E+01 800 -1.895E-07 4.878E-04 7.260E-01 4.552E+01 900 -1.765E-07 4.355E-04 7.788E-01 3.333E+01 1000 -1.770E-07 4.342E-04 7.808E-01 3.422E+01 1100 -1.843E-07 4.525E-04 7.697E-01 3.622E+01 C MC ₁ 700 0 0 1.018E+00 7.368E+00 800 0 0 1.010E+00 1.242E+01 900 0 0 1.002E+00 1.522E+01 1000 0 0 9.961E-01 1.939E+01 1100 0 0 9.937E-01 1.949E+01 MC ₂ 700 0 -1.277E-04 1.274E+00 -7.902E+01 800 0 -1.318E-04 1.276E+00 -7.714E+01 900 0 -1.360E-04 1.279E+00 -7.820E+01 1000 0 -1.447E-04 1.291E+00 -8.076E+01 1100 0 -1.488E-04 1.298E+00 -8.424E+01 mc ₃ 700 -1.684E-07 4.165E-04 7.760E-01 3.601E+01 800 -1.551E-07 3.721E-04 8.121E-01 2.994E+01 900 -1.530E-07 3.638E-04 8.172E-01 2.870E+01 1000 -1.469E-07 3.374E-04 8.444E-01 2.294E+01 1100 -1.401E-07 3.126E-04 8.691E-01 1.579E+01

In addition, when the heart rate interval is not considered, the error correcting apparatus 100 may calculate the correction functions having the correction coefficients shown in Table 3 below using T1 corresponding to the 900 ms heart rate interval (RRI).

Table 3 is a table showing correction factors for myocardial native T1 map before contrast medium injection and post (POST) T1 map after contrast medium injection at 900 ms heart rate intervals.

Calibration Method T1 map Method
Index Institution Coefficient of Calibration function a b c d Gold-Standard T1 map based
Calibration
(GC) IR-TSE
GC ₁ A 0 0 9.770E-01 7.528E+00 B 0 0 9.808E-01 5.505E+00 C 0 0 9.206E-01 2.295E+01 GC ₂ A 0 -6.234E-06 9.897E-01 3.284E+00 B 0 -7.538E-06 9.961E-01 3.755E-01 C 0 -3.446E-05 9.944E-01 -2.735E+00 GC ₃ A 5.520E-08 -1.834E-04 1.151E+00 -3.409E+01 B 4.178E-08 -1.415E-04 1.118E+00 -2.785E+01 C 5.046E-08 -2.054E-04 1.158E+00 -4.214E+01 MOLLI T1 map based Calibration
(MC) Native T1 MC ₁ A 0 0 1.035E+00 5.357E+00 B 0 0 1.036E+00 9.215E-01 C 0 0 1.002E+00 1.522E+01 MC ₂ A 0 -1.376E-04 1.308E+00 -8.543E+01 B 0 -1.274E-04 1.289E+00 -8.356E+01 C 0 -1.360E-04 1.279E+00 -7.820E+01 mc ₃ A -1.804E-07 4.381E-04 7.870E-01 3.356E+01 B -1.765E-07 4.355E-04 7.788E-01 3.333E+01 C -1.530E-07 3.638E-04 8.172E-01 2.870E+01 Post T1 MC ₁ A 0 0 1.180E+00 -5.357E+01 B 0 0 1.179E+00 -5.593E+01 C 0 0 1.146E+00 -4.305E+01 MC ₂ A 0 -9.653E-05 1.355E+00 -1.093E+02 B 0 -7.223E-05 1.310E+00 -9.752E+01 C 0 -1.034E-04 1.338E+00 -1.049E+02 mc ₃ A -4.142E-07 1.108E-03 3.479E-01 1.104E+02 B -4.002E-07 1.089E-03 3.407E-01 1.137E+02 C -3.633E-07 9.763E-04 4.180E-01 9.839E+01 Internal Reference based Calibration
(IC) Native T1 IC ₁ A 0 0 1.059E+00 -1.736E+00 B 0 0 1.056E+00 -4.362E+00 C 0 0 1.089E+00 -8.298E+00 IC ₂ A 0 -1.428E-04 1.342E+00 -9.595E+01 B 0 -1.288E-04 1.311E+00 -8.982E+01 C 0 -1.173E-04 1.327E+00 -8.886E+01 IC ₃ A -2.507E-07 6.571E-04 6.182E-01 6.938E+01 B -2.309E-07 6.078E-04 6.443E-01 6.317E+01 C -2.432E-07 6.768E-04 5.938E-01 8.096E+01 Post T1 IC ₁ A 0 0 1.207E+00 -6.174E+01 B 0 0 1.201E+00 -6.205E+01 C 0 0 1.244E+00 -7.093E+01 IC ₂ A 0 -1.012E-04 1.390E+00 -1.202E+02 B 0 -7.230E-05 1.332E+00 -1.037E+02 C 0 -7.316E-05 1.379E+00 -1.147E+02 IC ₃ A -5.079E-07 1.376E-03 1.551E-01 1.492E+02 B -4.709E-07 1.294E-03 1.921E-01 1.448E+02 C -4.907E-07 1.385E-03 1.372E-01 1.599E+02

