Updating computed tomography of bladder carcinoma in assessing response to immunotherapy and attenuated irradiation

Computed tomography was utilized as part of the surgical-pathological-radiological evaluation of 21 patients who were treated for bladder carcinoma with attenuated irradiation and immunotherapy. Fifteen patients had moderately infiltrative (Stage Tsub(2a-b) or less) disease and it was found that a routine high resolution CT technique using a modern fast scanner delineated the tumor in most cases. More accurate assessment of tumor response to therapy and evaluation of tumor progression was facilitated using a gas insufflation technique combined with intravenous contrast infusion. This was followed in selected cases by quantitative measurements of CT attenuation values using a recently introduced CT software program. Using this program, individual pixel values were obtained in selected areas and evaluation of the resulting numerical data and pixel histograms aided in the differentiation of tumor tissue from adjacent bladder wall and mapped out areas of tumor necrosis. Our preliminary observations suggest that quantitative CT studies incorporating assessment of printouts of attenuation values of adjacent pixels within a region of interest will improve the delineation of smaller (Tsub(2a)/Tsub(2b)) lesions and will aid objective characterization of tumor tissue during and following therapy. (orig.)