Acute intestinal ischemia and infarction are devastating abdominal emergencies, with mortality rates up to 93%. Clinical presentation is varied, with significant overlap with other acute abdominal disease. CT sensitivity for detection of acute bowel ischemia is poor, with reported values ranging from 60-80%. CT detection of bowel ischemia is challenging given that CT findings are non-specific. Here, we evaluate the utility of dual-energy CT (DECT) and iodine mapping in the diagnosis of acute intestinal ischemia.
METHOD AND MATERIALS64 consecutive patients presented to the emergency department of a quaternary hospital with features of acute intestinal ischemia or infarction between 2013 and 2014. Abdominal DECT (100 and 140 keV) with derived iodine maps (Liver VNC algorithm, Siemens) were reconstructed. An iodine map window of 270/160 was determined optimal for assessment of the intestinal mucosa (data not shown). Laboratory, clinical and pathological outcomes were recorded. Two abdominal trained radiologists were blinded to outcomes and independently rated the concordance of conventional CT and iodine maps with pathological outcomes. Qualitative analysis was also performed.
RESULTS18 of 64 cases were confirmed to represent intestinal ischemia or infarction on surgical pathology, colonoscopy or due to death from intestinal infarction. Conventional 120 keV CT sensitivity, specificity, PPV and NPV for acute ischemia or infarction were 77.8% (95% CI 52.4-93.5), 89.1% (76.4-96.33), 73.7% (48.8-97.8) and 91.1% (78.8-97.5), respectively. Iodine maps were more robust than conventional 120 keV CT in the diagnosis of this disease entity, demonstrating sensitivity, specificity, PPV and NPV of 94.4% (72.6-99.1), 93.5% (82.1-98.6), 85.0% (62.1-96.6) and 97.7% (87.9-99.6), respectively. Quantitative evaluation showed good intra and inter observer reproducibility. Iodine maps increased interpreter confidence by 20%, and interpreters considered iodine maps useful in 83% of cases.
CONCLUSIONDECT iodine mapping increase conspicuity of ischemic bowel and allow for evaluation of intestinal perfusion. Iodine maps are a reliable and reproducible imaging adjunct, which offer a robust increase in sensitivity and specificity in the diagnosis of acute intestinal ischemia or infarction over conventional CT, up to 94.4% and 93.5%, respectively.
CLINICAL RELEVANCE/APPLICATIONDECT iodine maps are superior to conventional CT in the diagnosis of intestinal ischemia.