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Biomedical subjects

K Kiyono

Publications and source records attributed to K Kiyono.

At least 19 recordsLinked to original sources
PubMed2001

Effects of JPEG and wavelet compression of spiral low-dose ct images on detection of small lung cancers.

PURPOSE: To compare the effect of compression of spiral low-dose CT images by the Joint Photographic Experts Group (JPEG) and wavelet algorithms on detection of small lung cancers. MATERIAL AND METHODS: Low-dose spiral CT images of 104 individuals (52 with peripheral lung cancers smaller than 20 mm and 52 control subjects) were used. The original images were compressed using JPEG or wavelet algorithms at a ratio of 10:1 or 20:1. Five radiologists interpreted these images and evaluated the image quality on a high-resolution CRT monitor. Observer performance was studied by receiver operating characteristic (ROC) analysis. RESULTS: There was no significant difference in the detection of cancers measuring 6 to 15 mm in uncompressed images and in those compressed by either of the algorithms, although the quality of images compressed at 20:1 with the wavelet algorithm was somewhat inferior. A lower diagnostic accuracy was noted using images compressed by the JPEG or wavelet algorithms at 20:1 in detecting lung cancers measuring 6 to 10 mm and cancers measuring from 6 to 15 mm with ground-glass opacity. CONCLUSION: Compression of low-dose CT images at a ratio of 10:1 using JPEG and wavelet algorithms does not compromise the detection rate of small lung cancers.

Algorithms↗
PubMed2000

Optimal tube current for lung cancer screening with low-dose spiral CT.

PURPOSE: To determine the optimal tube current for spiral CT for lung cancer screening. MATERIAL AND METHODS: Low-dose spiral CT images from 20 subjects were obtained with 50 mA, 25 mA, 10 mA and 5 mA tube currents. The accuracy in detecting 21 nodules measuring 3 to 14 mm in diameter was tested using receiver operating characteristics (ROC) to determine the diagnostic accuracy and statistical significance. RESULTS: Compared with 50 mA, 25 mA showed no statistical difference. A significant difference was seen between 50 mA and 5 mA images and between 25 mA and 10 mA images, in the detection of lung parenchymal nodular lesions. CONCLUSION: Approximately 25 mA is the optimal tube current for the detection of pulmonary nodules as it allows a reduction of the radiation dose without sacrificing diagnostic accuracy.

Adenocarcinoma↗
PubMed1999

Saccharomyces cerevisiae cultured under aerobic and anaerobic conditions: air-level oxygen stress and protection against stress.

Cells of Saccharomyces cerevisiae were grown aerobically and anaerobically, and levels of the protective compounds, cysteine and glutathione, and activities of defensive enzymes, catalase and superoxide dismutase, against an oxygen stress were determined and compared in both cells. Aerobiosis increased both the compounds and enzyme activities. The elevated synthesis of glutathione could be associated with the increased levels of cysteine which in its turn was found to be controlled by the oxygen-dependent activation of cystathionine beta-synthase.

Aerobiosis↗
PubMed1999

S-(1,2-Dicarboxyethyl)glutathione in yeast: partial purification of its synthesizing enzyme.

S-(1,2-Dicarboxyethyl)glutathione (DCE-GS) was found in Saccharomyces cerevisiae, but not in bacterial species nor in a unicellular alga (Acetabularia acetabulum). The enzyme that catalyzes condensation of L-malate and glutathione (GSH) to form DCE-GS was partially purified from baker's yeast. It had a molecular mass of 49 kDa and was monomeric and the Km values were 2.2 and 1.4 mM for L-malate and GSH, respectively. The enzyme had a pH optimum of 7.5. DCE-GS levels in yeast cells were significantly higher in aerobic cultures than in anaerobic ones. DCE-GS was synthesized in cells cultured between 20 and 35 degrees C.

Acetabularia↗
PubMed1998

Experiences of 23 patients > or = 90 years of age treated with radiation therapy.

