Biomedical subjects

Kenji Nakamura

Publications and source records attributed to Kenji Nakamura.

86 records · Page 5Linked to original sources

PubMed2002

[Radiofrequency ablation of pulmonary malignancies].

Radiofrequency ablation (RFA) with a maximum output of < or = 70 W was used under CT guidance to treat 14 tumors (median diameter 1.5 cm, range 0.8 to 2.4 cm) in 6 patients. Primary lung cancer was treated in 2 patients, and metastatic lung tumors were treated in 4 patients. Good response was confirmed in 6 tumors on CT images, in one tumor on PET images, and in 2 tumors by histologic examination. In the other 5 tumors, curative effect was not determined because consolidation shadows surrounded the tumors. Complications were mild (pneumothoraces, 5; sputum cruentum, 4; subcutaneous emphysema, 3) except for one case of pleurisy. RFA of pulmonary malignancies appears to be a safe, effective treatment if a low output of less than 70 W is applied.

Aged↗

PubMed2002

[An experience of the clinical study with angiography system using a Flat Panel Detector].

We had the chance of clinical studies by new proto-type Digital Subtraction Angiography (DSA) System with the Flat Panel Detector (FPD). That system has two types of detector, FPD and I.I.-CCD camera, and we can compare with image quality in clinical. We measured and discussed about the physical characteristic data of both detectors. Up to physical characteristic evaluation, FPD has good MTF and SNR performance, comparing with I.I.-CCD camera. In clinical evaluation, DSA image of FPD was superior to that of I.I.-CCD camera by visual comparison of medical doctors. Finally we discussed about the feasibility of replacement of detectors. We expect that DSA system will accept FPD in near future.

Angiography, Digital Subtraction↗

PubMedDate not supplied

Radiofrequency ablated lesion in the normal porcine lung: long-term follow-up with MRI and pathology.

PURPOSE: To evaluate the effectiveness of magnetic resonance imaging (MRI) in reflecting histopathologic changes after radiofrequency ablation (RFA) to the lung and to assess accurately the extent of tissue necrosis for evaluating untreated lesions. METHODS: Percutaneous RFA was performed on 72 lung regions in 12 pigs under computed tomographic guidance. After performing MRI, the animals were divided into three experimental phases: in the acute phase, 4 pigs were killed immediately after the procedure; in the subacute phase, 4 pigs were killed at 1 week; and in the chronic phases, 2 pigs were killed at 4 and 8 weeks after the procedure, respectively. MRI-histopathologic correlation was performed. RESULTS: In the acute phase, the inner zone showed hypointensity on T2-weighted images and isointensity on T1-weighted images, with a lack of enhancement on contrast-enhanced T1-weighted images, representing early changes in coagulative necrosis on histopathologic examination. The outer zone showed hyperintensity on T2-weighted images and isointensity on T1-weighted images, with ring-like enhancement on contrast-enhanced T1-weighted images. The histopathologic section showed alveolar fluid collections and congestion. In the subacute phase the MR zone pattern was essentially similar to that of the acute phase, but the ablated lesion showed extensive coagulative necrosis with a fibrovascular rim on histopathologic examination. In the chronic phase, there was no change in the zone pattern on MRI. The lesions showed gradual resorption of coagulative necrosis. The area of coagulative necrosis correlated closely with the histopathologic size (p < 0.05). CONCLUSIONS: MRI effectively visualized the histopathologic changes after RFA and accurately determined the extent of the necrotic lesion. MRI is potentially a useful modality for evaluating therapeutic efficacy after RFA to the lung.

Animals↗

PubMedDate not supplied

Dual balloon-occluded retrograde transvenous obliteration of gastric varix draining into the left adrenal vein and left inferior phrenic vein.

A 66-year-old woman with a gastric varix, draining into a dilated left adrenal vein and a left inferior phrenic vein, was treated with dual balloon-occluded retrograde transvenous obliteration (B-RTO). Under balloon occlusion of the left adrenal vein and the left inferior phrenic vein, retrograde injection of a sclerosant (5% ethanolamine oleate) into the gastric varix was performed. Two weeks later, disappearance of flow in the gastric varix was confirmed on endoscopic ultrasound examination.

Adrenal Glands↗

PubMedDate not supplied

Cartilage regeneration using slow release of bone morphogenetic protein-2 from a gelatin sponge to treat experimental canine tracheomalacia: a preliminary report.

