title: Comparison of ureteric stone size, on bone window versus standard soft-tissue window settings, on multi-detector non-contrast computed tomography.
abstract: OBJECTIVE
  To 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.
  
  
  METHODS
  In 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.
  
  
  RESULTS
  The 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).
  
  
  CONCLUSIONS
  The stone size measured using the soft-tissue window setting on a MDCT is significantly different from the measurement on the bone window setting.
authors.affiliation: Section of Urology, Department of Surgery, Aga Khan University, Karachi, Pakistan.
authors.forename: Hussam Uddin
authors.initials: HU
authors.lastname: Soomro
authors.affiliation: Section of Urology, Department of Surgery, Aga Khan University, Karachi, Pakistan.
authors.forename: M
authors.initials: M
authors.lastname: Hammad Ather
authors.affiliation: Department of Radiology, Aga Khan University, Karachi, Pakistan.
authors.forename: Basit
authors.initials: B
authors.lastname: Salam
keywords: Bone window setting; CT KUB, non-contrast enhanced CT of the kidney, ureter and bladder; Computed tomography; MDCT, multi-detector CT; MET, medical expulsive therapy; Soft-tissue window setting; US, ultrasonography; Urinary calculi