Comparison of spinal magnetic resonance imaging and myelography in cancer patients.

Spinal involvement by systemic malignancy is common, and often leads to extradural compression of the spinal cord and/or nerve roots by metastases. Rapid, anatomically accurate diagnosis is essential to the successful management of these patients. We compared spinal magnetic resonance imaging (MRI) with conventional myelography in a series of 31 cancer patients being evaluated for myelopathy (N = 10), or back/radicular pain (N = 21). All patients were evaluated between April 1985 and July 1986, and underwent both studies within ten days of each other (median, two days). MRI was performed on a 0.5 Tesla Technicare unit with a body surface coil, and results compared with standard contrast myelography. All studies were reviewed separately and in a "blinded" fashion. MRI and myelography were comparable in detecting large lesions that produced complete subarachnoid block (five of ten patients with myelopathy, three of twenty-one patients with back/radicular pain). In 19 of 31 patients, smaller but clinically significant extradural lesions were found. In nine of 19 cases, these lesions were demonstrated equally well by both modalities; in nine of 19 cases, these lesions were demonstrated by myelography alone; in one of 19, a lesion was demonstrated by MRI alone. Given our current technology, myelography appeared superior to MRI as a single imaging modality. However, MRI may be an alternative in patients where total myelography is technically impossible or unusually hazardous.