KR102396269B1 - Method to provide information necessary for CMT type 1A diagnosis by quantitative measurement of thigh muscle using MRI - Google Patents

Abstract

The present invention relates to a method for providing information necessary for diagnosing CMT type 1A through quantitative measurement of femoral muscle using MRI.

Description

{Method to provide information necessary for CMT type 1A diagnosis by quantitative measurement of thigh muscle using MRI}

The present invention relates to a method for providing information necessary for diagnosing CMT type 1A through quantitative measurement of femoral muscle using MRI.

Charcot-Marie-Tooth disease (hereinafter, CMT) is a hereditary neuromuscular disease associated with various gene mutations that cause axonal degeneration of peripheral nerves. The main clinical features are muscle loss and loss of sensation in the distal center of the upper and lower extremities. It has been reported that the clinical course of the disease may vary not only between different subtypes but also within the same subtype. Therefore, close monitoring of the patient is necessary.

Currently, there is no approved drug treatment, and symptomatic treatment is used as the main treatment for CMT.

In addition, several genes related to CMT have been identified through recent studies, raising the potential for gene therapy using these genes to be developed as a new treatment option in the future. In this regard, there is a need for an objective and reliable diagnostic and evaluation method to evaluate a patient's condition including treatment response evaluation.

Careful evaluation and monitoring of the affected muscle is important in the management of CMT patients. One of the common problems encountered in the management of patients with CMT in the practice setting is the lack of a standardized method to assess muscle degeneration. Numerous scoring systems have been developed for the diagnosis and monitoring of patients with CMT, consisting of several clinical parameters, including limb strength. Nevertheless, these systems have a problem of inconsistency among raters or limiting reproducibility in evaluations by raters themselves.

Although muscle biopsy can provide information on intramuscular fat infiltration, it is very difficult to use routinely because the procedure itself is invasive and the scope of the examination area is limited.

Magnetic resonance imaging (hereinafter, MRI) enables an overall visual evaluation of the extent and distribution of intramuscular fat infiltration that is expressed simultaneously in multiple muscle compartments, which is common in CMT patients. The conventional Goutallier grading system is a semi-quantitative grading system that uses T1-weighted image sequences, and is widely used for the evaluation of various muscular diseases. This system has significant disadvantages in that the subjectivity of the observer is highly likely to intervene and there is a lack of quantitative data. In addition, because this classification relies on macroscopic fat signals and consists of only five grades, there are limitations in the evaluation of early changes in microscopic fat infiltration or microscopic progression of fat infiltration between MRIs taken at regular intervals. have

Dixon MRI is a new imaging technology for fat percentage measurement that utilizes the ability to differentiate the individual contributions of water and fat in each voxel of the tissue by using the difference in chemical shifts in two tissues. A recent Dickson-based MRI technique generates a fat fraction map that can directly and quantitatively measure the percentage of fat within a designated region of interest (ROI). Given the important clinical implications of muscle evaluation in the management of CMT patients, there is a need for reproducible quantitative imaging parameters collected through Dickson-based MRI.

Republic of Korea Patent Publication No. 10-2014-0148206 (2014.12.31.)

Accordingly, the present inventors conducted a prospective comparative study on CMT patients and volunteers, and confirmed that intramuscular fat mass could be measured using a 3D multidimensional gradient echo-Dixon-based MRI sequence.

Specifically, an analysis of the femoral muscle was performed, and since distal muscle invasion is the main characteristic in CMT patients, intramuscular fat infiltration in the calf is prominent. In addition, we evaluated the potential of this imaging technique in terms of sensitivity by comparing the fat fraction obtained through a three-dimensional multiple gradient echo-Dixon sequence for muscles judged to be normal based on the Goutallier rating between CMT patients and volunteers.

Accordingly, an object of the present invention is to provide a method for providing information necessary for diagnosing CMT type 1A through quantitative measurement of the femoral muscle using MRI.

The present invention relates to a method for providing information necessary for diagnosing CMT type 1A through quantitative measurement of femoral muscle using MRI.

Hereinafter, the present invention will be described in more detail.

One embodiment of the present invention relates to a method of providing information necessary for diagnosing Charcot-Marie-Tooth disease (hereinafter, CMT) type 1A through quantitative measurement of the femoral muscle using MRI.

The method of the present invention may comprise the following steps:

A T1-weighted MRI image acquisition step of acquiring an axial T1-weighted MRI image of the thigh muscle;

A T2-weighted MRI image acquisition step of acquiring an axial T2-weighted MRI image of the thigh muscle;

a muscle boundary visualization step of visualizing a region of interest from the T1-weighted MRI image;

an image acquisition step for analysis of acquiring an image for analysis by combining the visualized region of interest with an axial T2-weighted MRI image;

A quantitative evaluation step of measuring the fat fraction of the thigh muscle from the image for analysis.

In the present invention, MRI images can be largely divided into T1- or T2-weighted MRI images. The T1- and T2-weighted images mean the spin-lattice relaxation time or the spin-spin relaxation time after nuclear spin is excited in MRI, respectively, and have different contrasting effects.

In the present invention, in the T1-weighted MRI image, water is expressed in black and fat is expressed in white.

In the present invention, in the T2-weighted MRI image, water is expressed in white and fat is expressed in black.

In the present invention, the T1-weighted MRI image may be an image of the upper 1/3 point and the lower 1/3 point of the thigh muscle, but is not limited thereto. Considering that the area and distribution of the thigh muscles are different in the proximal and distal regions, and that the CMT invades the distal muscles well, the evaluation was performed at one point each at the proximal and distal regions, and was determined as above.

The upper and lower 1/3 points may be measured with the proximal region as the upper part and the distal region as the lower part with respect to the femur.

In the present invention, the region of interest is the rectus femoris, vastus lateralis, vastus medialis, biceps femoris (long head), semitendinosus, and large thigh muscles of the thigh muscle. It may be the seven fractions of adductor magnus and gracilis.

