Lo-Yeh Lee MD, Presenter: Nothing to Disclose

Chiao-Yun Chen, Abstract Co-Author: Nothing to Disclose

Gin Chung Liu MD, Abstract Co-Author: Nothing to Disclose

Twei-Shiun Jaw MD, Abstract Co-Author: Nothing to Disclose

Jui-Sheng Hsu MD, PhD, Abstract Co-Author: Nothing to Disclose

Ming-Lai Dorothy Lai, Abstract Co-Author: Nothing to Disclose

Ming-Chen Paul Shih MD, Abstract Co-Author: Nothing to Disclose

To evaluate the image quality of a second-generation dual-source dual-energy computed tomography(DECT) scanner using the split-bolus portal venous phase CT urography protocol and the potential radiation dose reduction by eliminating the need for a nonenhanced scan.

Our institutional review board approved this retrospective study and waived informed consent. DECT urography was performed in 84 patients. Non-enhanced CT scan was performed 20 minutes after drinking of 800mL water. The split-bolus protocol consisted of a sequence of injections(200mL of normal saline [2.0mL/s], 50mL of contrast medium[2.5mL/s] at 0 second, and 70mL of contrast medium[2.5mL/sec] at 420 second) and a saline flush of 25mL thereafter. Scan started at 480 second. Virtual nonenhanced(VNE) images were reconstructed from enhanced DECT scans. The mean CT density and signal-to-noise ratio(SNR) of the upper urinary tract, renal parenchyma, vessels, renal/urothelial tumors, normal reference tissues, and image noise were measured. Image quality was rated by two radiologists.

Opacification of the intrarenal collecting system, proximal, middle, and distal ureters, and bladder was complete in 92.9%, 83.9%, 78.6%, 77.4%, and 26.2% of patients, respectively. Image quality of the renal parenchyma, arteries, and veins was excellent in 59.5%, 75%, and 97.6% of cases. The mean CT density of renal/urothelial tumors(n=16) was 90.9HU±6 in enhanced images, 31.7HU±2 in true nonenhanced(TNE) and 36.3HU±2 in VNE images. The SNR of all measured lesions except renal pelvis showed significant correlation(p<.01) between the TNE and VNE images. The overall sensitivity of stone detection was 87.5%(28 of 32; 95% CI: 70.4%, 95.4%) in VNE images. If the TNE would be omitted, the dose of this protocol could reduce from 15.6mSv to 6.7mSv.

Our single portal venous phase split-bolus protocol provides sufficient opacification of upper urinary tract collecting system, good enhancement of vessels, renal/urothelial tumors and potential to reduce radiation exposure.

Our split-bolus portal venous phase DECT urography protocol is timed to acquire good corticomedullary-nephrographic-excretory phase and vascular/tumor enhancement data and provide sufficient opacification of the collecting system. The “all-in-one’’ protocol has the inherent advantage of omitting the non-contrast scan, thus reducing the radiation dose.

Lee, L, Chen, C, Liu, G, Jaw, T, Hsu, J, Lai, M, Shih, M, Split-bolus Portal Venous Phase Dual-Energy Computed Tomography Urography: Protocol Design, Image Quality and Dose Reduction.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045720.html