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Biomedical subjects

T Ishigaki

Publications and source records attributed to T Ishigaki.

At least 19 recordsLinked to original sources
PubMed2001

Virtual endoscopy of the labyrinth, using a 3D-FastASE sequence.

Virtual endoscopy (VE) of the labyrinth was performed using three-dimensional (3D)-fast asymmetric spin-echo MR imaging. The spatial resolution requirements and the usefulness of zero-fill interpolation (ZIP) were evaluated, and VE was used to examine three patients. The (0.6-mm) voxel data with ZIP satisfies the minimum requirements for VE for evaluation of the complex 3D anatomy and pathology of the labyrinth. J. Magn. Reson. Imaging 2001;13:792-796.

Adolescent↗
PubMed2001

High- and moderately high-methionine uptake demonstrated by PET in a patient with a subacute cerebral infarction.

In patients with cerebral tumors, high accumulations of L-methyl-11C-methionine (11C-Met) have been reported in some cases of cerebral ischemic disease, but no high accumulations of 11C-Met in areas where only transient arterial occlusions are most likely to occur have been reported. Herein we present a case of a high accumulation of 11C-Met in an area of frontal interhemispheric cerebral infarction and a moderately high accumulation with an unclear margin in a distant frontal convexity area. A craniotomy revealed a subacute stage of cerebral infarction in the interhemispheric lesion, and an ischemic change in the distant convexity area. Sixteen months after onset, CT scans demonstrated an infarction area in the interhemispheric lesion only, and no atrophic changes were observed in the distant convexity area indicating that no serious tissue damage had occurred.

Adult↗
PubMed2001

Detection of subtle pulmonary disease on CR chest images: monochromatic CRT monitor vs color CRT monitor.

To clarify the diagnostic efficacy of color soft-copy computed radiographic (CR) images of the chest in the detection of subtle pulmonary abnormalities. Twenty observers compared 87 soft-copy CR images on four types of CRT monitor (nonmagnified monochromatic CRT, magnified monochromatic CRT, nonmagnified color CRT, and magnified color CRT). Of 87 test images, 45 (including two identical sets of 12 images to test intraobserver variability) were abnormal and 42 (including two identical sets of 12 images) were normal. Of the 45 abnormal images, 15 showed subtle abnormalities, 15 showed mild abnormalities, and 15 showed obvious abnormalities. In the receiver operating characteristic (ROC) analyses, there were no statistically significant differences among the four types of CRT display formats in the detection of subtle abnormalities. Color CRT monitors can replace monochromatic CRT monitors without any loss in the ability to detect subtle interstitial lung disease.

Adult↗
PubMed2001

Muscular sarcoidosis.

There are four types of muscular sarcoidosis: nodular, chronic myopathy, acute myositis, and asymptomatic. The nodular type is important because it may be confused with a soft tissue tumor. Magnetic resonance (MR) imaging provides specific findings. A star-shaped central structure of decreased signal intensity, a "dark star" sign, is seen on the axial images. A long nodule with an inner stripe of decreased signal intensity and outer stripes of increased signal intensity, a "three stripes" sign, is seen on the coronal and sagittal images. In the chronic myopathy type, the role of MR imaging is limited. Gallium scintigraphy, which reflects activity of inflammation, may show increased uptake. In the acute myositis type, MR imaging shows increased signal intensity, and gallium scintigraphy shows increased uptake; however, these findings are nonspecific.

Humans↗
PubMed2001

Further reduction of radiation dose in helical CT for lung cancer screening using small tube current and a newly designed filter.

A new aluminum filter, 5.8 mm thick at the center, was designed. The effective energy, exposure dose, absorbed dose, and noise were measured by using low-dose technique, very low-dose technique with a conventional filter, and very low-dose technique with a new filter on a chest phantom. Accuracy of very low-dose computed tomography (CT) with a new filter was compared against standard helical CT in 40 patients and against chest radiography in 35 patients. Effective energies were 42.6 keV and 51.6 keV at a conventional filter and the new filter, respectively. Compared against 20mA with a conventional filter, exposure dose was reduced by 17%, and absorbed dose was equivalent, at 30 mA with the new filter. Noise was improved by 9%. Compared with standard helical CT, the sensitivity, specificity, and accuracy of very-low-dose helical CT were 100%, 88%, and 95%, respectively. Very-low-dose helical CT was found to be significantly superior to chest radiography in the detection of lung cancers. Using a smaller tube current and an appropriate filter allows a further reduction in radiation dose in helical CT for lung cancer screening.