PURPOSE: To present 23 patients > or = 90 years old treated with radiotherapy, and to retrospectively evaluate the results of radiotherapy and tolerance in these patients. METHODS AND MATERIALS: The clinical records of 27 patients over 90 years of age who were treated with radiotherapy at the Department of Radiology, Shinshu University Hospital, and eight affiliated general hospitals from 1990 until 1995 were reviewed. The strategy of radiotherapy was individually planned depending on the stage of the disease and performance status (PS) of the patient; however, it was not modified, based solely on chronologic age. The overall survival rate and disease-free survival rate were determined using the Kaplan-Meier method. The Radiation Therapy Oncology Group scoring criteria of acute and late reactions of radiation therapy were used. RESULTS: This group of patients accounted for 0.37% of all patients treated with radiotherapy in these hospitals. Of these, 23 patients in whom cancer was pathologically confirmed and whose follow-up data were available for retrospective analysis were included in the final evaluation of data. The age of the 23 patients ranged from 90 to 96 years (median 93). Tumor was untreated and in the early stage in five patients, locoregionally advanced in 13, recurrent in four, and systemic in one. Definitive radiation therapy was administered in 12 patients (13 sites), preoperative intent in one, and palliative intent in 10. The period of observation ranged from 2.5 to 6 years (median 18 months). Seven patients were alive for 15-67 months. Fourteen patients died because of intercurrent diseases or senility associated with active cancer, and two because of senility without evidence of cancer. The overall and relapse-free survival rates were 65% and 30% at 1 year and 30% and 21% at 2 years, respectively. Definitive radiation therapy was completed in 13 of 13 patients (100%), and local control was attained in 9 of 13 patients at 6 months (62%). Palliative radiation therapy was completed as intended in 7 of 11 (64%), and effects of palliation were observed in 9 of 11 patients (81%). Acute dermatitis, mucositis, pharyngitis, esophagitis, and cystitis of grade 2-3 related to the definitive radiation therapy were tolerable for the patients with good PS. It took 3-7 weeks (median 5) for acute moist desquamation of six lesions of skin cancer to heal. Depending on the radiation doses, grade 1-2 atrophy of skin and telangiectasia were documented for eight patients followed up for more than 1 year. A brief description of representative case is presented. CONCLUSION: Patients older than 90 years with good PS may tolerate the acute effects of radiotherapy administered according to conventional fractionation schedules. Definitive radiation therapy should be considered, when applicable, even for patients older than 90 years.

Aged↗
PubMed1998

Relationship of 31P MR spectroscopy to the histopathological grading of chronic hepatitis and response to therapy.

PURPOSE: In vivo phosphorus-31 MR spectroscopy (31P MRS) was performed in the human liver in order to investigate the relation between: the ratios of phosphorus metabolites in the liver; the histopathological grading of chronic hepatitis; and the response to therapy. MATERIAL AND METHODS: Hepatic 31P MRS using the DRESS method (depth-resolved surface-coil spectroscopy) was carried out in 45 patients with chronic viral hepatitis or autoimmune hepatitis, and in 16 control subjects. We measured the ratios of the peak areas of phosphomonoesters (PME), inorganic phosphate (Pi), or phosphodiesters (PDE) to the peak area of beta-adenosine triphosphate (ATP). RESULTS: The PDE/ATP ratio of patients with chronic hepatitis or liver cirrhosis was lower than that of control subjects (liver cirrhosis = 0.74; chronic active hepatitis = 1.13-1.21; normal = 1.43); only a small difference was found in the PME/ATP and Pi/ATP ratios. There was no correlation between the spectra and histopathological grading or response to therapy, but the response to therapy was poor when a reduced PDE/ATP ratio was present. CONCLUSION: The PDE/ATP ratio measured by 31P MRS makes it possible to identify the transition of chronic active hepatitis into liver cirrhosis with a poor response to therapy.

Adenosine Triphosphate↗
PubMed1997

A novel brain-specific p53-target gene, BAI1, containing thrombospondin type 1 repeats inhibits experimental angiogenesis.

The genetic alteration of p53 is associated with neovascularization during progression of glioma to its more malignant form, glioblastoma. Hence, one or more of the genes transactivated by p53 is likely to function as an angiogenesis inhibitors. We isolated a novel p53-inducible gene that encodes a 1584-amino-acid product containing five thrombospondin type 1 (TSP-type 1) repeats and is specifically expressed in the brain. A recombinant protein corresponding to the TSP-type 1 repeats of this gene product inhibited in vivo neovascularization induced by bFGF in the rat cornea. The expression of this gene, designated BAI1 (brain-specific angiogenesis inhibitor 1) was absent or significantly reduced in eight of nine glioblastoma cell lines, suggesting BAI1 plays a significant role in angiogenesis inhibition, as a mediator of p53.

Amino Acid Sequence↗
PubMed1997

Lung nodule conspicuity using unsharp mask filters with storage-phosphor-based computed radiography.

