Virtual cystoscopy of the contrast material-filled bladder in patients with gross hematuria

OBJECTIVE. The objective of this study was to evaluate the usefulness of virtual cystoscopy of the contrast material-filled bladder in evaluating patients with gross hematuria. SUBJECTS AND METHODS. Seventy-three consecutive patients who had gross hematuria and whose upper urinary tracts had a normal appearance on single-detector helical CT scans were prospectively evaluated with virtual cystoscopy. Source CT data for virtual cystoscopy were obtained on a multidetector CT scanner with 1.25-mm slice thickness and transferred to a workstation for interactive navigation using volume rendering. Two radiologists independently interpreted the virtual cystoscopic images, and discrepancies were resolved by consensus. All patients also underwent conventional cystoscopy. We assessed the agreement between the findings on virtual and conventional cystoscopy. Using conventional cystoscopy as the gold standard, we evaluated the usefulness of virtual cystoscopy as an aid in identifying bladder lesions and detecting abnormal bladders. RESULTS. Virtual cystoscopy depicted 60 lesions in the bladders of 43 patients. Fifty-six lesions (in 41 bladders) revealed on virtual cystoscopy were true-positive findings. Four lesions in two bladders with abnormal findings were false-positive. On virtual cystoscopy, the radiologists missed three lesions in two abnormal bladders that were identified on conventional cystoscopy. On virtual cystoscopy, 15 (88%) of 17 lesions smaller than 0.5 cm were identified. The agreement between the findings of virtual and conventional cystoscopy was excellent in the reviewers' identification of bladder lesions (kappa = 0.83) and detection of abnormal bladders (kappa = 0.89). The sensitivity and specificity of virtual cystoscopy were 95% and 87% for identifying bladder lesions and 95% and 93% for detecting abnormal bladders. CONCLUSION. Virtual cystoscopy of the contrast material-filled bladder is useful for the evaluation of the bladder in patients with gross hematuria.