title: Necrotizing fasciitis versus pyomyositis: discrimination with using MR imaging.
abstract: OBJECTIVE
  We wanted to evaluate the MR findings for differentiating between necrotizing fasciitis (NF) and pyomyositis (PM).
  
  
  METHODS
  The MR images of 19 patients with surgically confirmed NF (n = 11) and pathologically confirmed PM (n = 8) were retrospectively reviewed with regard to the presence or absence of any MRI finding criteria that could differentiate between them.
  
  
  RESULTS
  The patients with NF had a significantly greater prevalence of the following MR findings (p < 0.05): a peripheral band-like hyperintense signal in muscles on fat-suppressed T2-weighted images (73% of the patients with NF vs. 0% of the patients with PM), peripheral band-like contrast enhancement (CE) of muscles (82% vs. 0%, respectively) and thin smooth enhancement of the deep fascia (82% vs. 13%, respectively). The patients with PM had a significantly greater prevalence of the following MRI findings (p < 0.05): a diffuse hyperintense signal in muscles on fat-suppressed T2-weighted images (27% of the patients with NF vs. 100% in the patients with PM), diffuse CE of muscles (18% vs. 100%, respectively), thick irregular enhancement of the deep fascia (0% vs. 75%, respectively) and intramuscular abscess (0% vs. 88%, respectively). For all patients with NF and PM, the superficial fascia and muscle showed hyperintense signals on T2-weighted images and CE was seen on fat-suppressed CE T1-weighted images. The subcutaneous tissue and deep fascia showed hyperintense signals on T2-weighted images and CE was seen in all the patients with NF and in seven (88%) of the eight patients with PM, respectively.
  
  
  CONCLUSIONS
  MR imaging is helpful for differentiating between NF and PM.
authors.affiliation: Department of Radiology, The Catholic University of Korea, Seoul, Korea.
authors.forename: Jee Hyun
authors.initials: JH
authors.lastname: Seok
authors.forename: Won-Hee
authors.initials: WH
authors.lastname: Jee
authors.forename: Kyung-Ah
authors.initials: KA
authors.lastname: Chun
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Chan-Kwon
authors.initials: CK
authors.lastname: Jung
authors.forename: Yang Ree
authors.initials: YR
authors.lastname: Kim
authors.forename: Wan-Kyu
authors.initials: WK
authors.lastname: Eo
authors.forename: Yang-Soo
authors.initials: YS
authors.lastname: Kim
authors.forename: Yang Guk
authors.initials: YG
authors.lastname: Chung
mesh_terms: D000038:Abscess / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005205:Fascia / Q000473:pathology; D019115:Fasciitis, Necrotizing / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology; D052880:Pyomyositis / Q000473:pathology*; D012189:Retrospective Studies; D055815:Young Adult