Back to Program


Computed tomogrpahy using adaptive statistical iterative reconstruction lowers radiation dose without compromising diagnostic accuracy
Brian H. Eisner, MD, Avinash Kambadakone, MD, Dushyant V. Sahani, MD.
Massachusetts General Hospital, Boston, MA, USA.

BACKGROUND: Multidetector computed tomography (MDCT) is the gold standard for evaluation of urolithiathisis at many institutions. However, recent studies have demonstrated that patients with stone disease may undergo several CT studies per year and that the cumulative ionizing radiation dose for these patients may increase the risk of secondary malignancy. We undertook this study to compare MDCT performed using a novel reconstruction algorithm (Adaptive Statistical Iterative Reconstruction or ASIR) with MDCT performed with standard Filtered Back Projection (FBP) reconstruction.
METHODS: In this ongoing IRB approved prospective study, 30 patients (Age range 20-63yrs, 20M: 10F) underwent low dose MDCT reconstructed with ASIR technique for evaluation of urolithiasis on a 64 MDCT (Discovery CT750 HDCT, GE Healthcare). In 15/30 patients previous standard MDCT studies reconstructed with filtered back projection (FBP) were reviewed for comparison. The low dose scan protocol included 120kVp, automated tube current modulation (ATCM) with noise index (NI, 20-30) and ASIR (range 20-60) while the standard protocol was 120kVp, ATCM with NI-20. Two blinded readers assessed the CT scans for image quality (IQ, 1-5 scale), image noise (N, 1-5 scale), stone detection, stone size and features of obstruction in ureteric calculi. Radiation dose (CTDI, DLP and effective dose) was recorded.
RESULTS: For the total 123 stones (mean diameter = 7mm, range 1.5 - 42mm) detected, MDCT performed with ASIR and MDCT performed with standard FBP had the same diagnostic accuracy (96.7% vs 93.3%, p<0.8). The image quality and image noise were also comparable in the ASIR and FBP group (IQ: 3.9 vs 3.8, N 1.7 vs 2.3, p=0.1). The average radiation dose reduction achieved with ASIR was 49.9% (range = 23-81%) compared to FBP technique (ASIR: 5 ± 1.69mSv, FBP: 10.1 ± 3.8mSv, p=0.01).
CONCLUSIONS: MDCT with ASIR has comparable diagnostic accuracy to standard MDCT with a significant reduction in ionizing radiation delivered to the patient. This technology has the potential to provide improvements in the care of stone patients by reducing exposure to radiation and the theoretical increased risk of radiation-induced malignancy.


Back to Program