Regional deconvolution method for partial volume correction in brain PET
Correction of PET images for partial volume effects (PVE) is of particular utility in studies of metabolism in brain aging and brain disorders. PVE is commonly corrected using voxel-by-voxel factors obtained from a high resolution brain mask (obtained from the coregistered MR scan), after convolution with the point spread function (PSF) of the imaging system. In a recently proposed regional deconvolution (RD) method, the observed regional activity is expressed as linear combinations of the true metabolic activity. The weights are obtained by integrating the PSF over the geometric extent of the brain regions. We have analyzed the accuracy of RD and two other PVE correction algorithms under a variety of conditions using simulated PET scans. Each of the brain regions was assigned a distribution of metabolic activity, with gray matter/white matter contrast representative of subjects in several age categories. Simulations were performed over a wide range of PET resolutions. The influence of PET/MR misregistration and heterogeneity of brain metabolism were also evaluated. Our results demonstrate the importance of correcting PET metabolic images for PVE. Without such correction, the regional brain activity values are contaminated with 30-40% errors. Under most conditions studied, the accuracy of RD and of the three-compartmental method were superior to the accuracy of the two-compartmental method. Our study provides the first demonstration of the feasibility of RD algorithm to provide accurate correction for a large number (n = 109) of brain compartments. PVE correction methods appear to be promising tools in studies of metabolism in normal brain, brain aging, and brain disorders.