Contrast-enhanced computed tomography in carcinoma of the urinary bladder. The use of different injection methods.

Computed tomography (CT) scans of the urinary bladder were taken before and in combination with intravenous contrast medium injection in 30 patients with invasive bladder carcinoma. Three different ways of injecting the same amount of intravenous contrast material were used in three groups, each consisting of ten patients. In the first group the contrast medium was given during 90 seconds, in the second group during 40 seconds and in the third one, the first half during 20 seconds and the second half during 90 seconds. The attenuation in the tumors and in the bladder wall was measured in Hounsfield units. Independent of injection method, all tumors showed significantly higher contrast enhancement than the bladder wall when the injection was terminated. The difference in contrast enhancement was greatest in the group where the shortest injection time was used and greatest immediately after the conclusion of the injection. The difference in contrast enhancement between tumor and bladder wall was visible on the monitor in all cases.