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Perfusion scintigraphy of the lungs with 99mTc-labeled microspheres was used for a study of changes of regional perfusion of lesser circulation in patients with chronic bronchitis of a varying degree of disturbed pulmonary hemodynamics. Even before a stable rise of pulmonary vascular resistance and development of pulmonary arterial hypertension, chronic bronchitis was characterized by redistribution of the blood flow from the lower parts of the lungs to the upper ones, which progressed with disturbance of pulmonary arterial circulation and the development of chronic cor pulmonale. This redistribution could be determined by an earlier and more important rise of the vascular tone and resistance to the blood flow in the lower parts of the lungs. The use of scintigraphic indices of the upper and lower parts (U/L) perfusion ratio led to adequate assessment of a degree of redistribution of the pulmonary blood flow in patients with chronic bronchitis.

Scintigraphy of the myocardium with 199Tl-chloride was performed in 59 patients. On the basis of the results of clinicoinstrumental investigation the diagnosis of chronic CHD was made in 36, that of acute myocardial infarction--in 7. The control group consisted of 16 persons without signs of coronary pathology. The sensitivity of scintigraphy with 199Tl-chloride in the detection of CHD was 92%, and this radionuclide was shown to be no inferior to 201Tl-chloride. 199Tl-chloride can be recommended for the diagnosis of CHD, cicatrical and necrotic myocardial lesions.

A study was made of the regional distribution of the pulmonary blood flow by means of perfusion scintigraphy of the lungs with 99mTc-albumin macroaggregates with relation to a clinical course of CHD, the state of intracardiac and pulmonary hemodynamics. The time course of microcirculation in the lesser blood flow during rehabilitation of patients after myocardial infarction was assessed. Redistribution of the pulmonary blood flow was shown to be connected with the clinical features of a course of CHD, severity of myocardial lesion, and a degree of disorder of intracardiac and pulmonary hemodynamics. Therefore these changes can be of important prognostic value in patients after myocardial infarction.

The authors conducted phantom, pharmacokinetic and scintigraphic investigation of the radionuclide thallium-199. It was shown that the spectrum of x-rays permitted good imaging of the phantom on photon energy peaks of 72 keV using a scintillation camera with a standard high resolution collimator. The physiochemical and pharmacokinetic characteristics of the radionuclide give an opportunity to use it for perfusion scintigraphy of the myocardium.

Pharmacokinetic and scintigraphic studies on 199Tl were conducted. Pharmacokinetic characteristics of 199Tl chloride give an opportunity to use it for perfusion scintigraphy of the myocardium which is no inferior in the resolving power to 201T1. The shorter half-life of 199Tl will make it possible to reduce radiation exposure of an examinee.

Spectrometric phantom studies on 199Tl were conducted. They showed that for this radionuclide low-energy parallel collimators should be used, the peak of a differential discriminator being adjusted to 72 keV. Image resolution of this radionuclide was no inferior to that of the commonly used radionuclide 99mTc.