Adult↗
PubMed2001

Automated detection of pulmonary nodules in helical CT images based on an improved template-matching technique.

The purpose of this study is to develop a technique for computer-aided diagnosis (CAD) systems to detect lung nodules in helical X-ray pulmonary computed tomography CT) images. We propose a novel template-matching technique based on a genetic algorithm (GA) template matching (GATM) for detecting nodules existing within the lung area; the GA was used to determine the target position in the observed image efficiently and to select an adequate template image from several reference patterns for quick template matching. In addition, a conventional template matching was employed to detect nodules existing on the lung wall area, lung wall template matching (LWTM), where semicircular models were used as reference patterns; the semicircular models were rotated according to the angle of the target point on the contour of the lung wall. After initial detecting candidates using the two template-matching methods, we extracted a total of 13 feature values and used them to eliminate false-positive findings. Twenty clinical cases involving a total of 557 sectional images were used in this study. 71 nodules out of 98 were correctly detected by our scheme (i.e., a detection rate of about 72%), with the number of false positives at approximately 1.1/sectional image. Our present results show that our scheme can be regarded as a technique for CAD systems to detect nodules in helical CT pulmonary images.

Algorithms↗
PubMed2001

Application of resampling techniques to the statistical analysis of the Brier score.

We investigated the application of resampling techniques to the statistical analysis of the Brier score (B), and extended them to the statistical comparison of two Bs derived from the same set of patients. The resampling techniques are helpful in the statistical analysis of B, and there are almost no differences between the jackknife method and the bootstrap method in this analysis. Thus, we believe that B should be used more often as an index to evaluate probabilistic judgments in the case in which the data sets for the assessment are "degenerate" as the "receiver operating characteristic data sets."

Case-Control Studies↗
PubMed2000

Abundance of polymers degrading microorganisms in a sea-based solid waste disposal site.

In order to assess the degradability of plastics in solid waste disposal landfill sites, microbial populations capable of degrading five kinds of plastic-constituting polymers, poly epsilon-caprolactone (PCL), polylactic acid (PLA), polyethylene glycol (PEG), poly-beta-hydroxybutyrate (PHB) and cellulose acetate (CA), in a sea-based solid waste disposal site were investigated. Enumeration of aerobic and anaerobic polymers-degrading microorganisms (PDMs) was performed against to total 8 leachate samples, which were seasonally collected from the facultative pretreatment pond and the aerated lagoon. Both aerobic and anaerobic PDMs for natural polymers, PHB and CA, were found in all of the samples, while those for chemically-synthesized polymers, PCL, PLA and PEG, could not be always detected. In most cases, the ratios of the PHB- and CA-degraders to the heterotrophic bacterial population were more than 0.1%. On the other hand, the ratios of PCL-, PLA- and PEG-degraders were often much lower. These data indicate that the plastics degradation potential is commonly present in the studied disposal site, and that the degradation potential for plastics composed of chemically-synthesized polymers is inferior to that of natural polymers. Population sizes of the PDMs correlated to those of heterotrophic bacteria, and the counts of aerobic heterotrophic bacteria and PDMs in the aerated lagoon tended to be higher than those of anaerobic ones, indicating that the aeration of the leachate resulted in the activation of growth of whole aerobic microbial community including the PDMs.

Bacteria↗
PubMed2000

High-dose-rate interstitial brachytherapy of Bartholin's gland: A case report.

OBJECTIVE: To preserve the organs and function of the anus and ureter, radiotherapy was chosen for an advanced vulvar tumor originating from Bartholin's gland. METHODS: The patient was a 74-year-old female with stage III (FIGO) vulvar cancer derived from the left Bartholin's gland. She received 63 Gy to the vulvar lesion with external beam irradiation followed by 30 Gy of high-dose-rate interstitial brachytherapy. RESULTS: One year after radiotherapy, simple vulvectomy and reconstructive surgery were performed. The anal and ureteral functions were preserved. Histological examination revealed no evident malignant cells. CONCLUSION: Owing to the technological development of radiotherapy and improved reconstructive surgery, radiotherapy in treatment of the vulvar area has become effective and safe and could be indicated more as a treatment option for the sake of organ preservation.

Aged↗
PubMed2000

Extrastriatal mean regional uptake of fluorine-18-FDOPA in the normal aged brain--an approach using MRI-aided spatial normalization.

