title: Muscle Quantitative MR Imaging and Clustering Analysis in Patients with Facioscapulohumeral Muscular Dystrophy Type 1.
abstract: BACKGROUND
  Facioscapulohumeral muscular dystrophy type 1 (FSHD1) is the third most common inherited muscular dystrophy. Considering the highly variable clinical expression and the slow disease progression, sensitive outcome measures would be of interest.
  
  
  RESULTS
  Using muscle MRI, we assessed muscular fatty infiltration in the lower limbs of 35 FSHD1 patients and 22 healthy volunteers by two methods: a quantitative imaging (qMRI) combined with a dedicated automated segmentation method performed on both thighs and a standard T1-weighted four-point visual scale (visual score) on thighs and legs. Each patient had a clinical evaluation including manual muscular testing, Clinical Severity Score (CSS) scale and MFM scale. The intramuscular fat fraction measured using qMRI in the thighs was significantly higher in patients (21.9 ± 20.4%) than in volunteers (3.6 ± 2.8%) (p<0.001). In patients, the intramuscular fat fraction was significantly correlated with the muscular fatty infiltration in the thighs evaluated by the mean visual score (p<0.001). However, we observed a ceiling effect of the visual score for patients with a severe fatty infiltration clearly indicating the larger accuracy of the qMRI approach. Mean intramuscular fat fraction was significantly correlated with CSS scale (p ≤ 0.01) and was inversely correlated with MMT score, MFM subscore D1 (p ≤ 0.01) further illustrating the sensitivity of the qMRI approach. Overall, a clustering analysis disclosed three different imaging patterns of muscle involvement for the thighs and the legs which could be related to different stages of the disease and put forth muscles which could be of interest for a subtle investigation of the disease progression and/or the efficiency of any therapeutic strategy.
  
  
  CONCLUSIONS
  The qMRI provides a sensitive measurement of fat fraction which should also be of high interest to assess disease progression and any therapeutic strategy in FSHD1 patients.
authors.affiliation: Centre de référence des maladies neuromusculaires et de la SLA, Centre hospitalier universitaire la Timone, Université Aix-Marseille, Marseille, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Lareau-Trudel
authors.affiliation: Aix-Marseille Université, Centre de Résonance Magnétique Biologique et Médicale, UMR CNRS 7339, Marseille, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Le Troter
authors.affiliation: Institut de Mathématiques de Marseille, Université Aix-Marseille, Marseille, France.
authors.forename: Badih
authors.initials: B
authors.lastname: Ghattas
authors.affiliation: Centre de référence des maladies neuromusculaires et de la SLA, Centre hospitalier universitaire la Timone, Université Aix-Marseille, Marseille, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Pouget
authors.affiliation: Centre de référence des maladies neuromusculaires et de la SLA, Centre hospitalier universitaire la Timone, Université Aix-Marseille, Marseille, France.
authors.forename: Shahram
authors.initials: S
authors.lastname: Attarian
authors.affiliation: Aix-Marseille Université, Centre de Résonance Magnétique Biologique et Médicale, UMR CNRS 7339, Marseille, France.
authors.forename: David
authors.initials: D
authors.lastname: Bendahan
authors.affiliation: Centre de référence des maladies neuromusculaires et de la SLA, Centre hospitalier universitaire la Timone, Université Aix-Marseille, Marseille, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Salort-Campana
mesh_terms: D000273:Adipose Tissue / Q000473:pathology; D000328:Adult; D016022:Case-Control Studies; D016000:Cluster Analysis; D018450:Disease Progression; D005260:Female; D006801:Humans; D007866:Leg / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology*; D020391:Muscular Dystrophy, Facioscapulohumeral / Q000175:diagnosis* / Q000473:pathology; D012720:Severity of Illness Index; D013848:Thigh / Q000473:pathology*