[Multidirectional pseudodynamic studies of the bilateral temporomandibular joint diseases with 0.2-Tesla MR imaging unit].
Explore the source record for details and available documents.
Adolescent↗
Biomedical subjects
Y Tamakawa
Publications and source records attributed to Y Tamakawa.
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↗
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↗
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↗
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↗
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↗
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↗
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↗
Hippocampal sulcus remnant: potential cause of change in signal intensity in the hippocampus.
A small area of changed signal intensity in the hippocampus is often seen on magnetic resonance (MR) images of the brain in patients without specific clinical signs or symptoms. To ascertain its cause by means of histologic examination, this finding was evaluated retrospectively in 109 patients and correlated with findings in two human brain specimens. This area of change was typically round or curvilinear and 1-2 mm in diameter. Its location was between the hippocampus and dentate gyrus. The signal intensity was the same as that of cerebrospinal fluid (CSF) with all MR sequences used. The incidence of change in signal intensity was greater in elderly patients. Correlation with histologic findings showed that this area of change, a dilated perivascular space, was the residual cavity of the hippocampal sulcus. Whenever an area of CSF-like signal intensity has this shape and topographic features, the possibility of anatomic variation should be considered before the change in signal intensity is diagnosed as brain injury.
Adolescent↗
[Fluid-fluid levels in bone and soft tissue tumors demonstrated by MR imaging].
Fluid-fluid levels in bone tumors have been described in aneurysmal bone cysts and other cystic tumors of bones and soft tissue tumors. We experienced three bone tumors (simple bone cyst, bone metastasis, and osteosarcoma) and three soft tissue tumors (fibrosarcoma, two cases of cavernous hemangioma) that showed fluid-fluid levels on MR, and investigated their cause. Causes included blood in the cystic spaces, hemorrhage in the tumor, the telangiectatic component of the osteosarcoma, and the cavernous component of the hemangioma. No specific diagnosis could be made based on the finding of fluid-fluid levels. We conclude that fluid-fluid levels on MR are rather nonspecific findings in bone and soft tissue tumors and that the diagnosis should be made on the basis of other radiological and clinical findings.
Adult↗
[Simultaneous pseudodynamic MR evaluation of bilateral temporomandibular joints].
Coordination of bilateral temporomandibular joints (TMJs) was evaluated using bilateral simultaneous pseudodynamic magnetic resonance (MR) imaging. Seven patients (6 patients with internal derangement and one with osteoarthritis) were examined by multiplanar gradient echo technique in closed-loop cine fashion on both sagittal and coronal planes. Incoordination of bilateral TMJ motion was observed in 2 of 7 patients. This technique might be suitable for evaluation of TMJ disorders.
Humans↗
[Small bright signal in the hippocampus on MR: dilated residual cavity of hippocampal sulcus].
Explore the source record for details and available documents.
Adult↗
[MRI and arthrography in the evaluation of TMJ disorders].
Arthrosis of the temporomandibular joint (TMJ) is a noninfectious, noninflammatory condition characterized by joint pain, noise (clicking) and abnormal motion. It contains various disease processes, such as abnormalities in the menisci or masticating muscles, subluxation of the condyle and degenerative joint disease. Analysis of the morphology and dynamics of TMJ by means of imaging modalities has become highly advanced since the development of arthrography in the late 1970s. Magnetic resonance imaging (MRI) has become the modality of choice in the evaluation of TMJ owing to the development of surface coils. We retrospectively studied MRI and inferior joint compartment arthrography in the evaluation of TMJ disorders. Nineteen joints of 14 patients included 15 with internal derangement, two with osteoarthrosis and two normal joints. Sagittal MR images were routinely obtained in a resting position and in positions with the mouth half open, and also with the mouth fully open on balanced images. Although perforation of the menisci was difficult to evaluate, MRI and arthrography were equally useful in identifying the shape and position of the meniscus. However, MRI was more reliable in depicting TMJ abnormalities than arthrography. MR is considered to be the modality of choice in screening arthrosis of TMJ, making the definitive diagnosis of internal derangement and monitoring conservative therapy for arthrosis.
Adult↗
Case report 675: Lipoblastoma of knee.
Lipoblastoma in the prepatellar region was observed in a 7-month-old girl. The diffuse (lipoblastomatosis) and circumscribed forms have different radiological appearances. Lobular proliferation of fatty tissue with fibrous septae is characteristic of the circumscribed form.
Female↗
Internal carotid origin of double ophthalmic arteries.
Explore the source record for details and available documents.
Adult↗
MR of the shoulder with a 0.2-T permanent-magnet unit.
Explore the source record for details and available documents.
Adult↗
[MR imaging of internal carotid artery occlusion].
Five patients with internal carotid artery occlusion were studied with MR imaging at 0.22 T. At the carotid siphon, occluded vessels showed absence of flow void in three patients. But two cases had "partial flow void" which mimicked small arterial caliber. In these patients angiography showed collateral circulation to the carotid siphon. So the partial flow void in the carotid siphon suggested internal carotid artery occlusion with collateral circulation.
Aged↗
[Insufficiency fracture of the sacrum].
Three cases of insufficiency fracture of the sacrum are reported. Cortical disruption and linear sclerosis with or without linear fracture line at the upper sacral segment parallel to the sacroiliac joint are characteristic. Bone scintigram is suitable for screening, but plain radiographic and CT findings are diagnostic. Insufficiency fracture of the sacrum should not be confused with other conditions, such as metastatic disease.
Aged↗