Principle and recent advances of neuroactivation study

Among the nuclear medicine imaging methods available today, H215O-PET is most widely used by cognitive neuroscientists to examine regional brain function via the measurement of regional cerebral blood flow (rCBF). The short half-life of the radioactively labeled probe, 15O, often allows repeated measures form the same subjects in many different task conditions. H215O-PET, however, has technical limitations relative to other methods of functional neuroimaging, e.g., fMRI, including relatively poor time and spatial resolutions, and, frequently, insufficient statistical power for analysis of individual subjects. However, recent technical developments, such as the 3-D acquisition method provide relatively good image quality with a smaller radioactive dosage, which in turn results in more PET scans from each individual, thus providing sufficient statistical power for the analysis of individual subject's data. Furthermored, the noise free scanner environment H215O PET, along with discrete acquisition of data for each task condition, are important advantages of PET over other functional imaging methods regarding studying state-dependent changes in brain activity. This review presents both the limitations and advantages of 15O-PET and outlines the design of efficient PET protocols, using examples of recent PET studies both in the normal healthy population, and in the clinical population