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Biomedical subjects

F Shishido

Publications and source records attributed to F Shishido.

At least 91 records · Page 5Linked to original sources
PubMed1987

Positron emission tomographic evaluation of radiochemotherapeutic effect on regional cerebral hemocirculation and metabolism in patients with gliomas.

Hemocirculatory and metabolic changes in tumor regions and the remote brain structure were analyzed using oxygen-15 and fluorine-18 positron emission tomography (PET) in eight patients with gliomas after radiation and chemotherapy of 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU) and N-(2-tetrahydrofuryl)-5-fluorouracil (FT-207). In the tumor regions after the radiochemotherapy, regional cerebral blood flow (rCBF) and cerebral blood volume (rCBV) varied widely and there was a tendency for oxygen consumption (rCMRO2) to fall. The change in glucose consumption (rCMRG1) was especially noteworthy with regard to clinical correlations. Six patients with decreased rCMRG1 values had 16% to 29% regressions in tumor size measured by X-ray computerized tomography (CT), and showed some period of clinical relief. In contrast, one patient with an increased rCMRG1 value had some progression of tumor growth, and there were no clinical amelioration. The hemocirculation and metabolism of the contralateral gray matter seem to fluctuate by various factors as intracranial pressure and the effectiveness of the therapy. In gliomas therapy, tumor rCMRG1 values can be a good indicator of therapeutic effectiveness.

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

[Cerebral blood flow measurement using H2(15)O intravenous injection and positron emission tomography: description of implementation and applications to cerebrovascular reactivity measurement].

The method for cerebral blood flow (CBF) measurement using an H215O intravenous injection and positron emission tomography (PET) was implemented, examined and applied to measure cerebrovascular reactivity to PaCO2(VRCO2) and to MABP (VRBP) in normal brain and in ischemic brain. Immediately after bolus intravenous injection of 30-40 mCi H2(15)O, a time-activity curve of H2(15)O concentration in the arterial blood and in the brain were measured for 60 sec by a beta detector and a PET, respectively. The PET was HEADTOME III and measured five planes. CBF was determined by the table-look up method based on the autoradiographic principle. Six volunteers were studied to examine region of VRCO2, and a moyamoya patient and a stroke patient with a bilateral-intracarotid circulation defect were studied to examine VRCO2 and VRBP in ischemic brain. The studies were carried out so as to be followed two or three H2(15)O CBF measurements with changing PaCO2 or MABP after control study at rest condition. In addition, prior to the H2(15)O study O15 gas steady state study was performed on all subjects. Validity of the method examined by simulation studies showed 3% error per 1 sec time shift of the artery curve for 60 sec PET scan duration and the error was rapidly increased to the shorter scan duration. Inhomogeneity of a brain tissue gave mild under-estimation by 5% for 60 sec PET scan duration. VRCO2 in normal brain was revealed to be almost uniform except that the infratentorium area showed a slight higher VRCO2 than the supratentorium area. The ischemic brain showed a negative correlation between VRCO2 and oxygen extraction fraction (OEF), and a positive correlation between VRBP and OEF.

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↗
PubMed1987

[Regional myocardial blood flow quantitatively measured using O-15 water and dynamic positron emission tomography].

This study was performed to measure regional myocardial blood flow (MBF) quantitatively using dynamic positron emission tomography (PET) and O-15 water. The subjects consisted of two normal volunteers, four patients with normal coronary angiograms (CAG), two patients with angina pectoris (3-vessel disease) and three patients with myocardial infarction. O-15 water (15-20 mCi) was injected via the cubital vein in a bolus, and dynamic PET was performed. MBF was calculated according to the method of Iida. The region of interest (ROI) was selected on the left ventricular wall (septum, anterior and lateral walls) and MBF was calculated in each ROI. In normal volunteers, MBF was 1.07 to 1.17 ml/g/min. It was 0.96 to 1.02 ml/g/min in patients with normal CAG, and 0.53 to 0.64 ml/g/min in patients with angina pectoris in the ischemic area. In patients with myocardial infarction, MBF was so diminished in the infarcted area as detected by 2-DE or ECG that the absolute value was almost 0 ml/g/min. In patients with angina pectoris, there was no definite defect on the MBF image, but we could estimate the severity of coronary stenosis by quantifying the MBF. The clinical advantages of this method include estimation of the severity of coronary arterial stenosis in the resting state.

