Mikihiko Harada

Liver parenchymal changes after transcatheter arterial embolization therapy for hepatoma: CT evaluation

We retrospectively reviewed computed tomographic (CT) findings of 118 patients with hepatoma who received sequential follow-up CT after transcatheter arterial embolization (TAE). Thirty-five patients received TAE using Gelfoam particles with cisplatin, 37 patients using Gelfoam particles and iodized oil (Lipiodol) with cisplatin, and 46 patients using iodized oil with cisplatin. Liver atrophy was observed in 33 patients, lobarly or focally, depending on the embolized area. It was frequently associated with portal vein occlusion by the tumor, usage of iodized oil, and repeated embolization therapy. The lobar atrophy was seen in patients who had portal vein occlusion and/or received repeated embolization therapy. The focal atrophy was observed in patients who were administered iodized oil. Infarction developed in four patients who had a thrombus in the portal vein and received peripheral embolization therapy using iodized oil. We conclude that liver parenchymal changes occur frequently in patients who have portal vein occlusion and/or receive peripheral embolization using iodized oil.

Sclerosing hepatocellular carcinoma: Radiologic findings

The radiologic findings of seven patients with sclerosing hepatocellular carcinoma (HCC), an unusual subtype of HCC, were evaluated. Computed tomography (CT) demonstrated a hypointense mass with marked delayed contrast enhancement. Although the tumor was well-defined, the tumor capsule was not seen. Focal atrophy was seen in four patients. Ultrasound (US) showed an isoechoic to hyperechoic mass without a rim. Angiography revealed prominent tumor vessels and prolonged stains in all cases. Arterial encasement was seen in four patients. On magnetic resonance (MR) imaging, all tumors were hypointense on T1-weighted images and hyperintense on T2-weighted images. On dynamic MR study, remarkable contrast enhancement, which continued to the delayed phase, seemed to be characteristic for sclerosing HCC. In the presence of liver tumors with homogeneous architecture, hypervascularity, prolonged enhancement, absence of tumor capsule, and focal atrophy in high-risk patients of HCC, sclerosing HCC should be considered.

Cystic renal cell carcinoma. Imaging findings with pathologic correlation.

Twenty-seven cystic renal cell carcinomas (RCC) in 23 patients were analyzed radiologically and histologically. They were classified into 4 histopathologic growth patterns: a) multilocular (n = 15, 9 with macrocystic and 6 with microcystic components); b) unilocular (n = 3); c) cystic necrosis (n = 9); and d) tumors originating in the wall of a simple cyst (n = 0). Macrocystic multilocular RCC showed multiloculated configuration on ultrasound and contrast enhanced CT. Angiography revealed neovascularity peripherally or within the tumor (7/9 tumors). Microcystic multilocular RCC did not fulfill the criterion for a cystic mass on ultrasound: they were irregularly hyperechoic. There was little enhancement on postcontrast CT and only slight neovascularity on angiography. Unilocular RCC showed a cystic mass with an irregular wall or mural nodules on ultrasound and contrast enhanced CT. Necrotic RCC showed various sonographic findings from anechoic to irregular echoic. The appearance on CT varied from cystic with mural nodules to a multiloculated or irregular architecture. Neovascularity was seen in the periphery in 8 of 9 tumors. Clinically, this type seemed to be the most aggressive.

Dynamic MR Imaging of Hepatoma Treated by Transcatheter Arterial Embolization Therapy Assessment of Treatment Effect

The effect of transcatheter arterial chemo-embolization therapy (TACE) for hepatoma was evaluated with dynamic MR imaging with Gd-DTPA in 37 patients (44 tumors). TACE was performed using Lipiodol/cis-platinum and gelatin sponge (or microspheres) as an embolic material. All patients were examined with dynamic CT and MR imaging before and after treatment. On conventional spin echo images, changes of signal intensity after treatment varied regardless of presence of Lipiodol. Dynamic MR imaging revealed changes of tumor vascularity before and after treatment. On histologic correlation, areas of persistent tumor enhancement on dynamic MR imaging corresponded to areas of viable tumor cells while areas of nonenhancement corresponded to areas of necrosis. Dynamic MR imaging was superior in contrast resolution and was not influenced by the presence of Lipiodol compared with dynamic CT, and therefore residual viable tumors were better defined by dynamic MR imaging.

