Necrotizing fasciitis: MRI helped rule it out.

Clinical bottom line (level 4)

  1. Patients with suspected necrotizing fasciitis were less likely to have it following a negative MRI.
Schmid et al: American Journal of Roentgenology 1998; 170: 615-620
Expires November 2004

The study

Setting: university hospital, Switzerland

17 patients (aged range 22 to 76 years; mean 41, 53% male) suspected necrotizing fasciitis. Nine had identifiable portal of entry, five had predisposing diseases (HIV, leukaemia, alcohol abuse, renal insufficiency).

Independent ?blinded reference standard, applied in all patients from a consecutive inappropriate spectrum.
Reference standard:
  • autopsy, surgical findings and/or clinical outcome
Diagnostic test: Magnetic resonance imaging 2 to 7 days (mean 3.3) after onset of symptoms, but <24h prior to any surgical intervention. Necrotizing fasciitis if involvement of deep fascia was visible or necrosis and abscesses present.

The evidence


diagnostic test necrotizing fasciitis cellulitis LR+
(95% CI)		 post-test probability LR-
(95% CI)		 post-test probability
MRI positive 11 1 6.0
(1.0 to 36) 		92% 0.0
(0.0 to 0.26) 		0%
total 11 6

  • In two patients, contrast could not be given secondary to clinical instability.
  • The one false positive reading was in a woman who had received an intramuscular injection in the area imaged.

Comments

  1. Imaging was performed quickly at the expense of some image quality.

Citation

  1. Schmid MR, Kossmann T, Duewell S: Differentiation of necrotizing fasciitis and cellulitis using MR imaging. American Journal of Roentgenology 1998; 170: 615-620
Search Terms: cellulitis and diagnosis
Contributor: John Epling and Chris Ball, November 2000
Reviewer:

Clinical Question.
Patient suspected necrotizing fasciitis
Intervention or Exposure MRI
Outcome diagnosis