Assessing the performance of SPM analyses of spect neuroactivation studies

Several simulations of SPECT neuroactivation studies have been performed in order to determine the influence of both study size and activation focus c haracteristics on the detection of brain activation foci following a pixel- based statistical analysis. This was achieved by developing a methodology b ased on the Hoffman software brain phantom, SPECT acquisition simulation so ftware, standard reconstruction software, and the Statistical Parametric Ma pping (SPM96) package. We present results on the minimal activation levels required for focus detection. Furthermore, the improved sensitivity of the analysis resulting from the use of an iterative reconstruction technique (O SEM) with regard to the classical filtered backprojection (FBP) is assessed quantitatively, and the various physical, processing and physiological par ameters that potentially influence the detection of foci are discussed. Fin ally, the influence is investigated of the height threshold as implemented in SPM96 upon the size of the detected foci. Practical guidelines are propo sed with regard to the number of subjects per group for SPECT activation st udies following the split-dose design. (C) 2000 Academic Press.