SUPERPOSITIONING OF 3-DIMENSIONAL NEUROANATOMICAL DATA SETS

Superpositioning of multiple 3-dimensional digital volumes is essentia l to extending neuroimaging capabilities from single-subject analysis to group evaluation. In this study, 6 rat heads were cryoplaned and di gital images of the specimen blockface were organized into data volume s. The midline plane of each brain guided coronal and horizontal rotat ions and medial-lateral positioning. Four different methods of determi ning sagittal rotation, dorsoventral position; and anteroposterior pos ition were tested. The first technique uses lambda and bregma as fiduc ial points; the second method employs bony sutures in the base of the skull; and the third strategy fits both sets of alignments points. The fourth method differs from the previous landmark-based approaches by employing cross-correlation of image densities. A composite of midsagi ttal cutplanes through the volumes aligned by the first method reveale d significant misalignment. Use of ventral fiducials resulted in impro ved correlation statistics for orthogonal cutplanes through the volume s and significantly reduced positional variability of anteroposterior landmarks. Combining dorsal and ventral fiducials produced a slight im provement in midsagittal image correlation but had mixed effects on la ndmark variability. Following the fourth method of registration, corre lation statistics and the alignment of reference points were similar t o those obtained with the 4-point approach.