Optimization of Split-Bolus CT Urography: Effect of Differences in Allocation of Contrast Medium and Prolongation of Imaging Delay

Abstract

A split-bolus CTU protocol with a larger CM volume administered at the second injection and an 8-minute imaging delay was the optimal protocol with regard to opacification of the ureter, renal parenchymal enhancement, and shorter examination time.

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

“…Ureter diameters were not significantly different among the tested CTU protocols. This result is compatible with that of a human study [ 13 ], in which the maximal diameter of the ureter did not differ significantly according to the different contrast medium allocation ratios, such as 70% and 30% of total dose as the first bolus, when the maximal diameter of the ureter was measured in each segment when using a split-bolus CTU protocol. However, in another human study, ureteral distention was significantly different when using 150 and 75 mL of contrast medium; in that study, ureteral diameters were measured at predefined locations [ 14 ].…”

“…In synchronous nephrographic-excretory-phase images, enhancement of the renal parenchyma and distention and opacification of the renal collecting system are affected by the contrast medium bolus allocation ratio [ 13 ]. Many different protocols for split-bolus contrast medium injection have been reported; for example, a smaller first injection of 30–50 mL of contrast medium followed by a larger second injection of 80–100 mL of contrast medium, or a 75–100 mL injection followed by a 40–50 mL injection were reported in a previous review article in human medicine [ 4 ].…”

“…Many different protocols for split-bolus contrast medium injection have been reported; for example, a smaller first injection of 30–50 mL of contrast medium followed by a larger second injection of 80–100 mL of contrast medium, or a 75–100 mL injection followed by a 40–50 mL injection were reported in a previous review article in human medicine [ 4 ]. In a recent study into allocation ratios of split-bolus CTU, provision of a larger first injection and a smaller second injection resulted in low renal parenchyma enhancement, which was insufficient for assessment of the urinary system [ 13 ]. Thus, after modifying the human study, the allocation ratios for split-bolus CTU in this study were assessed as a 30:70 ratio in split CTU 1 and a 50:50 ratio in split CTU 2 protocols, by modifying the human study.…”

“…In split-bolus CTU, the allocation ratio of the two portions of the contrast medium dose can affect CTU image quality; however, there is no consensus on the optimal ratio of the 2 contrast medium portions, even in human medicine [ 13 ].…”

Comparison between CT UROGRAPHY and MR UROGRAPHY in cases of Hematuria

“…This agreed with the results of Peter et al (34) who were able to diagnose many renal, ureteral, and bladder abnormalities using MDCT. To date, magnetic resonance (MR) urography has been used in patients with urinary tract dilation or urinary obstruction who either cannot receive iodinated contrast material or in whom imaging using ionizing radiation is undesirable (35,36) . As such, the patient populations in which this modality has been most widely used include children and pregnant patients (17) .…”