In an example of the present invention, when the T1-weighted MRI image is a T1-weighted MRI image of the upper third of the thigh muscle, the region of interest is the rectus femoris, the vastus lateralis, the internal vastus, semitendinosus, adductor serratus and extensor muscles. It may be six fractions. In some cases, the biceps femoris was not sufficiently included in the image range at this level, so it was excluded from the evaluation for consistency.

In an example of the present invention, when the T1-weighted MRI image is a T1-weighted MRI image of the lower third of the thigh muscle, the region of interest is the rectus femoris, the vastus lateralis, the internal vastus muscle, semitendinosus, biceps femoris, and brachii muscle. It may be six fractions. In some cases, the adductor adductor muscle was not sufficiently included in the image range at the corresponding level, so it was excluded from the evaluation for consistency.

In one embodiment of the present invention, the method of the present invention may include the following steps:

A T1-weighted MRI image acquisition step of acquiring an axial T1-weighted MRI image of the upper 1/3 point and the lower 1/3 point of the thigh muscle;

A T2-weighted MRI image acquisition step of acquiring an axial T2-weighted MRI image of the upper 1/3 point and the lower 1/3 point of the thigh muscle;

image visualization step of the upper thigh muscle to visualize the region of interest of six fractions of the rectus femoris, vastus lateralis, vastus internalis, semitendinosus, adductor serratus and extensor muscle from the T1-weighted MRI image of the upper third of the thigh muscle;

An image acquisition step for upper thigh muscle analysis of acquiring an image for analysis of the upper third of the thigh muscle based on the T2-weighted MRI image of the upper third of the thigh muscle in the visualized region of interest in the upper third of the thigh muscle;

Visualizing the lower part of the thigh muscle image from the T1-weighted MRI image of the lower third of the thigh muscle to visualize the regions of interest of six segments: the rectus femoris, the vastus lateralis, the internal vastus muscle, the semitendinosus, the biceps femoris and the extensor muscle;

An image acquisition step for analysis of the lower part of the thigh muscle of acquiring an image for analysis of the lower part of the thigh muscle based on the T2-weighted MRI image of the lower third of the thigh muscle in the visualized region of interest in the lower third of the thigh muscle;

A quantitative evaluation step of measuring the fat fraction of the thigh muscle from the image for analysis of the upper and lower thigh muscles.

The present invention relates to a method for providing information necessary for diagnosing CMT type 1A through quantitative measurement of femoral muscle using MRI.

1A is an axial T1-weighted image showing an example of a semi-quantitative analysis and region-of-interest (ROI) measurement performed for the analysis of the amount of fat in the thigh muscle of a 33-year-old male volunteer according to an embodiment of the present invention.
1B is a three-dimensional multi-gradient echo Dixon-based diagram showing an example of semi-quantitative analysis and region-of-interest (ROI) measurement performed for quantitative analysis of the amount of fat in the thigh muscle of a 33-year-old male volunteer according to an embodiment of the present invention; It is a water-only image obtained from magnetic resonance imaging of
1C shows the same shape, size, and location on a fat fraction map using a copy-paste function of a region of interest (ROI) performed for quantitative analysis of the amount of fat in the thigh muscle of a 33-year-old male volunteer according to an embodiment of the present invention; ROI is the generated image.
2A is a three-dimensional multi-gradient echo Dixon-based magnetic resonance diagram showing an example of a region of interest (ROI) measurement performed for measuring the amount of intramuscular fat in the thigh of a 35-year-old male CMT patient according to an embodiment of the present invention. This is a water-only video obtained from the video.
2B is a copy-paste function of a region of interest (ROI) for an example of a region of interest (ROI) measurement performed for measuring the amount of intramuscular fat in the thigh of a 35-year-old male CMT patient according to an embodiment of the present invention. ROIs of the same shape, size, and location on the fat fraction map using the generated image.
3A is an axial T1-weighted image showing an example of a semi-quantitative analysis and region-of-interest (ROI) measurement performed for quantification of fat in the upper thigh muscle of a 36-year-old male CMT patient according to an embodiment of the present invention.
3B is a three-dimensional multi-gradient echo Dickson-based MRI showing an example of a semi-quantitative analysis and region-of-interest (ROI) measurement performed for fat quantification in the upper thigh muscle of a 36-year-old male CMT patient according to an embodiment of the present invention. This is a water-only video obtained from
3c is a region of interest (ROI) performed for fat quantification in the upper thigh muscle of a 36-year-old male CMT patient in accordance with an embodiment of the present invention in the same shape and size in the fat fraction map using the copy-paste function. and the ROI of the location is an image generated.
4A is a box plot graph showing the distribution of fat fraction in 408 thigh muscles of all subjects of each Goutallier grade according to an embodiment of the present invention. (The number in parentheses is the number of muscles measured)
4B is a box plot graph showing the distribution of fat fraction in Goutallier grade 0 muscle of volunteer and CMT patient groups according to an embodiment of the present invention. (The number in parentheses is the number of muscles measured)

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, these examples are only for illustrating the present invention, and the scope of the present invention is not limited by these examples.

Study population

This study was approved by our institutional review board. Between February and June 2017, 18 patients diagnosed with CMT Type I by genetic analysis and electrophysiological examination underwent prospective MRI. Seventeen patients underwent genetic analysis were diagnosed with CMT Type IA. One patient without genetic testing was diagnosed with CMT Type I based on electrophysiological studies and clinical records. This cohort was suitable for patients aged 20 to 40 years (mean ± standard deviation: 30.1 ± 4.3 years, range: 23–37 years, 8 males and 10 females). No patients had claustrophobia or metal implants. A notice was posted to recruit 18 age- and sex-matched volunteers with no history of peripheral neuropathy or lower extremity disease.

A neurologist (21 years of experience) performed a neurological examination to evaluate for signs of abnormality prior to MRI. Finally, 18 healthy volunteers of age- and sex-matched age (mean age 28.2 ± 1.2 years, age range 20-36 years, 8 males and 10 females) were recruited. All participants provided informed written consent prior to MRI. As participants did not quit midway, data collected from 18 subjects in each group were used for analysis.

