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Osamu Tanaka

Publications and source records attributed to Osamu Tanaka.

At least 19 recordsLinked to original sources
PubMed2007

CT-based postimplant dosimetry of prostate brachytherapy: comparison of 1-mm and 5-mm section CT.

PURPOSE: The aim of this study was to compare the outcomes between 1-mm and 5-mm section computed tomography (CT)-based postimplant dosimetry. MATERIALS AND METHODS: A series of 21 consecutive patients underwent permanent prostate brachytherapy. The postimplant prostate volume was calculated using 1-mm and 5-mm section CT. One radiation oncologist contoured the prostate on CT images to obtain the reconstructed prostate volume (pVol), prostate V(100) (percent of the prostate volume receiving at least the full prescribed dose), and prostate D(90) (mean dose delivered to 90% of the prostate gland). The same radiation oncologist performed the contouring three times to evaluate intraobserver variation and subjectively scored the quality of the CT images. RESULTS: The mean +/-1 SD postimplant pVol was 20.17 +/- 6.66 cc by 1-mm section CT and 22.24 +/- 8.48 cc by 5-mm section CT; the difference in the mean values was 2.06 cc (P < 0.01). The mean postimplant prostate V(100) was 80.44% +/- 7.06% by 1-mm section CT and 77.33% +/- 10.22% by 5-mm section CT. The mean postimplant prostate D(90) was 83.28% +/- 10.81% by 1-mm section CT and 78.60% +/- 15.75% by 5-mm section CT. In the evaluation of image quality, 5-mm section CT was assigned significantly higher scores than 1-mm section CT. In regard to intraobserver variation, 5-mm section CT revealed less intraobserver variation than 1-mm section CT. CONCLUSION: Our current results suggested that the outcomes of postimplant dosimetry using 1-mm section CT did not improved the results over those obtained using 5-mm section CT in terms of the quality of the CT image or reproducibility.

Brachytherapy↗
PubMed2006

Importance of the CT/MRI fusion method as a learning tool for CT-based postimplant dosimetry in prostate brachytherapy.

BACKGROUND AND PURPOSE: To compare the CT-based and CT/MRI fusion-based postimplant dosimetry after permanent prostate brachytherapy and to evaluate the improvement in CT-based dosimetry by physicians with or without experience in using the CT/MRI fusion method. PATIENTS AND METHODS: Thirty-eight consecutive patients agreed to participate in a prospective study. The prostate contours from CT/MRI fusion are the gold standard for determining the prostate volume and dose volume histogram (DVH). CT-based postimplant dosimetries were performed by two physicians. Observer 1 was a radiologist who had never used CT/MRI fusion method for postimplant dosimetric analysis. Observer 2 was a radiation oncologist experienced in postimplant analysis using the CT/MRI fusion method. The prostate dosimetry was evaluated by prostate D90 and V100. RESULTS: No significant difference was observed in the mean prostate volumes between the two observers and the CT/MRI fusion data. However, the correlation coefficient value for observer 2 (R(2)=0.932) was greater than that for observer 1 (R(2)=0.793). The D90 and V100 values as evaluated by the two observers were significantly underestimated in comparison to those evaluated using the CT/MRI fusion methods. The DVH related parameters were underestimated more frequently by observer 1 than by observer 2: (prostate D90: 99.56% for observer 1, 102.97% for observer 2, 109.37% for CT/MRI fusion. Prostate V100: 88.12% for observer 1, 90.14% for observer 2, 91.91% for CT/MRI fusion). CONCLUSIONS: The difference in the mean value in D90 and V100 by observer 1 was significantly greater than that for observer 2. These findings suggest that the CT/MRI fusion method provides accurate feedback which thereby improves CT-based postimplant dosimetry for prostate brachytherapy.

Brachytherapy↗
PubMed2006

Isolation of protoplast from aerial mycelia and fruit-body formation from regenerated mycelia in Pleurotus cornucopiae.

We have developed a simple and efficient method for protoplast isolation from Pleurotus cornucopiae. Protoplasts were isolated from aerial mycelia cultured on potato dextrose agar medium without time-consuming propagation in liquid culture. Protoplast yield was significantly increased by means of a decompressing pretreatment of mycelia in enzyme solution and a subsequent enzyme reaction with vibrational mixing. The isolated protoplasts regenerated mycelia and these mycelia formed fruit-bodies without any morphological abnormalities.

