Diagnostic performance of advanced modeled iterative reconstruction applied images for detecting urinary stones on submillisievert low-dose computed tomography

Background: Repeated computed tomography (CT) scans may be an issue in young adults with urinary stones. Therefore, it is important to know how far the dose can be reduced while maintaining the diagnostic performance. Purpose: To generate a hypothesis that it is feasible to decrease the radiation dose to a sub-millisievert (mSv) level with the addition of advanced modeled iterative reconstruction (ADMIRE) while maintaining the sensitivity to standard-dose CT (SDCT) for the detection of urinary stones. Material and Methods: Ninety-two consecutive patients with urinary stones underwent non-enhanced CT that consisted of standard (120 kVp, 200 mAs) and lose-dose (LDCT) (80 kVp, 60 mAs). The LDCT images were reconstructed separately with five different strengths of ADMIRE (hereafter, S1-S5) and filtered back projection (FBP). Two blinded radiologists independently recorded a number of urinary stones in the six LDCT datasets and SDCT. The sensitivity of each set for detecting urinary stones was compared using the McNemar test. Results: A total of 240 urinary stones were analyzed. The sensitivities of the six LDCT datasets showed no difference (FBP, S1-S5, for reader 1: 78%, 79%, 79%, 80%, 80%, and 80%; for reader 2: 64%, 63%, 64%, 64%, 65%, and 66%, P > 0.05, respectively), which were lower than those of SDCT for both readers (reader 1: 88%; reader 2: 81%, P < 0.0001, respectively). Conclusion: Despite the addition of ADMIRE, it may not be feasible to decrease the radiation dose to a sub-mSv level while maintaining the sensitivity to SDCT for the detection of urinary stones.