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Lower limb muscle MRI fat fraction is a responsive outcome measure in CMT X1, 1B and 2A
Journal article   Open access   Peer reviewed

Lower limb muscle MRI fat fraction is a responsive outcome measure in CMT X1, 1B and 2A

Nick Zafeiropoulos, Katherine J Stephens, Tiffany Grider, Shawna M E Feely, Peggy Nopoulous, Mariola Skorupinska, Evelin Milev, Emma Nicolaisen, Magdalena Dudzeic, Amy McDowell, …
Annals of clinical and translational neurology, Vol.11(3), pp.607-617
03/2024
DOI: 10.1002/acn3.51979
PMCID: PMC10963306
PMID: 38173284
url
https://doi.org/10.1002/acn3.51979View
Published (Version of record) Open Access

Abstract

With potential therapies for many forms of Charcot-Marie-Tooth disease (CMT), responsive outcome measures are urgently needed for clinical trials. Quantitative lower limb MRI demonstrated progressive calf intramuscular fat accumulation in the commonest form, CMT1A with large responsiveness. In this study, we evaluated the responsiveness and validity in the three other common forms, due to variants in GJB1 (CMTX1), MPZ (CMT1B) and MFN2 (CMT2A). 22 CMTX1, 21 CMT1B and 21 CMT2A patients and matched controls were assessed at a 1-year interval. Intramuscular fat fraction (FF) was evaluated using three-point Dixon MRI at thigh and calf level along with clinical measures including CMT examination score, clinical strength assessment, CMT-HI and plasma neurofilament light chain. All patient groups had elevated muscle fat fraction at thigh and calf levels, with highest thigh FF and atrophy in CMT2A. There was moderate correlation between calf muscle FF and clinical measures (CMTESv2 rho = 0.405; p = 0.001, ankle MRC strength rho = -0.481; p < 0.001). Significant annualised progression in calf muscle FF was seen in all patient groups (CMTX1 2.0 ± 2.0%, p < 0.001, CMT1B 1.6 ± 2.1% p = 0.004 and CMT2A 1.6 ± 2.1% p = 0.002). Greatest increase was seen in patients with 10-70% FF at baseline (calf 2.7 ± 2.3%, p < 0.0001 and thigh 1.7 ± 2.1%, p = 0.01). Our results confirm that calf muscle FF is highly responsive over 12 months in three additional common forms of CMT which together with CMT1A account for 90% of genetically confirmed cases. Calf muscle MRI FF should be a valuable outcome measure in upcoming CMT clinical trials.

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