Muscle-MRI and Functional Levels for the Evaluation of Upper Limbs in Duchenne Muscular Dystrophy: A Critical Review of the Literature

Magnetic resonance imaging of masticatory muscles in patients with duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy in children. Impairment of masticatory function and swallowing disorders, potentially leading to aspiration and gastrostomy, are linked to fatty infiltration in the masticatory muscles, as previously observed in muscle ultrasound. This study aims to quantify muscle volume and fat fraction in muscle magnetic resonance imaging (MRI) in the masticatory muscles in non-ambulant DMD patients compared to healthy controls and evaluate their correlation with maximum bite force (MBF), which has not been previously described. Fifteen patients with DMD and 16 controls were included. MBF was measured with an oral dynamometer and total muscle volume (TMV) and fat signal fraction (FSF) were quantified using MRI with the Dixon technique. Four DMD patients presented with masticatory or swallowing difficulties. DMD patients had a significantly lower median MBF (141.8 N) compared with healthy controls (481.6 N, p < 0.0001). Additionally, median FSF was significantly higher in DMD patients (47.07 %) compared to controls (5.31 %, p < 0.0001). A strong negative correlation between TMV and MBF was observed in DMD patients (ρ = -0.70, p = 0.0048). A significant negative correlation between MBF and normalized FSF was observed in healthy controls (ρ = -0.5487, p = 0.300) and DMD patients (ρ = -0.5893, p = 0.0224). A non-significant positive correlation between age and FSF in DMD was detected (ρ = 0.38, p = 0.17). MBF, TMV and FSF quantified with the Dixon MRI are sensitive measures to evaluate masticatory function in DMD patients and may serve as biomarkers for clinical follow up. Studies in older patients are needed to evaluate the predictive role of MBF, TMV and FSF in the nutritional status of patients and the need for therapeutic interventions such as gastrostomy.

Neuromuscular imaging in clinical practice: an ESNR survey of 30 centers

PURPOSE

We assessed the current clinical imaging practice in the primary evaluation of neuromuscular disorders (NMD), with respect to standardized imaging, evaluation and reporting through a European and extra-European-wide survey.

METHODS

An online questionnaire was emailed to all European Society of Neuroradiology (ESNR) members (n = 1662) who had expressed their interest in NMD. The questionnaire featured 40 individual items. Information was gathered on the context of the practices, available and preferred imaging modalities, applied imaging protocols and standards for interpretation, reporting and communication.

RESULTS

A total of 30 unique entries from European and extra-European academic and non-academic institutions were received. Of these, 70% were neuroradiologists, 23% general radiologists and 7% musculoskeletal radiologists. Of the 30 responding institutes, 40% performed from 20 to 50 neuromuscular scans per year for suspected NMD. The principal modality used for a suspected myopathy was magnetic resonance imaging (MRI) (50%) or "mainly MRI" (47%). The primary imaging modality used for the evaluation of patients suspected of a neuropathy was MRI in 63% of all institutions and "mainly MRI" in 37%. For both muscle and nerve pathology, pelvic girdle and inferior limbs are the most scanned parts of the body (28%), followed by the thigh and leg (24%), whole body MR (24%), scapular girdle (16%), and the thigh in just 8% of institutions. Multiplanar acquisitions were performed in 50% of institutions. Convectional sequences used for muscle MRI included T2-STIR (88%), 2D T1weighted (w) (68%), T1 Dixon or equivalent (52%), T2 Dixon (40%), DWI (36%), 2D T2w (28%), T1 3D and T2 3D (20% respectively). For nerve MRI conventional sequences included T2-STIR (80%), DWI (56%), T2 3D (48%), 2D T2w (48%), T1 3D (44%), T1 Dixon or equivalent (44%), 2D T1 (36%), T2 Dixon (28%). Quantitative sequences were used regularly by 40% respondents. While only 28% of institutions utilized structured reports, a notable 88% of respondents expressed a desire for a standardized consensus structured report. Most of the respondents (93%) would be interested in a common MRI neuromuscular protocol and would like to be trained (87%) by the ESNR society with specific neuromuscular sessions in European annual meetings.

CONCLUSIONS

Based on the survey findings, we can conclude that the current approach to neuromuscular imaging varies considerably among European and extra-European countries, both in terms of image acquisition and post-processing. Some of the challenges identified include the translation of research achievements (related to advanced imaging) into practical applications in a clinical setting, implementation of quantitative imaging post-processing techniques, adoption of structured reporting methods, and communication with referring physicians.