title: Non-uniform muscle fat replacement along the proximodistal axis in Duchenne muscular dystrophy.
abstract: The progressive replacement of muscle tissue by fat in Duchenne muscular dystrophy (DMD) has been studied using quantitative MRI between, but not within, individual muscles. We studied fat replacement along the proximodistal muscle axis using the Dixon technique on a 3T MR scanner in 22 DMD patients and 12 healthy controls. Mean fat fractions per muscle per slice for seven lower and upper leg muscles were compared between and within groups assuming a parabolic distribution. Average fat fraction for a small central slice stack and a large coverage slice stack were compared to the value when the stack was shifted one slice (15 mm) up or down. Higher fat fractions were observed in distal and proximal muscle segments compared to the muscle belly in all muscles of the DMD subjects (p <0.001). A shift of 15 mm resulted in a difference in mean fat fraction which was on average 1-2% ranging up to 12% (p <0.01). The muscle end regions are exposed to higher mechanical strain, which points towards mechanical disruption of the sarcolemma as one of the key factors in the pathophysiology. Overall, this non-uniformity in fat replacement needs to be taken into account to prevent sample bias when applying quantitative MRI as biomarker in clinical trials for DMD.
authors.affiliation: C.J. Gorter Center for High Field MRI, Dept. of Radiology, Leiden University Medical Center, Zuid-Holland, Netherlands. Electronic address: m.t.hooijmans@lumc.nl.
authors.forename: M T
authors.initials: MT
authors.lastname: Hooijmans
authors.affiliation: Dept. of Neurology, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands.
authors.forename: E H
authors.initials: EH
authors.lastname: Niks
authors.affiliation: C.J. Gorter Center for High Field MRI, Dept. of Radiology, Leiden University Medical Center, Zuid-Holland, Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Burakiewicz
authors.affiliation: C.J. Gorter Center for High Field MRI, Dept. of Radiology, Leiden University Medical Center, Zuid-Holland, Netherlands; Dept. of Neuropediatrics and Muscle Disorders, University of Freiburg, Freiburg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Anastasopoulos
authors.affiliation: Dept. of Neurology, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands.
authors.forename: S I
authors.initials: SI
authors.lastname: van den Berg
authors.affiliation: Dept. of Biostatistics, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: van Zwet
authors.affiliation: C.J. Gorter Center for High Field MRI, Dept. of Radiology, Leiden University Medical Center, Zuid-Holland, Netherlands.
authors.forename: A G
authors.initials: AG
authors.lastname: Webb
authors.affiliation: Dept. of Neurology, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands.
authors.forename: J J G M
authors.initials: JJGM
authors.lastname: Verschuuren
authors.affiliation: C.J. Gorter Center for High Field MRI, Dept. of Radiology, Leiden University Medical Center, Zuid-Holland, Netherlands.
authors.forename: H E
authors.initials: HE
authors.lastname: Kan
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D006801:Humans; D035002:Lower Extremity / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D020388:Muscular Dystrophy, Duchenne / Q000000981:diagnostic imaging*
keywords: DMD; Fat replacement; MRI; Muscle