Magnetic resonance imaging acquisition

Magnetic resonance imaging (MRI) was acquired using a 3.0-T MRI system (Ingenia, Philips Healthcare, Best, the Netherlands) using a 16-channel front coil and a rear internal coil. The following MRI sequences were obtained for morphological imaging:

Coronal and axial T1-weighted turbo spin echo sequences and axial T2-weighted Dixon sequences.

Water-only, fat-only, in-phase and other phase images were generated from the Dixon sequence. The MRI protocol is shown in Table 1.

imaging parameters T1-weighted TSE imaging in axial plane T1-weighted TSE imaging in coronal plane T2-weighted Dixon imaging in axial plane mDixon-Quant Repetition time(ms) 613.7 450-650 4635.5 6.6 Echo time (ms) 16.7 15 80 1.01, 1.91, 2.81, 3.71, 4.61, 5.51 Flip angle (°) 90 90 90 3 No. of signals averaged One One One 2 Reconstructed voxel size (mm) 0.68 0.68 0.68 1.82 Matrix size 320 X 320 320 X 317 320 X 320 192 X 192 Field of view (mm) 350 X 350 350 X 350 350 X 350 350 X 350 Section thickness (mm) 2 5 2 6 Gap (mm) One 0.5 One 0 Number of slices 67 25 67 140 Imaging time (s) 162 200 194 72.5

mDixon-Quant, 3D multi-gradient echo Dixon - sequence of fat mass quantification; None. TSE, Turbo Spin Echo.

A three-dimensional multi-gradient echo Dixon-based MRI sequence (mDixon-Quant, Philips Healthcare, Best, the Netherlands) for fat fraction quantification was obtained by sampling six echo data. Images were obtained in the axial direction from the anterior inferior iliac spine to the distal end of the femur for the pelvis and femur. Fat-water only images were reconstructed and obtained automatically to generate an axial fat fraction map by correcting for the confounding effects of T2* decay.

Data analysis

Water only images and fat fraction maps were loaded into image processing software (IntelliSpace Portal, version 5.0, Philips Healthcare). Segmentation of all muscle compartments was performed manually by two independent radiologists (with 14 and 5 years of experience in musculoskeletal radiology, respectively) without knowledge of clinical information. The ROI was drawn in this image first because it allows better visualization of muscle boundaries in water-only images. ROIs of the same shape, size and location were generated on the fat fraction map using the copy-and-paste function on the workstation.

The thigh muscles are the rectus femoris, vastus lateralis, vastus medialis, biceps femoris (long head), semitendinosus, adductor magnus, and extensor muscles. (gracilis) was divided into 7 fractions (FIGS. 1 to 3). These muscles were selected for analysis because they consistently displayed relatively clear boundaries. Assessments were performed to determine the muscle fat fraction in the upper and lower thirds of the thighs on both sides. The upper and lower third points were determined using image slice numbers from the top of the femoral head to the bottom of the femoral condyles. The biceps femoris in the upper third and the adductor muscles in the lower third were not measured. The ROI was set to be within 1-2 mm from the muscle membrane. One radiologist recreated the ROI to measure the muscle cross-sectional area of the upper and lower thirds of both thighs.

All subjects were examined in duplicate to evaluate the test-retest reproducibility of 3-D multiple gradient echo Dixon-based MRI. Using the copy-paste function, each radiologist independently generated an ROI from the fat fraction map in the second set of images.

Semi-quantitative assessment

Two radiologists analyzed T1-weighted images of the thigh muscles and independently graded the presence of fat based on the five-grade semi-quantitative scale described by Goutallier:

Grade 0, normal;

Grade 1, some fatty streaks;

Grade 2, less fat than muscle;

Grade 3, fatty degeneration of 50%;

Grade 4, fat infiltration of more than 50%.

The radiologist was unaware of the clinical information, and the analysis was performed at the same point as the upper third of the thigh where the fat fraction was measured.

Clinical assessment

Demographic and clinical data of CMT patients are presented in Table 2.

Patient
number Gender Age Disease duration
(years) CMT
neuropathy score functional
disability scale Knee extension ^a
(left/right) Knee flexion ^a
(left/right) One Male 22 11 5 One 5/5 5/5 2 Male 24 2 7 One 5/5 5/5 3 Male 26 0 14 2 5/5 5/5 4 Male 27 12 16 2 5/5 5/5 5 Male 29 16 16 2 5/5 5/5 6 Male 34 19 11 One 5/5 5/5 7 Male 36 29 21 3 5/5 5/5 8 Female 20 5 15 3 5/5 5/5 9 Female 22 6 9 One 5/5 5/5 10 Female 23 2 7 One 5/5 5/5 11 Female 28 11 18 2 5/5 5/5 12 Female 32 30 9 One 5/5 5/5 13 Female 35 16 16 2 5/5 5/5 14 Female 33 33 6 One 5/5 5/5 15 Female 25 12 17 2 4+/4+ 5/5 16 Female 34 5 6 One 5/5 5/5 17 Female 31 18 9 One 5/5 5/5

^a : Assessment based on the scale of the British Medical Research Council.

