Search PubMed⌕ Search

Biomedical subjects

Y Tamakawa

Publications and source records attributed to Y Tamakawa.

At least 19 recordsLinked to original sources
PubMed2001

Disorganised unilateral cerebellar folia: a mild form of cerebellar cortical dysplasia?

We describe MRI findings in two patients with disorganised foliation of one cerebellar hemisphere, with folia running vertically rather than horizontally. The thickness of individual folia and corticomedullary interdigitations were normal. These patients have no cerebellar neurological deficit. This rare abnormality is probably a maldevelopment of the hemispheric part of the posterior lobe of the developing cerebellum, and no clinical significance can be elicited.

Adult↗
PubMed2001

The circuit of Papez in mesial temporal sclerosis: MRI.

We looked at abnormalities in the circuit of Papez in patients with the mesial temporal sclerosis (MTS). We reviewed the MRI studies of 15 patients with probable MTS, seeking changes in the fornix, mamillary body, mamillothalamic tract, thalamus and cingulate and parahippocampal gyri. We correlated any abnormalities with each other and with clinical severity. Atrophy and/or signal change in one or more structures in the circuit of Papez were found in five patients. They involved the parahippocampal gyri in all five, the fornices in four, mamillary bodies in three, the thalamus in two and the cingulate gyrus in one. Changes in the fornix, mamillary body, thalamus or cingulate gyrus were always accompanied by hippocampal and parahippocampal atrophy. The patients with abnormalities of the circuit of Papez did not have more severe epilepsy than those without. Changes in the parahippocampal gyrus, including the entorhinal cortex and subiculum, in which forniceal fibres originate, may be crucial in causing abnormalities more distally in the circuit.

Adolescent↗
PubMed2000

The correlation between spontaneous and radiation-induced apoptosis in T3B bladder cancer (histological grade G3), and the precedence between the two kinds of apoptosis for predicting clinical prognosis.

PURPOSE: The correlation between the frequency of spontaneous and radiation-induced apoptosis, and the precedence between those for predicting prognosis were studied at clinical level. METHODS AND MATERIALS: Twenty-one patients (mean age, 65.8 years; 16 men and 5 women) with bladder cancer (transitional cell carcinoma Grade 3, T3bN0M0, Stage IIIb) underwent intraoperative radiotherapy: single 30-Gy 12-MV electron beam irradiation to bladder, followed by total cystectomy 6 h after irradiation. The specimens of pretreatment and irradiated bladder cancer were assayed for apoptosis, using TUNEL staining with counter staining of hematoxylin. The apoptotic index (AI) was calculated by dividing the number of apoptotic cells by the total number of cells and multiplying by 100. The Pearson's linear fitting was used to test the correlation between spontaneous and radiation-induced apoptosis. The Kaplan-Meier product-limit estimation was used for overall survival (OS) and freedom from recurrence (FFR). The precedence between spontaneous and radiation-induced apoptosis for predicting the clinical prognosis was estimated using the proportional hazard regression. RESULTS: The mean AI of spontaneous and radiation-induced apoptosis was 1.18 +/- 0.16 and 2.63 +/- 0.45, respectively, which was significantly different. There was strong correlation between spontaneous and radiation-induced apoptosis (r(2) = 0.864, adjusted r(2) = 0.857). Radiation-induced apoptosis was estimated by equation: y (radiation-induced apoptosis) = 2.67 x (spontaneous apoptosis) -0.52. However, the proportional hazard regression test indicated that only spontaneous apoptosis was significant for predicting OS and FFR (&z.sfnc;t&z.sfnc; > 0.2), but radiation-induced apoptosis was not. CONCLUSION: Estimating AI in radiation-induced apoptosis from AI in spontaneous apoptosis is possible. However, spontaneous apoptosis is more accurate in predicting clinical prognosis.

Aged↗
PubMed2000

Pasteurized intercalary autogenous bone graft: radiographic and scintigraphic features.

