A METHODOLOGY FOR SPECIFYING PET VOIS USING MULTIMODALITY TECHNIQUES

Volume-of-interest (VOI) extraction for radionuclide and anatomical me asurements requires correct identification and delineation of the anat omical feature being studied, We have developed a toolset for specifyi ng three-dimensional (3-D) VOI's on a multislice positron emission tom ography (PET) dataset, The software is particularly suited for specify ing cerebral cortex VOI's which represent a particular gyrus or deep b rain structure, A registered 3-D magnetic resonance image (MRI) datase t is used to provide high-resolution anatomical information, both as o blique two-dimensional (2-D) sections and as volume renderings of a se gmented cortical surface, VOI's are specified indirectly in two dimens ions by drawing a stack of 2-D regions on the MRI data, The regions ar e tiled together to form closed triangular mesh surface models, which are subsequently transformed into the observation space of the PET sca nner, Quantification by this method allows calculation of radionuclide activity in the VOI's, as well as their statistical uncertainties and correlations, The methodology for this type of analysis and validatio n results are presented.