Pleurotus↗
PubMed2006

Comparison of MRI-based and CT/MRI fusion-based postimplant dosimetric analysis of prostate brachytherapy.

PURPOSE: The aim of this study was to compare the outcomes between magnetic resonance imaging (MRI)-based and computed tomography (CT)/MRI fusion-based postimplant dosimetry methods in permanent prostate brachytherapy. METHODS AND MATERIALS: Between October 2004 and March 2006, a total of 52 consecutive patients with prostate cancer were treated by brachytherapy, and postimplant dosimetry was performed using CT/MRI fusion. The accuracy and reproducibility were prospectively compared between MRI-based dosimetry and CT/MRI fusion-based dosimetry based on the dose-volume histogram (DVH) related parameters as recommended by the American Brachytherapy Society. RESULTS: The prostate volume was 15.97+/-6.17 cc (mean+/-SD) in MRI-based dosimetry, and 15.97+/-6.02 cc in CT/MRI fusion-based dosimetry without statistical difference. The prostate V100 was 94.5% and 93.0% in MRI-based and CT/MRI fusion-based dosimetry, respectively, and the difference was statistically significant (p=0.002). The prostate D90 was 119.4% and 114.4% in MRI-based and CT/MRI fusion-based dosimetry, respectively, and the difference was statistically significant (p=0.004). CONCLUSION: Our current results suggested that, as with fusion images, MR images allowed accurate contouring of the organs, but they tended to overestimate the analysis of postimplant dosimetry in comparison to CT/MRI fusion images. Although this MRI-based dosimetric discrepancy was negligible, MRI-based dosimetry was acceptable and reproducible in comparison to CT-based dosimetry, because the difference between MRI-based and CT/MRI fusion-based results was smaller than that between CT-based and CT/MRI fusion-based results as previously reported.

Brachytherapy↗
PubMed2006

Chest wall Castleman's disease: CT and MRI findings.

Castleman's disease is an usually benign lymphoid tumor of uncertain etiology that generally appears as a solitary mediastinal mass. We present a case of Castleman's disease in the right chest wall of a 60-year-old woman. Magnetic resonance imaging showed a well-defined, oval mass that was early enhanced on T1-weighted images. The mass was diagnosed by percutaneous core needle biopsy with computed tomography guidance. The patient has remained well for 5 years without an increase in tumor size. We also summarize the international literature.

Biopsy, Needle↗
PubMed2006

Successful portal-systemic shunt occlusion with balloon-occluded retrograde transvenous obliteration for portosystemic encephalopathy without liver cirrhosis.

A 68-year-old woman was admitted to the authors' hospital for hepatic encephalopathy. Her laboratory data and computed tomography findings were not suggestive of liver cirrhosis. Superior mesenteric angiography revealed an extrahepatic portal-systemic shunt with a main cause of hepatic encephalopathy. Despite treatment with branched-chain amino acid, lactulose, and kanamycin, hyperammonemia was prolonged, and the portal-systemic shunt was therefore treated with balloon-occluded retrograde transvenous obliteration. After the procedure, hyperammonemia was improved, and there were no signs of recurrent portal-systemic encephalopathy.

Aged↗
PubMed2006

Observation of root variations in human coronary arteries.

In dissection courses conducted from 1999 through to 2003, five specimens were found to have coronary arteries with variant roots and branches, as follows: in specimens 1-4, roots of the right coronary artery (RCA) and right conus branch arose independently from the right aortic sinus (RAS); in specimen 5, the RCA and left coronary artery (LCA) originated from the RAS. The LCA pierced the upper part of the muscular interventricular septum and appeared on the surface, then dividing into the anterior interventricular and the circumflex branches. In the present study, we considered that the right conus arteries in specimens 1-4 were the remnant blood capillaries around the aorta towards the RAS in the embryonic stage. In specimen 5, the vessel near the left aortic sinus was poorly developed as a small thin artery. Instead, the LCA was developed from the anterior and posterior interventricular septal branches.

Aged↗
PubMed2006

[Successful resuscitation of intractable hyperkalemic cardiac arrest].

