Investigation of Scan Delays for CT Evaluation of Inner Wall Layering and Peak Enhancement of the Canine Stomach and Small Intestine Using a 20 Second Fixed-injection-duration and Bolus Tracking Technique

Many gastrointestinal diseases affect the mucosal layer, suggesting that on computed tomography (CT) examination, detection of consistent inner wall layering of the gastrointestinal tract may aid in detection of disease. Changes in wall enhancement can also characterise specific diseases and provide prognostic information. The objectives of this mixed retrospective and prospective analytical study were therefore to identify the scan delays for peak detection of canine stomach and small intestinal inner wall layering and enhancement when using a 20 s fixed-injection-duration and bolus tracking technique. For each patient, 700 mg I/kg iohexol was administered intravenously. Bolus tracking was used to determine aortic arrival. Diagnostic scans were performed after a post-aortic arrival scan delay. Postcontrast CT series were grouped according to post-aortic arrival scan delay: 5 s (n = 17), 10 s (n = 18), 15 s (n = 23), 20 s (n = 10), 25 s (n = 6), 30 s (n = 14), 35 s (n = 17), 40 s (n = 24), and 180 s (n = 60). The stomach and small intestine were assessed for the presence of a contrast-enhancing inner wall layer and wall enhancement. Statistical modeling showed that the scan delays for peak inner wall layering and enhancement were 10 and 15 s for the small intestine, respectively, and 40 s for the stomach. For the injection protocol used in this study, assessment of the canine gastrointestinal tract may use scan delays of 10-15 s and 40 s.