Longitudinal study of multi-parameter quantitative magnetic resonance imaging in Duchenne muscular dystrophy: hyperresponsiveness of gluteus maximus and detection of subclinical disease progression in functionally stable patients

Multi-parameter quantitative magnetic resonance imaging for early detecting skeletal muscle involvement and predicting functional decline in children with Becker muscular dystrophy

BACKGROUND

The extreme clinical heterogeneity of children with Becker muscular dystrophy significantly poses a great challenge to accurately assess their disease status.

OBJECTIVE

To detect skeletal muscle involvement in children with Becker muscular dystrophy using multiple-parameter quantitative magnetic resonance imaging (qMRI), and to determine the preferred muscle site and qMRI biomarker.

MATERIALS AND METHODS

Fat fraction, T1, and T2 measurements were conducted in Becker muscular dystrophy (n=29) and healthy controls (n=23). North Star Ambulatory Assessment (NSAA) was performed in Becker muscular dystrophy. Group differences were compared by using the Mann-Whitney or Kruskal-Wallis test or a linear mixed-effect model. Receiver operating characteristic analysis with area under curve (AUC) was used to compare the diagnostic performance. Logistic regression was used to identify the predictor of functional decline.

RESULTS

Both fat fraction and T2 were effective in detecting muscle involvement across different functional stages that were categorized by NSAA, with fat fraction in gluteus maximus demonstrating the most superior diagnostic performance (AUC range, 0.85-0.98). The combination of T2 and T1 enables a good diagnosis of no abnormal fat-infiltrated muscles (AUC=0.82). Overall, fat fraction in gluteus maximus exhibited the strongest negative correlation with the NSAA score (r=-0.69, P<0.01) and emerged as an independent risk factor for functional decline (odds ratio=1.12, P=0.02).

CONCLUSION

Multi-parametric qMRI demonstrate effective capabilities for early detection of muscle involvement, with gluteus maximus being the preferred muscle site. Fat fraction in gluteus maximus may serve as a potential biomarker for predicting functional decline.

Quantitative Muscle MRI to Monitor Disease Progression in Hypokalemic Period Paralysis

Background and Objectives

Primary hypokalemic periodic paralysis (HypoPP) is a muscle channelopathy that can cause periodic paralysis and permanent weakness. Currently, little is known about how progressive this myopathy is. Natural history data for HypoPP can potentially answer the question of progressiveness and form the basis for outcome measures to be used in follow-up and emerging treatment trials. We aimed to describe the natural history of HypoPP and assess whether quantitative fat imaging is a valuable biomarker to monitor disease progression.

Methods

In this prospective follow-up study, we examined disease progression using Dixon MRI to monitor changes in fat replacement of the muscle and stationary dynamometry to monitor changes in muscle strength.

Results

We included 37 persons (mean age 43 years, range 18-79 years) with HypoPP-causing variants in CACNA1S. Three participants were asymptomatic carriers, 22 had periodic paralysis, 3 had permanent weakness, and 9 had periodic paralysis in combination with permanent weakness. The median follow-up time was 20 months (range 12-25). We found that fat fraction increased in 10 of 21 examined muscles. An increase in the composite fat fraction of at least 1 muscle group was found in all symptomatic phenotypes. By contrast, we found no significant change in muscle strength.

Discussion

The results from this follow-up study support the use of quantitative muscle MRI to monitor subclinical disease progression in HypoPP in patients with and without attacks of paralysis.

Utilization of Multi-Parametric Quantitative Magnetic Resonance Imaging in the Early Diagnosis of Duchenne Muscular Dystrophy

BACKGROUND

It is challenging to diagnose suspected Duchenne muscular dystrophy (DMD) patients in the very early stage of the disease. More evidence is needed to demonstrate the potential of quantitative MRI (qMRI) in precisely identifying patients before substantial physical decline occurs.

PURPOSE

To assess the early diagnostic performance of multi-parametric qMRI for DMD patients, and the ability to identify DMD patients with mild functional decline.

STUDY TYPE

Prospective.

SUBJECTS

One hundred and forty DMD subjects (9.0 ± 2.2 years old), 24 male healthy controls (HCs) (9.2 ± 2.5 years old).

FIELD STRENGTH/SEQUENCE

3.0 T/3-point Dixon, T1-mapping, and T2-mapping.

ASSESSMENT

qMRI measurements (fat fraction [FF], T1, and T2) of 11 thigh muscles (rectus femoris [RF], vastus lateralis [VL], vastus intermedius, vastus medialis, gracilis, sartorius, adductor longus, adductor magnus [AM], semitendinosus, semimembranosus, biceps femoris long head [BFLH]) on the right side were conducted. NorthStar ambulatory assessment (NSAA) score used to evaluate the function of DMD patients and divided them into three subgroups: mild (76-100 score), moderate (51-75 score), and severe (0-50 score) functional decline.

STATISTICAL TESTS

Independent t-test, ANOVA analysis, and receiver operating characteristic (ROC) curves. A P-value <0.05 was considered statistically significant.

RESULTS

Compared with HCs, FF and T2 were significantly higher in the group of all DMD patients, while T1 was significantly lower. The combination of T1 and T2 in RF, VL, AM, and BFLH achieved excellent area under curve (AUCs) (0.967-0.992) in differentiating five DMD patients without abnormal fat infiltration from HCs. Overall, T2 reached higher AUCs than FF and T1 in distinguishing DMD with mild functional decline from HCs, whereas FF achieved higher AUCs than T1 and T2 in distinguishing three DMD subgroups with functional decline.