OBJECTIVE: Pasteurized autogenous bone graft sterilized at a low temperature (60 degrees C) is one option for reconstruction after resection of bone and soft tissue tumors. The purpose of this investigation was to assess the normal and abnormal radiographic and scintigraphic findings of pasteurized intercalary autogenous bone graft after resection of bone and soft tissue sarcomas. DESIGN: This was a retrospective evaluation of the radiography and bone scintigraphy findings in patients after treatment of bone and soft tissue sarcomas using an intercalary pasteurized autogenous bone graft. PATIENTS: Among 10 consecutive patients, eight had intercalary grafts, and they constitute the subjects of this study. All available radiography and bone scintigraphy findings were reviewed for the healing process and the possibility of complications. RESULTS AND CONCLUSIONS: Healing and incorporation of the graft were observed in five patients during the follow-up, but the other three did not heal satisfactorily. Rapid incorporation of pasteurized autogenous bone graft can be demonstrated by means of radiography and bone scintigraphy.

Adolescent↗
PubMed2000

Nutrient canal of the fibula.

OBJECTIVE: To investigate the radiological features of the nutrient canal in the fibula. DESIGN AND PATIENTS: One hundred and seventy-nine dried fibulae were studied regarding the type, number, location, and direction of the nutrient canal. They were classified into a usual type (type I: a radiolucent line confined to the cortex) and an atypical type (type II: a radiolucent line extending beyond the cortex). RESULTS: Among the total of 230 nutrient canals seen on radiography, 197 (86%) were type I and 33 (14%) were type II. On CT scans, the ossified rim of the canal extended into the medullary cavity in type II canals. The most common site was the posteromedial aspect in both type I and type II canals. Type II canals were significantly more common in fibulae with two or three nutrient canals. The frequency of the upward direction was more common in type II canals. CONCLUSION: Nutrient canals with extension of the ossified rim into the medullary canal are the cause of linear lucency that may simulate a fracture. Their features are slightly different from those of usual canals.

Aged↗
PubMed2000

[Simultaneous query and retrieve from multiple DICOM image archives using a proxy server].

PURPOSE: DICOM clients could not access more than one archive simultaneously in the previous PACS systems. We developed a proxy server which makes it possible for clients to query and retrieve images from multivendor DICOM archives simultaneously. METHODS: We used a Web server that supports the DICOM query and retrieve(Q/R) service class as a proxy server. This system consisted of two DICOM servers and six DICOM clients of different vendors in the Radiology Department. Through Web browsers on the clients, requests for Q/R were transmitted to the proxy server by hypertext transfer protocol. The proxy server communicated with DICOM servers by DICOM Q/R Service Class(C-FIND, C-MOVE), and then DICOM servers directly transmitted images to DICOM clients by DICOM Storage Service Class(C-STORE). RESULTS: DICOM clients could transmit Q/R requests to two DICOM servers simultaneously via the proxy server and receive requested images promptly. Confirmation of conformance among the proxy server, DICOM archives, and DICOM clients became much easier than previously. CONCLUSION: A Web server working as a proxy server of the DICOM Q/R Service Class is an effective solution for allowing DICOM clients to communicate with multiple DICOM archives.

Computer Communication Networks↗
PubMed2000

[Intranet-based integrated information system of radiotherapy-related images and diagnostic reports].

PURPOSE: To use an intranet technique to develop an information system that simultaneously supports both diagnostic reports and radiotherapy planning images. METHODS: Using a file server as the gateway a radiation oncology LAN was connected to an already operative RIS LAN. Dose-distribution images were saved in tagged-image-file format by way of a screen dump to the file server. X-ray simulator images and portal images were saved in encapsulated postscript format in the file server and automatically converted to portable document format. The files on the file server were automatically registered to the Web server by the search engine and were available for searching and browsing using the Web browser. RESULTS: It took less than a minute to register planning images. For clients, searching and browsing the file took less than 3 seconds. Over 150,000 reports and 4,000 images from a six-month period were accessible. Because the intranet technique was used, construction and maintenance was completed without specialty. CONCLUSION: Prompt access to essential information about radiotherapy has been made possible by this system. It promotes public access to radiotherapy planning that may improve the quality of treatment.

