Magnetic resonance microscopy of hamster olfactory bulb: a histological correlation

Magnetic Resonance Imaging (MRI) has been widely used as a noninvasive diagnostic tool for obtaining morphological, metabolic, and functional information from tissue. However, its potential application in observing detailed structure comparable to that of the light microscope has not yet been fully explored. In order to evaluate the usefulness of MR microscopy, a high resolution three-dimensional (3-D) technique was applied to observe the laminar structure of the mammalian olfactory bulb (OB).

Adult male hamsters (Mesocrecitus auratus) were used as an animal model. Hamster OB and the attached anterior olfactory nucleus were removed from the skull for the MRI examinations. The images were performed with a Bruker AMX-400 system equipped with microimaging accessories. T2 weighted 3-D spin echo sequence was used with a field of view of 9 mm and data matrix of 128*128*128. The in-plane resolution was 70*70*70 microns. Histological preparation, including vibratome sectioning at 40 microns and Nissl staining, were used for light microscopic evaluations and comparisons.

Five distinct layers from the superficial to the center of the OB were distinguished in the MR images of coronal, sagittal and horizontal slices. As compared to the histological sections at the corresponding cutting planes, the laminar structure of the OB displayed in the MR microscopic images correlated well with its counterparts.

MR microscopy is capable of detecting cellular variation of unsectioned and unstained tissue. It can also be easily applied to obtain spatial information with good resolution. It appears to provide a great potential for diagnostic pathology.