Adult↗
PubMed1987

[Assessment of myocardial circulation and metabolism using positron CT].

Positron CT measurement can provide valuable information of myocardial circulation and metabolism. Our institute has participated in the development and use of this measurement since April 1983. At present, we can assess the circulation and metabolism of myocardium using a position CT device (HEADTOME-III) and some radiopharmaceuticals labeled with positron emitters. In this paper, we introduced our method about its measuring device, radiopharmaceuticals and theoretical model, and also indicated the clinical usefulness of the measurement.

Carbon Monoxide↗
PubMed1987

Automatic radiologic reporting system using speech recognition.

A radiograph report is usually made from an oral dictation by a radiologist, which is then typed. Typing Japanese is rather inconvenient and consumes many hours. In this paper we introduce a computer-assisted reporting system for radiologic images using speech recognition. The hardware of the reporting system consists of a speech recognizer DP-200(NEC) and a personal computer PC-8801 or PC-9801. The DP-200 has the capability of storing 500 different words spoken by a radiologist. At present, three application programs have been designed. These are for the interpretation of a liver scintigram, a bone scintigram and a chest radiograph. Data entry is done by the radiologist at a CRT display terminal in a conversational manner with predefined and predetermined branching. The time required to make a normal report using the liver or bone scintigram system was within one minute. The reporting time was several minutes in the case of an abnormality report. It is suggested that the system is useful for making an imaging report, for constructing the data base for the interpretation of medical images and for the picture archiving and communication system.

Bone and Bones↗
PubMed1986

Tomographic mapping of kinetic rate constants in the fluorodeoxyglucose model using dynamic positron emission tomography.

A quick computing algorithm to calculate the rate constants (k*1, k*2, k*3) in the [18F]2-fluoro-2-deoxy-D-glucose (FDG) model was developed. The algorithm solved for the rate constants pixel by pixel using a conventional least-squares method and two tables consisting of a set of various rate constants, to shorten the computing time. Five planes of rate constant images were obtained. A combined study using the dynamic FDG method and the 15O-labeled gas continuous inhalation method was performed on seven healthy male volunteers aged 26-35 years. Results indicated an apparent discrepancy between CMRglu and CMRO2 in the cerebellum, where the low glucose utilization was correlated with a low FDG phosphorylation rate (k*3) despite a sufficient FDG transportation rate (k*1) from plasma to tissue.

Autoradiography↗
PubMed1986

Positron emission tomographic evaluation of histological malignancy in gliomas using oxygen-15 and fluorine-18-fluorodeoxyglucose.

HEADTOME III, a high resolution PET, has been employed using 15O and 18F labelled pharmaceuticals to evaluate histological malignancy of gliomas preoperatively. PET study was applied on eighteen preoperative gliomas including two recurrent cases. Haemocirculatory and metabolic indices of regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction fraction (rOEF), cerebral metabolic rates for oxygen (rCMRO2) and glucose (rCMRGI) were measured in the viable portion of the tumour, and the contralateral grey and white matter. In the tumour region, rCBF and rCBV were variable and unrelated to grades of tumour malignancy. rCMRO2 and rOEF values reduced significantly (p less than 0.01) relative to the contralateral brain tissue. The average rCMRGI values was 3.00 +/- 1.06 mg 100 ml-1 min-1 (mean +/- SD) for 7 low grade gliomas (grade II), and 5.91 +/- 3.61 mg 100 ml-1 min-1 for 11 high grade gliomas (grade III and IV). These results would support that anaerobic glycolysis increased in the metabolism of gliomas with malignancy. In comparison with normal volunteers, rCBF, rCMRO2, and rCMRGI values in the contralateral grey matter of gliomas were markedly reduced (p less than 0.01, p less than 0.05, p less than 0.01, respectively) possibly due in part to raised intracranial pressure and depressed cerebral functional activity, so that rOEF was increased to a level of approximately 0.5.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
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↗