That is, the error correcting apparatus 100 may calculate the second correction function and the third correction function by subdividing the correction coefficients according to the heartbeat interval RRI.

Meanwhile, the error correction apparatus 100 may calculate the second correction function and the third correction function by subdividing the correction coefficients according to the heartbeat cycle.

For example, the error correcting apparatus 100 sets the heartbeat cycle of the subject 10 to 50, 60, 70, 80, or 90 bpm (beat per minute) to take pictures, and sets the correction coefficient according to the heartbeat cycle. Separately, the second correction function and the third correction function may be calculated.

Next, the error correction apparatus 100 may correct the error of the T1 map based on the calculated correction function ( S400 ).

Specifically, the error correction apparatus 100 may correct the T1 map pixel-by-pixel based on the correction function. In this case, the error correcting apparatus 100 may use at least one of a first correction function, a second correction function in which a correction coefficient is determined according to the heartbeat interval of the subject, and a third correction function.

For example, the error correcting apparatus 100 may correct the T1 map by using a correction function as in Equation 3 below.

[Equation 3]

In Equation 3, x is the uncorrected T1 value, y is the corrected T1 value, and a, b, c, and d are correction coefficients. can

That is, in the step of correcting ( S400 ), the error correcting apparatus 100 uses at least one of a first correction function, a second correction function in which a correction coefficient is determined according to the heartbeat interval of the subject, and a third correction function of the T1 map. error can be corrected.

Hereinafter, the error correction apparatus 100 performing the error correction method according to the present embodiment will be described with reference to FIG. 5 .

Referring to FIG. 5 , the error correcting apparatus 100 may include a T1 measuring unit 110 , a T1 map obtaining unit 120 , a correction function arithmetic weight 130 , and an error correcting unit 140 .

The T1 measuring unit 110 may measure or obtain T1 of the independent phantom for error correction through the MRI apparatus 1000 .

In addition, the T1 measuring unit 110 measures the first T1 of the phantom using a modified look-locker inversion recovery (MOLLI) sequence, and the phantom using an inversion recovery turbo spin echo and a MOLLI sequence. It is possible to measure or obtain the second T1 of .

In addition, the T1 map acquisition unit 120 maps the recovery time according to the reference recovery rate of protons in the heart tissue inverted by the RF (Radio Frequency) pulse to the subject through the MRI apparatus 1000 in units of pixels in the two-dimensional space. The generated T1 map can be acquired.

The correction function calculator 130 may calculate the correction function based on the measured phantom T1.

Specifically, the correction function calculator 130 calculates the first correction function through multiple polynomial regression analysis based on the phantom reference T1 and the second T1, and multiple polynomial regression based on the phantom reference T1 and the first T1. A second correction function may be calculated through the analysis, and a third correction function may be calculated through multiple polynomial regression analysis based on the first T1 and the second T1.

In this case, the correction function calculator 130 may calculate the second correction function and the third correction function by subdividing the correction coefficient according to the heartbeat interval RRI.

The error correction unit 140 may correct the error of the T1 map based on the calculated correction function.

Specifically, the error correcting unit 140 may correct the T1 map pixel-by-pixel based on the correction function.

In this case, the error correcting unit 140 may correct the error of the T1 map by using at least one of the first correction function, the second correction function in which the correction coefficient is determined according to the heartbeat interval of the subject, and the third correction function.

As described above, according to the present invention, accurate error correction is possible by using an independent phantom instead of an attached phantom.

In addition, by subdividing the correction function in consideration of the heartbeat interval, it is possible to have a high correction success rate in an actual clinical environment.

Furthermore, various embodiments described herein may be implemented in a computer-readable recording medium using, for example, software, hardware, or a combination thereof.

