Computerized densitometry and color coding of [14C] deoxyglucose autoradiographs

A computerized image processing system has been developed for quantitative analyses of autoradiographs obtained with the [14C]deoxyglucose method. The system is composed of standard, commercially available components and includes a scanning microdensitometer, computer, image memory and display system, and monochrome and color monitors. The associated computer programs are written in PASCAL. Autoradiographs are automatically scanned, and the optical density of each spot is digitized at a maximum resolution of 65,536 readings per 6.4 x 6.4 mm area and stored in memory. Images can be reconstructed from the data in memory, displayed on the monitors, and utilized for microdensitometric analyses or manipulated for image enhancement, enlargement, or weighted averaging of selected regions. The digitized data can also be utilized to solve the operational equation of the [14C]deoxyglucose method, and color-coded images of autoradiographs can be reconstructed so that each color represents a narrow range of the rate of glucose utilization. By means of this system, it is possible to generate quantitative metabolic maps that display the distribution of actual rates of local glucose utilization throughout the entire central nervous system in regions as small as 100 micrometers or less.