Positron Emission Tomography: Functional Neuroanatomy In Vivo

Abstract

Positron emission tomography (PET) is a well-established technique that allows to map in the living animal or human the distribution of radiopharmaceuticals in brain tissue, following the intravenous or inhalational administration of a molecule labeled with a positron emitting radionuclide. The main advantages of PET relative to other functional imaging methods are: 1) the availability of a wide array of compounds naturally labeled with ¹⁵O, ¹¹C, ¹³N or ¹⁸F; 2) the absolute quantitation, on a pixel-by-pixel basis, of the radioactivity concentration present in the tissue; and 3) the excellent time and spatial-resolutions of the data obtained, allowing, with state-of-the-art equipment, to determine the time course of radioactivity in brain structures that are only a few millimeters in size (Phelps and Mazziotta, 1985). Relative to in vitro autoradiography, the distinct advantage of PET is that it provides the opportunity to carry out sequential measurements in the same subject; in experimental animals, a pre-lesion (control) study can be performed allowing to use each subject as its own control.