Prospective Comparison of Unenhanced Spiral Computed Tomography with Intravenous Urography and Combination of CT Scout with Ultrasound in the Evaluation of Acute Renal Colic

Objective: 1) Prospective comparison of unenhanced spiral computed tomography (NCCT) with Intravenous Urography (IVU) and Combination of CT scout with Ultrasound (CT+US) in the Evaluation of acute renal colic. 2) To formulate a model for predicting the probability of the presence of ureterolithiasis while simultaneously assessing the effects of Body Mass Index (BMI), Size of calculi, Hydronephrosis and Imaging appearance of calculi in ureterolithiasis diagnosis. Subjects & Procedure: After giving informed consent, 100 adult patients with acute renal colic suspected of having urolithiasis underwent NCCT, IVU & CT+US. The diagnosis of ureterolithiasis was confirmed during follow-up either from direct stone recovery or urological interventions. Observations were made by two radiologists independently, unaware of the findings, in consensus reviewed and interpreted all images to determine the presence or absence of ureteral calculi. Sensitivity, specificity and positive predictive values for detecting ureteral calculi were determined and the effects of above mentioned factors were analyzed with Multivariate logistic regression model. Results: Per-patient sensitivity, specificity, positive predictive value, negative predictive value and accuracy for detecting ureteral calculi with NCCT (100% [80/80], 90% [18/20], 97.5% [80/82], 100% [18/18] and 98% [98/100] respectively) were significantly greater than those for IVU (97.2% [70/72], 57.1% [16/28], 85.3% [70/82], 88.8% [16/18] and 86% [86/100]) & combination of CT scout with Ultrasound examinations (92.5% [74/80], 60% [12/20], 90.2% [74/82], 66.6% [12/18] and 86% [86/100]) (p=0.000). Body Mass Index, Size of calculi, Hydronephrosis and Imaging appearance of calculi, were significant univariate predictors in diagnosing ureterolithiasis. Conclusion: NCCT remains the gold standard in initial imaging however its prudent to use a combination of CT scout + US in follow-up imaging due to minimal radiation exposure and significantly reduced cost.