Abstract

Magnetic Resonance Imaging (MRI) offers considerable promise for the quantitative study of the brain. We have investigated the application of MRI to measure the volume of six formalin-fixed cerebral hemispheres and their internal compartments. In particular, we have compared estimates of the volume of i) cortex (COR), ii) sub-cortex (SUBCOR, i.e. white matter plus central grey matter) and iii) whole cerebral hemisphere (i. e. TOTAL) obtainedfrom MR images with those obtained from physical sections of the same specimens. The method used for volume estimation was the Cavalieri method of modern design-based stereology, which is mathematically unbiased. Volume estimates were obtained from the physical sections by one observer and from the MR images by another observer. Application of paired t-tests revealed no significant differences between the mean volume of COR, SUBCOR and TOTAL obtained from the physical sections and MR images (p > 0.05). A tendency was, however, observed for estimates of SUBCOR and TOTAL obtained from the MR images to be lower than those obtained from the physical sections. In two specimens the under-estimation is significant in that the difference in the volumes of SUBCOR estimated from the physical sections and MR images is much greater than the predicted standard error on the respective volume estimates. We recommend that further investigations be performed to evaluate and compare the volume of the cerebral hemispheres and their internal compartments estimated from both physical sections and MR images of formalin-fixed specimens.

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