Factor analysis of dynamic structures in dynamic SPECT imaging using maximum entropy

Factor analysis of dynamic structures (FADS) is a technique used in the automatic extraction of time activity curves (TACs) from dynamic sequences. Although it has been reported that factor analysis with non-negativity constraints can in certain cases correlate with region of interest (ROI) measurements in SPECT and PET heart studies, the method does not ensure a unique solution. In this work it is shown that the FADS result is improved by using the Maximum Entropy Principle. Both the FADS technique and the new maximum entropy method were tested on simulated data and experimental /sup 99m/Tc-teboroxime canine cardiac data. The results showed that the FADS technique, using only non-negativity constraints, produced curves that did not always closely approximate the true curves. The new method, however, resulted in TACs that closely resembled the true curves. Thus, the inclusion of an entropy term is a useful method for obtaining more accurate extractions of TACs from dynamic SPECT data.