Computer Communication Networks↗
PubMed1998

[Report management system using Web server and search engine].

PURPOSE: To develop a management system of written reports using a Web server and search engine. METHODS: All the reports written through word processing software in the local area network in the radiology department were automatically transferred to one of the PC servers, in which a Web server and search engine were in operation. Previous reports, approximately eighty thousand, were also registered. Using Web browsers and the program developed by hypertext mark-up language and JavaScript, all the reports were readily accessible by keywords, or by any words within reports. RESULTS: Over 100, 000 reports were easily accessible using Web browsers, based on our one-year experience. Maintaining the Web server and search engine, and upgrading the program were easily managed in our daily practice. CONCLUSION: The report management system we developed is flexible, scalable, and easy to maintain. It is an effective way to manage a large volume of radiology reports written through word processing software.

Computer Communication Networks↗
PubMed1997

Embryonal rhabdomyosarcoma of foot with expansive growth between metatarsals.

The case of a 14-year-old girl with rhabdomyosarcoma of the right foot is reported. Plain radiography showed a large nonspecific soft tissue tumor between the metatarsals with bowing of the metatarsals away from the mass. MR imaging showed a large soft tissue mass involving the metatarsals. The findings were conflicting, because the tumor had an infiltrative soft tissue mass and bowing of the metatarsals more suggestive of slow expansive growth. Bowing of short tubular bones may be a process similar to cortical saucerization, which is typically seen in Ewing's sarcoma, and it can be one of the findings of high grade neoplasms, such as embryonal rhabdomyosarcoma.

Adolescent↗
PubMed1997

[Radiology information system using HTML, JavaScript, and Web server].

We have developed a radiology information system using intranet techniques, including hypertext markup language, JavaScript, and Web server. JavaScript made it possible to develop an easy-to-use application, as well as to reduce network traffic and load on the server. The system we have developed is inexpensive and flexible, and its development and maintenance are much easier than with the previous system.

Local Area Networks↗
PubMed1995

Muscular sarcoidosis.

A 57-year-old woman with sarcoid nodules in muscles of the lower leg was reported. A star-shaped low signal intensity in the lesion on MR imaging, supposedly corresponding to fibrous scar, appears characteristic of this condition, although its specificity is still uncertain.

Female↗
PubMed1995

Cortical defect of the distal fibula: variant of ossification.

PURPOSE: To elucidate the nature of a normally occurring cortical defect of the distal fibula. MATERIALS AND METHODS: In patients with sprain and nonspecific ankle pain during a 2-year period, the authors reviewed ankle radiographs, computed tomographic (CT) scans, and magnetic resonance (MR) images. Cases were added from our file. Dried skeletons and cadavers were evaluated with radiography for the presence of this cortical defect. RESULTS: Fifteen (1.8%) of 847 radiographs in 739 patients (male, 377; female, 362; age range, 15-84 years) showed a small cortical defect in the anterior aspect at the level of the distal tibiofibular joint. The age range of the subjects with the defect (male, four; female, 11) was 16-66 years. MR imaging in two patients showed a small low-signal-intensity area at the insertion site of the anterior tibiofibular ligament. Evaluation of 148 skeletons (75 subjects) revealed similar cortical defect in two cases (1.4%). CONCLUSION: The cortical defect of the distal fibula, at the insertion site of the anterior tibiofibular ligament, has no clinical significance and should not be confused with neoplasm.

Adolescent↗
PubMed1994

Case report 859: Massive calcium pyrophosphate dihydrate crystal deposition disease involving the wrist joint.

A case of massive calcium pyrophosphate dihydrate crystal deposition disease (MCPDD) is reported. A 41-year-old Japanese man presented with swelling, intermittent pain, and limitation of motion in the wrist. Radiological studies indicated amorphous calcification and bone erosion. MCPDD, although rare, should be included in the list of the differential diagnosis of periarticular calcific diseases.

