Ulrike L. Mueller-Lisse MD, Presenter: Nothing to Disclose

Thomas Michael Meindl MD, Abstract Co-Author: Nothing to Disclose

Eva Coppenrath MD, Abstract Co-Author: Nothing to Disclose

Maximilian F. Reiser MD, Abstract Co-Author: Nothing to Disclose

Christian Stief MD, Abstract Co-Author: Nothing to Disclose

Ullrich G. Mueller-Lisse, Abstract Co-Author: Nothing to Disclose

In patients with pelvic or retroperitoneal tumors, CT urography (CTU) may replace excretory urography for the delineation of the upper urinary tract (UUT) prior to treatment. However, radiation exposure is a concern. We retrospectively compared UUT delineation in standard and low-dose CTU.

CTU (excretory phase) images were obtained with 120 KV, 4x2.5 mm collimation, and pitch 0.875, after i.v. injection of 120 ml of non-ionic contrast media with 300 mg of iodine/ml with standard (January through March, 14 patients, n=116 UUT segments, 175 mAs/slice, average delay 16.8 minutes) or low-dose (April through September, 26 patients, n=344 UUT segments, 29 mAs/slice, average delay 19.6 minutes) protocols. UUT segments included intrarenal collecting system (IRCS), upper, middle, and lower ureter (UU,MU,LU). Two independent readers (R1,R2) graded UUT segment delineation as 1-absent, 2-partial, 3-complete (noisy margins), 4-complete and clear. Chi-square statistics were calculated for grades 1-2 vs. 3-4 (delineates UUT and may locate obstruction/dilation) and 1-3 vs. 4 (may locate intraluminal lesions).

Delineation of UUT was equally good for all segments in standard and low-dose CTU (R1, chi-square=0.0036-1.74, p>0.15; R2, chi-square=0.074-1.308, p>0.2). Grade-4-delineation was equal between standard and low-dose protocols for IRCS, UU, and MU (R1, chi-square=0.074-1.013, p>0.25; R2, chi-square=0.919-2.159, p>0.1). However, LU was more often completely and clearly delineated in standard protocols (R1, 18/24 standard, 38/69 low-dose, chi-square=2.178, p>0.1; R2 18/24 standard, 21/69 low-dose, chi-square=12.75, p<0.05).

Low-dose CTU appears sufficient to delineate UUT and perhaps locate obstruction/dilation, but unsuited to locate intraluminal LU lesions.

Option to decrease dose in excretory phase CT of the abdomen

Mueller-Lisse, U, Meindl, T, Coppenrath, E, Reiser, M, Stief, C, Mueller-Lisse, U, Retrospective Comparison of Delineation of Upper Urinary Tract Segments at Multidetector Row CT Urography between Standard and Low-Dose Protocols.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8015792.html