Akihiko Arakawa

Percutaneous microwave coagulation therapy in liver tumors

Purpose: Percutaneous microwave coagulation therapy (PMCT) is an interventional alternative for inoperable malignant liver tumors. in this paper, we report the results of our 3-year experience of PMCT in order to establish suitable indications for this treatmentMaterial and Methods: We studied a total of 27 inoperable liver tumors in 24 patients. Histology of the tumors showed 20 hepatocellular carcinomas (HCCs) (13 well differentiated, 4 moderately differentiated, and 3 poorly differentiated) and 7 metastases. These tumors were treated by PMCT and were followed for 4–40 months (average 18 months). Under US guidance, the tumors were coagulated by microwaves emitted from an electrode. the changes of tumor size after PMCT were evaluated by CT. When the tumors disappeared or were reduced in size after treatment, PMCT was regarded as effective. Complications from PMCT were also evaluated. the patient survival rate was obtained by means of the Kaplan-Meier methodResults: in tumors of 30 mm or less, treatment r...

Percutaneous microwave coagulation therapy in liver tumors: A 3-year experience

Purpose: Percutaneous microwave coagulation therapy (PMCT) is an interventional alternative for inoperable malignant liver tumors. in this paper, we report the results of our 3-year experience of PMCT in order to establish suitable indications for this treatment. Material and Methods: We studied a total of 27 inoperable liver tumors in 24 patients. Histology of the tumors showed 20 hepatocellular carcinomas (HCCs) (13 well differentiated, 4 moderately differentiated, and 3 poorly differentiated) and 7 metastases. These tumors were treated by PMCT and were followed for 4–40 months (average 18 months). Under US guidance, the tumors were coagulated by microwaves emitted from an electrode. the changes of tumor size after PMCT were evaluated by CT. When the tumors disappeared or were reduced in size after treatment, PMCT was regarded as effective. Complications from PMCT were also evaluated. the patient survival rate was obtained by means of the Kaplan-Meier method. Results: in tumors of 30 mm or less, treatment response was obtained in 70% of cases, while 55% of tumors larger than 30 mm responded. the tumor became smaller or disappeared in 85% of the well differentiated HCCs, and in 25% of the moderately differentiated HCCs, but none of the poorly differentiated HCCs responded. in metastatic tumors, PMCT was effective in 57% of cases, Slight pain (24%), fever (20%) and subcutaneous hematoma (8%) were experienced immediately after PMCT. in 2 poorly differentiated HCCs, needle tract seeding was observed. No case of liver dysfunction was seen after PMCT. the overall survival rate was 83.1% at 1 year and 68.7% at 2 years. Conclusion: Good therapeutic results were achieved with PMCT in lesions of 30 mm or less, and in well differentiated HCCs.

Assessment of lung volumes in pulmonary emphysema using multidetector helical CT: comparison with pulmonary function tests

The purpose of this study is to evaluate the usefulness of multidetector helical CT (MDCT) with three-dimensional (3D) postprocessing for assessing the lung volume at inspiration and expiration of the pulmonary emphysema and for comparing it with pulmonary function tests. Percentage lung volume at the threshold of -930, -900, -810, -790, and -770 at expiration showed good correlation with FEV1, FEV1/FVC, and DLCO/Va. Excellent correlation was observed between percentage lung volume at the threshold of -900 and FEV1/FVC. CT densitometry at expiration showed better correlation than that at inspiration with pulmonary function tests. MDCT with 3D technique is useful for assessing the severity of pulmonary emphysema.

Radiation therapy of invasive thymoma

Between 1978 and 1987, 30 cases of invasive thymomas were treated with radiotherapy after surgery. Surgical therapy consisted of total resection in 15 patients, subtotal resection in 1 patient, and biopsy in 14 patients. Myasthenia gravis (MG) was associated in nine patients (MG(+) group), but in 21 patients there was no evidence of myasthenia gravis (MG(-) group). Irradiation in the dose range of 30 to 58.7 Gy was delivered. The total average 5-year survival rate was 71.8%; it was 39.2% in MG(+) group and 78.3% in MG(-) group, though there was no significant statistical difference. Myasthenia gravis was well controlled by the tumorectomy and associated radiotherapy in 7 of the 9 patients. However, in 3 of 7 patients (42.9%) myasthenia gravis recurred at 2 years, 2 years and 7 months, and 5 years and 8 months after initial therapy. Total body irradiation of 2 Gy with 0.1 Gy fractions was administered for uncontrollable myasthenia gravis in one patient with marked improvement. Radiation therapy is an important therapeutic modality for unresectable malignant thymoma as well as for postoperative combined therapy. Total body irradiation may be an effective method to treat patients with otherwise resistant myasthenia gravis.

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.

Improved tissue characterization of focal liver lesions with ferumoxide-enhanced T1 and T2-weighted MR imaging.

The purpose of our study was to evaluate the potential value of ferumoxide‐enhanced T1‐weighted magnetic resonance (MR) imaging for tissue characterization of focal liver lesions when combined with T2‐weighted sequences. Images were acquired within 30 minutes after the end of ferumoxide administration, when ferrite particles were not totally cleared from the intravascular compartment. Thirty‐eight patients with 47 focal liver lesions underwent T1‐weighted gradient‐echo (TR/TE 150/4.1 msec) and T2‐weighted fast spin‐echo (3180–8638/90 msec) MR imaging at 1.5 T before and after intravenous administration of ferumoxides (10 μmol/kg body weight). A qualitative and quantitative analysis was performed. During the early phase after infusion of ferumoxide, blood vessels showed hypersignal intensity on T1‐weighted fast low‐angle shot (FLASH) images, while liver signal decreased. Hemangiomas showed both homogeneous and inhomogeneous enhancement patterns, and liver metastasis most typically showed ring enhancement. Hypervascular tumors (hepatocellular carcinomas and focal nodular hyperplasias) showed a slight degree of homogeneous enhancement. Quantitatively, the degree of enhancement and lesion‐to‐liver contrast on ferumoxide‐enhanced images were significantly different among these tumors. Our results demonstrate that distinct enhancement patterns obtained on ferumoxide‐enhanced T1‐weighted MR imaging improve tissue characterization of focal liver lesions when combined with T2‐weighted images. J. Magn. Reson. Imaging 2000;11:647–654.

