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Biomedical subjects

A Inugami

Publications and source records attributed to A Inugami.

At least 73 records · Page 4Linked to original sources
PubMed1988

Measurement of absolute myocardial blood flow with H215O and dynamic positron-emission tomography. Strategy for quantification in relation to the partial-volume effect.

An in vivo technique was developed for measuring the absolute myocardial blood flow with H215O and dynamic positron-emission tomography. This technique was based on a new model involving the concept of the tissue fraction, which was defined as the fraction of the tissue mass in the volume of the region of interest. The myocardium was imaged dynamically by positron-emission tomography, starting at the time of intravenous bolus injection of H215O. The arterial input function was measured continuously with a beta-ray detector. A separate image after C15O inhalation was also obtained for correction of the H215O radioactivity in the blood. The absolute myocardial blood flow and the tissue fraction were calculated for 15 subjects with a kinetic technique under region-of-interest analysis. These results seem consistent with their coronary angiographic findings. The mean value of the measured absolute myocardial blood flows in normal subjects was 0.95 +/- 0.09 ml/min/g. This technique detected a diffuse decrease of myocardial blood flow in patients with triple-vessel disease.

Angina Pectoris↗
PubMed1988

Delayed radiation necrosis of brain evaluated positron emission tomography.

In four patients highly suspected of having delayed radiation necrosis of the brain, regional cerebral blood flow and metabolism were studied by using positron emission tomography (PET) with the 15O-labelled gases, 18F-fluorodeoxyglucose (18FDG). All four patients showed marked decreases in glucose and oxygen consumption in the lesion with that suspected pathology in comparison with those in normal brain parenchyma. Two of them were histologically proved to have radiation injuries (one was radiation necrosis and another was early delayed reactions). But one patient was histologically proved to have a recurrent tumor. Although metabolic study with PET using 18FDG is generally an excellent procedure for differentiation between radiation injuries and recurrent brain tumor, these results imply that in some cases the differential diagnosis is difficult even with 18FDG. The present study demonstrated considerably more pronounced reduction in the metabolism than the decrease of the blood flow in the lesion with radiation necrosis. This result would indicate that the primary effect causing the radiation necrosis is a direct effect of irradiation on neural tissue rather than the capillary damage.

Adult↗
PubMed1988

[Cases similar to cerebrovascular moyamoya disease--investigation by angiography and computed tomography].

The criteria of the cerebrovascular Moyamoya disease is defined by the characteristic findings of its cerebral angiograms, as follows; 1) The internal carotid siphon is narrowed or obstructed bilaterally. 2) The "Moyamoya vessels" are observed at the base of the brain or the basal ganglionic regions. 3) Main trunks of the cerebral arteries such as the anterior, the middle, and/or the posterior cerebral arteries are often not or poorly visualized. 4) Its etiology is unknown. It has been known that the occlusion of the internal carotid fork with Moyamoya vessels is not infrequently seen in patients with tuberculous meningitis, sickle cell anemia, head trauma, and so on. In the definition of the disease, patients with known etiology and/or unilateral occlusion in the carotid fork must be excluded. However, the cases who cannot fulfil its criteria of the cerebrovascular Moyamoya disease, but have its characteristic Moyamoya vessels and collateral pathways have been reported. We investigated the findings of cerebral computed tomograms in 13 patients who did not fulfil the criteria of the cerebrovascular Moyamoya disease, but revealed the Moyamoya vessels. The subjects are 5 males and 8 females, ranging 15 to 70 years old. The past histories of 9 patients among them revealed hypertension, radiation therapy for pituitary adenoma, head trauma, aplastic anemia, and the Raynaud phenomenon. By angiographic evaluations, occlusions in the unilateral carotid forks were seen in 7 patients, and stenoses in those were in 5 patients. One patient showed only a severe stenosis in the horizontal portion of the middle cerebral artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

A system for cerebral blood flow measurement using an H215O autoradiographic method and positron emission tomography.

A system for CBF measurement using an H215O autoradiographic method and positron emission tomography (PET) has been designed and installed as a clinical tool. Following an intravenous injection of H215O, a radioactivity accumulation in the brain tissue for 60 s and a continuous record of radioactivity in arterial blood were measured by a high counting speed PET device and a beta-ray detector, respectively, and CBF was calculated by a table-lookup procedure. First, this method was compared with the C15O2 inhalation steady-state method on 17 cerebrovascular disease patients and four normal subjects. The two values for CBF agreed with each other when H215O autoradiographic method was applied by correction for the dispersion in the measured arterial radioactivity-time curve. However, without the correction, the CBF by the H215O autoradiographic method revealed substantial overestimation by 30.6 +/- 17.5%. A reduced gray/white ratio of CBF was also observed in the H215O autoradiographic method. Second, simulation was performed in order to determine optimal accumulation time by PET scan; the result was that errors due to dispersion and time mismatch became critical as the accumulation time was shortened to less than 60 s.

