A Comparison Between Injection Speed and Iodine Delivery Rate in Contrast-Enhanced Computed Tomography (CT) for Normal Beagles

Abstract

ABSTRACT. The purpose of this study was to compare between the injection speed and iodine delivery rate in order to establish a concept for reproducible contrast timing in contrast-enhanced computed tomography (CT) for small animals. Clinically healthy beagle dogs were administered a nonionic iodinate contrast medium at a dose of 800 mgI/kg; they were divided into 3 groups (n=5, crossover method): in one group, the injection speed was fixed at 1.0 ml/sec, and in the second and third groups, the iodine delivery rate was fixed (the injection durations were 30 and 60 sec, respectively). The variation in scatter of the time to aortic and hepatic peak enhancement in the fixed iodine delivery groups was lower than that in the fixed injection speed group. These results suggest that in contrast-enhanced CT for small animals, the contrast medium should be injected at a fixed iodine delivery rate in order to provide reproducible contrast timing. KEY WORDS: canine, contrast medium, CT, injection speed, iodine delivery rate.J. Vet. Med. Sci. 70(10): 1027-1030, 2008 Computed tomography (CT) was first introduced in veterinary medicine in the 1980s [3]. The performance of CT improved thereafter, with a shorter scan time and better imaging quality, and CT is now one of the most valuable diagnostic tools, especially for oncological diseases [7]. In abdominal CT, contrast examination is quite important, since it differentiates between abnormal masses and normal tissue by indicating blood flow or vascular permeability, thereby providing diagnostic information. In human medicine, contrast studies with abdominal CT are considered useful in more than 95% cases for the diagnosis of mass lesions [6].The iodine concentration decreases soon after injection of intravenous contrast medium, because it is diluted in the vessels, distributed in the entire body, and excreted from the kidneys. Thus, the contrast effect is influenced by the time of scanning in that an optimal scan timing provides the greatest contrast enhancement. While a detailed contrastenhanced CT protocol is well established in human medicine, there are very few standards for the contrast enhancement protocol in small animals. The injection speed (in terms of ml/sec) is often standardized, but the iodine delivery rate is rarely set. Different volumes of contrast medium may alter the injection duration, and it may be difficult to set an appropriate scan timing. This study focused on the injection speed and iodine delivery rate in the case of normal beagles in order to establish a concept for reproducible contrast timing in contrast-enhanced CT for small animals. MATERIALS AND METHODSFive clinically healthy beagle dogs (3-5 years old, 8.9-15.4 kg) were used in a crossover method, and the experiments were performed following the guidelines of the institutional policies for veterinary clinical investigations. The animals were starved for 12 hr before the CT study. A physical examination was conducted, and the complete blood count and serum chemistry profile (blood urea nitrogen,...

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

“…The results of this study showed that the CT images of the portal phase and hepatic parenchymal phase are influenced to a relatively lesser degree by injection duration in the multi-phase CT scan. However, a longer injection duration of 30 and 60 sec resulted in differences in the hepatic parenchymal enhancement peak in a veterinary study [30]. In previous veterinary literature, although the start of the portal phase cannot always be set at the PVP by the inter-scan reset, it has been reported that the variation does not affect scan quality [32].…”

“…Among these, the injection duration of the contrast material is a major injection-related factor influencing contrast enhancement timing in CT [230]. In veterinary literature, arrival times to the aortic enhancement peak (AEP) and hepatic parenchymal peak (HPP) following 30 and 60 sec injection durations of contrast material have been reported [30]. In addition, the optimal diagnostic scan delay of the arterial and pancreatic parenchymal phases was recently investigated using a fixed injection rate of contrast material [10].…”

Computed tomography of the prostate gland in apparently healthy entire dogs

“…Following the non‐contrast CT study, contrast material was administered in 24 dogs, 800 mgI/kg iohexol (Omnipaque, Daiichi Sankyo, Japan) injected using an autoinjector (Autoenhance A‐60, Nemoto Kyorindo, Tokyo, Japan). Postcontrast CT was performed with the same slice thickness and body regions as for the non‐contrast CT scan, 1 minute after starting of the administration of the contrast material (Tateishi and others 2008).…”

Effect of a saline chaser for contrast enhancement of computed tomographic angiography in cattle

“…The mean MEV in the maxillary artery was 244.45 HU with the saline chaser, and 202.29 HU without the saline chaser. In previous studies, the range of contrast attenuation values in dogs where a saline chaser was not used was 292 to 387 HU in the aorta (Kishimoto and others 2008, Tateishi and others 2008). Despite the relatively low blood volume per body weight of cows compared with dogs (Swenson 1993), the contrast enhancement effect in cows is lower than in dogs.…”