Optimal Scan Delay for Computed Tomographic Evaluation of the Canine Pancreas Using a Fixed Injection Duration Technique

Various pancreatic diseases can focus, multifocally, or diffusely affect the pancreatic parenchyma and regional vasculature; therefore, consistent computed tomographic (CT) evaluation of the pancreas is invaluable for disease detection. Alterations to pancreatic attenuation and contrast enhancement can indicate specific pathology and provide prognostic information. Establishing enhancement patterns of the normal canine pancreas with CT is thus key to optimizing its evaluation. The objective of this mixed retrospective and prospective analytical study was to determine the optimal CT scan delay for assessment of the pancreas based on the detection of peak contrast enhancement of the pancreatic parenchyma, the aorta, and the portal vein when using a fixed injection duration and bolus tracking technique. Sixty-nine canine patients had Iohexol administered intravenously over a fixed injection duration of 20 s (s). Bolus tracking was employed to detect aortic contrast arrival, and diagnostic scans were acquired after a post-aortic arrival scan delay. Post-contrast CT studies were categorized according to the post-aortic arrival scan delay: 5 s (n = 16), 10 s (n = 18), 15 s (n = 22), 20 s (n = 10), 25 s (n = 6), 30 s (n = 13), 35 s (n = 17), 40 s (n = 23), and 180 s (n = 58). Statistical modeling showed that the arterial, pancreatic, and portovenous phases occurred sequentially after contrast arrival in the abdominal aorta-at 5-10, 15-20, and 20-35 s scan delays, respectively-corresponding to peak enhancement of the arteries, pancreatic parenchyma, and portal vein.