Norio Nakao

A novel 3D hepatectomy simulation based on liver circulation: Application to liver resection and transplantation

Hepatectomy is a complicated operative procedure because of its anatomical complexity, vascular variability, and impaired hepatic function due to associated hepatitis or cirrhosis. Thus preoperative detailed topography and precise liver resection volume measurements should be obtained for a curative hepatectomy. The aim of this study was to assess the feasibility and accuracy of a novel three‐dimensional (3D) virtual hepatectomy simulation software in patients who underwent liver resection or living donor liver transplantation. We developed the hepatectomy simulation software, which was programmed to analyze detailed 3D vascular structure and to predict liver resection volume and margins. In 72 patients receiving hepatectomy, the predicted liver resection volumes and margins revealed a significant correlation with the actual value with a mean difference of 9.3 mL (P < .0001) and 1.6 mm (P < .01), respectively. The drainage area by hepatic veins was quantified to achieve reconstruction of the corresponding venous branch. In conclusion, this hepatectomy simulation software reliably predicted an accurate liver resection volume, the cancer‐free margin, and the drainage volume of hepatic vein branches. This software may promote curative hepatectomy and may be used for other interventional therapies in the treatment of liver disease. (HEPATOLOGY 2005.)

Cone-Beam CT with Flat-Panel-Detector Digital Angiography System: Early Experience in Abdominal Interventional Procedures

We developed a cone-beam computed tomography (CBCT) system equipped with a large flat-panel detector. Data obtained by 200° rotation imaging are reconstructed by means of CBCT to generate three-dimensional images. We report the use of CBCT angiography using CBCT in 10 patients with 8 liver malignancies and 2 hypersplenisms during abdominal interventional procedures. CBCT was very useful for interventional radiologists to confirm a perfusion area of the artery catheter wedged on CT by injection of contrast media through the catheter tip, although the image quality was slightly degraded, scoring as 2.60 on average by streak artifacts. CBCT is space-saving because it does not require a CT system with a gantry, and it is also time-saving because it does not require the transfer of patients.

Clinicoradiological factors influencing the reversibility of posterior reversible encephalopathy syndrome : a multicenter study

PurposeThe aim of this retrospective study was to clarify the relation between the reversibility of posterior reversible encephalopathy syndrome (PRES) with three factors: the anatomical region of the brain involved, the background clinical cause, and the diffusion weighted image (DWI) intensity of PRES lesions.Material and methodsThis multicenter study, conducted by the PRES Study Group of the Neuroradiology Workshop, involved 52 cases from 28 institutions. Initial and follow-up magnetic resonance imaging were compared regarding the reversibility of PRES lesions according to anatomical location and clinical background. Initial DWI and apparent diffusion coefficient (ADC) maps were reviewed in 20 cases.ResultsReversibility was significantly lower (P < 0.01) in the brain stem (44%) and deep white matter (47%) compared to the other cortical and subcortical areas (76%–91%). The reversibility was greater in the eclampsia subgroup followed by the hypertension and chemotherapy subgroups. DWI, even with ADC maps, had limitations in predicting the outcome of PRES lesions.ConclusionThe typical cortical and subcortical PRES lesions showed reversibility, whereas the brain stem and deep white matter lesions showed less reversibility. PRES due to eclampsia showed maximum reversibility compared to hypertension- and drug-related PRES. DWI, even with ADC maps, had limitations in predicting the course of PRES.

Intrahepatic metastases in hepatocellular carcinoma: the role of the portal vein as an efferent vessel.

The mechanism and pathogenesis of the high frequency of intrahepatic metastasis in hepatocellular carcinoma (HCC) has not yet been elucidated. Two hundred and thirty one tumors (⩽ 5 cm in diameter) of resected specimens of HCC were examined for the relationship between mode of tumor spread and tumor size. Efferent vessels in HCC were identified by direct injection of radiopaque material into the tumor in 23 resected liver specimens selected at random from the 231 tumors. The most frequent site for tumor spread in HCC was capsular invasion followed by extracapsular invasion, vascular invasion, and finally intrahepatic metastasis. There was a strong statistical correlation between the presence of intrahepatic metastasis and the frequency of vascular invasion (correlation coefficient = 0.998). Radiopaque material injected directly into 23 resected tumors entered only the portal vein in 17 tumors and into both the portal and hepatic veins in six tumors. In all eight patients with unresectable lesions, radiopaque media injected percutaneously into tumor nodules flowed only into the portal vein. These findings suggest that tumor spread in HCC progresses from capsular invasion to intrahepatic invasion and that the portal vein may act as an efferent tumor vessel.

Pathologic and Radiographic Studies of Intrahepatic Metastasis Hepatocellular Carcinoma; The Role of Efferent Vessels

The efferent vessel of hepatocellular carcinoma (HCC) and the mechanism and pathogenesis of the high frequency of intrahepatic metastasis in HCC has not yet been clarified. Three hundred ninety-three resected specimens of HCC were examined for tumor thrombosis in the portal vein and the hepatic vein: 231 tumors ≤5 cm in diameter were examined for the relationship between mode of tumor spread and tumor size. Efferent vessels in HCC were identified by direct injection of radiopaque material into the tumor in 23 resected liver specimens and by percutaneous infusion of radiopaque media into tumor nodules in 8 patients. The mode of tumor spread in HCC progressed from capsular invasion to extracapsular invasion, then to vascular invasion, and finally to intrahepatic metastasis. There was a strong statistical correlation between the presence of intrahepatic metastasis and portal vein thrombosis (p<0.05, R=0.998). Radiopaque material injected directly into 23 resected tumors entered only the portal vein in 17 tumors and into both the portal and hepatic veins in 6 tumors. In all 8 patients with unresectable lesions, radiopaque media injected percutaneously into tumor nodules flowed only into the portal vein. These findings suggest that intrahepatic invasion by HCC may occur through the portal vein as an efferent tumor vessel.

