Role of Computerized Tomography in the Diagnosis of Calcium Oxalate Calculi




Urolithiasis, Calcium oxalate, Computed tomography, Hounsfield units


Background: CT can be used to determine the composition of a stone. Using Hounsfield Units (HU), a CT scan of the abdomen and pelvis may be utilized to diagnose and evaluate renal stones (all types).

Objective: To determine the role of CT in the diagnosis of Calcium oxalate renal calculi on the basis of Hounsfield unit, taking chemical analysis as the gold standard.

Methodology: Study Design: Cross-sectional study. Settings: Department of Radiology, Allied Hospital, Faisalabad. Study duration: 1st July 2020 to 31st December 2020. Sampling: Non-probability consecutive sampling technique. A sum of 200 patients with urinary stones of both genders (Male and Female) with age 15-55 years were incorporated. Hounsfield units were calculated for each stone using in-built software in the CT scan machine. The presence of CT attenuation density of >1200 HU was taken as calcium oxalate stone and ≤1200 HU was taken as non-calcium oxalate stones. Stones of all patients after surgery were shipped off to the pathology research facility for compound investigation.

Results: In CT positive cases, 95 were true positive and 08 were false positive. While in CT negative patients, 90 were true negative and 07 were false negative. Overall sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of CT in separating diverse renal calculi based on the Hounsfield unit, accepting compound investigation as the gold standard was 93.13%, 91.83%, 92.23%, 92.78%, and 92.5% respectively.

Conclusion: This study concluded that the diagnostic accuracy of CT Hounsfield units for the detection of calcium oxalate stones is very high.