CT Documentation of Renal Exc retion after Intraperitoneal Administration of Gastrografin in Rats

PURPOSE: To measure, using spiral CT, the time interval between intraperitoneal injection of gastrografin and its renal excretion, and to demonstrate sequential change in the urinary bladder. MATERIALS AND METHODS: Five rats underwent serial CT scanning at one minute and every three minutes after the intraperitoneal injection of 0.5ml of 33 % gastrografin until opacification of the urinary bladder occurred. The procedure was repeated 15, 30, and 60mins later. We analyzed sequential change in the attenuation coefficient of the urinary bladder, as seen on CT scans and measured the time interval between gastrografin administration and opacification of the renal collecting system. RESULTS: All rats which received an intraperitoneal injection (n=5) showed opacification of the renal collecting system and urinary bladder 3 -9mins and 6.7 -1 2 .8mins, respectively, after gastrografin administration. The attenuation coefficient increased continuously until 1 hr after administration; its mean maximal level was 1 7 5 1 .6HU. CONCLUSION: The mean period required for opacification of the renal collecting system and of the urinary bladder, as seen on CT scans, was 6 mins and 9 mins, respectively, after intraperitoneal administration of gastro-grafin. The attenuation coefficient of the bladder increased continuously until 1 hr after injection.