Bowel Peristalsis Artifact on Dual-Energy CT: In-Vitro Study of the Influence of Different Dual-Energy CT Platforms and Enteric Contrast Agents.

Background: The value of dual-energy CT (DECT) for bowel wall assessment is increasingly recognized. While technical improvements have been shown to reduce peristalsis artifact in conventional CT, the effects of peristalsis on DECT image reconstructions remain poorly studied. Objectives: To evaluate the influence of different DECT scanners and enteric contrast agents on the severity of bowel peristalsis artifact in vitro. Methods: To simulate bowel peristalsis, a 3-cm diameter corrugated hollow "bowel" tube was oscillated constantly in z-axis within a larger water-filled cylinder. The bowel was serially filled with air, water, and iodinated or experimental dark contrast material and scanned on four different DECT platforms (spectral-detector, rapid-kVp-switching, split-filter and dual-source) to reconstruct 120-kVp-like and iodine images. Two readers rated each image reconstruction for artifact severity from 0 (none) to 3 (severe) and recorded the ability of iodine images to reveal bowel wall hyperattenuation on 120-kVp-like images as artifactual. Artifact severity scores were compared using ANOVA with Bonferroni correction. Results: Interrater agreement for artifact scores was excellent, with intraclass correlation coefficient (ICC) of 0.82 [95%-CI: 0.79-0.84]. For 120-kVp-like images, mean peristalsis artifact scores were lower (all p<.001) for split-filter (1.47) and dual-source (1.86) scanners than for spectral-detector (2.58) or rapid-kVp-switching (2.74) scanners. Compared with 120-kVp images, peristalsis artifacts for iodine images were lower for spectral-detector (1.03, p<.001) and rapid-kVp-switching (2.09, p<.001), but more severe for dual-source (2.77, p<.001) and split-filter (2.62, p<.001) systems. Peristalsis artifact was minimized by use of experimental dark bowel contrast (1.79) compared to other bowel contrast agents (all p<.001). Iodine images helped identify bowel wall hyperattenuation as artifactual in 94.6% and 40.7% of reviewed cases for spectral-detector and rapid-kVp-switching scanners, respectively. Conclusions: For spectral-detector and rapid-kVp-switching DECT, iodine images minimize peristalsis artifact, but for dual-source and split-filter DECT, mixed 120-kVp-like images are preferred. Experimental dark bowel contrast material reduces peristalsis artifact compared to iodinated contrast material or water. Clinical impact: Knowledge of the preferred images to reduce peristalsis artifact can lessen the impact of peristalsis on clinical dual-energy CT interpretation. Dark enteric contrast agents, once clinically available, may further reduce the effects of peristalsis.