title: Quantitative MRI and loss of free ambulation in Duchenne muscular dystrophy.
abstract: The purpose of this ethics approved trial was to correlate quantitative MRI with functional abilities in both ambulant and non-ambulant Duchenne muscular dystrophy (DMD). Twenty patients with genetically confirmed DMD were recruited. Physical assessment was performed using the motor function measurement (MFM) scale. Axial 3T MRI scans of the thighs were acquired using T1-weighted in- and opposed-phase images (TR = 20 ms, TE1 = 2.45 ms, TE2 = 3.68 ms, flip angle = 15°) to calculate the relative fat fraction according to the two-point Dixon method in the knee extensors, flexors, and adductor muscles. The average MFM was 65.3 % and correlated negatively to age (r (2) = 0.60). Overall mean fat fraction correlated positively to age (r (2) = 0.51-0.64). An average of 5 % increase in mean fat fraction per year was calculated. Mean fat fraction of the quadriceps showed a high negative correlation (r (2) = 0.93) to the D1 (standing position and transfers) component of the MFM. A cutoff for mean fat fraction of 50 % predicted loss of ambulation with a sensitivity of 100 % and a specificity of 91 %. Therefore, quantitative muscle MRI seems to be a promising endpoint for short clinical trials evaluating the effect of newer treatments on the time of loss of ambulation in DMD.
authors.affiliation: Division of Diagnostic and Interventional Neuroradiology, Department of Radiology, University of Basel Hospital, Petersgraben 4, 4031 Basel, Switzerland. arne.fischmann@unibas.ch
authors.forename: Arne
authors.initials: A
authors.lastname: Fischmann
authors.forename: Patricia
authors.initials: P
authors.lastname: Hafner
authors.forename: Monika
authors.initials: M
authors.lastname: Gloor
authors.forename: Maurice
authors.initials: M
authors.lastname: Schmid
authors.forename: Andrea
authors.initials: A
authors.lastname: Klein
authors.forename: Urs
authors.initials: U
authors.lastname: Pohlman
authors.forename: Tanja
authors.initials: T
authors.lastname: Waltz
authors.forename: Rocio
authors.initials: R
authors.lastname: Gonzalez
authors.forename: Tanja
authors.initials: T
authors.lastname: Haas
authors.forename: Oliver
authors.initials: O
authors.lastname: Bieri
authors.forename: Dirk
authors.initials: D
authors.lastname: Fischer
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004185:Disability Evaluation; D005260:Female; D007839:Functional Laterality; D020233:Gait Disorders, Neurologic / Q000209:etiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology; D020388:Muscular Dystrophy, Duchenne / Q000150:complications* / Q000473:pathology*; D016138:Walking / Q000502:physiology*; D055815:Young Adult