Grey and white matter SPECT neuroimaging: iterative reconstruction using a high resolution anatomical image to correct for 3-D detector response, attenuation, and scatter

In the presence of a 3-D detector response, attenuation, scatter, and noise, an iterative reconstruction algorithm (IRA) for single photon emission computed tomography (SPECT) neuroimaging overcomes major limitations of applying standard filtered back-projection (FBP) reconstruction to projection data which have been degraded by convolution of the true radioactivity distribution with a 3-D detector response: the nonuniformity within the grey (or white) matter voxels which results even though the true model is uniform within these voxels; a significantly lower ratio of grey/white matter voxel values than in the true model; and an inability to detect an altered radioactivity value within the grey (or white) matter voxels. The IRA permits the detection of subtle variations in both grey and white matter radioactivity distribution. These results indicate that the IRA implicitly performs accurate partial voluming, attenuation, and scatter corrections. The presence of noise, however, is a partially limiting factor. Thus, the IRA provides the potential for quantitative SPECT imaging of diseases involving both grey and white matter