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Biomedical subjects

G B Saha

Publications and source records attributed to G B Saha.

36 records · Page 2Linked to original sources
PubMed1990

A prospective comparison of rubidium-82 PET and thallium-201 SPECT myocardial perfusion imaging utilizing a single dipyridamole stress in the diagnosis of coronary artery disease.

The purpose of the present study is to prospectively compare myocardial perfusion imaging with rubidium-82 (82Rb) by positron emission tomography (PET) with thallium-201 (201Tl) imaging by single-photon emission tomography (SPECT) by recording both studies with a single dipyridamole handgrip stress, and reading both sets of images with the same display technique. In a series of 202 patients with previous coronary arteriography, the sensitivity, specificity, and accuracy of 82Rb PET were 93%, 78%, and 90% and for 201Tl SPECT 76%, 80%, and 77%, respectively. When 70 patients with previous therapeutic interventions were excluded, the remaining 132 patients showed a sensitivity, specificity, and accuracy of 95%, 82% and 92% for 82Rb PET and 79%, 76%, and 78% for 201Tl SPECT. The improved contrast resolution of PET resulted in markedly superior images and a more confident identification of defects.

Coronary Circulation↗
PubMed1989

Conditions of radioiodination with iodogen as oxidizing agent.

Different factors that give the maximum iodination of proteins by iodogen method have been evaluated. The quantity of iodogen was varied from 2 to 20 micrograms; pH from 3 to 9; the quantity of bovine serum albumin (BSA) from 25 micrograms to 2 mg; the 131I activity from 200 microCi to 5 mCi and the reaction time from 2 to 30 min. The maximum iodination of proteins is achieved with iodogen-to-iodide molar ratio of 100-200 and iodogen-to-protein molar ratio of 1-2 at pH 6-8 for 10-15 min at room temperature.

Animals↗
PubMed1977

Labeling human lymphocytes with mercury-197.

A simple method for labeling human lymphocytes with Hg-197 is described. Lymphocytes were isolated from human blood and purified by the Ficoll-Hypaque method. Labeling was carried out by incubating viable cells suspended in saline with Hg-197 for different time intervals and at different temperatures. The labeling yield varied from 48% for 1 million cells to about 70% for 10 million cells after incubation with 2 muCi of Hg-197 for 2 hr at 37 degrees C. The temperature and incubation period beyond 1 hr had no appreciable effect on the labeling yield. The yield increased by a factor of 1.5 when the cells were stimulated by phytohemagglutinin. Subcellular distribution studies showed that 60% of the tracer localized in the nucleus and cell membrane, while the remaining portion concentrated in the mitochondrial and microsomal fractions.

Humans↗
PubMedDate not supplied

The incidence of scintigraphically viable and nonviable tissue by rubidium-82 and fluorine-18-fluorodeoxyglucose positron emission tomographic imaging in patients with prior infarction and left ventricular dysfunction.

BACKGROUND: Although reversible perfusion defects, perfusion-metabolism mismatch and match patterns are important for differentiating viable from nonviable myocardium, the frequency of these scintigraphic patterns has not been reported. The study objective was to establish the incidence of these scintigraphic patterns to estimate the clinical need for metabolic positron emission tomography for evaluating tissue viability in patients with prior myocardial infarction (MI). METHODS AND RESULTS: 82Rb perfusion images were interpreted to identify reversible or irreversible defects, followed by determination of their 18F-fluorodeoxyglucose (18F-FDG) uptake pattern. In 155 patients with prior MI, analysis of 613 abnormal segments showed reversible perfusion defects in 13%. The 87% irreversible defects, 18% showed perfusion-metabolism mismatch, whereas 69% showed the match pattern. Reversible perfusion defects and perfusion-metabolism mismatches were noted in 20% (31/155) and 29% (45/155) of patients, respectively, whereas the match pattern was noted in 51% (79/155) of patients. CONCLUSION: Irreversible perfusion defects were common in our patients with prior MI, and distinction between viable and nonviable tissue was not possible by perfusion imaging alone. The identification of hibernating myocardium was possible only with the additional 18F-FDG imaging in about one third of patients. This indicates a significant clinical demand for 18F-FDG imaging that identifies patients who will benefit from revascularization.

Adult↗
PubMedDate not supplied

Gd-DISIDA--a potential contrast agent for magnetic resonance imaging of the hepatobiliary system.

Gadolinium (Gd) labeled diisopropyliminodiacetic acid (DISIDA) was prepared by mixing a Gd solution and a DISIDA solution in appropriate proportions and at controlled pH. Optimal complexation was obtained at a Gd:DISIDA molar ratio of 1:2.5 and the pH of the final solution was 7.3 to 7.5. The complex was found to be stable both in vitro and in vivo. Gd-DISIDA (12.5 mumol/kg) was injected into mice, and T1 and T2 relaxation times of various tissues were measured and compared with those of normal tissues. Only the T1 values of the blood and the liver markedly decreased after Gd-DISIDA administration and also the reduction in T1 values depended on the dose of Gd-DISIDA. Magnetic resonance imaging of the rabbit liver showed considerable contrast enhancement at 30 minutes after administration of 12.5 mumol/kg of Gd-DISIDA.

Animals↗