Flip angle


Contrast agents

of fatty tissue on T2 (FSE) might hide pathologies unless a fat suppression technique is applied.

MRI Features of the Spine

MRI is considered the best single imaging modality of the spine for its ability to demonstrate all of the spinal components—bone, discs, ligaments, fatty tissue, dura, CSF, neural tissue, and blood ves-sels—with superb contrast resolution.

Cortical bone and air both contain scarce water molecules and therefore scarce hydrogen protons. Hence they both present as a very low signal element on the MR image and therefore appear black in the image produced. The medullary bone has higher intensity in both T1- and T2-weighted images as compared with the cortical bone. The fibrous compact tissue of the outer annulus and the Sharpey's fibers have a low signal (dark) on both T1- and T2WI, whereas the nucleus pulposus, composed of fibrocartilaginous tissue with a mucoid matrix, has a high signal intensity on T2WI. In T1WI normal discs appear homogenous and the nucleus and annulus cannot be differentiated. (Figures 2-13A and 2-13B).

On axial sections, the roots of the filum terminale typically lie in a symmetric, crescent-shaped pattern with the lower sacral roots positioned dorsally and the lumbar roots positioned more anterolater-ally. The most laterally positioned roots at each level are those about to

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