Disease duration was determined by questioning patients when symptoms such as peripheral muscle weakness, erectile dysfunction, and/or sensory changes first appeared. The severity of CMT was assessed using the dysfunctional rating and the CMT Neuropathy Score (CMTNS). A British Medical Research Council metric was used to evaluate thigh muscle strength. Knee flexion and extension were examined from both sides. One CMT patient had Medical Research Council Grade 4+ in bilateral knee extension, but all other patients had no abnormalities. None of the patients complained of subjective weakness related to thigh movement. Table 3 shows the results of electrophysiological studies of peroneal and tibial nerves in CMT patients.

peroneal nerve Tibial nerve Patient
number TL (ms)
(left/right) CMAP (mV)
(left/right) NCV (m/s)
(left/right) TL (ms)
(left/right) CMAP (mV)
(left/right) NCV (m/s)
(left/right) One 16.3/16.8 0.9/2.6 16.5/16.9 14.5/12.3 3.2/4.7 17.4/17.4 2 13.5/13.2 0.4/1.2 18.7/18.2 10.0/10.2 7.8/8.0 20.8/19.1 3 12.3/12.5 1.5/0.6 16.3/19.0 8.5/8.2 0.5/0.3 14.4/15.2 4 A/A A/A A/A 10.6/11.4 1.0/0.5 14.4/12.7 5 11/A 1.6/A 13.0/A 12.0/12.2 0.2/0.6 16.2/14.3 6 9/7.4 2.7/2.7 20.8/20.2 11.9/8.6 0.7/3.3 20.8/23.4 7 9.4/10.2 0.8/0.6 17.6/16.4 7.8/7.1 2.3/2.0 18.6/16.4 8 A/16.5 A/0.3 A/13.7 20.1/21.2 0.3/0.9 17.3/15.1 9 9.1/9.0 1.1/1.8 24.9/21.8 9.9/7.5 4.9/6.3 28.4/26.5 10 11.6/11.1 0.8/0.8 15.3/15.1 10.2/10.7 3.6/4.1 17.1/18.5 11 A/A A/A A/A 11.3/16.9 0.2/0.4 A/19.2 12 7.6/8.2 4.2/3.1 34.2/31.8 5.0/9.1 10.0/3.3 26.7/36.6 13 A/A A/A A/A A/A A/A A/A 14 12.9/9.6 2.9/4.6 17.2/19.5 10.5/10.5 7.7/7.7 19.3/19.3 15 A/A A/A A/A 10.4/12.6 0.6/0.5 13.7/10.0 16 A/A A/A A/A A/13.6 A/1.0 A/18.2 17 17.3/A 0.2/A 14.8/A 11.3/8.1 0.7/4.7 14.3/13.1

A, Absent; CMAP, compound muscle action potential; NCV, nerve conduction velocity; TL, terminal latency.

statistical analysis

Statistical analysis was performed using SAS version 9.4 (SAS Institute, Cary, NC, USA). Inter-rater agreement and retest reproducibility were interpreted as follows using intra class correlation coefficient:

0.81-1.00, excellent; 0.61-0.80, good and ≤0.60, bad.

Inter-observer agreement for quasi-quantitative assessments using Korman's kappa analysis was interpreted as follows:

0.81-1.00, almost perfect; 0.61-0.80, substantial; 0.41-0.60, medium; 0.21-0.40, fair; and ≤0.20, slight agreement.

Bland-Altman analysis was used to obtain mean differences and standard deviations for inter-rater agreement and inter-test reproducibility.

Comparison of mean muscle fat ratio and cross-sectional area of both thighs between CMT patients and volunteers was performed using Wilcoxon rank sum test. For thigh muscles classified as Goutallier grade 0, the average intramuscular fat fraction between the two groups was compared using the Wilcoxon rank sum test. We compared the fat fractions of proximal femoral fat, vastus lateralis, vastus medialis, and semitendinosus in CMT patients using the Wilcoxon signed rank test.

The relationship between thigh muscle fat fraction and clinical data (ie, disease duration, CMTNS, and dysfunction measures) was assessed using Spearman correlation analysis in CMT patients. Comparison of body mass index (BMI) between the two groups confirmed whether there was a significant difference that could affect the intramuscular fat fraction using the Wilcoxon rank sum test. In addition, the presence or absence of correlation between BMI and thigh muscle fat fraction in both groups was confirmed through Spearman correlation analysis.

result

Fat-water swap caused by error in fat-water exchange was shown in both sets of 3D multiple gradient echo-Dixon-based MRI in one volunteer and CMT patient, respectively. Also, in one volunteer, image noise due to fat water exchange error was shown in a set of three-dimensional multiple gradient echo Dickson-based MRI. These image sets were not included in the analysis. Therefore, an observer-consensus assessment and comparison of muscle fat fractions between the two groups were performed for 17 volunteers and 17 CMT patients. Semi-quantitative analyzes of the upper thigh muscles were equally performed on 17 volunteers and 17 CMT patients. A retest reproducibility evaluation was performed on 33 subjects, 16 volunteers and 17 CMT patients. There was no significant difference in BMI between the two groups (P = 0.270, volunteers: median ± standard deviation, 21.60 ± 3.09, interquartile range, 20.60-25.10, CMT patients: median ± standard deviation, 23.06 ± 4.99, interquartile range, 21.48 -27.63).

As can be seen in Tables 4 and 5, the inter-observer agreement in the measurement of the muscle fat fraction was excellent for all fat quantitative analyses.

Interobserver agreement Upper ICC 95% CI Lower ICC 95% CI Rectus femoris Right 0.91 0.84 - 0.96 0.89 0.79 - 0.94 Left 0.95 0.90 - 0.97 0.83 0.70 - 0.91 Vastus lateralis Right 0.90 0.82 - 0.95 0.99 0.99 - 1.00 Left 0.86 0.75 - 0.93 1.00 0.99 - 1.00 Vastus medialis Right 0.95 0.91 - 0.98 0.97 0.95 - 0.99 Left 0.98 0.95 - 0.99 0.96 0.93 - 0.98 Semitendinosus Right 0.99 0.98 - 1.00 1.00 1.00 - 1.00 Left 0.94 0.89 - 0.97 1.00 0.99 - 1.00 Biceps femoris Right NA NA 1.00 1.00 - 1.00 Left NA NA 0.98 0.97 - 0.99 Adductor magnus Right 0.83 0.70 - 0.91 NA NA Left 0.91 0.84 - 0.95 NA NA Gracilis Right 0.91 0.83 - 0.95 0.98 0.95 - 0.99 Left 0.91 0.84 - 0.96 0.97 0.93 - 0.98

ICC = intraclass coefficient, CI = confidence interval, R1 = reviewer 1, R2 = reviewer 2, and NA = not applicable.