We report on a 42-year-old oliguric uremic man on regular hemodialysis who developed sudden cardiac arrest, secondary to severe hyperkalemia, with a plasma potassium concentration of 9.7 mEq x l(-1). The cardiac arrest persisted after the initiation of cardiopulmonary resuscitation and intensive treatment for marked hyperkalemia for an hour and 55 minutes. Therefore a portable percutaneous cardiopulmonary support (PCPS) system had to be instituted while the patient had very prolonged refractory ventricular fibrillation. His cardiac rhythm was restored immediately after application of PCPS and he recovered without neurological sequelae. We therefore suggest that PCPS should be considered as a therapeutic option during cardiopulmonary resuscitation for life-threatening cardiac arrest secondary to severe hyperkalemia.

Adult↗
PubMed2006

[Prolonged paralysis after long-term administration of vecuronium in the intensive care unit].

A 51-year-old woman with renal failure requring hemodialysis received a total of 446 mg of vecuronium over a period of 4 days to help mechanical ventilation and developed generalized muscle weakness after its discontinuation. It took 2 wks to wean her from mechanical ventilation and 3 wks for her to be able to walk. She did not receive drugs which might alter neuromuscular transmission such as corticosteroid and aminoglycoside antibiotics. Electromyogram and nerve conduction studies were normal. We believe that the cause is the accumulation of vecuronium and active metabolites due to renal failure. The case suggests that we should minimize the duration of neuromuscular block in patients with renal failure by aggressive use of sedatives and analgesics and the optimization of ventilator settings.

Female↗
PubMed2006

Can selective CT angiography reduce the incidence of severe complications during transcatheter arterial embolization or infusion chemotherapy for thoracic diseases?

PURPOSE: To evaluate the usefulness of selective computed tomography (CT) angiography in preventing severe complications, such as spinal cord injury and broncho- esophageal fistula, during the transcatheter arterial embolization or infusion chemotherapy for thoracic diseases. MATERIALS AND METHODS: Data from 28 patients with thoracic diseases were retrospectively analyzed in terms of selective CT angiography procedures carried out before transcatheter arterial embolization or transcatheter arterial infusion chemotherapy. RESULTS: There were no spinal cord injuries (0/13 and 0/15) or broncho-esophageal fistula developments (0/13 and 0/15) during transcatheter arterial embolization and transcatheter arterial infusion chemotherapy, respectively. CONCLUSION: We conclude that selective CT angiography is potentially useful for reducing the incidence of severe complications during transcatheter arterial embolization or infusion chemotherapy for thoracic diseases.

Adult↗
PubMed2005

Higher lesion conspicuity for SENSE dynamic MRI in detecting hypervascular hepatocellular carcinoma: analysis through the measurements of liver SNR and lesion-liver CNR comparison with conventional dynamic MRI.

The aim of our study was to compare the signal-to-noise ratio (SNR) of liver parenchyma and the contrast-to-noise ratio (CNR) of hypervascular hepatocellular carcinoma (HCC) between conventional and SENSE dynamic MRI. Thirty-one consecutive patients who were strongly suspected of having HCC were enrolled in our study. The subjects consisted of 20 men and 11 women aged 52 years to 79 years (mean 66.8 years). Dynamic MRI was performed for each patient, with SENSE (SENSE MRI) and without SENSE (conventional MRI) on separate days. For the quantitative analysis, the liver SNR and the lesion-liver CNR of 25 hypervascular HCCs detected on both conventional and SENSE dynamic MRI were measured. The liver SNR of the arterial phase and the portal venous phase was 84.1+/-24.7 and 104.7+/-34.3, respectively, in conventional MRI, while it was 62.9+/-19.5 and 44.5+/-18.2, respectively, in SENSE MRI. SENSE MRI showed a statistically significantly lower SNR than conventional MRI (P<0.01). The lesion-liver CNR was 26.3+/-15.9 in conventional MRI and 39.0+/-19.6 in SENSE MRI. The lesion-liver CNR in SENSE MRI was significantly higher than in conventional MRI (P<0.01). The SNR in SENSE MRI is significantly lower than in conventional MRI, although the lesion CNR is significantly higher than in conventional MRI.

Aged↗
PubMed2005

ATP-sensitive K+-channel subunits on the mitochondria and endoplasmic reticulum of rat cardiomyocytes.