Evaluation of vascular supply with cone-beam computed tomography during intraarterial chemotherapy for a skull base tumor.

A cone-beam lowers the X-ray exposure level and the contrast material dose used compared to those for the conventional angiography-computed tomography (angio-CT) technique. Herein we present a patient with a metastatic skull base bone tumor in which the subtraction image of cone-beam CT with a flat panel detector was useful for evaluating the vascular supply during superselective intraarterial chemotherapy. Although the image quality of cone-beam CT is poorer than that of conventional angio-CT, the cone-beam CT system is sufficient for clinical use.

Phase I/II study of intravenous nedaplatin and intraarterial cisplatin with transcatheter arterial embolization for patients with locally advanced uterine cervical carcinoma

Nedaplatin, a platinum analog with less renal toxicity and similar efficacy for cervical carcinoma, recently has been shown to have a synergistic effect on cervical carcinoma lines in combination with cisplatin. To determine the clinical efficacy of this combination in patients with cervical carcinoma, the authors conducted a Phase I/II study of intravenous nedaplatin and intraarterial cisplatin combined with transcatheter arterial embolization (TAE).

CT Angiography in Hepatocellular Carcinoma

In 32 cases of hepatocellular carcinoma (HCC) computed tomographic angiography (CTA) was performed to evaluate its diagnostic usefulness. The contrast material was infused into both the hepatic artery and superior mesenteric artery. Computed tomography was performed during the arterial and the portal phase. According to the CTA findings, HCC could be classified into four types; 28 of 32 cases (87.5%) showed the characteristic findings of HCC. It was also apparent that CT portography was quite efficient in detecting the existence of tumor, in particular the presence of small intrahepatic metastatic lesions and tumor infiltration into the portal vein. Computed tomographic angiography performed during both the arterial and portal phase is useful in evaluating HCC prior to hepatic lobectomy or arterial embolization therapy.

Balloon-occluded retrograde transvenous obliteration for portal hypertension.

Currently in Japan more than 1.5 million patients have viral hepatitis or hepatic cirrhosis, which may lead to portal hypertension. Thus, treatment of esophageal or gastric varices due to portal hypertension has become important in the clinician’s daily practice. The treatment for portal hypertension includes endoscopic treatment, surgical treatment, interventional radiology (IR) using a catheter, and conservative therapy. In recent years, IR treatment using a catheter has become an important and leading treatment for portal hypertension because of the extensive range of procedures available. IR treatment has made rapid progress because of the development of techniques such as transjugular intrahepatic portosystemic shunt (TIPS) and balloon-occluded retrograde transvenous obliteration (B-RTO). IR has extended its armamentarium with percutaneous transhepatic esophageal varices embolization (PTO) and partial splenic arterial embolization (PSE). Surgical operations such as esophageal transection and Hassab’s operation, as well as endoscopic treatment, have mainly targeted esophageal varices. There are no effective treatments to alleviate the symptoms of portal hypertension (portal hypertensive gastropathy, refractory ascites, gastric varices, refractory esophageal varices, duodenal varices, hypersplenism, shunt hepatic encephalopathy), which therefore have tended not to be sufficiently treated up to now, with only conservative treatment given. Today, however, IR has an excellent treatment effect even on these entities. In particular, B-RTO is a treatment method developed in Japan, and the research, including ours, has clarified that it is not only excellent treatment for gastric varices but improves hepatic function. Furthermore, it is possible to apply B-RTO to portal hypertension with shunt. In this report, we discuss the current situation and development including changes in the treatment method, focusing on the role of B-RTO among the IR techniques for portal hypertension.

Radiologic Variations in Gastrorenal Shunts and Collateral Veins from Gastric Varices in Images Obtained Before Balloon-Occluded Retrograde Transvenous Obliteration

PurposeTo investigate variations in the features of gastrorenal shunts and collateral veins shown by balloon-occluded retrograde venography (B-RTV) and by superior mesenteric and celiac arteriography.MethodsA retrospective analysis was performed of the variation in these features on B-RTV and arteriography images obtained from 130 patients who have undergone these studies prior to balloon-occluded retrograde transvenous obliteration at our hospital since 1993.ResultsAt least one gastrorenal shunt was revealed in 97% (126/130) of cases. Types of gastrorenal shunts observed were as follows: only one main gastrorenal shunt, 94% (118/126) of cases; two main gastrorenal shunts with a ring-like appearance, 3% (4/126); and some gastrorenal shunts to the left renal vein, 3% (4/126). Collateral veins detected were as follows: left inferior phrenic vein, 75% (95/126) of cases; pericardiacophrenic vein, 40% (50/126); gonadal vein, 13% (16/126); retroperitoneal veins, 65% (82/126).ConclusionIt is very important to know the exact configuration of any gastrorenal shunts in order to guide advancement of the balloon catheter into the shunt and to avoid unexpected injection of the sclerosing agent.