We investigated whether saber sheath-type tracheomalacia could be treated by the slow release of bone morphogenetic protein (BMP)-2 from a gelatin sponge. A 1 cm gap was made in the middle portion of each of 10 consecutive tracheal cartilage rings in the canine cervix (control group, n = 3), then a gelatin sponge containing 12 microg of BMP-2 solution was implanted in the gap (12 microg group, n = 3). In another group (120 microg + P group, n = 3), the implanted gelatin sponge contained 120 microg of BMP-2 solution, and the gap was covered with periosteum. All of the control dogs developed saber sheath-type tracheomalacia, whereas tracheomalacia was not observed in the 12 microg and 120 microg + P groups. In the 12 microg group, fibrous cartilage was observed at the ends of the cartilage stumps. In the 120 microg + P group, newly formed bone and cartilage were observed to form a bridge between the cartilage stumps. The regeneration of cartilage or bone induced by the slow release of BMP-2 from a gelatin sponge might be useful for treatment of tracheomalacia.

Animals↗

PubMedDate not supplied

Detection of portal perfusion abnormalities: comparison of 3 ferucarbotran-enhanced magnetic resonance imaging sequences.

OBJECTIVE: To estimate the accuracy, sensitivity, and specificity of 3 ferucarbotran-enhanced magnetic resonance (MR) imaging sequences prospectively for the detection of nontumoral portal perfusion abnormalities. METHODS: Thirty-nine noncirrhotic patients with liver metastases underwent computed tomography during arterial portography (CTAP) and MR imaging comprising T1-weighted gradient recalled echo (GRE), T2-weighted fast spin echo (FSE), and T2*-weighted GRE sequences with and without ferucarbotran. Magnetic resonance images were reviewed by 4 blinded observers for rating based on the confidence scale. The accuracy, sensitivity, and specificity for each sequence were measured by receiver operating characteristic analysis. Contrast-to-noise ratio (CNR) and relative signal-to-noise ratio changes were statistically compared. RESULTS: Thirty-nine nontumoral perfusion defects were observed in 22 patients by CTAP. Receiver operating characteristic analysis showed the accuracy was higher for T2*-weighted GRE (0.884) than for T1-weighted GRE (0.572) and T2-weighted FSE (0.597). T2*-weighted imaging achieved the highest sensitivity (81.4%) and the lowest specificity (86.6%). Postenhanced T2*-weighted imaging achieved the highest CNR (19.3 +/- 9.2). CONCLUSIONS: T2*-weighted imaging was the most accurate and sensitive method for detecting portal perfusion abnormalities compared with T1- or T2-weighted imaging, whereas T1- or T2-weighted imaging is superior in specificity to T2*-weighted imaging during ferucarbotran-enhanced MR imaging.

Contrast Media↗

PubMedDate not supplied

Hemodynamics in the microvasculature of thioacetamide-induced cirrhotic rat livers.

BACKGROUND/AIMS: To evaluate the hepatic microcirculatory changes in liver cirrhosis, in vivo microscopic findings were assessed quantitatively in cirrhotic rats. METHODOLOGY: Using in vivo microscopy, the blood flow velocity through terminal portal venules and terminal hepatic venules, and their diameters were measured. The rats were classified into a normal group, fibrosis group, and cirrhosis group, histopathologically. To estimate intrahepatic blood flow of the liver surface, laser-Doppler flowmeter was used for the three groups, and portal venous pressures were measured. RESULTS: Blood flow velocity through terminal portal venules increased significantly in cirrhosis rats. However, among the three groups, there were no significant differences with blood flow velocity through terminal portal venules, diameters of terminal portal venules and terminal hepatic venules. Portal venous pressure and intrahepatic blood flow of the liver surface increased significantly. CONCLUSIONS: These data indicate that pre-sinusoidal alterations to hemodynamics become manifest in the liver cirrhosis, which might be related to intrahepatic shunt formation.

Animals↗

PubMedDate not supplied

Percutaneous ethanol injection under CT fluoroscopy for hypervascular hepatocellular carcinoma following transcatheter arterial embolization.

BACKGROUND/AIMS: The present study was conducted to accurately monitor the pattern of ethanol distribution during percutaneous ethanol injection by computed tomography fluoroscopy and to examine the relationship between the distribution pattern and therapeutic effect. METHODOLOGY: Twenty-five hypervascular hepatocellular carcinomas were studied. Each was treated with transcatheter arterial embolization. However, as residual parts were detected, percutaneous ethanol injection under real-time computed tomography fluoroscopy was performed. For analysis, ethanol distribution and local recurrence rate were compared. RESULTS: Ethanol distribution in a tumor was classifiable into 3 patterns. In pattern 1, ethanol solution was distributed spherically. In pattern 2, ethanol solution spread forming linear boundaries indicating interruption of distribution by septa. In pattern 3, ethanol spread circumferentially only along the periphery sparing the central part of a tumor. The 6-month recurrence rate of the tumors in which ethanol solution was distributed to the whole viable part was 25% (pattern 1), 100% (pattern 2) and 0% (pattern 3), respectively. CONCLUSIONS: In the tumors showing distribution pattern 3 by computed tomography fluoroscopy, a combination therapy of transcatheter arterial embolization and percutaneous ethanol injection was more effective than in other patterns. Computed tomography fluoroscopy was useful for accurate monitoring and predicting the therapeutic effect of percutaneous ethanol injection.

