[MR measurement of normal brainstem cerebellum and corpus callosum on midsagittal section].

The dimensions of the brainstem, cerebellum and corpus callosum were measured on magnetic resonance (MR) images with sagittal spin-echo sequence. Eighty-two normal adults (average 49.6 years old) were measured. The mesencephalic, pontine or cerebellar diameters and lengths could be measured more accurately and reproducibly than medullary diameter and length. The anterio-posterior diameter of the pons and the cerebellum was 23.2 +/- 1.4 mm and 26.4 +/- 2.5 mm respectively. The length of the pons and the cerebellum was 27.8 +/- 2 mm and 45.8 +/- 3.5 mm respectively. We have observed focal thinning at the body of corpus callosum in 73%. This narrowing is almost unquestionably a normal variant.