Overview of quantitative autoradiography

Realizing the diversity in neural function, structure, metabolism, and pathology within the central nervous system, Kety, Sokoloff, and coworkers (Landau et al., 1955; Reivich et al., 1969; Sokoloff et al., 1977; and Sakurada et al., 1978) developed quantitative autoradiography (QAR) and used it to demonstrate variations in cerebral blood flow and glucose utilization not only among brain regions but also within them at the level of nuclei, layers, and tracts. In the extreme, QAR can localize and quantitate 14C-radioactivity with reasonable accuracy in a tissue volume of less than 100 μm x 100 μm x 20 μm when care is taken to minimize intratissue redistribution during and after the experimental period. Because of this ability to localize radioactivity in brain tissue, the measured parameters and functions are often referred to as ‘local,’ e.g. local cerebral blood flow (LCBF) and local cerebral glucose utilization (LCGU). This localizing capability is the major reason for using quantitative autoradiography in animal studies.

In brief, the technique of quantitative autoradiography involves administering a radiotracer into an experimental animal, usually intravenously, taking a series of blood samples for assessing radioactivity, killing the animal, and rapidly removing and freezing the brain.