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H Imada

Publications and source records attributed to H Imada.

33 records · Page 2Linked to original sources
PubMed1990

MR imaging of wallerian degeneration in the human brain stem after ictus.

Magnetic resonance (MR) imaging of wallerian degeneration in the brain stem was studied in 30 hemiplegic patients within 12 months of ictus. As early as 25 days after the ictus, decreased signal intensities on proton-density(PD)-weighted images were observed in the brain stem ipsilaterally. This hypointensity gradually approached an isointense stage during 70-80 days after the ictus, abnormal intensities were not detected in any pulse sequence. We termed this phenomenon "Fogging effect of wallerian degeneration". In later stages, at least 81 days after the ictus, increased signal intensities on T2-weighted images, with or without decreased signal intensities on T1-weighted images, were observed in the brain stem, ipsilaterally. Finally, at least six months after the ictus, mild shrinkage of the ipsilateral brain stem was newly detected on the T1-weighted images. MR imaging has proven to be a sensitive diagnostic modality for evaluating wallerian degeneration in the brain stem.

Brain Stem↗
PubMed1989

[A comparison of win-shift and win-stay performance of rats in a radial arm maze].

The purpose of the present experiment was to compare the performance of rats in a win-shift task and a win-stay task in a radial arm maze. To this end, three experiments were conducted using a variety of procedures. In general, the win-shift task required the rats to choose the unvisited arms and the win-stay task required the rats to return the visited arms. In Experiment 1, a free-choice memory recognition procedure was used, and in Experiments 2 and 3, a forced-choice memory recognition procedure was used. All three experiments showed that in the win-shift task, rats rapidly learned the task and performed well whereas in the win-stay task, the rats consistently showed a chance-level performance despite of the prolonged training. In addition to these findings, when the tasks were reversed (i.e. from the win-shift to the win-stay, and vice versa), the rats still showed a response strategy previously adopted (Experiment 3). These findings seem to be important in considering the characteristics of spatial memory in rats.

Animals↗
PubMed1989

[Computed tomography of thymic hyperplasia in older children].

Computed tomography (CT) findings of 8 cases of thymic hyperplasia in children aged 7 to 15 years were retrospectively analyzed in comparison to 8 cases of tumors of anterior mediastinum. All cases of thymic hyperplasia retained a somewhat triangular or arrowhead-like shape at least on one side while tumors showed bilateral globular contour with lobulated border. No compression of the air way or pleural fluid was observed in thymic hyperplasia. These CT features are useful for making a diagnosis of thymic hyperplasia when an older child is presented with an anterior mediastinal mass on chest X-ray.

Adolescent↗
PubMed1982

Acquisition and maintenance of postshock response pattern in nondiscriminated avoidance with rats.

Five experimentally naive albino rats were placed under a nondiscriminated lever-press avoidance schedule in which the delay to the next shock for responses after a shock was longer than the delay for responses after a response. Four rats acquired the postshock response pattern and maintained it for a prolonged period. The results revealed that postshock responding was under operant control and was not purely shock-elicited. It was suggested that the two kinds of response-shock interval, i.e. the shock-response-shock interval and the response-response-shock interval, could and should be independently controlled in nondiscriminated avoidance schedules.

Journal Article↗
PubMedDate not supplied

Magnetic resonance imaging of intracranial venous angiomas.

Magnetic resonance imagings (MRI) were made of intracranial venous angioma (six angiographically proved, four presumed). All draining veins were identified as a linear or a small round structure with a flow void. The stellate configuration was observed in seven of the ten patients. In two of the ten, the associated intraparenchymal hematoma was evident. Increased intensity of adjacent parenchyma on T2-weighted images was detected in four of ten patients, and a decreased intensity on the T1-weighted images was noted in three of eight. Thus, MRI is a pertinent diagnostic modality for evaluating intracranial venous angioma. Angiography does not seem to be required for confirmation in patients with typical MR findings.

Brain↗
PubMedDate not supplied

Pancoast tumour treated with combined radiotherapy and hyperthermia--a preliminary study.

Six patients with Pancoast (superior sulcus) tumours were treated with combined radiotherapy and hyperthermia from April 1986 to December 1989. Radiotherapy was performed using 10 MV X-ray, and all patients received total doses of 60-74 Gy, in five fractions per week, during 5.5-15 weeks. Hyperthermia was performed once or twice a week within 30 min after each irradiation, using 8 MHz RF capacitive heating equipment (Thermotron RF-8). Partial response, defined as 50% or more regression of the tumour, was observed in four of the six patients. Three patients are alive 30, 28, and 14 months after their treatments. Radiotherapy combined with hyperthermia appears to be a promising and effective means for treating Pancoast tumours.

Adenocarcinoma↗
PubMedDate not supplied

Spontaneous abdominal aortic dissection: case report and review.

An abdominal aortic dissection was incidentally imaged by contrast infusion computed tomography (CT) in a patient with an abdominal liposarcoma. Previously reported cases of spontaneous abdominal aortic dissection with radiographs are reviewed.

Aortic Dissection↗