Split-bolus CT urography with synchronous nephrographic and excretory phase in dogs: comparison of image quality with three-phase CT urography and optimal allocation ratio of contrast medium

Abstract

Background: Computed tomography urography (CTU), based on the excretion of contrast medium after its injection, allows visualization of the renal parenchyma and the renal collecting system. Objectives: To determine the optimal contrast medium dose allocation ratio to apply in splitbolus CTU in dogs. Methods: This prospective, experimental, exploratory study used 8 beagles. In 3-phase CTU, unenhanced-, nephrographic-, and excretory-phase images were obtained with a single injection of 600 mg iodine/kg iohexol. In split-bolus CTU, two different contrast medium allocation ratios (30% and 70% for split CTU 1; 50% and 50% for split CTU 2) were used. Unenhanced phase image and a synchronous nephrographic-excretory phase image were acquired. Results: Although the attenuation of the renal parenchyma was significantly lower when using both split CTUs than the 3-phase CTU, based on qualitative evaluation, the visualization score of the renal parenchyma of split CTU 1 was as high as that of the 3-phase CTU, whereas the split CTU 2 score was significantly lower than those of the two others. Artifacts were not apparent, regardless of CTU protocol. The diameter and opacification of the ureter in both split CTUs were not significantly different from those using 3-phase CTU. Conclusions: Split-bolus CTU with a contrast medium allocation ratio of 30% and 70% is feasible for evaluating the urinary system and allows sufficient enhancement of the renal parenchyma and appropriate distention and opacification of the ureter, with similar image quality to 3-phase CTU in healthy dogs. Split-bolus CTU has the advantages of reducing radiation exposure and the number of CT images needed for interpretation.

Comparison of sonographic and CT findings for the identification of renal nodules in dogs and cats

“…Diagnostic imaging plays a fundamental role in investigating kidney diseases: ultrasonography (US) is the first approach in clinical practice, however CT is becoming more popular, especially in large dogs and in patients where the sonographic window is suboptimal. Cross‐sectional imaging is less operator‐dependent compared to US, allows examination of all body parts independently from animal size and conformation, enables reviews of the studies to obtain multiplanar reconstructions, and allows optimization of sequence timing with an improved evaluation of the renal parenchyma and the collecting system 12,13 . A diagnostic multimodal approach is preferred in human beings, where CT, MRI, and PET‐CT have shown a higher diagnostic accuracy in demonstrating renal disease compared to US 8,12,13,14 .…”

“…Cross-sectional imaging is less operator-dependent compared to US, allows examination of all body parts independently from animal size and conformation, enables reviews of the studies to obtain multiplanar reconstructions, and allows optimization of sequence timing with an improved evaluation of the renal parenchyma and the collecting system. 12,13 A diagnostic multimodal approach is preferred in human beings, where CT, MRI, and PET-CT have shown a higher diagnostic accuracy in demonstrating renal disease compared to US. 8,12,13,14 In veterinary medicine, a single investigation evaluated different abdominal conditions and CT was superior in lesion detection compared to US in dogs over 25 kg.…”

“…12,13 A diagnostic multimodal approach is preferred in human beings, where CT, MRI, and PET-CT have shown a higher diagnostic accuracy in demonstrating renal disease compared to US. 8,12,13,14 In veterinary medicine, a single investigation evaluated different abdominal conditions and CT was superior in lesion detection compared to US in dogs over 25 kg. However, renal nodules were not included.…”

Split bolus method in computerized tomography

“…In addition, perfusion defects can be demonstrated reliably by performing contrast-enhanced examinations in the transplanted kidney. [ 6 ] The split-bolus technique is especially beneficial for children, young women, and patients with the possibility of benign disease or with chronic symptomatic stone disease, urinary diversions, or risky patients with clinical exposure to radiation [ 7 ] ( Fig. 7 ).…”