CORTICAL REGION OF INTEREST DEFINITION ON SPECT BRAIN IMAGES USING X-RAY CT REGISTRATION

We present a method for brain single photon emission computed tomography (SPECT) analysis based on individual registration of anatomical (CT) and functional (Xe-133 regional cerebral blood flow) images and on the definition of three-dimensional functional regions of interest. Registration of CT and SPECT is performed through adjustment of CT-defined cortex limits to the SPECT image. Regions are defined by sectioning a cortical ribbon on the CT images, copied over the SPECT images and pooled through slices to give 3D cortical regions of interest. The proposed method shows good intra- and interobserver reproducibility (regional intraclass correlation coefficient almost-equal-to 0.98), and good accuracy in terms of repositioning ( almost-equal-to 3.5 mm) as compared to the SPECT image resolution (14 mm). The method should be particularly useful for analysing SPECT studies when variations in brain anatomy (normal or abnormal) must be accounted for.