DATA CONCLUSION

Multi-parametric qMRI demonstrate effective diagnostic capabilities for DMD patients in the early stage of the disease, and can identify patients with mild physical decline.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 3.

Magnetic Resonance Imaging Biomarkers of Muscle

This review is focused on the current status of quantitative MRI (qMRI) of skeletal muscle. The first section covers the techniques of qMRI in muscle with the focus on each quantitative parameter, the corresponding imaging sequence, discussion of the relation of the measured parameter to underlying physiology/pathophysiology, the image processing and analysis approaches, and studies on normal subjects. We cover the more established parametric mapping from T1-weighted imaging for morphometrics including image segmentation, proton density fat fraction, T2 mapping, and diffusion tensor imaging to emerging qMRI features such as magnetization transfer including ultralow TE imaging for macromolecular fraction, and strain mapping. The second section is a summary of current clinical applications of qMRI of muscle; the intent is to demonstrate the utility of qMRI in different disease states of the muscle rather than a complete comprehensive survey.

Longitudinal changes in magnetic resonance imaging biomarkers of the gluteal muscle groups and functional ability in Duchenne muscular dystrophy: a 12-month cohort study

BACKGROUND

Quantitative magnetic resonance imaging (MRI) is considered an objective biomarker of Duchenne muscular dystrophy (DMD), but the longitudinal progression of MRI biomarkers in gluteal muscle groups and their predictive value for future motor function have not been described.

OBJECTIVE

To explore MRI biomarkers of the gluteal muscle groups as predictors of motor function decline in DMD by characterizing the progression over 12 months.

MATERIALS AND METHODS

A total of 112 participants with DMD were enrolled and underwent MRI examination of the gluteal muscles to determine fat fraction and longitudinal relaxation time (T1). Investigations were based on gluteal muscle groups including flexors, extensors, adductors, and abductors. The North Star Ambulatory Assessment and timed functional tests were performed. All participants returned for follow-up at an average of 12 months and were divided into two subgroups (functional stability/decline groups) based on changes in timed functional tests. Univariable and multivariable logistic regression methods were used to explore the risk factors associated with future motor function decline.

RESULTS

For the functional decline group, all T1 values decreased, while fat fraction values increased significantly over 12 months (P<0.05). For the functional stability group, only the fat fraction of the flexors and abductors increased significantly over 12 months (P<0.05). The baseline T1 value was positively correlated with North Star Ambulatory Assessment and negatively correlated with timed functional tests at the 12-month follow-up (P<0.001), while the baseline fat fraction value was negatively correlated with North Star Ambulatory Assessment and positively correlated with timed functional tests at the 12-month follow-up (P<0.001). Multivariate regression showed that increased fat fraction of the abductors was associated with future motor function decline (model 1: odds ratio [OR]=1.104, 95% confidence interval [CI]: 1.026~1.187, P=0.008; model 2: OR=1.085, 95% CI: 1.013~1.161, P=0.019), with an area under the curve of 0.874.

CONCLUSION

Fat fraction of the abductors is a powerful predictor of future motor functional decline in DMD patients at 12 months, underscoring the importance of focusing early on this parameter in patients with DMD.

Clinical utilisation of multimodal quantitative magnetic resonance imaging in investigating muscular damage in Duchenne muscular dystrophy: a study on the association between gluteal muscle groups and motor function

BACKGROUND

Duchenne muscular dystrophy (DMD) is a neuromuscular disease characterised by progressive muscular weakness and atrophy. Currently, studies on DMD muscle function mostly focus on individual muscles; little is known regarding the effect of gluteal muscle group damage on motor function.

OBJECTIVE

To explore potential imaging biomarkers of hip and pelvic muscle groups for measuring muscular fat replacement and inflammatory oedema in DMD with multimodal quantitative magnetic resonance imaging (MRI).

MATERIALS AND METHODS

One hundred fifty-nine DMD boys and 32 healthy male controls were prospectively included. All subjects underwent MRI examination of the hip and pelvic muscles with T1 mapping, T2 mapping and Dixon sequences. Quantitatively measured parameters included longitudinal relaxation time (T1), transverse relaxation time (T2) and fat fraction. Investigations were all based on hip and pelvic muscle groups covering flexors, extensors, adductors and abductors. The North Star Ambulatory Assessment and stair climbing tests were used to measure motor function in DMD.

RESULTS

T1 of the extensors (r = 0.720, P < 0.01), flexors (r = 0.558, P < 0.01) and abductors (r = 0.697, P < 0.001) were positively correlated with the North Star Ambulatory Assessment score. In contrast, T2 of the adductors (r = -0.711, P < 0.01) and fat fraction of the extensors (r = -0.753, P < 0.01) were negatively correlated with the North Star Ambulatory Assessment score. Among them, T1 of the abductors (b = 0.013, t = 2.052, P = 0.042), T2 of the adductors (b = -0.234, t = -2.554, P = 0.012) and fat fraction of the extensors (b = -0.637, t =  - 4.096, P < 0.001) significantly affected the North Star Ambulatory Assessment score. Moreover, T1 of the abductors was highly predictive for identifying motor dysfunction in DMD, with an area under the curve of 0.925.

CONCLUSION

Magnetic resonance biomarkers of hip and pelvic muscle groups (particularly T1 values of the abductor muscles) have the potential to be used as independent risk factors for motor dysfunction in DMD.