Renal colic is a common clinical condition which is often investigated with a CT of the kidneys, ureters and bladder (CTKUB). Recent technological improvements have allowed a reduction in dose with the emergence of low-dose CTKUB (LD-CTKUB) techniques. The present meta-analysis aims to determine the diagnostic accuracy of LD-CTKUB in the diagnosis of clinically significant uroliths. A systematic review was performed using nine electronic databases from their dates of inception to May 2016. Inclusion criteria included studies reporting comparative outcomes using LD-CTKUB with a dose less than 3 millisieverts compared to an imaging gold standard or clinical and surgical evaluation. The primary endpoint was detection of a urolith ≥3 mm where specified and any urolith when size was unspecified. Twelve studies were identified according to selection criteria, involving 1250 patients. LD-CTKUB demonstrated a pooled sensitivity of 93.1% (95%CI 91.5-94.4), specificity of 96.6% (95%CI 95.1-97.7%), positive likelihood ratio of 19.9 (95%CI 12.7-31.2), negative likelihood ratio of 0.05 (95%CI 0.02-0.10) and AUC of 0.9877 in the detection of clinically significant uroliths. Although 86 alternative diagnoses were noted across seven studies, none assessed the accuracy of LD-CTKUB in their detection. The majority of newer studies report an average radiation dose from 1 to 1.5 millisieverts. This study demonstrates a high sensitivity, specificity and positive predictive value in the detection of uroliths, however, its accuracy in the detection of alternative diagnoses is unknown. Therefore, we recommend using LD-CTKUB when the pre-test probability of stone disease is significantly higher than the pre-test probability of alternative diagnoses, such as follow-up of known calculi. We suggest caution when the pre-test probability of alternative diagnoses is high, such as the initial presentation of renal colic.
Journal of medical imaging and radiation oncology. 2017 Jan 31 [Epub ahead of print]
Hao Xiang, Michael Chan, Victoria Brown, Ya Ruth Huo, Lewis Chan, Lloyd Ridley
Department of Radiology, Concord Repatriation General Hospital, Sydney, New South Wales, Australia., Emergency Department, Concord Repatriation General Hospital, Sydney, New South Wales, Australia., Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia., Department of Urology and Institute of Academic Surgery, Concord Repatriation General Hospital, Sydney, New South Wales, Australia.