3-DIMENSIONAL REALIGNMENT OF ACTIVATION BRAIN SINGLE-PHOTON EMISSION TOMOGRAPHIC STUDIES

Two methods for 3D realignment of activation brain single-photon emiss ion tomographic (SPET) studies are analyzed. The first is based on pri ncipal axes transformation (PAT). The second uses the results of the f irst method as initial values to start a least-squares iterative proce ss (LS) to search for the maximum value of the correlation function. B oth methods were tested with simulated and real studies. The results o f the PAT method showed a maximum translation error of 0,3 +/- 0.1 pix els and a rotational error of 1.2 +/- 0.7 degrees in a total of 100 ru ns. For the LS method these errors were 0.2 +/- 0.1 and 0.6 +/- 0.3. T he realignment for 34 real studies was assessed by three expert observ ers. The alignment was found to be satisfactory in all cases for the L S method, and in 18 cases (53%) for the PAT method. From the results w e conclude that a combination of both methods allows the accurate real ignment of SPET neuroactivation studies.