title: The 6-minute walk test, motor function measure and quantitative thigh muscle MRI in Becker muscular dystrophy: A cross-sectional study.
abstract: Becker muscular dystrophy (BMD) has an incidence of 1 in 16 000 male births. This cross-sectional study investigated the relation between validated functional scores and quantitative MRI (qMRI) of thigh muscles in 20 ambulatory BMD patients, aged 18.3-60 years (mean 31.2; SD 11.1). Clinical assessments included the motor function measure (MFM) and its subscales, as well as timed function tests such as the 6-minute walk test (6MWT) and the timed 10-m run/walk test. Quantitative MRI of the thigh muscles included the mean fat fraction (MFF) using a 2-point Dixon (2-PD) technique, and transverse relaxation time (T2) measurements. The mean MFM value was 80.4%, SD 9.44 and the D1 subscore 54.5%, SD 19.9. The median 6MWT was 195m, IQR 160-330.2. The median 10-m run/walk test was 7.4 seconds, IQR 6.1-9.3. The mean fat fraction of the thigh muscles was 55.6%, SD 17.4%, mean T2 relaxation times of all muscles: 69.9 ms, SD 14.4. The flexors had the highest MFF and T2 relaxation times, followed by the extensors and the adductors. MFF and global T2 relaxation times were highly negatively correlated with the MFM total, D1-subscore and 6MWT, and positively correlated with the 10 m run/walk test time (p < 0.01). Age was not correlated with MFF, global T2 relaxation time or clinical assessments. Both MFF and T2 measures in the thigh muscle were well correlated with clinical function in BMD and may serve as a surrogate outcome measure in clinical trials.
authors.affiliation: Division of Neuropaediatrics, University of Basel Children's Hospital, Switzerland; University Clinic of Internal Medicine, Kantonsspital Baselland, Bruderholz, Switzerland; Department of Neurology, University of Basel Hospital, Switzerland.
authors.forename: Dirk
authors.initials: D
authors.lastname: Fischer
authors.affiliation: Division of Neuropaediatrics, University of Basel Children's Hospital, Switzerland; University Clinic of Internal Medicine, Kantonsspital Baselland, Bruderholz, Switzerland.
authors.forename: Patricia
authors.initials: P
authors.lastname: Hafner
authors.affiliation: Division of Neuropaediatrics, University of Basel Children's Hospital, Switzerland.
authors.forename: Daniela
authors.initials: D
authors.lastname: Rubino
authors.affiliation: Division of Neuropaediatrics, University of Basel Children's Hospital, Switzerland.
authors.forename: Maurice
authors.initials: M
authors.lastname: Schmid
authors.affiliation: Therapy Department, University of Basel Children's Hospital, Switzerland.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Neuhaus
authors.affiliation: Department of Neurology, University Hospital and University of Zurich, Switzerland.
authors.forename: Hans
authors.initials: H
authors.lastname: Jung
authors.affiliation: Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Switzerland.
authors.forename: Oliver
authors.initials: O
authors.lastname: Bieri
authors.affiliation: Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Switzerland.
authors.forename: Tanja
authors.initials: T
authors.lastname: Haas
authors.affiliation: Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Switzerland.
authors.forename: Monika
authors.initials: M
authors.lastname: Gloor
authors.affiliation: Division of Neuroradiology, Institute of Radiology, University of Basel Hospital, Switzerland; Hirslanden Klinik St. Anna, Lucerne, Switzerland.
authors.forename: Arne
authors.initials: A
authors.lastname: Fischmann
authors.affiliation: Division of Neuropaediatrics, University of Basel Children's Hospital, Switzerland. Electronic address: ulrike.bonati@ukbb.ch.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Bonati
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D003430:Cross-Sectional Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000503:physiopathology; D020388:Muscular Dystrophy, Duchenne / Q000000981:diagnostic imaging* / Q000235:genetics / Q000503:physiopathology*; D012720:Severity of Illness Index; D013848:Thigh / Q000000981:diagnostic imaging* / Q000503:physiopathology; D000070857:Walk Test; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Becker muscular dystrophy; Dystrophinopathy; Imaging biomarker; Quantitative MR; Timed function tests