MR-based statistical atlas of the Gottingen minipig brain

The domestic pig is increasingly being used as, an experimental model for b rain imaging studies with positron emission tomography (PET). The recording of radiotracer uptake by PET gives functional and physiological informatio n, but with poor spatial resolution. To date, anatomical regions of interes t in pig brain have been defined in AM images obtained for each individual animal, because of the lack of a standard stereotaxic coordinate system for the pig brain. In order to define a stereotaxic coordinate system, we core gistered T1-weighted MR images from 22 male Gottingen minipigs and obtained a statistically defined surface rendering of the average minipig brain in which stereotaxic zero is defined by the position of the pineal gland. The average brain is now used as a target for registration of dynamic PET data, so that time-activity curves can be extracted from standard volumes of int erest. In order to define these volumes, MR images from each individual pig were manually segmented into a total of 34 brain structures, including cor tical regions, white matter, caudate and putamen, ventricular system, and c erebellum. The mean volumes of these structures had variances in the range of 10-20%. The 34 brain volumes were transformed into the common coordinate system! and then used to generate surface renderings with probabilistic th reshold greater than 50%. This probabilistic threshold gave nearly quantita tive recovery of the mean volumes: in native space. The probabilistic volum es in stereotaxic space are now being used to extract time-radioactivity cu rves from dynamic PET recordings. (C) 2001 Academic Press.