MRI has the highest reported sensitivity of 93% for the diagnosis of NF because of this detection of fluid signal on T2 fat suppressed or short tau inversion recovery (STIR) sequences [49,52]. Furthermore, the absence of fluid signal along the fascia essentially excludes the diagnosis of NF [2,52,56,57]. However, MRI findings of superficial and deep fascial fluid or edema are not specific for NF and can be seen in other soft tissue infections, such as severe cellulitis and non-NF. If the MRI is negative or with nonspecific findings and there is high clinical suspicion of NF, appropriate surgical treatment should be planned [49]. Also, in stable yet nonimproving patients, obtaining follow- up MRI can be of benefit to assess for progression of necrosis or fascial fluid and edema [49]. Although CT is more sensitive for detecting soft tissue gas, it can be seen as low punctate or curvilinear signal on all MRI sequences (T1-weighted, T2-weighted, STIR) and can be detected with high sensitivity with gradient echo sequences because of blooming artifact and susceptibility artifact. The presence of soft tissue gas is highly associated with NF; however, the absence of soft tissue gas on MRI should not exclude the diagnosis of NF and may be seen in late stages of NF [50,52,56]. Although some degree of fascial thickening, indistinctness of fascial planes, and fluid accumulation can be seen on CT, the MRI high signal intensity appearance of fascial fluid and edema on T2 fat suppression/STIR sequences is far superior for the detection of NF [56]. Yoon et al [50] also compared 2 parameters for diagnosing NF: utilization of the LRINEC score only and when both MRI findings and the LRINEC scores where applied to the diagnostic scenario. When the LRINEC score was used alone, the sensitivity, specificity, positive predictive value, and negative predictive value were 57%, 84%, 77%, and 67%, respectively.
Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. MRI has the highest reported sensitivity of 93% for the diagnosis of NF because of this detection of fluid signal on T2 fat suppressed or short tau inversion recovery (STIR) sequences [49,52]. Furthermore, the absence of fluid signal along the fascia essentially excludes the diagnosis of NF [2,52,56,57]. However, MRI findings of superficial and deep fascial fluid or edema are not specific for NF and can be seen in other soft tissue infections, such as severe cellulitis and non-NF. If the MRI is negative or with nonspecific findings and there is high clinical suspicion of NF, appropriate surgical treatment should be planned [49]. Also, in stable yet nonimproving patients, obtaining follow- up MRI can be of benefit to assess for progression of necrosis or fascial fluid and edema [49]. Although CT is more sensitive for detecting soft tissue gas, it can be seen as low punctate or curvilinear signal on all MRI sequences (T1-weighted, T2-weighted, STIR) and can be detected with high sensitivity with gradient echo sequences because of blooming artifact and susceptibility artifact. The presence of soft tissue gas is highly associated with NF; however, the absence of soft tissue gas on MRI should not exclude the diagnosis of NF and may be seen in late stages of NF [50,52,56]. Although some degree of fascial thickening, indistinctness of fascial planes, and fluid accumulation can be seen on CT, the MRI high signal intensity appearance of fascial fluid and edema on T2 fat suppression/STIR sequences is far superior for the detection of NF [56]. Yoon et al [50] also compared 2 parameters for diagnosing NF: utilization of the LRINEC score only and when both MRI findings and the LRINEC scores where applied to the diagnostic scenario. When the LRINEC score was used alone, the sensitivity, specificity, positive predictive value, and negative predictive value were 57%, 84%, 77%, and 67%, respectively.