Deformation-based morphometry and its relation to conventional volumetry of brain lateral ventricles in MRI

Deformation-based morphometry (DBM) is a useful technique to detect morphol ogical differences over the entire brain since it analyses positional diffe rences between every voxel and a standard brain. In this report we compare DBM to semimanual tracing of brain ventricles in a population of 39 patient s with schizophrenia. High-resolution T-1-weighted magnetic resonance image s were obtained and processed with DBM and interactive tracing software. We evaluate the validity of the DBM in two different approaches. First, we di vide subjects into two groups based on the mean ventricular/brain ratios an d compute statistical maps of displacement vectors and their spatial deriva tives. This analysis demonstrates a striking consistency of the DBM and vis ual tracing results. We show that restricting the information about the def ormation fields by computing the local Jacobian determinant (as a measure o f volume change) provides evidence of the shape of ventricular deformation which is unavailable from ventricular volume measures alone. Second, we com pute a mean measure of the Jacobian values over the entire ventricles and o bserve a correlation of r = 0.962 with visual tracing based ventricular/bra in ratios. The results support the usefulness and validity of DBM for the l ocal and global examination of brain morphology, (C) 2001 Academic Press.