Prevention of Intimal Hyperplasia by Irradiation: An experimental study in rabbits

Purpose: This experimental study was designed to investigate the effect of irradiation in prevention of intimal hyperplasia. Material and Methods: Twenty rabbits were divided into 4 groups, which were irradiated with 2, 5, 10, and 20 Gy, respectively. The intima of both femoral arteries was injured by air-drying, and irradiation was performed on the unilateral side. The contralateral femoral artery served as a control. Angiograms as well as histologic specimens were obtained 1 month later. Results: Marked intimal hyperplasia was observed in all control sites. There were no significant differences in thickness of intimal hyperplasia between irradiated and control sites in groups irradiated with 2 and 5 Gy. However, in the 10-Gy- and 20-Gy-irradiated groups, intimal hyperplasia of the irradiated site was significantly suppressed. Medial thinning and dilation of the lumen were observed in the 20-Gy-irradiated group. Conclusion: Radiation may prevent intimal hyperplasia. Further investigation of the optimal dose, timing of irradiation, and long-term patency of irradiated vessels may be needed.

Unruptured interstitial pregnancy: A pitfall of MR imaging

We report two cases with interstitial pregnancy, which showed completely different MR appearances. In case 1, a gestational sac was demonstrated and the diagnosis of ectopic pregnancy was straightforward. In case 2, a hypervascular mass was shown without demonstration of a gestational sac, the findings usually seen in gestational trophoblastic disease (GTD). MR imaging may play some role in the diagnosis of interstitial pregnancy when sonography is insufficient or equivocal. If GS is visualized, diagnosis is easy. However, if not, the appearance may have a spectrum and can be similar to GTD.

Transarterial embolization of an extrahepatic portal vein aneurysm with arterioportal fistula.

We successfully performed transcatheter arterial embolization of an extrahepatic arterioportal fistula with a portal vein aneurysm. The fistula was considered secondary to cholecystectomy for cholecystolithiasis 5 years earlier. After occlusion of the fistula with platinum coils, the aneurysmal cavity thrombosed.

Intravascular hyperthermia: Experimental study of transcatheter treatment

RATIONALE AND OBJECTIVES External hyperthermia has frequently been used to treat superficial malignant tumors. We postulated that transarterial internal hyperthermia may be effective for deeply located hypervascular tumors. We performed intravascular hyperthermia (IVH) for malignant hypervascular tumors that were transplanted into animals and evaluated the resulting histologic changes and antitumoral effects. METHODS We designed a special catheter to heat the injected saline. Sixteen rabbits with hypervascular VX2 tumors ranging from 2 to 2.5 cm in diameter in their left hindlimb muscles served as subjects. IVH was performed via the left femoral artery (temperature = 50 degrees C) in 11 rabbits. Two sessions of IVH were performed during 1 week. Two weeks after the two sessions of IVH, the rabbits were sacrificed and their tumors and feeding arteries were resected. Five control rabbits had 37 degrees C saline infused using the same technique. RESULTS The temperature in the central zone of the tumor increased markedly to 42.3 +/- 0.5 degrees C (mean +/- standard deviation), compared with 40.3 +/- 0.4 degrees C and 39.2 +/- 0.5 degrees C in the peripheral zones of the tumor and the surrounding tissue, respectively. Tumor sizes were calculated on angiograms as having decreased by 63 +/- 35% of their initial sizes during the 2 weeks after the two IVH sessions. However, tumor sizes increased to 171 +/- 41% in the control group (p < .01). Necrosis in the peripheral zones of the tumors in the IVH group was more severe than that in the control group (p < .05). Necrosis in the central zones of the tumors in the IVH group was slightly more severe. The surrounding tissue was not damaged. Although the femoral artery was not severely damaged, there was severe damage to the feeding arteries. CONCLUSION IVH reduced the size of hypervascular tumors in our rabbits. The antitumoral effects are attributed to direct damage of the tumor vessels and to the effect of heat on the tumor cells.