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Biomedical subjects

F Sakai

Publications and source records attributed to F Sakai.

At least 109 records · Page 6Linked to original sources
PubMed1994

[High-speed/high resolution teleradiology system based on university microwave network].

A high-speed, high-resolution teleradiology system with full duplexing based on the Shinshu University Video and Communication Network System (SUNS) using Giga-Herz microwaves is described. The LAN at Nagano Red-Cross Hospital and The Radiology Department of Shinshu University Hospital are interfaced to a personal computer with a laser film digitizer, interactive display, and network interface. The throughput per digitized high-resolution radiographic image was 65 sec, and the mean transmission rate was 805 kilobit per sec. Teleradiology conferencing is also possible with this system. Radiologists at both hospitals interactively observe the same high-resolution images on the CRT screen using mouse cursor synchronization.

Computer Communication Networks↗
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

Physical mapping of 5S rDNA loci by direct-cloned biotinylated probes in barley chromosomes.

5S rDNA loci have been mapped on barley chromosomes by in situ hybridization using five reciprocal translocation lines. Two kinds of DNA probes covering either the 5S rDNA coding region or the 5S rDNA coding and flanking noncoding regions were used. They were prepared by direct cloning from interphase nuclei and simultaneous direct labeling in PCR. Four 5S rDNA loci were detected in a haploid genome by the 5S rDNA coding region, whereas in addition, the four or six 5S rDNA related sites, depending on the variety used, were revealed by the probe covering the flanking region. The four 5S rDNA loci revealed and mapped on the barley chromosomes: 2 (2I), 3 (3I), 1 (7I), and 4 (4I) were designated 5SRrn-I1, 5SRrn-I2, 5SRrn-I3 and 5SRrn-I4, respectively, in descending order of copy number of 5S rRNA genes.

Base Sequence↗
PubMed1994

[Visual hallucination in the hemianopic field caused by dural arteriovenous malformation].

We presented a 65-year-old man with the right occipital dural arteriovenous malformation (AVM) who first experienced photopsia in his left inferior quadrantanopic field and then developed formed hallucinations 8 days later. His visual hallucinations disappeared with saccadic eye movements. EEG showed no epileptic discharge. MRI revealed hyperintensity in the right medial occipital lobe on proton density image. 123I-IMP SPECT during the hallucinations revealed decrease of regional cerebral blood flow (r-CBF) not only in the right medial occipital lobe but also in the right lateral occipital and in the right medial temporal lobe. Both left inferior quadrantanopia and visual hallucinations disappeared following the treatment of the dural AVM by transarterial embolizations. Because the lesion on MRI improved after the treatment, we considered that the lesion was brain edema, not infarction. Additionally decreased r-CBF in the temporo-occipital lesion on SPECT improved after the treatment, we emphasized the role of the temporo-occipital lesion as the cause of visual hallucinations in the hemianopic field.

Aged↗
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↗
PubMed1994

Ultrasonography of thymoma with pathologic correlation.

Preoperative ultrasonograms of 11 surgically proved thymomas and ex vivo ultrasonograms of 3 resected specimens were compared with pathologic findings of resected specimens. Among 11 thymomas 7 appeared solid, 3 were solid with several cystic regions, and the remaining one was unilocular cystic in appearance. Cystic regions on ultrasonograms corresponded to cystic changes on pathologic specimens. Six malignant thymomas showed a typical lacy appearance on ultrasonograms, which corresponded to the lobulated configuration separated by fibrous septa shown on the pathologic specimens.

Adult↗
PubMed1993

WS1279, a novel lipopeptide isolated from Streptomyces willmorei. Biological activities.

WS1279, a new lipopeptide isolated from the fermentation broth of Streptomyces willmorei No. 1279, stimulated the proliferation of mouse bone marrow cells in vitro and accelerated the recovery of granulocyte counts in bone marrow from leukopenia induced by mitomycin C (MMC) in mice. The glycerylcysteine moiety of WS1279 is necessary and the lipid peptide structure is required for manifestation of full stimulating activity in vitro. WS1279 was the most effective on the proliferation of bone marrow cells among the tested immunostimulants in vitro. However, the effect of WS1279 on restoration of reduced granulocyte counts in MMC-induced leukopenia in mice was less than that of FK-565, lipopolysaccharide, picibanil or forphenicinol. WS1279 augmented host resistance to infection with Staphylococcus aureus 47 in normal and immunosuppressed mice.

Adjuvants, Immunologic↗
PubMed1993

Chest imaging with dual-energy subtraction digital tomosynthesis.

Dual-energy subtraction digital tomosynthesis with pulsed X-ray and rapid kV switching was used to examine calcifications in pulmonary lesions. The digital tomosynthesis system used included a conventional fluororadiographic TV unit with linear tomographic capabilities, a high resolution video camera, and an image processing unit. Low-voltage, high-voltage, and soft tissue subtracted or bone subtracted tomograms of any desired layer height were reconstructed from the image data acquired during a single tomographic swing. Calcifications, as well as their characteristics and distribution in pulmonary lesions, were clearly shown. The images also permitted discrimination of calcifications from dense fibrotic lesions. This technique was effective in demonstrating calcifications together with a solitary mass or disseminated nodules.

Humans↗
PubMed1992

Thin-rim enhancement in Gd-DTPA-enhanced magnetic resonance images of tuberculoma: a new finding of potential differential diagnostic importance.

