Abstract
1764
Objectives Acetate is a metabolic substrate that is accumulated and metabolized selectively in the TCA cycle in astrocytes. Recently, many researches show the astrocytes play important roles in several diseases such as cerebrovascular disease, degenerative diseases, and psychiatric disorders. Study with PET and [C-11]Acetate is performed for measuring myocardial oxygen consumption and kmono which is calculated by exponential curve fitting is often used for evaluating oxygen consumption. We utilized kmono value in order to evaluate astrocyte specific energy metabolism quantitatively.
Methods 10 male normal volunteers (mean age, 33.4 ± 3.0 years) were recruited in this study. After transmission scan, 740 MBq of [C-11]Acetate was injected and 40 minutes (20 x 2 min) dynamic PET study was performed. PET camera was SET2400W system (Shimadzu). All data were reconstructed by OSEM algorithm (subset 12, iteration 3). Pixel-by-pixel kmono image was computed using PET data 10 minutes after the injection. SPM8 software was used to normalize to standard brain of CMRO2 image, and regional comparisons ware carried out.
Results The averaged kmono value for whole brain was 7.0e-4 ± 2.3e-4 1/min and regional differences of kmono values were observed, for instance, high kmono values in occipital cortex and pons, and low kmono values in basal ganglia. There were large discrepancy between kmono image and CMRO2 image, which suggests specificity of astrocyte metabolism by [C-11]Acetate.
Conclusions Although it is necessary to have further studies to confirm physiological background of kmono image, our study showed kmono image has potential to offer simple, noninvasive, and quantitative evaluation of astrocyte specific energy metabolism in human brain