ATP-sensitive K(+) (K(ATP)) channel subunits on the subcellular structures of rat cardiomyocytes were studied with antibodies against Kir6.1 and Kir6.2. According to the results of Western blot analysis, Kir6.1 was strongly expressed in mitochondrial and microsome fractions, and faintly expressed in cell membrane fraction, whereas Kir6.2 was mainly expressed in the microsome fraction and weakly in cell membrane and mitochondrial fractions. Immunohistochemistry showed that Kir6.1 and Kir6.2 were expressed in the endocardium, atrial and ventricular myocardium, and in vascular smooth muscles. Immunoelectron microscopy revealed that Kir6.1 immunoreactivity was mainly localized in the mitochondria, whereas Kir6.2 immunoreactivity was mainly localized in the endoplasmic reticulum and a few in the mitochondria. Both Kir6.1 and Kir6.2 are candidates of mitochondrial K(ATP) channel subunits. The data obtained in this study will be useful for analyzing the composition of K(ATP) channels of cardiomyocytes and help to understanding the cardioprotective role of K(ATP) channels during heart ischemia.

ATP-Binding Cassette Transporters↗
PubMed2005

Time course and sequence of pathological changes in the cerebellum of microsphere-embolized rats.

Ischemia is a major cause of damage to the central nervous system as a consequence of stroke or trauma. Here, we analyzed with high temporal resolution the time course of pathological changes in the neurons (granule and Purkinje cells) and glia (Bergmann and astroglia cells) in the cerebellar cortex and white matter. The period studied ranged from 30 min to 7 days after a microsphere-induced embolism used as a model of stroke and multi-infarct dementia. Some pathological changes in the neurons in the cerebellar cortex were identified early, that is, beginning at 3 h after the microsphere-induced embolism, and glial pathology appeared only later. The pathological changes in the white matter also appeared slightly later, that is, 6 h after embolism and were less pronounced than those in the cerebellar cortex. This suggests that neuronal pathology is induced more rapidly and/or more easily than the glial pathology. In addition, BrdU staining shows that cell proliferation is limited to a 1-day period beginning about 1 day after the embolism. These data demonstrate that changes after an ischemic lesion of the cerebellum proceeds from upper cerebellar cortex to deeper cerebellar cortex or white matter and also that microsphere-induced changes proceed from neuronal to glial pathology.

Animals↗
PubMed2005

Solitary mediastinal lymph node metastasis of hepatocellular carcinoma: MR imaging findings.

A 65-year-old man with multiple hepatocellular carcinomas in the liver with type C viral hepatitis had a solitary mediastinal lymph node metastasis in the right paratracheal to tracheobronchial region. Surgical resection for the mediastinal metastasis was undertaken based on magnetic resonance (MR) imaging findings, suggesting its radicality. We assess the MR imaging findings and presumable pathways of lymphatic metastasis from the liver to mediastinal lymph nodes in this report.

Aged↗
PubMed2005

Neurogenic tumors of the mediastinum and chest wall: MR imaging appearance.

Various histologic types of neurogenic tumors may originate in the mediastinum and chest wall. It is possible to make accurate diagnosis of these tumors by using the multiplanar capability and high contrast resolution of MR imaging because of these characteristic imaging findings. MR and histologic features of these tumors are illustrated and described in this essay.

Diagnosis, Differential↗
PubMed2005

Catheter redundancy in the aortic arch increases the risk of stroke in left subclavian arterial port-catheter systems.

PURPOSE: The stroke rate after left subclavian arterial port-catheter placement was compared in two groups: one with minimal redundancy of the catheter and one with pronounced redundancy in the aortic arch designed to minimize the likelihood of catheter dislocation. MATERIALS AND METHODS: One hundred forty-eight patients (102 men, 46 women; age range, 26-83 years; mean age, 64.3 years) with inoperable advanced liver cancers underwent percutaneous implantation of port-catheter systems via the left subclavian artery. In 33 patients, a pronounced redundancy of the catheter was intentionally looped in the aortic arch. Redundancy was intentionally avoided in the remaining 115 patients. The rates of brain infarction complications in these two groups were retrospectively compared. RESULTS: Among the 33 patients with pronounced redundant catheter looping, brain infarctions occurred in four cases (12.1%). In contrast, brain infarctions occurred in only three of the 115 patients with minimal redundant catheter looping (2.6%). The frequency of brain infarction complications was significantly higher in the patients with pronounced redundant catheter looping in the aortic arch than in patients with minimal pronounced redundant catheter looping (P = .044, Fisher exact test). CONCLUSION: Catheter redundancy in the aortic arch increases the risk of stroke in patients undergoing implantation of port-catheter systems via a left subclavian arterial approach for repeated hepatic arterial infusion chemotherapy.

Adult↗