[Radioisotopic methods of estimating perfusion and viability (metabolism) of the myocardium].

Radioisotope methods play a special role in cardiological diagnostics. At present, studies of myocardial perfusion also allow the estimation of cardiomyocyte metabolism. These methods are suitable for the detection of stunned, hibernating or scarred myocardium as well. The radiopharmaceuticals which accumulate in myocardium proportionally to regional blood flow (thallium-201, MIBI-Tc99m, teboroxime-Tc99m, tetrophosmin-Tc99m, furifosmin-tc99m) are used for the estimation of perfusion. In the nuclear medicine departments myocardial perfusion imaging can be performed with planar or tomographic (SPECT) methods. The techniques have high sensitivity (80%, 90%) and specificity (90%, 80%) for detection of coronary artery diseases. The radioisotopic methods have higher sensitivity than other noninvasive techniques (ECG sensitivity-60%, specificity-85%, ECHO sensitivity-81%, specificity-89%). Positron emission tomography is still the "gold" standard for the estimation of myocardial viability. This method uses substrates for different metabolic pathways (acetate-C-11, amino-acids-C-11, fatty acids-C-11, fluorodeoxyglocuse-F-18) labelled with positron emitters. Modifications in thallium protocols make estimation of myocardial metabolism possible. Recently MIBI-Tc99m has also been used in the assessment of myocardial viability. Results of these studies are of great clinical importance. They allow to predict a success of a surgical revascularysation and the return of normal myocardial function.