Diagnostic accuracy of dual-layer spectral CT for acute bowel ischemia

OBJECTIVES: To evaluate whether adding dual-layer spectral CT (DLCT) to conventional CT (CCT) improves diagnostic accuracy for acute bowel ischemia (ABI).

MATERIALS AND METHODS: This retrospective single-center study included 387 consecutive patients (61 ± 15 years; 42% female) who underwent biphasic abdominal DLCT for clinically suspected ABI. After testing interobserver agreement with an enriched sample of 25 scans (ĸ:0.41-0.68), the scans were divided into four batches and independently evaluated by four radiologists. Each scan was evaluated twice: first using CCT, then with added iodine density and 40 keV monoenergetic (monoE40) reconstructions. The presence of ABI was rated in accordance with our clinical practice on a five-point Likert scale. The reference standard was a composite of surgery, pathology, endoscopy, endovascular intervention, and/or clinical follow-up data. Diagnostic accuracy was calculated with 95% confidence intervals.

RESULTS: Fifty-five patients (14%) had ABI, of whom 65% with surgical and/or pathological proof. The most common etiologies were arterial occlusion (44%) and non-occlusive mesenteric ischemia (33%). For CCT, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 65% (95% CI 51-78), 93% (90-96), 61% (50-71), 94% (92-96), and 89% (86-92), respectively. Adding DLCT reconstructions did not improve sensitivity (65%), but had a limited improvement in the positive predictive value (61% to 67%) for monoE40 reconstruction (p = 0.046).

CONCLUSION: Qualitative assessment of additional DLCT reconstructions (iodine density and monoE40) alongside CCT did not improve sensitivity for ABI diagnosis, but a small overall improvement in positive predictive value was observed for monoE40.