The aim of this study was to define the mean regional 6-[(18)F]fluoro-l-dopa (FDOPA) uptake rate constant (K(i)) values in the striatal and extrastriatal regions of the brain of normal subjects using magnetic resonance imaging (MRI)-aided spatial normalization of the FDOPA K(i) image and using automatic region of interest (ROI) analysis. Dynamic three-dimensional FDOPA positron emission tomography (PET) and three-dimensional magnetic resonance (MR) images were acquired in 13 aged normal subjects. The FDOPA add image and the K(i) image of each subject were transformed into standard stereotactic space with the aid of individual coregistered MR image. The mean regional K(i) values of the striatal and extrastriatal regions before normalization were compared with the respective values after normalization. Then automatic ROI analysis was performed on the MRI-aided spatially normalized K(i) images of the 13 normal subjects. The K(i) values on original images and those on spatially normalized images were in good agreement, indicating that the spatial normalization technique did not change the regional K(i) values appreciably. Automatic ROI analysis of the spatially normalized FDOPA K(i) images of the normal subjects, showed high K(i) values in ventral and dorsal regions of the midbrain, amygdala, hippocampus, and medial prefrontal cortex, in addition to caudate nucleus and putamen, which correspond to the dopaminergic projections in the brain. Spatial normalization technique helped to establish a database of FDOPA K(i) images of normal subjects and high K(i) values were observed widely besides striatal regions corresponding to the dopaminergic projections in the brain.

Aged↗
PubMed2000

Determination of optimal radiation energy for different breast sizes using CT-simulator [correction of simulatior] in tangential breast irradiation.

BACKGROUND: The purpose of this study is to determine and recommend the optimal radiation source according to breast size for tangential irradiation in breast conserving therapy. METHODS: Twenty-eight patients treated at our department from January 1994 to January 1996 were studied. The dose distribution within the irradiated breast was calculated using a (60)Co-gamma ray and 6 MV-X ray. Then we compared 3-D dose distributions of the (60)Co-gamma ray and 6 MV-X ray in different-sized breasts. Three parameters (breast volume, chest wall separation, and breast height) were adopted as representative of breast size. We also examined correlations among the three parameters. RESULTS: When the breast size was large (breast volume >400 cm(3), chest wall separation > 19.5 cm, or breast height > 6.5 cm), the average volume of normal tissue which received more than 110% of the isocenter dose ("hot spot") was significantly greater with the (60)Co-gamma ray than with the 6 MV-X ray (p < 0.05). A similar result was obtained with regard to hot spots in the clinical target volume. The cold area that received less than 95% of the isocenter dose was greater using a 6 MV-X ray when the breast size was small (breast volume <200 cm(3), chest wall separation <17.5 cm, or breast height <5.0 cm). However, the difference was not significant. There was a significant correlation between breast volume and chest wall separation (r =0.849, p <0.001). Breast volume and breast height were also significantly correlated (r =0.813, p <0.001). CONCLUSIONS: Since breast volume and shape are different in each patient, the optimal energy should be selected for each case to obtain uniform dose distribution in breast-conserving therapy. Chest wall separation or breast height, which are measurable without a 3-D planning system, can substitute for breast volume as parameters for breast size. We recommend that the (60)Co-gamma ray not be used for treating large breasts, those with chest wall separation > or =19.5 cm or breast height > or =6.5 cm.

Anthropometry↗
PubMed2000

A case of malignant lymphoma of the hand.

Malignant lymphoma is rarely seen in the hand. We present a case of malignant lymphoma of the hand with Ga-67 citrate and MR images, and discuss the usefulness of Ga-67 citrate scintigraphy for diagnosing this condition.

Aged↗
PubMed2000

Role of ultrasonography in the detection of intraductal spread of breast cancer: correlation with pathologic findings, mammography and MR imaging.

The purpose of this study was to assess the role of US in the detection of intraductal spread of breast cancer in comparison with mammography (MMG) and MRI. In 46 patients with breast cancer, US features of the intraductal component were classified as ductal type or distorted type. Histopathologically, 29 of 46 (63%) cases had intraductal components, and the sensitivity, specificity, and accuracy rates in detection of intraductal spread were 89, 76, and 85%, respectively. Each US pattern demonstrated good correspondence to the histologic components, and the distorted type correlated well with comedo-type carcinoma. Mammography was performed in all cases, and the sensitivity, specificity, and accuracy rates in detection of intraductal spread were 55, 100, and 72%, respectively. In comedo type, MMG could diagnose the extent of intraductal spread more accurately compared with US examination. Magnetic resonance imaging comparison was available in 25 cases. Magnetic resonance imaging depicted intraductal extension as an enhanced area during the early phase of a contrast enhancement study with a sensitivity of 93%. Ultrasound and MRI were closely related in terms of morphologic characteristics: the ductal type of US image correlated well with linear enhancement on MRI, whereas the distorted type correlated with regional or segmental enhancement. Current US examination is useful in depicting the intraductal spread of breast cancer; however, US has a tendency to underestimate intraductal component of comedo type compared with MMG and MRI.

