Correction for partial volume effect in PET blood flow images

摘要

Current positron emission tomography techniques for the measurement of cerebral blood flow assume that voxels represent pure material regions. In this work, a method is presented which utilizes anatomical information from a high resolution modality such as MRI in conjunction with a multicompartment extension of the Kety model to obtain intravoxel, tissue specific blood flow values. In order to evaluate the proposed method, noisy time activity curves (TACs) were simulated representing different combinations of gray matter, white matter and CSF, and ratios of gray to white matter blood flow. In all experiments it was assumed that registered MR data supplied the number of materials and the fraction of each present. For each TAC, three experiments were run. In the first it was assumed that the fraction of each material determined by MRI was correct, and, in the second two, that the value was either too high or too low. Using the tree annealing method, material flows were determined which gave the best fit of the model to the simulated TAC data. The results indicate that the accuracy of the method is approximately linearly related to the error in material fraction estimated for a voxel.