Aged↗

PubMedDate not supplied

Diagnostic localization of extra-adrenal pheochromocytoma: comparison of (123)I-MIBG imaging and (131)I-MIBG imaging.

The accurate diagnostic localization of extra-adrenal pheochromocytoma is important in the treatment of primary and metastatic tumors. In this study, we report on a case of extra-adrenal pheochromocytoma in which the tumor could not be diagnosed by 131I-metaiodobenzylguanidine (MIBG) scintigraphy but only by 123I-MIBG scintigraphy. Our patient was a 16-year old girl whose chief complaint was headaches. High levels of catecholamines were detected in the blood and urine samples. 131I-MIBG scintigraphy could not detect any abnormal accumulation, but an accumulation of 123I-MIBG was found in the pelvis. Magnetic resonance imaging (MRI) revealed a broad-based bladder tumor at the site of the accumulation. Partial cystectomy was performed, and immunohistochemical staining examination confirmed the diagnosis of extra-adrenal pheochromocytoma in the urinary bladder. In this report, we compare 131I-MIBG scintigraphy with 123I-MIBG scintigraphy and discuss their characteristics.

3-Iodobenzylguanidine↗

PubMedDate not supplied

Cimetidine reduces impairment of cellular immunity after transcatheter arterial embolization in patients with hepatocellular carcinoma.

BACKGROUND/AIMS: Natural killer cells have an intrinsic ability to recognize and attack some tumor cells and infected cells. Natural killer cell cytotoxicity is depressed in patients with hepatocellular carcinoma. In particular, cell-mediated immunity is impaired after transcatheter arterial embolization, which is an effective therapy for hepatocellular carcinoma. There have been reports that cimetidine can activate cellular immunity and increase the survival time in patients with some cancers. Therefore, we investigated whether cimetidine could improve cellular immunity after transcatheter arterial embolization, especially in relation to natural killer activity. METHODOLOGY: Thirty-four patients with hepatocellular carcinoma and cirrhosis who underwent transcatheter arterial embolization at our hospital were studied prospectively after giving informed consent. The patients were divided into three groups. In group A, 14 patients were administered 800 mg of cimetidine a day. In group-B, 13 patients were administered 40 mg of famotidine or 300 mg of nizatidine a day. In group-C 7 patients did not receive histamine 2 receptor antagonists. Natural killer cell activity in peripheral blood was measured before transcatheter arterial embolization and on days 1 and 7. RESULTS: The % natural killer cell activity on day 1 was 74 in group A, 52 in group B, and 52 in group. The % activity on day 7 was 98 in group A, 71 in group B, and 82 in group C. Cimetidine group showed the significant higher % natural killer cell activity on day 1 (p = 0.032). CONCLUSIONS: Our study raises the possibility that cimetidine has the effect to preserve cell-mediated immune response during transcatheter arterial embolization.

Aged↗

PubMedDate not supplied

A clinicopathological study of inflammatory pseudotumors of the liver with special reference to vessels.

BACKGROUND/AIMS: Inflammatory pseudotumor of the liver is rare, and patients with inflammatory pseudotumor frequently undergo unnecessary surgical resection as a result of misdiagnosis of malignancy. In this study, we therefore investigated inflammatory pseudotumor clinicopathologically to clarify its characteristics. METHODOLOGY: Twenty patients including 3 with inflammatory pseudotumor and 17 with various malignant liver tumors were studied. We further investigated tumor vessels by means of immunohistochemistry using monoclonal antibodies against CD34, factor VIII-related antigen and alpha-smooth muscle actin. RESULTS: Although serum levels of alkaline phosphatase were significantly higher in inflammatory pseudotumor patients than in other patients, the laboratory data alone could not precisely distinguish inflammatory pseudotumor from other hepatic tumors. On imaging studies such as ultrasonography and computed tomography, significant changes in tumor size, especially size reduction, during relatively short follow-up periods were often observed in inflammatory pseudotumor but not in other liver tumors. An enhancement of the peripheral regions of inflammatory pseudotumor was frequently observed in the early phase of contrast-medium dynamic computed tomography. This might be due to abnormal vessels located in the peripheral regions of inflammatory pseudotumor which might result from obliteration of some pre-existing vessels in portal tracts within inflammatory pseudotumor. Immunohistochemical analysis further revealed that abnormal vessels in the peripheral regions of inflammatory pseudotumor were positively stained with CD34, factor VIII-related antigen and alpha-smooth muscle actin as were tumor sinusoids within hepatocellular carcinoma and tumor capillaries in other malignant liver tumors. CONCLUSIONS: Although inflammatory pseudotumor seems to have some features in imaging studies, a biopsy is needed for a correct diagnosis of inflammatory pseudotumor.

