Inpyeong Hwang MD, Abstract Co-Author: Nothing to Disclose

Jeong Yeon Cho MD, Abstract Co-Author: Nothing to Disclose

Myoung Seok Lee MD, Presenter: Nothing to Disclose

Sang Youn Kim MD, Abstract Co-Author: Nothing to Disclose

Seung Hyup Kim MD, Abstract Co-Author: Nothing to Disclose

The aim of the present study was to investigate the image quality and feasibility of CT urography with low iodine concentration (240 mg/mL) contrast media and low (80 kVp) tube voltage with iterative reconstruction algorithm.

This prospective study enrolled 63 patients who underwent CT urography. The subjects were randomized into two arm of excretory phase CT urography protocol; 480 seconds after intravenous injection of 1.5 mL/kg of ioversol with concentration of 240 mg/mL (low-concentration protocol, n = 29) or 350 mg/mL (conventional protocol, n = 26). In low-concentration protocol, tube voltage was reduced to 80 kVp (120 kVp in conventional protocol) to increase attenuation vale, and iterative reconstruction algorithm were used to reduce the noise. Two genitourinary radiologists were qualitatively evaluated images with 5-point scale for overall diagnostic acceptability. Mean attenuation, signal to noise ratio (SNR), contrast to noise ratio (CNR) and figure of merit (FOM = CNR2 / effective dose) were measured at urinary tract. Mean image noise were measured at background tissue. Mann Whitney U test were used to compare quantitatively measured values and qualitative rated scores.

In terms of radiation dose, low-concentration protocol showed significantly lower effective dose (3.4 vs. 5.7 mSv, P < .001). Subjective diagnostic acceptability was significantly lower in low-concentration group (4.1 ± 0.5 vs. 4.5 ± 0.4, P < .001). However, all subjects showed more than standard diagnostic acceptability (score ≥ 3) in each group. Mean image noise showed no significant difference (15.0 vs. 14.3, respectively, P = .243). SNR, CNR and FOM were significantly higher at all segments of urinary tract in low-concentration protocol (P = .004 for CNR of left lower ureter, P = .005 for CNR of urinary bladder, P < .001 for all other values).

Image quality of CT urography with 240 mgI/mL iodine content contrast media, 80 kVp tube voltage and iterative reconstruction algorithm were lower than conventional protocol. However, it showed higher CNR and FOM, and its diagnostic acceptability were still maintained above standard quality. Therefore it can be performed for clinical use to reduce total amount of iodine and radiation dose.

Considering risk of contrast-induced nephropathy and radiation, low iodine content contrast media with low tube voltage CT urography might be beneficial.

Hwang, I, Cho, J, Lee, M, Kim, S, Kim, S, Low Iodine Content Contrast Media with Low Tube Voltage Technique in MDCT Urography: Initial Experience in Single Center.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007719.html