title: [Different aspects of magnetic resonance imaging of muscles between dermatomyositis and polymyositis].
abstract: BACKGROUND
  Although dermatomyositis (DM) and polymyositis (PM) share many clinical features in common, they have distinct pathophysiological and histological features. It is possible that these distinctions reflect also macroscopically, for example, in muscle alterations seen in magnetic resonance images (MRI).
  
  
  OBJECTIVE
  To compare simultaneously the MRI of various muscle compartments of the thighs of adult DM and PM.
  
  
  METHODS
  The present study is a cross-sectional that included, between 2010 and 2013, 11 newly diagnosed DM and 11 PM patients (Bohan and Peter's criteria, 1975), with clinical and laboratory activity. They were valued at RM thighs, T1 and T2 with fat suppression, 1.5 T MRI scanner sequences.
  
  
  RESULTS
  The mean age at the time of MRI, the time between onset of symptoms and the realization of the MRI distribution of sex and drug therapy were comparable between the two groups (p>0.050). Concerning the MRI, muscle edema was significantly found in DM, and mainly in the proximal region of the muscles. The area of fat replacement was found predominantly in PM. The partial fat replacement area occurred mainly in the medial and distal region, whereas the total fat replacement area occurred mainly in the distal muscles. There was no area of muscle fibrosis.
  
  
  CONCLUSIONS
  DM and PM have different characteristics on MRI muscles, alike pathophysiological and histological distinctions.
authors: Serviço de Reumatologia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil.
authors: Sofia Silveira de Castro
authors: SS
authors: Miranda
authors: Departamento de Radiologia, Instituto de Ortopedia e Traumatologia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil.
authors: Daniel
authors: D
authors: Alvarenga
authors: Departamento de Radiologia, Instituto de Ortopedia e Traumatologia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil.
authors: João Carlos
authors: JC
authors: Rodrigues
authors: Serviço de Reumatologia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil; Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil. Electronic address: samuel.shinjo@gmail.com.
authors: Samuel Katsuyuki
authors: SK
authors: Shinjo
mesh_terms: D003430:Cross-Sectional Studies; D003882:Dermatomyositis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D017285:Polymyositis / Q000000981:diagnostic imaging*
keywords: Dermatomiosite; Dermatomyositis; Doença muscular; Magnetic resonance; Muscular diseases; Polimiosite; Polymyositis; Ressonância magnética