Tumor detection by virtual cystoscopy with color mapping of bladder wall thickness

Purpose: We determine the value of color mapping of bladder wall thickness for detection of tumor as a component of virtual cystoscopy. Materials and Methods: A total of 31 subjects with hematuria and/or a history of bladder tumor underwent helical computerized tomography of the pelvis after distention of the bladder with air. Three-dimensional (D) models were constructed, and thickness of the wall was color mapped according to a fixed and validated mm. scale. Axial source images and 3-D models were reviewed and graded for the presence of wall thickening. A comparison was made with findings on conventional cystoscopy in 31 patients and pathological specimen in 13. Results: Compared with conventional cystoscopy, the analysis of axial image yielded a sensitivity of 0.80, specificity 0.90, positive predictive value 0.80 and negative predictive value 0.90 for the presence of tumor. Examination of color mapped 3-D renderings resulted in 0.83, 0.36, 0.42 and 0.71, respectively. Conclusions: Thin axial computerized tomography of the air distended bladder shows promise as a potential screening tool for bladder cancer. The low specificity of color mapped 3-D renderings makes the technique inappropriate for screening. It may valuable for guiding urologists to additional suspicious sites in a patient with a known tumor.