text: what is being looked for on an mri to determine m.s.?   * mri of head with gadolinium            o typical mri findings support the diagnosis (ie, 50% progress to clinically definite ms within 2 years), but 5% of suspected patients with normal mri findings similarly progress to ms.            o t1 shows active lesions (2-6 weeks) reflecting perivascular inflammation and breakdown of blood-brain barrier (bbb). t2 most commonly shows old lesions in periventricular supratentorial white matter, but old lesions occasionally are seen in the cerebellum and brain stem.            o to visualize the optic nerve, a special mri technique is required to suppress the fat signal.            o acute disseminated encephalitis may be radiographically indistinguishable from ms.      * mri of spine with gadolinium            o for patients with acute transverse myelitis, this is indicated to rule out a compressing lesion.            o for ms lesions of the spine, a special mri technique is required to obliterate csf signal on t2-weighted images.      * ct scan of the cervical vertebrae: this is used as a screening test for cervical radiculopathy secondary to trauma and for osteoarthritis.