Transcatheter hepatic subsegmental arterial chemoembolization therapy using iodized oil for small hepatocellular carcinomas. Correlation between lipiodol accumulation pattern and local recurrence.

Lipiodol accumulation patterns were correlated with local recurrences after subsegmental or conventional arterial chemoembolization therapy using iodized oil (Lipiodol-TAE). Thirty-six patients with solitary small hepatocellular carcinomas (HCCs) less than 3 cm in diameter were included in this retrospective study. Superselective subsegmental catheterization was performed in 14 patients (subsegmental Lipiodol-TAE). In the remaining 22 cases, embolization was performed from the proximal portion of the hepatic artery (conventional Lipiodol-TAE). Patterns of Lipiodol accumulations within the tumors were classified in 2 groups: complete and incomplete accumulation. Complete accumulation was observed in 71% of subsegmental Lipiodol-TAE and in 32% of conventional Lipiodol-TAE. The rate of local recurrences within 12 months was significantly higher (p < 0.01) in incomplete accumulation (100%) than in complete accumulation (13%). We suggest that when small HCCs are to be treated with TAE, subsegmental Lipiodol-TAE should be performed because of its superior capability for achieving complete Lipiodol accumulation.

Intraductal papillary tumors of the pancreas. Histopathologic correlation of MR cholangiopancreatography findings.

Purpose: To evaluate MR cholangiopancreatography (MRCP) findings of intraductal papillary tumors of the pancreas and correlate them with histopathology. Material and Methods: Seventeen patients with intraductal papillary tumor of the pancreas underwent MRCP before surgery. MRCP findings were correlated to histopathology with regard to the presence of septa and excrescent nodules in the cystic lesion, communication between the cystic lesion and the main pancreatic duct (MPD), degree of dilatation of MPD, and dilatation of the common bile duct (CBD). Results: MRCP demonstrated septa in 17 cases (100%), excrescent nodules in 8 cases (47.1%), communication between the intraductal papillary tumor and the MPD in 14 cases (82.3%), dilatation of MPD over 50% in 6 cases (35.3%), and dilatation of CBD in 3 cases (17.6%). These findings showed excellent correlation with histopathology. The septum on MRCP corresponded with a layer of connective tissue with pancreatic duct epithelium. Excrescent nodules in the carcinomas consisted not only of malignant cells, but also of dysplasia and adenoma. Excrescent nodules in adenomas were consistent not only with minimal papillary growth of adenoma, but also with proliferation of fibrosis, and hematoma and organized fibrin with minimal fibrosis. Pancreatic tissue was affected by chronic pancreatitis in all cases. Cases with dilatation of CBD on MRCP were due to microscopic invasion by the carcinoma. Conclusion: MRCP appearances of intraductal papillary tumors are well correlated with the findings at histopathology.

Diagnostic accuracy of helical CT arterial portography and CT hepatic arteriography for hypervascular hepatocellular carcinoma in chronic liver damage: An ROC analysis

PURPOSE To evaluate the detectability of hypervascular hepatocellular carcinomas (HCCs) in chronic liver damage with helical CT arterial portography (CTAP) and CT hepatic arteriography (CTHA). MATERIAL AND METHODS Thirty-nine HCC patients who underwent CTAP and CTHA were studied. Diagnostic abilities of CTAP alone, CTHA alone, or combined CTAP and CTHA were evaluated by receiver operating characteristic (ROC) analysis. Fifty-three images with 53 HCC nodules were evaluated. Tumor size ranged from 5 to 90 mm (mean 22.8 mm). Sensitivities and specificities for all techniques were calculated. RESULTS ROC analysis showed the diagnostic ability significantly better with combined CTAP and CTHA (mean area under the ROC curve (Az)=0.95), or CTHA alone (Az=0.93) than CTAP alone (Az=0.87) (p<0.01). Combined CTAP and CTHA showed the best sensitivity (95.0%), followed by CTHA alone (88.1%) and CTAP alone (85.5%). The specificities of all three imaging techniques were relatively low (54.1% for combined CTAP and CTHA, 71.1% for CTHA alone, and 54.1% for CTAP alone) because of perfusion abnormalities of the liver parenchyma. CONCLUSION The combination of CTAP and CTHA is superior to CTAP alone for detection of hypervascular HCCs. However, its specificity was relatively low in chronic liver damage.

Radiological findings of retroperitoneal leiomyoma and leiomyosarcoma: report of two cases.

Radiologic findings in cases of retroperitoneal leiomyosarcoma and leiomyoma were reported. These cases showed very similar findings: irregularly marginated large masses with central cyst formation and no calcification on CT and ultrasonography. Angiography showed tumor vessels and tumor stains. Cystic region due to central necrosis or hemorrhage was the most prominent radiologic finding in these cases. However, it was difficult to distinguish leiomyosarcoma from leiomyoma on the basis of the radiologic findings alone.