Autoradiography↗
PubMed1987

[Oxygen extraction fraction and cerebrovascular reactivity to PaCO2 changes in ischemic brain measured by positron emission tomography].

Interrelations between oxygen extraction (OEF) and cerebrovascular reactivity to PaCO2 change (VRCO2) in ischemic brain were measured by the 15O gases steady state method and the H215O autoradiographic method using a positron emission tomography. OEF at rest and VRCO2 for hypercapnia and hypocapnia were assessed successively in five cross sections of 10 mm image resolution. With each study correlation coefficients between OEF and VRCO2 were calculated using 30 to 40 regions of interest. In hypercapnic measurements those which had a larger ischemic region resulted in a higher incident of a negative correlation. Fifteen of 19 studies (79%) showed the negative correlation. From the regression lines which showed significant correlation a mean OEF at VRCO2 =0 was 0.54 +/- 0.09, which might indicate the point at the maximal dilatation of the resistance vessels. On the other hand, in hypocapnic studies only five of 18 (28%) showed apositive correlation, and the other measurements showed diffusely negative VRCO2 over the whole regions in the brain.

Autoradiography↗
PubMed1986

Relation between tissue nature and (18F) fluorodeoxyglucose kinetics evaluated by dynamic positron emission tomography in human brain tumors.

Using dynamic positron emission tomographic (PET) scans, kinetic rate constants in the (18F) fluorodeoxyglucose (18FDG) model and glucose consumption rate were measured in human brain tumors. In the tumor tissue, all rate constants were higher on the average in the glioma grade IV and the non-glial tumor groups. The k*3 showed wide deviation in the glioma grade IV group. Discrepancy was found between the k*3 and the glucose consumption rate in several cases. The k*1 correlated with the neovascularity in tumors confirmed at angiography. Analysis of the rate constants might be useful for interpreting tumor nature and predicting its malignancy.

Adult↗
PubMed1986

Cerebral glucose metabolic change after high-dose methotrexate treatment in patients with acute lymphocytic leukemia.

An investigation was carried out to study the changes in the cerebral metabolic rate for glucose (CMRGlc) after high-dose methotrexate infusion (HD-MTX) in leukemic children, compared with the rate before such treatment. This is the first report on the relation between HD-MTX and the CMRGlc. An infusion of HD-MTX significantly reduced the glucose metabolism. It is suggested that this depression of the CMRGlc may have been associated with acute neurotoxicity of MTX. Measurement of the CMRGlc may be of value in detecting neurotoxicity of MTX. The reasons for these metabolic alterations need further investigation.

Adolescent↗
PubMed1986

Positron emission tomography in patients with a primary intracerebral hematoma.

Using positron emission tomography, the regional cerebral blood flow (CBF), oxygen extraction fraction (OEF) and oxygen consumption (CMRO2) were studied in 21 patients with hypertensive intracerebral hematomas. The study showed a very localized decrease of CBF and CMRO2 around a hematoma, and revealed in two cases (9.1%) distinct luxury perfusion around it. There was diffuse reduction of CBF with increased OEF in hematomas larger than 4.5 cm in diameter. The results suggested that surgical evacuation should be considered for hematomas with a diameter exceeding 4.5 cm.

Adult↗
PubMed1986

Regional cerebral blood flow and metabolism in patients with chronic obstructive carotid disease.

Regional cerebral blood flow (CBF), oxygen extraction fraction (OEF) and oxygen consumption (CMRO2) were studied by PET in 26 patients with chronic occlusion(s) or severe stenosis of the internal carotid or middle cerebral artery(ies) without a large (greater than 2 cm) infarction. Most of them showed a coupled decrease of CBF and CMRO2 in the internal carotid distribution. In 5 patients (19%), the CBF in the least perfused but structurally normal tissue was reduced to critically low values while maintaining CMRO2, considerably increasing OEF. Since detection of a lesion with hemodynamic insufficiency was important for the indication for an EC/IC bypass operation, only 19 per cent of the present series would have had an indication for surgery.

Blood Volume↗