SPIRAL CT IN THE EVALUATION OF FLANK PAIN - OVERALL ACCURACY AND FEATURE ANALYSIS

Purpose: Our goal was to assess test reliability and identify those fe atures that have the strongest positive and negative predictive values in the diagnosis of renal colic using spiral CT. Method: Fifty non-co ntrast-enhanced CT scans (5 mm slice thickness) obtained in patients p resenting with flank pain were reviewed by three radiologists blinded to the final diagnoses. The sensitivity, specificity, and positive and negative predictive values for nine pertinent findings were determine d as compared to clinical follow-up. Results: Twenty-nine cases had fi ndings of ureteral obstruction. Findings with the strongest positive p redictive values (>0.90) were ureteral stone, hydronephrosis, hydroure ter, periureteral stranding, and ureterovesical junction edema. Findin gs with the strongest negative predictive values (>0.89) were absence of hydronephrosis and hydroureter. The areas under the receiver operat ing curves for Readers 1, 2, and 3 were 0.970 +/- 0.030, 0.942 +/- 0.0 36, and 0.982 +/- 0.020. Conclusion: Absence of hydroureter and hydron ephrosis on spiral CT images should prompt a search for a diagnosis ot her than an obstructing ureteral stone.