PURPOSE: To compare the performance of various types of unsharp mask filter applied in storage-phosphor-based computed radiography (SR), and to improve the detection of faint nodules of the lung cancer type. MATERIAL AND METHODS: A total of 120 SR radiographs were obtained by means of an anthropomorphous chest phantom and a combination of 3 types of small simulated nodule (5-mm sphere-shaped, and 5-mm and 10-mm hemisphere-shaped) placed on the phantom's surface. Eight combinations of nodule site were selected from 16 predetermined chosen sites, and 5 types of parameter were used for unsharp mask filtering. Eight observers evaluated the images, and the detectability of the lung nodules was evaluated from the images by a ROC analysis. RESULTS: The visibility of the 10-mm hemispherical nodules was nearly equivalent at each site when 5 types of unsharp mask filter were used. The detection of the 5-mm nodules with mid-frequency suppressing and very-low-frequency enhancing filters was better than with a conventional (department standard) mid-frequency enhancing filter. CONCLUSION: Mid-frequency suppressing versions of the filter helped to demonstrate faint nodular opacity, which is often shown by early bronchogenic carcinoma. This filter could replace conventional filters in the detection of lung nodules.

Carcinoma, Bronchogenic↗
PubMed1996

Magnetic resonance imaging of neurogenic tumors of the thoracic inlet: determination of the parent nerve.

To investigate the value of magnetic resonance imaging (MRI) in determining the parent nerves of neurogenic tumors in the thoracic inlet, analysis of MR images was performed in nine patients with surgically resected neurogenic tumors in the thoracic inlet (two neurofibromas and one schwannoma of the vagus nerve, three schwannomas of the brachial plexus, and two schwannomas and one ganglioneuroma of the sympathetic nerves). These MR images were compared with surgical and pathologic findings. The multidirectional capability and excellent tissue contrast of MRI facilitated recognition of the location, shape, and extent of the tumors. MRI, which permitted an easy understanding of the spatial relation between the tumors and the subclavian vessels, scalenus muscles, and brachial plexus, was useful in determining the nerves of origin. Two neurofibromas, four of six schwannomas, and one ganglioneuroma were recognized to extend along the axes of the parent nerves on MR images. MRI is useful in determining the parent nerve of neurogenic tumors in the thoracic inlet and is helpful in planning surgical treatment of these tumors.

Brachial Plexus↗
PubMed1996

[Evaluation of image quality of medical facsimile as a radiological image recording system].

We examined the usefulness of a new medical facsimile (MFAX) system in recording and transmitting various kinds of medical images, including X-ray images and colored histopathologic images. The system consists of an image scanner, a magnetic disk for image storage, a transmission circuit and a thermal image printer. Transmission time for a FCR (Fuji computed radiography) image by super-fine mode was 6 minutes. We used ROC (receiver operating characteristics) curves to evaluate the ability of eight radiologists to detect the small simulated nodules placed on an anthropomorphic chest phantom and shown on MFAX images. The radiologists observed both the FCR films and MFAX copies and determined the presence or absence of simulated nodules using five confidence levels. The results obtained for FCR films and MFAX images showed no statistically significant difference.

Humans↗
PubMed1996

[High-resolution CT of epidermoid carcinoma in peripheral lung fields: radiologic-pathologic correlation].

We correlated high-resolution CT (HR-CT) images of 30 surgically resected epidermoid carcinomas in peripheral lung fields with pathologic findings. We classified peripheral epidermoid carcinomas into three types based on HR-CT findings. All tumors showed a notch along their margin. Type 1 shows scanty speculations without the convergence of surrounding lung structures. Type 2, which has two subtypes, shows a spiculated border with the convergence of peripheral lung structures. Type 2a has fine irregularities in its border, while type 2b has few fine irregularities. The convergence of peripheral lung structures seen in type 2 carcinoma is caused by the presence of scar tissue within tumors. Speculations corresponded to tumor extension or lymphocytic infiltration, sometimes along pulmonary vessels or interlobular septa, and fine irregularities seen in type 2a corresponded to summation of fibrous thickening of alveolar septa. Nine tumors showed varying-sized cavities, which were caused by the circulatory disturbance and/or central necrosis seen in tumor nests. In conclusion, HR-CT images were well correlated with pathologic findings of the resected specimens; however, some type 2a tumors may mimic adenocarcinoma on HR-CT findings.

