title: MRI of muscle strain injuries.
abstract: OBJECTIVE
  The purpose of our study was to evaluate (a) the characteristics of muscle strain injuries on MRI and (b) the potential of a frequency-selective fat suppression technique for diagnosing such injuries.
  
  
  METHODS
  Muscle strain injuries in seven athletes were examined by MRI. Spin echo sequences were obtained with and without fat suppression sequences. The absolute values of the contrast-to-noise (C/N) ratios for lesion versus muscle or fat were then compared for both types of images.
  
  
  RESULTS
  We obtained two types of characteristic findings for muscle strain. Lesions of the fascia and adjacent muscles showed a characteristic spray-like or fan-like appearance, extending longitudinally from a shared tendon to the muscle belly in five athletes. This finding was better displayed on coronal images. In contrast, lesions inside a muscle showed a diffuse and inhomogeneous appearance in two athletes. The absolute C/N ratios for lesion versus fat and lesion versus muscle were not significantly different for images with and without fat suppression according to the sign test. However, fat-suppressed images revealed subtle abnormalities that were not seen on conventional images.
  
  
  CONCLUSIONS
  Magnetic resonance can provide detailed information on muscle strain injuries, especially when coronal fat-suppressed images are obtained.
authors.affiliation: Department of Radiology, University of Tsukuba, Ibaraki, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Yoshioka
authors.forename: I
authors.initials: I
authors.lastname: Anno
authors.forename: M
authors.initials: M
authors.lastname: Niitsu
authors.forename: H
authors.initials: H
authors.lastname: Takahashi
authors.forename: K
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Y
authors.initials: Y
authors.lastname: Itai
mesh_terms: D000293:Adolescent; D000328:Adult; D001265:Athletic Injuries / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009132:Muscles / Q000293:injuries* / Q000473:pathology; D013180:Sprains and Strains / Q000175:diagnosis*