Qualitative evaluation of decreased bowel-wall enhancement by CT as supporting ischemia in mechanical small bowel obstruction: diagnostic performance of the arterial vs. the portal phase

Decreased bowel-wall enhancement (DBE) is a specific and clinically relevant sign of bowel ischemia in adhesive small-bowel obstruction (SBO). It has almost exclusively been studied at the portal phase. To compare the diagnostic performance of CT-arterial vs. CT-portal phase to assess DBE as a sign of ischemia in SBO. 158 consecutive patients explored by a triphasic CT (unenhanced, arterial, and portal phases) with a final diagnosis of SBO were included. Clinical and surgical outcomes with histopathological findings were recorded as the reference standard. Two radiologists performed two blinded, independent, and retrospective reviews of CT studies for evaluating DBE. Read 1: unenhanced and arterial phase, read 2: unenhanced CT and portal phase. In case of disagreement, a consensus reading with a third radiologist was performed. Diagnostic performances of DBE for ischemia were calculated for consensual reading. Ischemia was confirmed in 48 of 158 (30.4%) cases. After consensus, sensitivity and specificity were 75%, 85%, and 65%, 91%, without significant differences for arterial and portal phase, respectively. Consensus analyses differed between arterial and portal phases for 17/158 patients (10.8%). 8/14 (57%) patients with arterial DBE and no portal DBE did not have ischemia. Ischemia was confirmed in 2/3 (67%) of the patients with portal DBE and no arterial DBE. Although differences were not statistically significant, the addition of an arterial phase in the SBO CT protocol increases sensitivity at the expense of a moderate decreased specificity, suggesting that the arterial phase may be useful to visualize early perfusion deficits. Question The added value of the arterial phase for assessment of ischemia in SBO remains a subject of debate . Findings Adding the arterial phase in the SBO CT protocol increases sensitivity from 65% to 75% and decreases specificity from 91% to 85% . Clinical relevance Addition of an arterial phase in the SBO CT protocol increases sensitivity at the expense of a moderate decreased specificity for assessment of DBE as a sign of ischemia, suggesting potential utility for the arterial phase to visualize early perfusion deficits in selected high-risk patients .