Actins↗

PubMedDate not supplied

Mental health of patients visiting an outpatient menopause clinic.

OBJECTIVE: It is understood that psychological factors affect climacteric disturbances. However, details behind these issues remain unknown. The aim of this study was to investigate the mental health of climacteric patients. SUBJECTS AND METHODS: The subjects were 127 Japanese women who visited our outpatient menopause clinic, complaining chiefly of climacteric disturbances. There were 38 premenopausal patients included. The responses to the HADS (Hospital Anxiety and Depression Scale) and the SDS (Self-rating Depression Scale), obtained at the first examination, were compared with HADS data from 2,943 healthy women and 94 patients hospitalized to receive gynecological surgery. RESULTS: The HADS score and the SDS score of the outpatients of the menopause clinic showed a relatively high (statistically significant) correlation. The average HADS total, anxiety and depression scores for these patients were significantly higher than those for healthy controls. The total and depression scores were also significantly higher than those for patients hospitalized to undergo surgery for benign conditions, and were comparable to those for patients with malignant conditions. The comparison between pre- and postmenopausal patients showed that the premenopausal group was more likely to be depressed. The anxiety score was also high in this group (not significantly). CONCLUSIONS: These results indicate that patients with climacteric disturbances, especially premenopausal patients, often experience psychological discomfort, and that attention should be given not only to their depression but also to their anxiety.

Adult↗

PubMedDate not supplied

The influence of radiofrequency ablation on hepatic vessels in porcine liver.

BACKGROUND/AIMS: The objective of this study was to clarify the influence of radiofrequency ablation on the portal and hepatic vein. METHODOLOGY: Hepatic radiofrequency ablation was performed on 18 swine (mean weight, 22 kg). The livers were removed immediately, 1 week or 3 weeks following ablation. Vessel patency and diameter were determined by computed tomography, and the severity of endothelial injuries was determined histopathologically. RESULTS: The patency rate for portal and hepatic veins with diameters less than 3.0 mm decreased sequentially. At three weeks following ablation, the patency rate for vessels with diameters more than 3.0 mm was significantly higher (P<0.05) compared to those with diameters less than 2.0 mm. In portal and hepatic veins contiguous to ablated hepatic parenchyma, the endothelium with intimal thickening was found at 1 to 3 weeks following ablation, although its detection rate was decreased until 3 weeks. CONCLUSIONS: The portal and hepatic vein with diameters more than 3.0 mm in radiofrequency lesions maintained high patency. The endothelium seems to play an important role for maintaining vessels patency and the distal hepatic tissue following ablation. We believe that this maintained vascular patency may be the advantage of radiofrequency ablation over the PEIT.

Animals↗

PubMedDate not supplied

Influence of aging, gastric mucosal atrophy and dietary habits on gastric secretion.

BACKGROUND/AIMS: Studies in Japan have reported on the association between gastric secretion and age with consideration given to gastric mucosal atrophy but not pepsin secretion. Though recent reports have shown enhanced gastric secretion in the Japanese, attributed to dietary westernization, the association between diet and gastric secretion is not clear. In this study, the association between gastric secretion and mucosal atrophy, age, and dietary habits was evaluated. METHODOLOGY: The subjects were 47 preoperative patients without upper gastrointestinal disorders. Acid secretion, pepsin secretion, serum pepsinogen level, and serum Helicobacter pylori antibody titer were measured. Dietary habits were investigated by questionnaire. RESULTS: Gastric secretion did not differ among the young, middle, and elderly age groups. Compared with the group without atrophy (pepsinogen I/II > 3.0, 32 subjects), the group with atrophy (I/II < or = 2.5, 11 subjects) showed significantly decreased gastric secretion and a significantly high Helicobacter pyloriseropositive rate. In the group without atrophy, acid and pepsin secretion was significantly correlated with energy intake, pepsin secretion was significantly correlated with glucose intake, and gastric secretion tended to increase with age. CONCLUSIONS: In the absence of gastric mucosal atrophy, gastric secretion does not decrease with age, and is related to dietary habits.

Adult↗