Joonho Hur, Presenter: Nothing to Disclose

Sung Bin Park MD, Abstract Co-Author: Nothing to Disclose

Jong Kyou Kwon, Abstract Co-Author: Nothing to Disclose

Jong Beum Lee, Abstract Co-Author: Nothing to Disclose

Hyun Jeong Park, Abstract Co-Author: Nothing to Disclose

Yang Soo Kim MD, Abstract Co-Author: Nothing to Disclose

The purpose of this study was to evaluate the efficacy of iterative reconstruction (IR) technique for reducing image noises in low-dose non-enhanced CT (LDCT) and the diagnostic performance of LDCT-IR for urolithiasis.

116 patients diagnosed with urinary stones (n=197) using both a standard dose non-enhanced CT using filtered-back projection (SDCT-FBP, 120 kV and 150 mAs) and a low dose non-enhanced CT using hybrid IR (LDCT-IR, iDOSE4 level 5, 100 kV and 60 mAs) were enrolled in the study. Interpretations of the two scans were performed prospectively with respect to stone characteristics (size, volume, location, Hounsfield unit (HU), skin-to-stone distance (SSD)), radiation dose, objective image noise, and subjective image assessment. With SDCT-FBP as the reference standard, diagnostic performance and inter-observer agreement of LDCT-IR for urinary stones according to the stone size; all sizes, ≥ 3 mm, and <3 mm were assessed between one urologist and one radiologist.

No statistically significant differences were found in stone characteristics between the two scans. The average effective radiation dose of SDCT and LDCT was 5.92 mSv, and 1.39 mSv, respectively, and the average radiation dose reduction rate was 76.6% (p<0.001). Objective image noise was higher in LDCT-IR (p<0.01), but there were no significant differences in subjective image assessment between the two scans. The sensitivity and specificity of LDCT-IR were 99.1% to 100.0% with a diagnostic accuracy of 99.1% to 99.6% for diagnosing stones ≥3 mm. All statistical parameters for diagnostic accuracy were similar between the urologist and radiologist (p>0.05, respectively). Inter-observer agreement of LDCT-IR between the two reviewers in the diagnosis of stones was high with kappa values ranging from 0.901 to 1.000 in all three groups.  

LDCT-IR provided a significant reduction in radiation dose while maintaining the image quality comparable to that of SDCT-FBP, thus making it an attractive option for the urologist as well as radiologist for diagnosing urinary stones.

Patients with urolithiasis can be evaluated with low dose non-enhanced CT using hybrid iterative reconstruction at a substantially reduced radiation dose by urologist as well as radiologist, thereby minimizing risks to patient from radiation exposure while providing the diagnostic benefits of low dose non-enhanced CT using iterative reconstruction.

Hur, J, Park, S, Kwon, J, Lee, J, Park, H, Kim, Y, Usefulness of Low-dose Non-enhanced CT with Hybrid Iterative Reconstruction for Evaluation of Urolithiasis: Diagnostic Performance and Agreement between the Urologist and the Radiologist.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045572.html