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Biomedical subjects

E Takeyama

Publications and source records attributed to E Takeyama.

23 records · Page 2Linked to original sources
PubMed1976

[Existence of triphasic flow pattern in regional cerebral blood flow of prolonged unconscious patients (author's transl)].

Anticipating to get some new informations about the cerebral circulations of the comatous patients, two kinds of radioisotopic techniques were combined and applied to twelve unconscious patients of various etiologies. The first step was the conventional gas clearance method using xenon 133 as the indicator. Regional cerebral blood flows were measured at the six areas over each hemisphere. Immediately following this procedure, about 150 muCi of I-131 MAA (I-31 macroaggregated human serum albumin) were injected into internal carotid artery via the same catheter inserted already for the first procedure. Radioactivities of the head and lungs were measured and the relative shunt flow was calculated based on the formula already described elsewhere. Profil scanning of the whole body of the patient was also performed after the intracarotid injection of I-131 MAA. Consciousness states of the ten patients were all severely damaged and causes of the disturbed consciousness were various, including 5 of subdural hematoma, 2 of occlusive cerebrovascular disease, 2 of brain tumor and 1 of ruptured intracranial aneurysm. This investigation revealed the following results; 1) In all patients, regional cerebral blood flows were shown decreased over all areas detected. The regional cerebral blood flows could not be increased by 5% carbon dioxide inhalation, suggesting angioparalysis in these areas. 2) Graphical analysis of the clearance curves revealed triphasic flow pattern in rCBF in four cases. In three cases among the four, the intracarotid injection of I-131 MAA showed the radioisotope labelled particles were captured not only in the brain, but also in the lungs and the relative shunt flow calculated increased up to twice as much as normal controls. It indicates that some of the particles larger than the cerebral capillary size passed through the brain and were captured by the capillary net work of the lungs. From the above described data, it might be concluded that the initial rapid component of triphasic flow pattern in rCBF measurement does not represent the hyperemia of luxury perfusion of metabolic origin, but arteriovenous shunting blood flow, probably, through the precapillary thoroughfare channels which have been anatomically demonstrated by Hasegawa et al.

Adult↗
PubMed1975

[Diagnostic value of isocount scanning in cerebrovascular diseases (author's transl)].

In the previous report the theoretical background and technical details of the isocount scanning were described. Based on clinical experiences of various brain diseases, the newly developed scanning method was confirmed to be more useful than the conventional scintiscanning. Besides the new scanning method, a new display system was also developed for the sake of more precise analysis of the isocount scanned data. This display method is called multilevel analysis or multilevel slicing of the scanned data. In the present investigation, this method was applied to thirty-two cases of cerebrovascular diseases, including seven cases of cerebral arterio-venous malformation, four cases of hypertensive intracerebral hemorrhage and twenty-one cases of cerebral infarction, positive rates being 86%, 100% and 90% respectively. In case of arterio-venous malformation, minimum size detected by the isocount method was 2 cm in diameter. To twenty one cases of the cerebral infarction, total thirty two scanning examinations were performed, including postictal follow up studies. It is often said that it is two or three weeks after the ictus when the infarcted cerebral lesion is most clearly detectable by the scintigraphic procedures, presumably due to focal neovascularizations which may occur in the lesion most prominently at this postictal stage. Contradicted to the current concept, our experiences show that abnormal dot accumulations are recognized in the scintigrams even at the earlier stage, thus among five cases of cerebral infarction scanned within a week after the ictus positive figures were obtained in four cases, two of which were examined within two days after the ictus. Focal breakdown of blood brain barrier at the acute stage is considered to be responsible for the early positivity in cerebral infarctions. In eight cases among twenty one cerebral infarctions angiographies failed to demonstrate the vessel occluded. The isocount scanning method, however, succeeded in getting positive results in seven of the eight cases. It will be emphasized that the isocount scanning is a preferable diagnostic procedure in the cerebrovascular diseases, especially when the angiography is hesitated to be performed because of the patient severely affected.

Adolescent↗
PubMed1975

Penetration of 99mTcO4- into cerebrospinal fluid from blood on brain scintigraphy (author's transl).

It is well known that the permeability of the blood brain barrier and blood cerebrospinal fluid barrier changes more or less in various diseases of the central nervous system. At present, thee is no clinically available index which reflects the alteration of the permeability of the blood brain barrier and blood cerebrospinal fluid barrier. The brain scintiraphy is an examination which detects a breakdown in the blood brain barrier, its clinical usefullness is limited only in a localized and extremely pathological proces of the brain. In this report, a cerebrospinala fluid isotope measurement comined with the brain scintigraphy was presented as a clinical examination for blood brain barrier function. Thirty minutes prior to brain scintigraphy, potassium perchlorate (4 mg/kg) was given orally to reduce the accumulation of 99mTc04-in the choroid plexus and to minimize iradiation for tr other organs. Spinal tap was performed two hours after injection of 99mTc04- according to Haines's method...

Adolescent↗
PubMed1975

[Isocount scanning of the brain (author's transl)].

It is well known that the gamma ray emitted by a radionuclide is a Poisson process, so its statistic nature should be taken in consideration when the scintiscanning is performed. But very few attempts have been done from this point of view. After examining in detail the imaging pulse charactristics, the authors introduced a mean for evaluating the fidelity of the collected data, and based on this criterion, pointed out some problems in the conventional scanning method and finally described a statistical way of improving the scintigram. In the present investigation, as a measure of the stochastic fidelity of the scanned data the relative deviation eplision(n) = sigma(n)/E(n) is introduced; sigma is the standard deviation and E(n) is the expectation value of the counting rate. In the conventional scanning in which the detector moves with a costant speed, the relative deviation varies from area to area according to the concentration of the radioisotope in the brain. In the so-called cold area of the brain scintigram, the relative deviation fluctuates remarkably because of a rather low density of radioisotope in this area.

Adult↗