Breast↗
PubMed2000

Diagnostic utility of tumor vascularity on magnetic resonance imaging of the breast.

The objective of this study was to examine the relation of tumor vascularity on magnetic resonance imaging (MRI) with differential diagnosis malignant from benign lesions and tumor invasiveness in breast carcinoma. Forty-nine patients with breast cancer or benign lesion (median 49 yrs) were examined with dynamic MRI. Scanning of the entire breast was performed at 1.5 T with a three-dimensional fast spin echo sequence, using an original polarity altered spectral and spatial selective acquisition (PASTA) technique for fat suppression. Subsequently 0.1 mmol/Kg Gd-DTPA was administered and 3-6 images were obtained. The presence or absence of intratumoral, marginal and peritumoral vascularity on MRI was recorded. The excised specimen was histopathologically examined for the size of lesion, the presence and extent of local invasion. Tumor size on MRI correlated closely with the size at morphologic examination (r = 0. 96). Intratumoral (p = 0.04), marginal (p = 0.05) and peritumoral vascularity (p = 0.01) were less common in benign than in malignant lesions. Among the latter, intratumoral (p = 0.01) and marginal (p = 0.03) vascularity were more common in invasive carcinomas than in DCIS. In the subset of invasive carcinomas (n = 31); however, the tumors exhibiting intratumoral vascularity were markedly larger (p = 0.03). The presence of intratumoral and marginal vascularity on MRI can help predict both the differential diagnosis malignant from benign lesions and the presence tumor invasion in breast carcinomas.

Adolescent↗
PubMed2000

Absence of correlation of MUC1 expression to malignant behavior of renal cell carcinoma in experimental systems.

A correlation between MUC1 expression in renal cell carcinomas (RCCs) and the clinical stages was previously demonstrated. To assess whether MUC1 expression is causally related to malignant tumor behavior, MUC1 cDNA was stably transfected into a renal carcinoma cell line SN12C that expresses trace levels of MUC1. MUC1 with sialylated carbohydrate chains was detected on the surface of transfected cells in two independent experiments. There was no correlation between MUC1 expression and in vitro growth and motility. In vivo growth of the transfectants at the site of orthotopic transplantation in nude mice was slower than mock transfected cells. Therefore, MUC1 alone did not seem to confer a malignant phenotype to RCCs.

Animals↗
PubMed2000

Lung cancer screening: minimum tube current required for helical CT.

PURPOSE: To investigate the minimum tube current required for helical computed tomography (CT) for lung cancer screening. MATERIALS AND METHODS: Thirty helical scans of the lung were obtained at effective tube currents of 50, 30, 20, 18, 12, 10, and 6 mAs in seven healthy volunteers. Computer-generated nodules 6 mm in diameter that showed ground-glass opacity were superimposed on the images. The image quality and detectability of nodules were evaluated subjectively by six observers. The SDs of measured CT numbers were calculated. The results were analyzed according to location in the lung. RESULTS: Compared with the subjective quality of images obtained at 50 mAs, the subjective quality of images obtained at 20 mAs was not significantly different. The detectability of nodules was not significantly degraded by reducing the tube current to 20 mAs in the upper zone of the lung, to 12 mAs in the middle zone, or to 18 mAs in the lower zone. The SDs at the apex and base of the lung were larger than those at other levels, and the difference became greater as the dose was reduced. CONCLUSION: The minimum tube current required for screening helical CT differs for different locations in the lung. An ideal CT protocol for the lung should permit the tube current to be changed during helical scanning.

Adult↗
PubMed2000

Endovascular stent-graft deployment: temporary vena caval occlusion with balloons to control aortic blood flow-experimental canine study and initial clinical experience.

Vena caval occlusion was evaluated in animal experiments. In five patients with thoracic aortic aneurysms, two balloon catheters were introduced via the femoral vein to the inferior vena cava and superior vena cava and inflated before stent-graft deployment. Aortic pressure and flow were immediately decreased, which minimized the downstream shift of the stent-grafts. Temporary vena caval occlusion is safe and effective for precise aortic stent-graft deployment.

Aged↗