[Clinical value of pulmonary scintigrams].
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Adolescent↗
Biomedical subjects
K Hisada
Publications and source records attributed to K Hisada.
New diagnostic approach to brain lesions in nuclear medicine. Differential diagnosis of brain lesions with a computed brain scan diagnosis by the likelihood method.
Using 240 true positive brain scans, a computer system for the differential diagnosis of brain lesions has been evaluated. Eighty-six parameters were extracted from brain scan findings without relationship to neurological signs and symptoms, and the likelihood method was adopted as an example of mathematical logic. The results of our experiment indicated that the overall accuracy was 77 per cent for the maximum likelihood method. The digital computer gave satisfactory results, particularly for diseases such as infarct, meningioma, acoustic neurinoma, and subdural hematoma. In spite of several problems to be solved, this method could provide invaluable help in differential diagnosis of brain lesions.
Arteriovenous Malformations↗
Evaluation of cerebrospinal fluid flow through a Pudenz 12 mm or a standard Rickham reservoir: phantom experiments.
We have investigated the assessment of fluid flow through a Pudenz and a Rickham shunt using radioactive tracer. Experimentally, the radioactivity clearance curve obtained, using either shunt, is defined by two exponents. The relationship between flow-rate (F) and clearance half-time (T1/2) of the first component is identical with the clearance formula (formula: see text) or log10(F) =-LOG10(T1/2) + LOG100.693V using the physical volume. The value of the second component in a Pudenz 12 mm and a standard Rickman reservoir is log10(F) = -1.3LOG10(T1/2) + 0.087 and log 10(F) =-1.8log10(T1/2) + 0.019 respectively. In clinical practice, the first component may not be recorded adequately because the interval between appearance of the first and second components is very short. To calculate the CSF flow, we recommend referring to the line of "radioactivity clearance half-time and flow-rate" of the second component instead of the calculation based on clearance formula using a physical volume.
Cerebrospinal Fluid↗
Acutely administered haloperidol-induced widespread reduction of regional cerebral blood flow observed from subtraction of brain imaging with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime.
Changes in brain images with single photon emission computed tomography (SPECT) using technetium-99m hexamethyl-propyleneamine oxime (99mTc HMPAO) before and after intramuscular injection of haloperidol (0.08 mg/kg) were studied in 2 unmedicated schizophrenic patients and 2 normal controls by a new technique, i.e. subtraction of brain images. The haloperidol injection reduced regional cerebral blood flow extensively in the bilateral cerebral hemispheres in one of the schizophrenics and one of the normal controls, with little or no haloperidol-induced effects in the remaining 2 subjects. The widespread cortical reduction is considered to be due to a nonspecific or indirect effect of haloperidol in view of the broad action sites inconsistent with the known anatomy of the mesocortical dopaminergic system.
Acute Disease↗
Age-matched normal values and topographic maps for regional cerebral blood flow measurements by Xe-133 inhalation.
The relationship between normal aging and regional cerebral blood flow (rCBF) computed as initial slope index (ISI) by Fourier method was investigated in 105 right-handed healthy volunteers (132 measurements) by Xe-133 inhalation method, and age-matched normal values were calculated. Mean brain ISI values showed significant negative correlation with advancing age (r = 0.70, p less than 0.001), and the regression line and its 95% confidence interval was Y = -0.32 (X - 19) + 63.5 +/- 11.2 (19 less than or equal to X less than or equal to 80). Regional ISI values also showed significant negative correlations for the entire brain (p less than 0.001). The regional reductions of ISI values with advancing age were significantly greater in the regional distribution of the middle cerebral arteries bilaterally, compared with regions in the distribution of the other arteries (p less than 0.05). Therefore, measured rCBF values for patients must be compared to age-matched normal values for mean hemispheric and each region examined. Two kinds of topographic maps, brain map showing rCBF compared to age-matched normal values and showing hemispheric differences were made by dividing patient's values by the 95% confidence limits for age-matched normal values and displaying laterality index calculated as follows, respectively. (formula; see text) These maps were useful for evaluating significantly decreased or increased regions and regional hemispheric differences.
Adult↗
Liquid chromatographic determination of ochratoxin A in coffee beans and coffee products.
A liquid chromatographic method for the determination of ochratoxin A in coffee beans (green and roast), instant coffee, and coffee drink is described. The sample is subjected to extraction with methanol-1% aqueous sodium bicarbonate (1 + 1) and C18 cartridge cleanup. The extract is chromatographed on a Nucleosil 5C18 column with a mobile solvent of acetonitrile-water-0.2M phosphate buffer pH 7.5 (50 + 47 + 3) containing 3 mM cetyltrimethylammonium bromide as an ion-pair reagent. Ochratoxin A is detected with a fluorometer (excitation 365 nm, emission 450 nm). The sensitivity was increased 20-fold by using ion-pair resolution. The detection limits corresponded to 2 micrograms/kg for coffee beans, 5 micrograms/kg for instant coffee, and 0.2 microgram/kg for coffee drink. The recoveries from coffee products were generally better than 80.7% and the relative standard deviations were 3.43-5.93%. The peak coinciding with ochratoxin A can be confirmed by treatment using alcohol (methanol, ethanol, or n-propanol) and H2SO4.
Chromatography, Liquid↗
Reverse phase liquid chromatographic determination and confirmation of aflatoxin M1 in cheese.
A systematic method is proposed for determination and confirmation of aflatoxin M1 in cheese by liquid chromatography (LC). A sample of cheese is extracted with chloroform, cleaned up on 2 silica gel columns followed by a Sep-Pak C18 cartridge, and chromatographed on a 5 microns octadecyl silica column with fluorometric detection. The sample extract or standard is treated with n-hexane-trifluoroacetic acid (TFA) (4 + 1) for 30 min at 40 degrees C. Analysis by LC with TFA-treatment of the extract provides quantitative data. Multiple assays of 5 samples of Gouda cheese spiked with aflatoxin M1 at levels of 0.5, 0.1, and 0.05 ng/g showed average recoveries of 93.2, 91.6, and 92.4%, with coefficients of variation of 2.63, 3.97, and 4.52%, respectively. Assay of 5 naturally contaminated cheeses resulted in 0.051-0.448 ng/g of aflatoxin M1. Limit of quantitation is about 0.01 ng/g. The identity of aflatoxin M1 is confirmed by treating aflatoxin M1 or the M2a derivative with TFA-methanol (or ethanol) (3 + 1). The TFA-methanol reaction products of M2a could be detected quantitatively.
Aflatoxin M1↗