Improved pelvicalyceal visualization with multidetector computed tomography urography; comparison with helical computed tomography

Abstract

Our aim was to compare the quality of pelvicalyceal visualization on computed tomography (CT) urography using a small intravenous contrast material dose, hydration, and high-resolution multidetector CT (MDCT) with that of conventional helical CT. The test (MDCT) group (49 consecutive patients, 98 kidneys) was scanned 5 min following an intravenous bolus of 30 ml of iodinated contrast material. The control (helical CT) group (50 consecutive patients, 95 kidneys) was scanned 5 min following injection of 120-150 ml of intravenous contrast material. Enhancement and quality of calyceal detail were measured using a five-scale grading system (1 for no detail, 5 for cupped calyces). Calyceal attenuation was substantial in both groups (more than 220 Hounsfield units, HU) but less in the test group compared with the control group (mean 475 and 920 HU, respectively), p<0.0001. In the test group, the calyceal attenuation was less than 500 HU in the majority of cases (65/98 kidneys), while the opposite was true for the control group, where calyceal attenuation was more than 750 HU in 50/95 kidneys (p<0.001). The quality of calyceal detail was 3.4/5 in the test group compared with 1.8/5 in the control group (p<0.0001). The combination of hydration, low-contrast dose, and the high image resolution achieved with MDCT significantly improves calyceal visualization in CT urography.

Multi-Detector row CT urography on a 16-row CT scanner in the evaluation of urothelial tumors

“…With the use of 4-detector or 8-detector row CT scanners, CT urography demonstrated satisfactory results compared with IVU in the evaluation of abnormalities involving the urothelium [10][11][12][13]. Raptopoulos et al showed a significantly improved visualization of pelvicaliceal details with MDCTU [14]. However, the sensitivity of MDCTU in the detection of uroepithelial malignancies, especially tumors of small size need to be further evaluated [15].…”

Understanding multislice CT urography techniques: many roads lead to Rome

“…Artefacts from concentrated iodinated contrast material inside the calices and papillae may degrade the visibility of caliceal details [3,5,35]. Raptopoulos et al demonstrated that improvement of caliceal delineation is achieved by using wide windowsettings, supplemental hydration, and a contrast agent bolus of only 30 ml [35].…”

“…250 ml of saline is an empirically selected dose, which is clinically practical but unproven scientifically. Those investigators, who preferred oral supplementation of water, had administered 750 to 1000 ml within 20 min prior to scanning [18] or a volume of "six cups" during 60 minutes before scanning [35].…”

“…Axial images, reconstructed with a thickness of 5 mm, are for the most part sufficient for diagnosis and MPR images used for display [23]. Many authors recommend wide window settings for the evaluation of the urothelium and caliceal details on excretory-phase images, because artefacts from dense endoluminal contrast material are less disturbing [3,6,19,24,35].…”

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

“…Several investigators used similar regimes describing that 20 min prior to scanning patients ingested up to 1l of tap water [16][17][18] or "six cups" of water during 60 min before scanning. [19] Saline infusion might be used as an alternative. [6,20,21] However, some studies showed no particular benefit for saline injection or administration of oral water.…”