The article describes rim enhancement seen on Gd-DTPA-enhanced magnetic resonance (MR) images of two patients with tuberculoma. Pathologic examination of the surgical specimens disclosed that the peripheral portion of the tuberculoma, which showed contrast enhancement, was composed mainly of a fibrous capsule and epithelioid granulomas and that the central zone, which showed no contrast enhancement, was composed of caseous necrotic material. In a retrospective study of MR images from 20 consecutive cases of surgically proven bronchogenic carcinoma, none showed a thin enhancing rim on postcontrast MR images. Although confirmation of these findings must await further experience, the postcontrast MR findings described here may prove to be of value in distinguishing tuberculoma and possibly other granulomatous lesions from bronchogenic carcinoma.

Adult↗
PubMed1992

MR imaging of thymoma: radiologic-pathologic correlation.

MR images in 17 patients with surgically proved thymomas (12 malignant and five benign) were reviewed and compared with pathologic specimens. In nine cases, MR images of excised specimens also were made and evaluated. On T2-weighted images, 11 of 12 malignant thymomas had an inhomogeneous signal intensity, half with and half without a lobulated internal architecture. None of the five benign thymomas had a lobulated internal architecture, and they all had a moderately or slightly inhomogeneous signal. Cystic regions and/or hemorrhage were noted pathologically, and corresponded to areas of inhomogeneous high signal intensity seen on T2-weighted images. Examination of the excised specimens in malignant thymomas showed that the lobulated configuration seen in the tumors was caused by thick fibrous septa. Our experience suggests that, although calcification cannot be identified, MR is helpful in making a differential diagnosis of mediastinal tumors and in determining malignancy of thymoma.

Adult↗
PubMed1992

Intrathoracic neurogenic tumors: MR-pathologic correlation.

An MR-pathologic correlation of nine intrathoracic neurogenic tumors (three neurofibromas, four schwannomas, and two ganglioneuromas) was performed to characterize their MR appearances. The three types of intrathoracic neurogenic tumor were found to have characteristic appearances on MR images that should be helpful when establishing the differential diagnosis of posterior mediastinal tumors. The MR and histologic features of these tumors are illustrated and described in this essay.

Adolescent↗
PubMed1992

[Neurological and neuroimaging studies of eclampsia].

Clinical and neuroimaging studies were made in twenty-one patients during the attack of eclampsia. Most frequent neurological signs and symptoms were the impairment of consciousness, headache, seizure and visual disturbance. Mean arterial blood pressure increased by 46 mmHg (n = 21) during the attacks. Eight of 9 patients studied by CT and/or MRI showed transient abnormalities on brain images during the attack in the occipital cortex, basal ganglia, and internal and external capsule. The findings were compatible with brain edema and were seen mainly in the white matter. Cerebral blood flow measured by SPECT method in one patient during an attack with visual disturbance showed increased blood flow in the occipital cortex. Acute increase in blood pressure, cerebral hyperperfusion and edema, similar to the pathophysiology of hypertensive encephalopathy, were considered to play an important role in the pathogenesis of eclampsia.

Adult↗
PubMed1991

[MR evaluation of wallerian degeneration of the pyramidal tract].

This study is based on 135 magnetic resonance (MR) exams of 110 patients with wallerian degeneration of the pyramidal tract shown on MR images acquired on a mid field imaging scanner. The MR findings of wallerian degeneration were abnormal signal band along the course of the pyramidal tract and ipsilateral brain stem shrinkage. In all 110 cases an abnormal signal band was seen on T2-weighted spin-echo images, that is, a hypointense band in four exams between 30 days and 116 days after onset of symptoms, and hyperintense bands in 122 exams. The hyperintense signal on T2-weighted images was shown in most cases after 200 days from the onset. In one case a signal of the pyramidal tract showed a hyperintense band at 7 days, hypointense at 30 days, and hyperintense again at 123 days after onset. Sequential MR exams of another case showed gradual narrowing of the hyperintense signal band and progression of the ipsilateral brainstem shrinkage. The narrowing of the pyramidal tract and the ipsilateral brain stem shrinkage tended to be shown after 6 months from onset.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Magnetic resonance imaging of the brain in patients with migraine.

Magnetic resonance imaging (MRI) was studied in 91 patients with migraine and in 98 controls. Risk factors known to cause MRI lesions were carefully examined. In 36 patients with migraine (39.6%), small foci of high intensity on T2-weighted and proton-density-weighted images were seen in the white matter. Of patients with migraine who were less than 40 years old and without any risk factor, 29.4% showed lesions on MRI; this was significantly higher than the 11.2% for the group of age-matched controls (n = 98). The lesions were distributed predominantly in the centrum semiovale and frontal white matter in young patients, but extended to the deeper white matter at the level of basal ganglia in the older age group. The side of the MRI lesions did not always correspond to the side of usual aura or headache. Migraine-related variables such as type of migraine, frequency, duration or intensity of headache or consumption of ergotamine showed no significant correlation with the incidence of MRI abnormalities. Our data indicated that migraine may be associated with early pathologic changes in the brain.

Adult↗
PubMed1991

Development of a high-resolution digital tomosynthesis system and its clinical application.

Conventional tomography has been criticized for its low contrast caused by scattered radiation and tomographic blur. The authors developed a digital tomosynthesis system as a substitute for conventional tomography. With the image processor in the system, two types of postprocessing can be performed to improve the quality of synthesized tomograms. One-dimensional spatial frequency filtering effectively reduces linear tomographic blur and enhances image information when an appropriate filter is used. Correction of structure mottle helps enhance the image clarity. The system allows reconstruction of tomograms at any desired depth and performance of tomosynthetic angiography and dual-energy subtraction. The system solves some of the problems associated with plain tomography and dual-energy subtraction and provides diagnostic clinical images.

Humans↗