High-resolution MR imaging of the cadaveric human spinal cord: normal anatomy

The purpose of this study was to demonstrate the regional MR anatomy of a normal human spinal cord under near optimal conditions. A spinal cord and meninges were excised and segments from the cervical (C6), thoracic (T6), lumbar (L3), and sacral/cauda equina regions were examined on a 2-T MR system. By using a 2.5 x 2.0 cm solenoid coil and a multislice spin-echo sequence, we achieved a resolution of 58 microns in the readout direction and 117 microns in the phase-encode direction. Histological sections corresponding to the areas imaged by MR were retained and treated with stains that demonstrated the distributions of collagen (hematoxylin, phloxine, saffron), myelin (Luxol fast blue/H and E), or neuritic processes (Bielschowsky's). Subarachnoid vascular, white matter, and gray matter structures were demonstrated by MR and light microscopy. The resulting MR images and photomicrographs were correlated. Different signal intensities were observed in the gracile and cuneate fasciculi, and these differences were similar to the pattern seen with the myelin stain. Decreased signal intensity was present in the region of the spinocerebellar tracts. The anatomic detail demonstrated by this study was clearly superior to that shown by clinical MR examinations.