A scoring system named Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) is often used, which takes into consideration WBC, hemoglobin, blood chemistry values, and C-reactive protein [50]. Although NF is primarily diagnosed clinically, imaging findings can be critical to support the diagnosis, to aid in surgical planning, and to map disease extent and involvement. However, obtaining imaging studies, such as MRI, should not delay appropriate surgical treatment in patients who are severely ill and unstable [49]. CT Area of Interest The CT findings in NF correlate with the pathophysiology of the infection causing soft tissue inflammation and liquefactive necrosis. Skin thickening, inflammatory subcutaneous fat stranding, and fluid or gas in the superficial or deep fascial planes are the typical CT findings [49,51,52]. In a study evaluating 20 surgically proven cases of NF, Wysoki et al [53] reported that CT demonstrated subcutaneous fat stranding and fascial fluid or thickening in 80%, soft tissue gas in 55%, and abscesses in 35% of cases. Tso et al [52] concluded that although the overall sensitivity of CT in diagnosing NF is 80%, the specificity is low because similar findings may be present in non- NF, cellulitis, pyomyositis, bursitis, and other soft tissue infections. Compared with radiography, US, and MRI, CT is the most sensitive modality for detection of soft tissue gas [51,52,54]. Fernando et al [54] reported in a meta-analysis of 23 studies that the visualization of soft tissue gas on radiographs had a sensitivity of 49% and a specificity of 94% for the diagnosis of NF. Soft tissue gas on CT was associated with a sensitivity of 89% and a specificity of 93% for diagnosing NF. Gas within fascial planes and fluid collections is an important finding and can be a CT hallmark of NF; however, the absence of soft tissue gas does not exclude NF [2,49,51,52].
Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. A scoring system named Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) is often used, which takes into consideration WBC, hemoglobin, blood chemistry values, and C-reactive protein [50]. Although NF is primarily diagnosed clinically, imaging findings can be critical to support the diagnosis, to aid in surgical planning, and to map disease extent and involvement. However, obtaining imaging studies, such as MRI, should not delay appropriate surgical treatment in patients who are severely ill and unstable [49]. CT Area of Interest The CT findings in NF correlate with the pathophysiology of the infection causing soft tissue inflammation and liquefactive necrosis. Skin thickening, inflammatory subcutaneous fat stranding, and fluid or gas in the superficial or deep fascial planes are the typical CT findings [49,51,52]. In a study evaluating 20 surgically proven cases of NF, Wysoki et al [53] reported that CT demonstrated subcutaneous fat stranding and fascial fluid or thickening in 80%, soft tissue gas in 55%, and abscesses in 35% of cases. Tso et al [52] concluded that although the overall sensitivity of CT in diagnosing NF is 80%, the specificity is low because similar findings may be present in non- NF, cellulitis, pyomyositis, bursitis, and other soft tissue infections. Compared with radiography, US, and MRI, CT is the most sensitive modality for detection of soft tissue gas [51,52,54]. Fernando et al [54] reported in a meta-analysis of 23 studies that the visualization of soft tissue gas on radiographs had a sensitivity of 49% and a specificity of 94% for the diagnosis of NF. Soft tissue gas on CT was associated with a sensitivity of 89% and a specificity of 93% for diagnosing NF. Gas within fascial planes and fluid collections is an important finding and can be a CT hallmark of NF; however, the absence of soft tissue gas does not exclude NF [2,49,51,52].