Test-retest reproducibility (R1/R2) Upper ICC 95% CI Lower ICC 95% CI Rectus femoris Right 0.96 / 0.97 0.91 - 0.98 / 0.94 - 0.99 0.95 / 0.97 0.90 - 0.97 / 0.95 - 0.99 Left 0.95 / 0.97 0.90 - 0.97 / 0.94 - 0.99 0.99 / 0.98 0.98 - 1.00 / 0.96 - 0.99 Vastus lateralis Right 0.91 / 0.94 0.83 - 0.95 / 0.89 - 0.97 1.00 / 1.00 1.00 - 1.00 / 1.00 - 1.00 Left 0.93 / 0.94 0.86 - 0.96 / 0.89 - 0.97 1.00 / 1.00 1.00 - 1.00 / 1.00 - 1.00 Vastus medialis Right 0.87 / 0.95 0.76 - 0.93 / 0.90 - 0.97 0.99 / 0.99 0.99 - 1.00 / 0.99 - 1.00 Left 0.95 / 0.94 0.90 - 0.97 / 0.89 - 0.97 0.99 / 0.99 0.99 - 1.00 / 0.98 - 1.00 Semitendinosus Right 1.00 / 1.00 1.00 - 1.00 / 1.00 - 1.00 1.00 / 1.00 1.00 - 1.00 / 0.99 - 1.00 Left 0.89 / 1.00 0.79 - 0.94 / 0.99 - 1.00 1.00 / 1.00 1.00 - 1.00 / 1.00 - 1.00 Biceps femoris Right NA NA 1.00 / 1.00 1.00 - 1.00 / 1.00 - 1.00 Left NA NA 1.00 / 1.00 0.99 - 1.00 / 1.00 - 1.00 Adductor magnus Right 0.94 / 0.96 0.89 - 0.97 / 0.92 - 0.98 NA NA Left 0.67 / 0.99 0.47 - 0.83 / 0.99 - 0.99 NA NA Gracilis Right 0.98 / 0.99 0.97 - 0.99 / 0.98 - 0.99 1.00 / 1.00 0.99 - 1.00 / 0.99 - 1.00 Left 0.99 / 0.99 0.99 - 1.00 / 0.98 - 1.00 0.99 / 0.99 0.99 - 1.00 / 0.99 - 1.00

ICC = intraclass coefficient, CI = confidence interval, R1 = reviewer 1, R2 = reviewer 2, and NA = not applicable.

The retest reproducibility results of quantitative fat fraction measurement were excellent in all rater evaluations except for the frontal muscle of the left femur measured by rater 1 (internal correlation coefficient = 0.67). Data obtained from rater 1 using the first set of images were used for comparison of the intramuscular fat fraction. The results of the Bland-Altman analysis of inter-rater agreement and retest reproducibility are shown in Tables 6 to 8.

variable Mean difference Standard deviation upper right thigh Rectus Femoris -0.1000 2.1808 Vastus Lateralis 0.0015 1.6884 Vastus Medialis -0.0924 2.2500 Semitendinosus 0.0691 11.8903 Adductor Magnus 0.1145 1.5290 Gracilis 0.1200 5.0616 upper left thigh Rectus Femoris 0.1673 2.6887 Vastus Lateralis 0.0124 2.0291 Vastus Medialis -0.0558 2.5842 Semitendinosus -0.1942 5.5897 Adductor Magnus 0.5215 3.0997 Gracilis 0.0061 5.4197 lower right thigh Rectus Femoris -0.0339 3.3111 Vastus Lateralis -0.1488 6.1245 Vastus Medialis -0.0239 3.2668 Biceps Femoris 0.0742 6.6118 Semitendinosus -0.0648 16.6934 Gracilis -0.0433 9.2064 lower left thigh Rectus Femoris -0.0024 6.1787 Vastus Lateralis 0.1967 6.9462 Vastus Medialis 0.0297 2.6954 Biceps Femoris 0.2209 7.1914 Semitendinosus 0.0955 6.3866 Gracilis -0.1285 7.4625

variable Mean difference Standard deviation upper right thigh Rectus Femoris -0.0973 2.6268 Vastus Lateralis -0.0430 1.9809 Vastus Medialis -0.0703 2.0642 Semitendinosus 0.0994 10.8342 Adductor Magnus 0.1494 1.8925 Gracilis -0.1473 5.3971 upper left thigh Rectus Femoris 0.0224 2.6532 Vastus Lateralis 0.0764 2.2738 Vastus Medialis 0.0406 2.4622 Semitendinosus 0.0842 6.2397 Adductor Magnus 0.0655 3.2066 Gracilis 0.0033 5.7254 lower right thigh Rectus Femoris -0.1536 3.4795 Vastus Lateralis -0.1412 6.3110 Vastus Medialis -0.0158 3.2808 Biceps Femoris -0.0049 6.7260 Semitendinosus -0.0618 16.5874 Gracilis -0.2988 8.5118 lower left thigh Rectus Femoris -0.0052 3.7255 Vastus Lateralis 0.1882 7.3410 Vastus Medialis 0.0715 2.9069 Biceps Femoris 0.1488 7.1755 Semitendinosus 0.1115 6.8287 Gracilis -0.1039 7.9353

variable Mean difference Standard deviation upper right thigh Rectus Femoris -0.5515 2.3468 Vastus Lateralis -0.3603 1.7082 Vastus Medialis 0.0645 2.0674 Semitendinosus -0.1176 11.3727 Adductor Magnus -0.6764 1.6620 Gracilis 0.1561 5.2154 upper left thigh Rectus Femoris 0.0891 2.5939 Vastus Lateralis -0.5367 2.0513 Vastus Medialis 0.0776 2.4564 Semitendinosus -0.2842 5.8724 Adductor Magnus -0.5867 3.3414 Gracilis -1.1209 5.5468 lower right thigh Rectus Femoris -0.1609 3.3986 Vastus Lateralis -0.2273 6.2470 Vastus Medialis -0.0724 3.2673 Biceps Femoris -0.1794 6.6249 Semitendinosus 0.0039 16.6238 Gracilis 0.1494 8.8566 lower left thigh Rectus Femoris 0.2436 5.1230 Vastus Lateralis -0.3027 7.1482 Vastus Medialis -0.2670 2.8166 Biceps Femoris -0.0333 7.1460 Semitendinosus -0.2848 6.6623 Gracilis -0.3173 7.6650

As can be seen in Table 9, in the upper thigh muscles, all the measured muscles except the frontal muscle showed a significantly higher average fat percentage in CMT patients.

