Multi-phase Computed Tomography of the Canine Stomach and Small Intestine

Abstract

Objectives: Determine the optimal scan delays for computed tomography (CT) evaluation of the stomach and small intestine using a 20 second fixed-injection-duration and bolus tracking technique, describe the associated contrast enhancement characteristics and describe gastrointestinal wall thickness. Study design: A retrospective cohort study was performed, including contrast-enhanced CT examinations of the abdomen between July 2016 and January 2019. Gastric and small intestinal segments were identified and assessed for the presence of contrast-enhancing wall layering, gastrointestinal content and level of luminal distension, and wall thickness and wall attenuation were measured. Results: 71 multi-phase contrast-enhanced CT examinations were included. One dog received two CT examinations. Each post-contrast series was grouped by scan delay: 5 seconds (s), 10 s, 15 s, 20 s, 25 s, 30 s, 35 s, 40 s and 180 s. Statistical modelling suggested that the optimal scan delay for evaluation of the stomach was 40 s. Ten seconds was the optimal scan delay for small intestinal inner wall layering with mild compromise on wall attenuation. Gastrointestinal wall thickness is dependent on bodyweight (p = 0.00). The gastric wall ranged from 2.12-4.63 mm thick, duodenum 4.82-5.23 mm, jejunum 3.62-4.16 mm and ileum 3.1-3.16. Distended segments were associated with less layering and attenuation, and had thinner walls, than partially distended or collapsed segments. Conclusion and clinical relevance: The 20 second fixed-duration-injection contrast medium administration technique is easily reproducible. Using this technique, a 10 s delay appears best for assessment of the small intestine and 40 s best for the stomach. Presumed normal contrast enhancement characteristics and thickness of the canine stomach and small intestine are described. Future studies can use these scan delays to investigate and describe morphological abnormalities associated with gastrointestinal diseases.