Influence of bladder distension on opacification of urinary collecting system during CT urography

Abstract

The purpose of the study was to evaluate and compare opacification of the renal collecting system and ureters detected by computed tomographic urography (CTU) performed 20 min and 1 h after the ingestion of 1,000 ml of water. CTU was performed on 89 patients (55 men, 34 women; age 28-77 years) and 168 collecting systems and ureters were evaluated. A 16-detector-row scanner (Sensation 16, Siemens) was used; a two-phase protocol with a split bolus of contrast agent (total 120 ml) was applied. A combined nephrographic-excretory phase was obtained 100 s after the second injection. Three-dimensional reconstructions of the excretory phase were created and used to evaluate the degree of opacification of the collecting system and ureters. In 44 patients, water was administered 20 min before examination, and in 45 patients, 1 h before examination. CTU performed 1 h after water ingestion demonstrated complete opacification of calices in 87.5%, of renal pelvis in 97.5%, of upper ureter in 91.8% and of lower ureter in 87.5% of patients. CTU performed 20 min after water ingestion demonstrated complete opacification of calices in 79.5%, of renal pelvis in 85%, of upper ureter in 62.5% and of lower ureter in 54.5% of patients. Complete opacification of the proximal and distal ureter in the group with a 1-h delay was statistically higher (P<0.01). CTU performed on the distended bladder, 1 h after the oral ingestion of water, enables excellent opacification of collecting system, including distal ureters.

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

“…A previous review article [5] pointed out the existence of many different protocols for split-bolus CM injection: either a smaller first injection (30-50 mL) of CM followed by a larger second injection (80-100 mL) [10,12,17,18,[20][21][22][23][24][25][26] or a larger first injection (75-100 mL) followed by a smaller second Note-The imaging delay time means the time delay between start of the first contrast medium (CM) bolus administration and the start of scanning for synchronous nephrographic-excretory phase imaging. Group A received 30% of CM as the first bolus and 70% of CM as the second bolus; group B, 70% and 30%; and group C, 50% and 50%.…”

“…Opacification of the whole ureter depends on this time interval between injections. Some studies set this time interval to be as short as 2-5 minutes [17,19,20], whereas others extend it to 10-12 minutes [10,12,13,22,24,27,28]. A study found that delaying imaging of the excretory phase from 300 to 450 seconds significantly increased distention of the intrarenal collecting system and proximal ureter [2].…”

“…However, despite many efforts to optimize the split-bolus protocol, there is still no consensus about the optimal ratio of CM given in the two separate CM bolus administrations and the optimal imaging delay for synchronous nephrographic-excretory phase imaging after administration of the first CM bolus [5]. Some institutions use a smaller volume of CM first [10,12,17,18,[20][21][22][23][24][25][26], whereas others use a larger volume first [11,13,27]. The time interval between the two CM administrations also differs in many centers, from as short as 2 minutes to as long as 15 minutes [10][11][12][13][17][18][19][20][21][22][23][24][25][26][27][28].…”

MDCT Urography With High-Volume Low-Concentration IV Contrast Material, Peroral Hydration, IV Furosemide, and IV Saline: Qualitative and Quantitative Assessment in 100 Consecutive Patients

“…Although the 7-minute delay used for urographic phase acquisition was determined largely on the basis of institutional experience and workflow efficiency, Kemper et al [17] experimentally validated precisely 7 minutes as the median urographic phase delay required for maximal distal ureteral opacification. In addition, the 60-minute delay we apply between initiating peroral hydration and image acquisition is supported by the work of Ćurić et al [18], who showed improved ureteral opacifi-cation in patients who ingested 1000 mL of water 60 minutes before scanning, compared with those who ingested water 20 minutes before scanning. We do not use compression devices or longer urographic phase delays, because their application has not proven sufficiently beneficial for their cost and time [19,20].…”

CT-Urography: Comparison of different methods for increasing the intra-abdominal pressure

“…10 min after the first IV injection of contrast medium, the third scan was obtained, as a longer time delay has been described as preferable regarding distension and opacification of the distal urinary tract. [6,14] Patients were placed randomly into one of the three maneuver groups. After the split-bolus CT (scan 2) we could demonstrate that no significant difference exists among the groups regarding distention and opacification.…”