Upper Thigh Lower Thigh Volunteers CMT Patients p value Volunteers CMT Patients p value Rectus Femoris 3.066 ± 1.313 4.916 ± 2.939 <0.001* 2.684 ± 1.068 6.694 ± 6.277 <0.001* Vastus Lateralis 3.587 ± 1.425 4.649 ± 1.854 0.011* 4.298 ± 1.585 9.248 ± 8.393 0.003* Vastus Medialis 3.730 ± 1.513 5.669 ± 2.818 0.001* 3.273 ± 1.547 5.648 ± 3.565 <0.001* Semitendinosus 5.238 ± 2.181 11.473 ± 11.965 <0.001* 5.199 ± 1.691 11.410 ± 8.440 <0.001* Adductor Magnus 3.195 ± 1.202 4.581 ± 3.581 0.109 N/A N/A N/A Biceps Femoris N/A N/A N/A 4.231 ± 2.691 13.381 ± 16.369 <0.001* Gracilis 5.349 ± 1.914 10.849 ± 5.754 <0.001* 6.185 ± 2.760 14.062 ± 10.012 <0.001*

Data are displayed as mean values (%) ± standard deviation. * indicates statistical significance. N/A = not applicable.

A significantly higher mean fat fraction was observed in CMT patients in all measured muscles of the lower thigh muscles.

As can be seen in Table 10, there was no significant difference in the mean muscle cross-sectional area between the two groups.

Upper Thigh Lower Thigh Volunteers CMT Patients p value Volunteers CMT Patients p value Rectus Femoris 916.014 ± 222.276 918.407 ± 252.904 0.973 263.305 ± 178.248 199.123 ± 112.889 0.496 Vastus Lateralis 1704.049 ± 356.582 1732.060 ± 334.948 0.658 1617.485 ± 506.403 1575.501 ± 535.228 0.734 Vastus Medialis 693.467 ± 115.891 732.520 ± 124.404 0.433 1432.448 ± 342.284 1512.382 ± 180.755 0.17 Semitendinosus 379.169 ± 97.406 418.864 ± 120.585 0.357 462.466 ± 122.657 448.270 ± 111.431 0.734 Adductor Magnus 2041.183 ± 493.057 2102.977 ± 365.292 0.193 N/A N/A N/A Biceps Femoris N/A N/A N/A 1007.295 ± 249.165 920.659 ± 276.730 0.586 Gracilis 278.711 ± 64.237 273.254 ± 65.575 0.946 220.881 ± 90.093 231.924 ± 75.237 0.563

Data are displayed as mean values (mm ² ) ± standard deviation. N/A = not applicable.

As can be seen in Table 11, in the comparison of the fat fraction made between the upper third and lower third thigh muscles of CMT patients, one ranking test result showed a significantly higher fat percentage in the lower third in the vastus lateralis muscle. There was no significant difference in the fat fraction in the upper third and lower third in the other muscles.

variable upper thigh lower thigh p value Rectus Femoris 4.011 (3.352-5.730) 5.022 (2.802-8.173) 0.517 Vastus Lateralis 4.293 (3.530-5.212) 6.560 (4.091-10.353) <0.001* Vastus Medialis 4.741 (3.810-6.812) 4.212 (3.680-5.631) 0.644 Semitendinosus 7.645 (5.810-12.680) 8.095 (6.535-10.300) 0.210

Data are median values (%), with interquartile range in parentheses. * indicates statistical significance.

The agreement for quasi-quantitative analysis between the two radiologists was almost perfect (kappa value 0.843). In 9 muscles (9/408, 2.20%: grade 0 vs. grade 1, grade 2, grade 1 vs. grade 2, grade 6, grade 0 vs. grade 2, 1 case) there was a discrepancy in grade classification, all patient group. One of our readers' data was used for analysis. The femoral muscles of all volunteers were grade 0 (100%, 204/204). The outcomes for patients with CMT were grade 0 (86.3%, 176/204), grade 1 (12.7%, 26/204), grade 2, and grade 4 (0.05%, 1/204). Grade 0 (mean 4.72, standard deviation 2.61, range 0.87-18.60), grade 1 (mean 14.40, standard deviation 5.19, range 7.07-26.34), grade 2 (27.37%), grade 4 (72.08%) were (Figure 4) . Gallallier grade 0 muscle (mean ± standard deviation, 4.54 ± 3.03, interquartile range, 3.58–6.82) in the CMT patient group had a significantly higher mean fat fraction compared to the volunteer group (median ± standard deviation, 3.58 ± 1.86; interquartile range, 2.70-5.00) (P < 0.001).

As can be seen in Table 12, the correlation coefficient between the intramuscular fat fraction of the upper thigh and CMTNS was 0.5191 (P < 0.05).

In addition, as can be seen in Table 13, there was no significant correlation between the fat fraction of different muscles and other clinical variables. No significant correlation was found between BMI and thigh muscle fat percentage in CMT patients or volunteer cohorts.

