title: "Target" and "Sandwich" Signs in Thigh Muscles have High Diagnostic Values for Collagen VI-related Myopathies.
abstract: BACKGROUND
  Collagen VI-related myopathies are autosomal dominant and recessive hereditary myopathies, mainly including Ullrich congenital muscular dystrophy (UCMD) and Bethlem myopathy (BM). Muscle magnetic resonance imaging (MRI) has been widely used to diagnosis muscular disorders. The purpose of this study was to evaluate the diagnostic value of thigh muscles MRI for collagen VI-related myopathies.
  
  
  METHODS
  Eleven patients with collagen VI gene mutation-related myopathies were enrolled in this study. MRI of the thigh muscles was performed in all patients with collagen VI gene mutation-related myopathies and in 361 patients with other neuromuscular disorders (disease controls). T1-weighted images were used to assess fatty infiltration of the muscles using a modified Mercuri's scale. We assessed the sensitivity and specificity of the MRI features of collagen VI-related myopathies. The relationship between fatty infiltration of muscles and specific collagen VI gene mutations was also investigated.
  
  
  RESULTS
  Eleven patients with collagen VI gene mutation-related myopathies included six UCMD patients and five BM patients. There was no significant difference between UCMD and BM patients in the fatty infiltration of each thigh muscle except sartorius (P = 0.033); therefore, we combined the UCMD and BM data. Mean fatty infiltration scores were 3.1 and 3.0 in adductor magnus and gluteus maximus, while the scores were 1.3, 1.3, and 1.5 in gracilis, adductor longus, and sartorius, respectively. A "target" sign in rectus femoris (RF) was present in seven cases, and a "sandwich" sign in vastus lateralis (VL) was present in ten cases. The "target" and "sandwich" signs had sensitivities of 63.6% and 90.9% and specificities of 97.3% and 96.9% for the diagnosis of collagen VI-related myopathies, respectively. Fatty infiltration scores were 2.0-3.0 in seven patients with mutations in the triple-helical domain, and 1.0-1.5 in three of four patients with mutations in the N- or C-domain of the collagen VI genes.
  
  
  CONCLUSIONS
  The "target" sign in RF and "sandwich" sign in VL are common MRI features and are useful for the diagnosis of collagen VI-related myopathies. The severity of fatty infiltration of muscles may have a relationship with the mutation location of collagen VI gene.
authors.affiliation: Department of Neurology, Peking University First Hospital, Beijing 100034, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Fu
authors.affiliation: Department of Neurology, Peking University First Hospital, Beijing 100034, China.
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Zheng
authors.affiliation: Department of Neurology, Peking University First Hospital, Beijing 100034, China.
authors.forename: Su-Qin
authors.initials: SQ
authors.lastname: Jin
authors.affiliation: Department of Neurology, Peking University First Hospital, Beijing 100034, China.
authors.forename: Jun-Fei
authors.initials: JF
authors.lastname: Yi
authors.affiliation: Department of Neurology, Peking University First Hospital, Beijing 100034, China.
authors.forename: Xiu-Juan
authors.initials: XJ
authors.lastname: Liu
authors.affiliation: Department of Neurology, Peking University First Hospital, Beijing 100034, China.
authors.forename: He
authors.initials: H
authors.lastname: Lyn
authors.affiliation: Department of Neurology, Peking University First Hospital, Beijing 100034, China.
authors.forename: Zhao-Xia
authors.initials: ZX
authors.lastname: Wang
authors.affiliation: Department of Neurology, Peking University First Hospital, Beijing 100034, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Peking University First Hospital, Beijing 100034, China.
authors.forename: Jiang-Xi
authors.initials: JX
authors.lastname: Xiao
authors.affiliation: Department of Neurology, Peking University First Hospital, Beijing 100034, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Yuan
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D024142:Collagen Type VI / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology*; D009135:Muscular Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D009154:Mutation / Q000235:genetics; D012680:Sensitivity and Specificity; D013848:Thigh / Q000473:pathology*; D055815:Young Adult
chemical_list: D024142:Collagen Type VI