DECT-based stratification of nonocclusive mesenteric ischemia using bowel-wall iodine concentration: a prospective single-center cohort

OBJECTIVE: We evaluated whether bowel-wall iodine concentration (BWIC) on dual-energy computed tomography (DECT) improves the diagnosis of non-occlusive mesenteric ischemia (NOMI) and allows differentiation of irreversible transmural necrosis (ITN) from non-ITN. MATERIALS AND METHODS: In this prospective single-center ethically approved study, consecutive patients with shock who underwent DECT between November 2022 and October 2024 were included. NOMI was classified as absent, present without ITN, or present with ITN using a composite reference standard. On 70- and 50-keV virtual monoenergetic imaging (VMI), one reader assessed signs of bowel ischemia. On iodine maps, BWIC was measured by placing five full-thickness bowel-wall regions of interest within the affected digestive segment(s). BWIC was measured by one reader and independently repeated by four additional readers in patients with NOMI. Diagnostic performance was assessed using the area under the curve (AUC) at receiver operating characteristic analysis and Youden J index. RESULTS: Among 177 patients (median age 65 years; 44% males), NOMI was diagnosed in 31/177 (18%), including 23/31 (74%) with ITN. Absent enhancement on 50-keV VMI yielded the highest accuracy for NOMI diagnosis (J = 0.94) and was not outperformed by minimum BWIC (J = 0.87). In NOMI patients, no binary signs differentiated ITN from non-ITN. Minimum BWIC was lower in ITN (median 0.54 mgI/mL [interquartile range 0.42-0.60]) than in non-ITN (0.85 mgI/mL [0.74-0.99]; p < 0.001) with a pooled AUC of 0.86 and optimal threshold of 0.52 mgI/mL (J = 0.74). CONCLUSION: BWIC did not outperform visual assessment for diagnosing NOMI, but uniquely discriminated ITN from non-ITN. RELEVANCE STATEMENT: Using a two-step strategy-50-keV-VMI bowel enhancement assessment followed by segmental BWIC measurement-correctly classified 173/177 patients as no NOMI, NOMI without or with irreversible transmural necrosis. KEY POINTS: Non-occlusive mesenteric ischemia (NOMI) affected 18% of shocked intensive care unit patients who underwent abdominal DECT. Absent bowel-wall enhancement at 50-keV virtual monoenergetic imaging best detected NOMI. Only bowel-wall iodine concentration discriminated transmural necrosis from reversible ischemia (pooled AUC = 0.86), with an optimal cutoff of 0.52 mgI/mL.