Adult↗
PubMed1994

Fluid-fluid levels in cavernous hemangioma of soft tissue.

Five cases of cavernous hemangioma with fluid-fluid levels on magnetic resonance imaging and/or computed tomography are reported. The signal characteristics were those of blood and histological analysis of the fluid-fluid levels showed that they were blood-filled cavities in the tumor. Although this finding itself is not specific, it may help in confirming the diagnosis of cavernous hemangioma.

Biomarkers↗
PubMed1994

Sub-kilohertz flash X-ray generator utilising a glass-enclosed cold-cathode triode.

The construction and fundamental studies are described for a sub-kilohertz X-ray generator for producing low-dose rate flash X-rays. The X-ray tube was a glass-enclosed cold-cathode triode, composed of a tungsten plate target, a rod-shaped graphite cathode, a mesh-type trigger electrode made of tungsten wires, and a glass tube body. The coaxial condenser was charged up to 60 kV by a power supply, and the electric charges in the condenser were discharged to the X-ray tube repetitively when a negative high-voltage pulse was applied to the trigger electrode. The maximum tube voltage before the discharging was equivalent to the initial charged voltage of the condenser, and the maximum tube current was about 0.3 kA with a charged voltage of 60 kV. The X-ray durations were about 1 microsecond, and the X-ray intensity was about 0.47 microC kg-1 at 0.5 m per pulse with a charged voltage of 60 kV. The maximum repetition rate of the X-rays was about 0.4 kHz, and high-speed radiography was performed.

Animals↗
PubMed1994

10 kHz microsecond pulsed X-ray generator utilising a hot-cathode triode with variable durations for biomedical radiography.

A 10 kHz pulsed X-ray generator utilising a hot-cathode triode in conjunction with a new type of grid control device for controlling X-ray duration is described. The energy-storage condenser was charged up to 70 kV by a power supply, and the electric charges in the condenser were discharged to the X-ray tube repetitively by the grid control device. The maximum values of the grid voltage (negative value), the tube voltage, and the tube current were -1.5 kV, 70 kV, and 0.4 A, respectively. The duration of the flash X-ray pulse was primarily determined by the time constant of the grid control device and the cut-off voltage of thermoelectrons. The X-ray duration was controlled within a region of less than 1 ms; the X-ray intensity with a pulse width of 0.27 ms, a charged voltage of 70 kV, and a peak tube current of 0.4 A was 0.92 microC kg-1 at 0.5 m per pulse. The maximum repetition rate was about 10 kHz, and the size of the focal spot was about 3.5 x 3.5 mm.

Animals↗
PubMed1993

Disk-cathode flash X-ray tube driven by a repetitive two-stage Marx pulser.

Fundamental studies of a repetitive flash X-ray generator using a disk-cathode radiation tube are described. The high-voltage pulser employed a modified two-stage surge-Marx circuit. The two condensers in the pulser were charged from 40 to 60 kV, and the electric charges were discharged to the X-ray tube repetitively to generate flash X-rays. The total capacity during the main discharge was 425 pF, and the maximum output voltage from the pulser was about 1.9 times the charged voltage. The flash X-ray tube was of the demountable-diode type and was composed of a rod-shaped anode tip made of tungsten, a disk cathode made of graphite and a tube body made of polymethylmethacrylate. The peak tube voltage was primarily determined by the anode-cathode (A-C) space, and the peak tube current was less than 0.5 kA. Thus the maximum photon energy could be easily controlled by varying the A-C space, and the tube current roughly increased according to increases in the charged voltage. The pulse width ranged from 40 to 100 ns, and the X-ray intensity was less than 1.1 microC kg-1 at 0.5 m per pulse. The repetition rate was less than 50 Hz, and the effective focal spot size was equivalent to the anode diameter.

X-Ray Therapy↗