title: T1-weighted MRI imaging features of pathologically proven non-pedal osteomyelitis.
abstract: OBJECTIVE
  The objective of our study was to determine if the T1-weighted magnetic resonance imaging (MRI) features associated with diabetic pedal osteomyelitis are present in histopathologically proven cases of non-pedal osteomyelitis.
  
  
  METHODS
  Seventy-five patients with a histopathologically proven diagnosis of non-pedal osteomyelitis and a preoperative MRI were identified between 2000 and 2007. The MRIs were retrospectively reviewed for signal characterization of T1-weighted images, including the signal intensity compared with skeletal muscle, distribution of abnormal signal intensity, and pattern of abnormal signal intensity. A subsequent chart review was performed to identify potential clinical factors that were more associated with atypical T1 features of osteomyelitis. Fisher's exact test was performed to determine if there was a statistically significant difference in the T1-weighted imaging features of the hematogenous and nonhematogenous mechanisms of infection.
  
  
  RESULTS
  Seventy of 75 cases demonstrated T1-weighted imaging features typical of pedal osteomyelitis with a confluent region of decreased signal intensity, hypointense, or isointense relative to skeletal muscle in a geographic pattern with medullary distribution. Of the 5 cases that did not demonstrate the typical T1 features associated with pedal osteomyelitis, 4 were considered to have a hematologic mechanism of infection given the absence of surgery, skin ulceration, or a penetrating injury.
  
  
  CONCLUSIONS
  The majority of cases of non-pedal osteomyelitis in our study demonstrate the typical T1-weighted imaging features previously documented to correlate with the diagnosis of pedal osteomyelitis. The cases in our series that did not demonstrate the typical T1-weighted features were predominantly secondary to a hematologic mechanism of infection.
authors.affiliation: Department of Radiology, Mayo Clinic-Rochester, Rochester, MN 55902, USA. howe.benjamin@mayo.edu
authors.forename: Benjamin Matthew
authors.initials: BM
authors.lastname: Howe
authors.forename: Doris E
authors.initials: DE
authors.lastname: Wenger
authors.forename: Jay
authors.initials: J
authors.lastname: Mandrekar
authors.forename: Mark S
authors.initials: MS
authors.lastname: Collins
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010019:Osteomyelitis / Q000473:pathology*; D012189:Retrospective Studies