Anatomical location Clinical parameters correlation coefficient p value upper thigh Rectus Femoris Disease duration 0.1974 0.4476 CMTNS 0.2431 0.3472 FDS 0.0429 0.8700 Vastus Lateralis Disease duration 0.1709 0.5120 CMTNS 0.1282 0.6238 FDS -0.0463 0.8598 Vastus Medialis Disease duration -0.0344 0.8957 CMTNS 0.5191 0.0327* FDS 0.3870 0.1249 Semitendinosus Disease duration 0.1697 0.5148 CMTNS 0.0321 0.9027 FDS -0.1602 0.5391 Adductor Magnus Disease duration -0.2975 0.2462 CMTNS 0.2552 0.3228 FDS 0.0164 0.9503 Gracilis Disease duration -0.2286 0.3774 CMTNS 0.4303 0.0847 FDS 0.1976 0.4472 lower thigh Rectus Femoris Disease duration -0.0025 0.9925 CMTNS 0.3181 0.2133 FDS 0.0041 0.9876 Vastus Lateralis Disease duration 0.0332 0.8994 CMTNS 0.1640 0.5294 FDS 0.1104 0.6732 Vastus Medialis Disease duration 0.1648 0.5273 CMTNS 0.3387 0.1836 FDS 0.1807 0.4878 Biceps Femoris Disease duration 0.2286 0.3774 CMTNS 0.1418 0.5872 FDS 0.0041 0.9876 Semitendinosus Disease duration 0.2139 0.4098 CMTNS 0.2589 0.3156 FDS 0.1526 0.5587 Gracilis Disease duration -0.2262 0.3827 CMTNS 0.3181 0.2133 FDS 0.0640 0.8071

CMTNS = Charcot-Marie-Tooth neuropathy score, FDS = functional disability scale.

* indicates statistical significance.

Anatomical location correlation coefficient p value Charcot-Marie-Tooth Disease Patient upper thigh Rectus Femoris 0.024 0.935 Vastus Lateralis 0.288 0.318 Vastus Medialis 0.407 0.149 Semitendinosus 0.117 0.691 Adductor Magnus -0.138 0.637 Gracilis 0.371 0.191 lower thigh Rectus Femoris 0.150 0.958 Vastus Lateralis 0.442 0.114 Vastus Medialis 0.248 0.392 Biceps Femoris 0.103 0.725 Semitendinosus 0.358 0.208 Gracilis 0.095 0.748 Volunteer upper thigh Rectus Femoris 0.235 0.418 Vastus Lateralis -0.455 0.102 Vastus Medialis -0.020 0.946 Semitendinosus -0.002 0.994 Adductor Magnus -0.132 0.653 Gracilis 0.160 0.584 lower thigh Rectus Femoris 0.468 0.091 Vastus Lateralis -0.262 0.366 Vastus Medialis -0.081 0.782 Biceps Femoris -0.253 0.383 Semitendinosus 0.062 0.834 Gracilis -0.620 0.180

Review

In this study, the intramuscular fat fraction of the thigh obtained using three-dimensional multiple gradient echo-Dickson-based MRI showed significantly higher mean values in CMT patients compared to volunteers in all muscles except adducto magnus. The excellent results of interobserver agreement and test reproducibility suggest that fat measurements using this technique are very reliable. To our knowledge, MRI evaluation of fat infiltration of the thigh muscles in CMT patients has been rarely reported. The significant difference in the femoral muscle fat fraction between the two groups demonstrated in our study may be due to the fact that a finding that was not revealed by conventional imaging techniques was revealed thanks to the sensitivity of the 3D multiple gradient echo Dickson-based MRI technique.

It has been reported that only a few patients cause severe thigh muscle weakness late in the clinical course because the distal extremity muscles are characteristically affected in CMT patients. Most of the past studies have focused on the assessment of fat infiltration in the calf muscle. According to a recent study by Morrow et al., comparing intramuscular fat fractions using Dixon-based MRI techniques between CMT type IA groups and volunteer groups showed significant differences in intramuscular fat percentages in the calves rather than the thighs. known In addition to the clinical factors of enrolled subjects, the difference between our study results and this study may be related to technical factors. In Morrow's study, a three-point Dixon technique without information on T2* correction was used for fat quantitation. In our study, a T2* corrected 6-point Dixon technique was used. Another previous study showed that intramuscular fat quantitation using T2*-corrected 6 Echo Dixon sequences was significantly higher in fat compared to T2* corrected 3 Echo Dixon images or T2* uncorrected Dixon images. It showed a degree of agreement with the absolute value of the content. The importance of T2* correction was mainly emphasized in hepatic fat quantitation considering the presence of iron causing local magnetic inhomogeneity. It has been reported that skeletal muscle also contains a large amount of iron that cannot be ignored. In addition, as in the present invention, there is also a study proposed that it is necessary to acquire six echoes for T2* correction for optimal separation of water and fat signals. Our findings suggest that three-dimensional multiple gradient echo-Dixon-based MRI may reveal fat infiltration in the thigh muscle, which may be present in a relatively early stage of CMT. As with previous studies using Dixon-based MRI for the evaluation of patients with CMT or other neuromuscular disorders, our results support that it would be helpful to apply this imaging technique for quantitative analysis of intramuscular fat fraction in other future studies. do.

Interobserver agreement and test reproducibility were excellent in 3-D multi-gradient echo Dickson-based MRI. It was reported that intramuscular fat mass measurement using a Dickson-based quantitative MRI sequence showed high observer and retest reproducibility. Our findings are also consistent with previous results and suggest that Dickson-based MRI may provide a reliable measure of fat that is advantageous over subjective analyzes based on Goutallier classification reported with high observer dependence. The Goutallier grade 0 muscle of the CMT patient group showed a significantly higher mean intramuscular fat fraction compared to the volunteer group (FIG. 4). These results suggest that intramuscular fat measurement using a Dixon-based quantitative MRI sequence could be a more sensitive and objective tool for examining muscle degeneration. In addition, 3D multiple gradient echo Dickson-based MRI could be obtained in a reasonable scan time (72.5 s), which was shorter compared to other conventional sequences (Table 1). Therefore, it can be easily integrated as part of routine imaging sequences in the evaluation of patients with neuromuscular disease.

