Optimal scan delay depending on contrast material injection duration in abdominal multi-phase computed tomography of pancreas and liver in normal Beagle dogs

Abstract

This study was conducted to establish the values for optimal fixed scan delays and diagnostic scan delays associated with the bolus-tracking technique using various contrast material injection durations in canine abdominal multi-phase computed tomography (CT). This study consisted of two experiments employing the crossover method. In experiment 1, three dynamic scans at the porta hepatis were performed using 5, 10 and 15 sec injection durations. In experiment 2, two CT scans consisting of five multi-phase series with different scan delays of 5 sec intervals for bolus-tracking were performed using 5, 10 and 15 sec injection duration. Mean arrival times to aortic enhancement peak (12.0, 15.6, and 18.6 sec for 5, 10, and 15 sec, respectively) and pancreatic parenchymal peak (17.8, 25.1, and 29.5 sec) differed among injection durations. The maximum mean attenuation values of aortas and pancreases were shown at the scan section with 0 and 5, 0 and 10 and 5 and 10 sec diagnostic scan delays during each injection duration, respectively. The optimal scan delays of the arterial and pancreatic parenchymal phase in multi-phase CT scan using fixed scan delay or bolus-tracking should be determined with consideration of the injection duration.

Vascular conspicuity differs among injection protocols and scanner types for canine multiphasic abdominal computed tomographic angiography

“…The absence of optimal portal timings explains the overall low quality of the portal phase using the bolus‐tracking protocol on 64‐row multidetector CT scanner. Previous publications have established optimal delays using bolus‐tracking technique for the pancreas and liver, although the need for organ‐specific delays is not practical for daily use . Weight is another variable that has to be taken into account for the bolus‐tracking protocol since the time‐to‐arterial peak is influenced by body weight when the injection rate is fixed .…”

“…Multiphasic multidetector computed tomographic angiography is currently a standard diagnostic test for canine vascular disorders such as portosystemic shunts, arteriovenous fistulae, or vascular tumor invasion . This method is also commonly used for characterizing parenchymal disease such as pancreatic insulinoma and may help characterizing benign and malignant lesions . A major advantage of multiphasic multidetector computed tomographic angiography is the ability to separate the arterial from the portal and systemic venous phases in order to reach an optimal visualization of each vascular bed and to identify hypervascular or hypovascular parenchymal lesions …”

“…The bolus‐tracking multidetector computed tomographic angiography protocol uses software tools to monitor the arrival of contrast medium into a vessel and triggers an automatic or manual start of the acquisition once the preset density threshold has been reached. This type of protocol provides an individualized timing of the arterial phase . The fixed‐injection‐duration multidetector computed tomographic angiography protocol is another technique that has been recently described in cats and dogs using a fixed injection duration of 20 s and adjusted injection rate .…”

Triple‐phased mesenteric CT angiography using a test bolus technique for evaluation of the mesenteric vasculature and small intestinal wall contrast enhancement in dogs

“…Mesenteric vessels are observed on conventional CT angiography images scanning for other primary lesions; however, it has limitations in the evaluation of small mesenteric branches and their complex anatomy, particularly in small breed dogs and cats. Moreover, differentiating between small arteries and veins is difficult with standard single‐phase CT. Multi‐phase dynamic CT angiography studies have been performed in dogs, but most of them focused on the cranial abdominal vessels, or specific organs such as the liver, kidney, and pancreas . We hypothesized that triple‐phase CT angiography focusing on the mesenteric vessels and intestines could prove useful for visualizing the mesenteric arteries and veins, as well as for evaluation of intestinal wall enhancement in dogs.…”

Effect of different contrast administration protocols on contrast enhancement and image quality in CT scan

“…Nonetheless, for patients with no underlying cardiovascular disorder, this technique was capable of producing a good quality image and contrast enhancement [7][8][9].…”