Adult↗
PubMed1996

[Detectability of simulated nodules on chest phantom by Fuji computed radiography: comparison of different nodule sizes, configurations and tube voltages].

The detectability of simulated nodules placed on a chest phantom and shown on FCR images has been studied. Different tube voltages (130 kVp, 100 kVp), presence or absence of compensation filter, various sites and different sizes (5 mm/10 mm) and configurations (spherical or broad based) of the nodule were examined. 112 FCR chest phantom images were evaluated by ten radiology specialists utilizing ROC analysis. The detection rate for nodules was influenced in general by the site. The detection rate was as follows in decreasing order: intercostal, overlaid with one rib, two ribs, diaphragm and heart. Detection of nodules of 10 mm in height was mainly influenced by the density of the lung where the nodule was located, whereas that of nodules of 5 mm in height was more dependent on the site of the nodule, probably greatly influenced by the amount of structure mottle. Spherical nodules of 5 mm in height were more frequently recognized than the broad-based ones. High kVp (130 kVp) resulted in a higher detection rate for both sizes of nodules than low kVp (100 kVp). Detection of spherical nodules overlying the heart or diaphragm was improved with the use of a compensation filter.

Humans↗
PubMed1994

[Study of X-ray filter and peak kilovoltage in film-screen chest radiographs in regard to detection of simulated pulmonary nodules: comparison between film-screen combination and FCR].

We compared the ability of standard film-screen chest radiographs to detect simulated pulmonary nodules. The radiographs were taken with different X-ray filters and tube voltages. Detection capability was analyzed utilizing receiver operating characteristic (ROC) curves formed from the interpretation of six readers. Nodule detection was slightly better in images obtained with a tube voltage of 135 kVp than with one of 100 kVp (not statistically significant). Approximately equal detection performance was shown by a conventional film-screen system and FCR with three X-ray filter sets: a copper filter backed by aluminium, a tungsten filter backed by yttrium and aluminium, and a lead filter backed by yttrium and aluminium. Results showed less X-ray exposure with the two latter filter sets. Unenhanced FCR images taken with approximately the same X-ray exposure as conventional radiographs showed nearly equal ability to detect the simulated nodules.

Humans↗
PubMed1994

[Study of X-ray filter and peak kilovoltage in Fuji Computed Radiography in regard to the detection of simulated pulmonary nodules].

To determine a suitable combination of X-ray filter and tube kilovoltage for Fuji Computed Radiography (FCR), to provide better detection of pulmonary nodules and reduce patient exposure, we compared observer performance with different X-ray filters and tube voltages. Radiographs were obtained with a copper filter backed by aluminium, with a tungsten filter backed by yttrium and aluminium, and with a lead filter backed by yttrium and aluminium, at both 100 kVp and 135 kVp. Observer performance in detecting simulated lung nodules, which were placed on the posterior aspect of a chest phantom, was compared using receiver operating characteristic (ROC) techniques for each combination of the X-ray filter and tube voltage. The results of the study indicated that 1) nodule detection was superior for the images obtained with 135 kVp as compared with 100 kVp; 2) approximately equal detection rates were obtained for the three X-ray filter sets, although results with the tungsten filter were slightly inferior to the other two filters; and 3) the absorbed dose may be reduced by 30% with the use of a lead filter backed by yttrium and aluminium compared with a copper filter backed by aluminium. We conclude that chest radiography with FCR should preferably be conducted with a higher kilovoltage, e.g., 135 kVp rather than 100 kVp, to ensure a higher detection rate of pulmonary nodules and in conjunction with a lead filter backed by yttrium and aluminium to reduce X-ray exposure to the patient.

Filtration↗
PubMed1994

MR of pulmonary hamartoma: pathologic correlation.

We describe the magnetic resonance (MR) appearance with pathologic correlation of six pulmonary hamartomas. All six tumors showed intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Four of the six tumors showed a lobulated appearance separated by septa on precontrast T1-weighted or T2-weighted images. Gadolinium-enhanced T1-weighted images showed marked enhancement of the septa that separated the tumors into less well enhanced lobules; this was seen in all six tumors. Comparison between MR images and pathologic specimens showed that the regions with less enhancement corresponded to core cartilaginous tissue and septa; areas of marked contrast enhancement corresponded to cleft-like branching mesenchymal connective tissue that dipped into the cartilaginous core. MR images correlated well with the surgically resected tumors.

Adult↗