None of the patients showed subjective weakness of the thigh muscles, and the strength of knee extension was slightly decreased on physical examination. In this regard, our patient is asymptomatic in terms of proximal lower extremity weakness, and Dickson-based MRI of filtered intramuscular fat observed via three-dimensional multi-gradient echoes may show early symptoms of degeneration before clinically apparent muscle weakness. can. Morrow et al. reported that calf fat fraction measured using Dixon-based MRI significantly increased over 12 months in a cohort of CMT patients. In the future, it would be beneficial to investigate longitudinal changes in thigh muscle fat fraction in a large cohort of CMT patients. In addition, since a significant proportion of patients develop hip muscle weakness, it will be interesting to expand the evaluation to include hip muscle in future studies.

In the present invention, the correlation coefficient between the fat fraction of the upper thigh and CMTNS was 0.5191. A recent study by Morrow et al. reported a strong correlation between calf muscle fat mass and CMTNS. In the case of thigh muscles, the relationship between the degree of fat infiltration and clinical status in CMT patients is unknown. Because most of our study included patients with early fat infiltration of the thigh muscle, the study should be conducted including patients with more advanced disease for correlation with clinical indicators, and further investigation in a larger cohort is needed.

Among the 72 sets of 3D multidimensional gradient echo Dixon-based MRI, 5 image sets (6.9%) showed fat-water swap due to errors in fat-water exchange. Image noise due to local water exchange error is usually caused by a phase shift error and is a common problem encountered in images using Dixon technology. A multi-point Dixon technique was developed to overcome these artifacts by dealing with the non-uniformity of the B0 field. However, image noise caused by errors in fat exchange still remains a problem in 3D multi-gradient echo Dickson-based MRI. Advances in technology to solve this problem are needed for clinical application and accurate measurement of intramuscular fat mass measurement by Dickson-based MRI.

In conclusion, muscle fat mass measurement using three-dimensional multi-gradient echo-Dixon-based MRI revealed a significant difference in the fat fraction in the thigh muscle between CMT patients and normal volunteers. In CMT patients, the extremity muscles are mainly affected, and the thigh muscles are less prominent than the calf muscles. Confirming these results suggests that the sensitivity of this imaging technique is high. Also, in Goutallier grade 0 muscle, a significant difference in fat fraction between the two groups was confirmed with this technique, which can confirm the initial fat infiltration, which may be difficult to confirm through visual evaluation of conventional T1-weighted images, with this imaging technique. means This technique was very reproducible and could be achieved with a relatively short scan time. Introduction of three-dimensional multi-gradient echocardiography There is clinical value in including Dixon-based MRI as part of routine MRI to evaluate patients with CMT and other neuromuscular diseases.

Claims (5)

obtaining water-only images from three-dimensional multi-gradient echo Dixon-based magnetic resonance imaging;
a T2-weighted MRI image acquisition step of acquiring an axial T2-weighted MRI image of the thigh muscle;
A muscle boundary visualization step of visualizing a region of interest from a water-only image obtained from a three-dimensional multi-gradient echo Dixon-based magnetic resonance image;
an image acquisition step for analysis of generating the visualized region of interest on a fat fraction map obtained from a three-dimensional multi-gradient echo Dickson-based magnetic resonance image based on a T2-weighted MRI image; and
Including; a quantitative evaluation step of measuring the fat fraction of the thigh muscle from the image for analysis;
The region of interest is the rectus femoris, vastus lateralis, vastus medialis, biceps femoris (long head), semitendinosus, adductor of the thigh muscle. magnus) and seven fractions of gracilis, Charcot-Marie-Tooth disease (Charcot-Marie-Tooth disease) a method of providing information necessary for the diagnosis of type 1A. delete According to claim 1, wherein the water-only image in the three-dimensional multi-gradient echo Dixon-based magnetic resonance image is an image of the upper 1/3 point and the lower 1/3 point of the thigh muscle, Charcot-Marie- How to provide the necessary information to diagnose Tooth disease type 1A. The method of claim 1, wherein the T2-weighted MRI image is an image of the upper third and lower third of the thigh muscle, Charcot-Marie-Tooth disease type 1A diagnosis. The method according to claim 1, wherein the method comprises the steps of:
T1-weighted MRI image acquisition step of acquiring water-only images from three-dimensional multi-gradient echo Dixon-based magnetic resonance imaging of the upper third and lower third of the thigh muscle;
a T2-weighted MRI image acquisition step of acquiring an axial T2-weighted MRI image of the upper third and lower third of the thigh muscle;
Six fractions of the rectus femoris, vastus lateralis, internalis, semitendinosus, adductor adductor and extensor muscle from water-only images obtained from three-dimensional multi-gradient echo Dixon-based magnetic resonance imaging of the upper third of the thigh muscle. image visualization step of the upper thigh muscle to visualize the region of interest;
A fat fraction map obtained from a three-dimensional multi-gradient echo Dickson-based magnetic resonance image based on a T2-weighted MRI image of the upper third of the thigh muscle for the visualized region of interest in the upper third of the thigh muscle. Image acquisition step for analysis of the upper thigh muscle generated in the;
Six fractions of the rectus femoris, vastus lateralis, internalis, semitendinosus, biceps femoris and extensor muscle from water-only images obtained from three-dimensional multi-gradient echo Dixon-based magnetic resonance imaging of the lower third of the thigh muscle. Visualizing the lower thigh muscle image to visualize the region of interest;
A fat fraction map obtained from a three-dimensional multi-gradient echo Dickson-based magnetic resonance image based on T2-weighted MRI image of the lower third of the thigh muscle for the visualized region of interest in the lower third of the thigh muscle. Image acquisition step for analysis of the lower thigh muscles generated in the; and
A quantitative evaluation step of measuring the fat fraction of the thigh muscle from the image for analysis of the upper and lower thigh muscles.

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