According to the hardware implementation, the embodiments described herein include ASICs (application specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays, It may be implemented using at least one of processors, controllers, micro-controllers, microprocessors, and other electrical units for performing functions. The described embodiments may be implemented in the control module itself.

According to the software implementation, embodiments such as the procedures and functions described in this specification may be implemented as separate software modules. Each of the software modules may perform one or more functions and operations described herein. The software code may be implemented as a software application written in a suitable programming language. The software code may be stored in the memory module and executed by the control module.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains may make various modifications, changes and substitutions within the scope without departing from the essential characteristics of the present invention. will be.

Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are intended to explain, not to limit the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments and the accompanying drawings . The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Claims (17)

In a magnetic resonance image error correction method using a heartbeat interval,
measuring T1 of the independent phantom for the error correction;
acquiring a T1 map generated by mapping a recovery time according to a reference recovery rate of protons in cardiac tissue inverted by a radio frequency (RF) pulse to the subject in units of pixels in a two-dimensional space;
calculating a correction function based on the measured phantom T1;
and correcting the error of the T1 map based on the calculated correction function. The method of claim 1,
In the measuring step, the first T1 of the phantom is measured using a modified look-locker inversion recovery (MOLLI) sequence, and the second T1 of the phantom is measured using an inversion recovery turbo spin echo and a MOLLI sequence. 2 An error correction method comprising measuring T1. 3. The method of claim 2,
The step of calculating the correction function is
calculating a first correction function through multiple polynomial regression analysis based on the phantom reference T1 and the second T1;
The reference T1 is a ground-truth that is a reference of the previously measured T1 of the phantom. 4. The method of claim 3,
The calculating of the correction function comprises calculating a second correction function through multiple polynomial regression analysis based on the phantom reference T1 and the first T1. 4. The method of claim 3,
The calculating of the correction function comprises calculating a third correction function through multiple polynomial regression analysis based on the first T1 and the second T1. 6. The method according to claim 4 and 5,
The calculating of the correction function comprises calculating the second correction function and the third correction function by classifying the correction coefficients according to the heart rate interval (RRI). 7. The method of claim 6,
The correcting is an error correction method, wherein the T1 map is corrected pixel-by-pixel based on the correction function. 8. The method of claim 7,
The correcting comprises correcting the error of the T1 map by using at least one of the first correction function, a second correction function in which a correction coefficient is determined according to the heartbeat interval of the subject, and a third correction function. Error correction method. In the magnetic resonance image error correction device using a heartbeat interval,
a T1 measurement unit for measuring T1 of the independent phantom for the error correction;
a T1 map acquisition unit that acquires a T1 map generated by mapping the subject to a pixel unit in a two-dimensional space and a recovery time according to a reference recovery rate of protons in cardiac tissue inverted with a radio frequency (RF) pulse;
a correction function calculator for calculating a correction function based on the measured phantom T1;
and an error correction unit that corrects the error of the T1 map based on the calculated correction function. 10. The method of claim 9,
The T1 measurement unit measures the first T1 of the phantom using a Modified Look-Locker Inversion Recovery (MOLLI) sequence, and uses an Inversion Recovery turbo spin echo and a MOLLI sequence to measure the second T1 of the phantom. Error correction device, characterized in that for measuring T1. 11. The method of claim 10,
The correction function calculation unit
calculating a first correction function through multiple polynomial regression analysis based on the phantom reference T1 and the second T1;
The reference T1 is a ground-truth that is a reference of the previously measured T1 of the phantom. 12. The method of claim 11,
The correction function calculator calculates a second correction function through multiple polynomial regression analysis based on the phantom reference T1 and the first T1. 12. The method of claim 11,
The correction function calculator calculates a third correction function through multiple polynomial regression analysis based on the first T1 and the second T1. 14. The method according to claim 12 and 13,
and the correction function calculator calculates the second correction function and the third correction function by dividing the correction coefficients according to the heart rate interval (RRI). 15. The method of claim 14,
and the error correcting unit corrects the T1 map in a pixel-by-pixel manner based on the correction function. 16. The method of claim 15,
The error correction unit corrects the error of the T1 map by using at least one of the first correction function, a second correction function in which a correction coefficient is determined according to the heartbeat interval of the subject, and a third correction function correction device. A computer-readable recording medium storing a program for executing the error correction method according to any one of claims 1 to 8.

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