Bowel ischemia detection on portal venous CT: multireader evaluation of dual-energy and photon-counting spectral imaging.

Abstract

To compare the diagnostic performance of portal-venous (PV) blended CT images alone vs PV blended images supplemented with spectral reconstructions for detecting acute bowel ischemia, stratified by scanner platform (dual-energy CT [DECT] vs photon-counting CT [PCCT]). This retrospective single-center, multireader, crossover diagnostic accuracy study compared PV blended images alone (image set A) with PV blended images supplemented by spectral reconstructions (image set B: 40-keV virtual monoenergetic images, iodine maps, and virtual non-contrast images) acquired on DECT and PCCT. The reference standard was a prespecified composite derived from surgical and index-hospitalization documentation. Diagnostic performance was analyzed using mixed-effects logistic models for accuracy, sensitivity, and specificity, cumulative link mixed models for 7-point suspicion scores, and ROC analyses using a multireader multicase framework. A total of 378 patients (mean age, 68.1 years ± 7.4, 206 men) were evaluated. 150/378 (39.7%) were ischemia-positive by the composite reference standard. Accuracy increased from 73% (95% CI: 68-77) with blended images to 86% (82-89) with spectral reconstructions (OR: 2.30; 95% CI: 1.70-3.10; p < 0.001). Sensitivity increased from 75% (68-82) to 87% (81-92) (p = 0.008) and specificity from 72% (65-78) to 86% (80-90) (p < 0.001). Mean AUC improved by 0.16 (95% CI: 0.12-0.20; p < 0.001). Effects were similar on DECT and PCCT (interaction p = 0.24). Adding spectral reconstructions to PV blended images improved accuracy, sensitivity, specificity, and diagnostic confidence for bowel ischemia detection, without evidence of platform-specific effect modification. Question Can spectral reconstructions improve bowel ischemia detection on portal venous (PV) phase abdominal CT, and are these gains consistent across DECT and PCCT? Findings Adding spectral reconstructions to PV blended images improved diagnostic performance and agreement for bowel ischemia on abdominal CT, with comparable effects on DECT and PCCT. Clinical relevance Spectral reconstructions from a single PV acquisition may improve emergency abdominal CT interpretation for bowel ischemia without additional acquisitions or radiation.