Biphasic CT imaging of deep neck infections (DNIs): how does dual injection mode helps in differentiation between types of collections?

Abstract

Abstract Background Deep neck infections are showing resurgence in the current era and still pose threatening diagnosis. CT is the gold standard imaging modality; still, the reported low sensitivity and specificity was suggested in view of monophasic injection technique. The purpose of the study was to discuss the diagnostic accuracy of CT with biphasic mode of injection using and a single scanning phase. The first 50–60 cc of IV contrast are injected at a slow rate of 1 cc/s to (tissue impregnation phase). The other 50–60 cc was injected at a high rate of 2 cc/sec, approximately 1 min after the first injection. The single phase of scanning is made followed by multi-planar image analysis of collection. Discrimination of abscess versus phlegmon is made according to described criteria. Results Radiological diagnosis was made of 64/66 cases of abscess and two cases only had phlegmon. The 64 cases of abscess underwent drainage by ENT surgeon showing correctly diagnosed drainable abscess in 59 out of 64 cases and 5 falsely diagnosed as abscess proved to be non-drainable phlegmon. The two patients with radiological diagnosis of non-drainable phlegmons were correctly diagnosed. Conclusion The study achieved a high accuracy of 92%. This is likely attributed to dual-phase technique that allows enhancement of the core of a phlegmon by slow interstitial phase, while combined dual injections allow enhancing the “rim enhancement sign” of abscess.