MRI-BASED HIPPOCAMPAL VOLUMETRICS - DATA-ACQUISITION, NORMAL RANGES, AND OPTIMAL PROTOCOL

The process of producing magnetic resonance (MR) volume measurements c an be divided into considerations of acquisition and postprocessing of the MR data. With careful attention to both of these, precise and rep roducible measurements can be achieved, A statistical description of h ippocampal measurements in normal volunteers must be available for com parison if volumetrics are employed either for clinical or research pu rposes. A wide range in ''normal'' hippocampal volume is present in th e studies of normal young adults that have been reported to date, This variability is most probably due to interinstitutional differences in hippocampal boundary criteria, and in the software employed for count ing pixels in a defined region of interest (ROI), Because the numeric output from the volume measurement procedure is highly technique-depen dent, the statistical description of ''normal'' should be determined o r calibrated at each institution wishing to use these techniques.