Comparison of overall brain volume and midsagittal corpus callosum surface area as obtained from NMR scans and direct anatomical measures: a within-subject study on autopsy brains.

Formalin fixed brains obtained from autopsy were studied by magnetic resonance imaging, using FLASH and MPR sequences. The overall volume and the midsagittal surface area of the corpus callosum (cc) of these brains were also directly measured by water displacement for overall volume determination and morphometry for cc surface area measures, allowing comparisons of these measures in a within-subject design. Thin NMR sections (1 mm thickness for FLASH and 1.25 mm for MPR) yielded overall brain volume estimates that did not differ significantly from direct volume estimations but thicker (5 mm) sections led to a significant overestimation of brain volume for NMR measures relative to direct displacement measures. There was no overall effect of type of NMR measure: FLASH and MPR scans did not yield significantly different values for overall brain volume or callosal surface area. Direct and NMR measures of the corpus callosum surface at midsagittal level did not yield significantly different estimates.