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Purpose : To determine normal postoperative CT findings and tumor recurrence in patients who have under-goneradical cystectomy and urinary diversion. Materials and Methods : We retrospectively reviewed the postoperative CTscans of 51 patients who had un-dergone radical cystectomy with urinary diversion, and in analysis speciallyemphasised normal postoperative CT findings and recurrent cancer in the surgical bed. Among these 51 patients, 43had undergone incontinent urinary diversion(Bricker operation), while for six, diversion had been continent (Kockprocedure). Attempts were also made to characterise the CT findings of each procedure according to the location ofthe ileal pouch, the pattern of contrast collection within the pouch, and the morphology of the ileocutaneostomysite. Results : Each urinary diversion procedure demonstrated characteristic postoperative CT appearances. TheBricker procedure revealed a contrast-filled ileal conduit in the right lower quadrant excreting into theileocu-taneostomy site, while the Kock procedure demonstrated layering of contrast and urine within the pouch aswell as artificially intussuscepted afferent and efferent ileal loops at the anastomotic sites. Thirty-three smallsoft tissue density lesions in the surgical bed were seen in 19 patients (37%). Thirty one were bilateral (n=28)or unilateral (n=3) triangular or oval shaped soft-tissue-density lesions and two were unilateral irregular shapedlesions. Follow-up CT scans showed that all triangular or oval-shaped lesions were smaller (n=8) or show no changein size (n=23) ; they were thought to represent postoperative fibrosis or granulation tissue. Two cases ofirregular-shaped soft-tissue-density lesions were seen on follow-up CT scans to be larger, and these wereconfirmed by percutaneous biopsy to be recurrent cancer. Conclusion : It is important for the radiologist to befamiliar with normal postoperative CT findings of various urinary diversion procedures as well as to recognize arelatively high incidence (37%) of small soft tissue den-sity lesions in a surgical bed. In our study, smalltriangular or oval-shaped soft-tissue-density lesions in the sur-gical bed (especially when these were bilateral)were thought to represent postoperative fibrosis or granulation tissue, and close follow-up by means of CTscanning rather than an invasive procedure is therefore warranted.

Purpose: To investigate the safety and usefulness of Lipiodol-percutaneous transhepatic ethanolinjection(L-PEI) and to determine the appropriate concentration of Lipiodol during L-PEI. This was achieved by evalvating CT findings and histopathologic changes according to the concentration of Lipiodol, amount of ethanol, and the time interval after injection into normal rabbit liver. Materials and Methods: This experimental study involved 18 New Zealand rabbits under US guidance. They were divided into five groups according to injected materials; two rabbits with 0.4cc of normal saline(group I), six with 0.4cc of ethanol in the left hepaticlobe(group II), and 0.4cc of Lipiodol in the right hepatic lobe(group III), five rabbits with 5%Lipiodol-ethanol(5% vol. of Lipiodol+95% vol. of ethanol), 0.2cc in the right hepatic lobe, and 0.4cc in theleft(group IV); and five rabbits with 10% Lipiodol-ethanol as per group IV(group V). CT was performed immediately, one week, two weeks, and three-four weeks after injection, and pathologic specimens were obtained on the third day(acute phase) and during the third or fourth week(chronic phase) after injection. Results: On CT, intrahepatic localization of the L-PEI injection site was well demonstrated as a focal high attenuated area which gradually decreased in attenuation on follow up CT. The opacification of the inferior vena cava by Lipiodol, the linear distribution of Lipiodol along portal veins or fissures, and peritoneal leakage were clearly demonstrated in groups III-V, though the effects gradually disappeared during follow-up CT. There was no remarkable difference in gross CT attenuation between group IV and group V. The main pathologic findings during the acute phase of group II were coagulation necrosis surrounded by macrophage, inflammatory reaction, and early periportal and subcapsular fibrosis. The findings in group IV and V were similar to those in group II and additional fat vacuole accumulations in the necrotic area were also seen. During the chronic phase of group II, areas of necrosis were absent or smaller and were surrounded or replaced by more organized fibrosis, macrophage or multinucleated giantcell infiltration. Periportal, subcapsular fibrosis was also found. In group IV and V, the findings were similarto those of group II, though additional fat vacuoles in fibrotic or necrotic areas, foreign body reaction to fatvacuole, regenerating nodule and calcification were also observed. Conclusion: L-PEI is more useful for thedetection by CT of an injection site than PEI alone, and with regard to CT and histopathologic findings, there wasno significant difference between the 5% and 10% Lipiodol-ethanol groups. Compared to PEI, L-PEI provoked nosighificant additional hepatic injury; only fatty change and foreign body reaction were noted. Thus, L-PEI is moreuseful than PEI for the management of HCC.

Cross-sectional imaging plays an increasing role in the diagnosis of appendiceal diseases due to known high negative appendectomy rate. It is important for radiologists to be aware of the computed tomographic(CT) appearances of various pathologies and common associated findings which can mimic other diagnostic entities. In this article, the author illustrates the CT appearances of a spectrum of appendiceal disaeses and outlines potential diagnostic pitfalls.