Isotope studies provide valuable data about an organ's function in vivo. Thanks to positron emission tomography (PET)
using the radiolabeled natural metabolites, such as [18F]-2-fluoro-deoxy-d-glucose (FDG), biological and physiological
meaning of nuclear medicine scans has been considerably increased. Therefore it is of interest to elucidate the
possibilities of the technique in a study of some natural metabolites like glycine influencing the blood microcirculation.
Glycine, as a medicine, was recently shown to have a positive therapeutic effect in the treatment of patients with
ischemic stroke and some other neurological disorders based on vascular disturbances. By previous direct
biomicroscopic investigations of pial microvessels in laboratory rats an expressed vasodilatory effect of topically applied
glycine was proved. The arterioles diameters depending on initial size have been increased by 200-250% for arterioles of
20-40 μm and by 150-200% for arterioles of 50-80 μm. The PET images were acquired before and after sublingual
application of glycine (200 mg). The quantitative analysis of FDG volume concentration (Bq/ml) in the rat brain
demonstrated that, in studies after glycine administration, maximal, minimal and mean FDG volume concentration in the
brain increased by 200-250% in comparison with the baseline data. Thus, our results revealing evident correlation
between FDG-PET images and direct biomicroscopic observations confirm the great potential of molecular imaging
techniques to explore in vivo process in the brain.
Mycardial gated SPECT (gSPECT) is widely used to evaluate different parameters of cardiac function. Semi-quantitative analysis of the images (a visual analysis of the images with a simple scaling of function) can be performed after image segmentation using 4- or 5-point scale. The purpose of this study was to compare two functional images (KL0 and KL1) obtained by KLT (Karhunen-Loeve transform) and "clinical" images of gSPECT and to test feasibility of semi-quantitative analysis of perfusion and contraction by KLT. 99mTc-gSPECT studies were performed in 105 patients with suspected coronary artery disease. We performed visual and semi-quantitative of gSPECT and KLT images (KLT was applied to images from central slices of 3 axes). Our results showed that KL0 images match with myocardial perfusion images; KL1 images combine the data on spatial and temporal evolution of each pixel and regroup pixels by families. We suggest that opposite parts of KL1 images characterize two components of myocardial contraction: wall motion and thickening. These preliminary results showed relations between KLT images and myocardial function: KL0 images and myocardial perfusion, KL1 images and cardiac mechanics. These findings prove the potential of KLT for yielding additional useful clinical information.