Comparison of ureteric stone size, on bone window versus standard soft-tissue window settings, on multi-detector non-contrast computed tomography

Abstract

ObjectiveTo compare the difference in mean stone size, as measured on bone window vs standard soft-tissue window setting using multi-detector computed tomography (MDCT) in patients with a solitary ureteric stone. Patients and methodsIn all, 60 patients presenting to the emergency and outpatient departments of a University Hospital from May 2015 to October 2015 and fulfilling the inclusion criteria were included in the study. A 64-slice MDCT was used to assess the locations and size of the ureteric stones. A consultant radiologist independently analysed the MDCT scans of all the patients. The mean difference in stone size was calculated between both window settings in axial and coronal planes. ResultsThe mean (SD) age of the patients was 37.13 (11.9)years. Males constituted ∼68% of the cohort and 32% were female. In all, 85% of the patients had left ureteric stones and 15% had right ureteric stones. The mean (SD) stone size, as measured on the soft-tissue window setting was 6.68 (2.01)mm, and on the bone window setting was 4.8 (1.9)mm. The mean (SD) difference in stone size between the two window settings was +1.85 (0.55)mm. The two means were compared using Student’s t-test, and the difference was found to be statistically significant (P<0.05). ConclusionThe stone size measured using the soft-tissue window setting on a MDCT is significantly different from the measurement on the bone window setting.