MRI in the diagnosis and treatment of suspected malignant spinal cord compression.

It remains unclear whether MRI is essential in all patients with suspected malignant spinal cord compression (MSCC), or whether some patients can be treated on the basis of plain radiographic findings and neurological examination. A prospective study was carried out of 280 consecutive patients with suspected MSCC, and the results of neurological examination plus plain radiographs were compared with MRI. 201 patients had MSCC (186 extradural, 5 intradural extramedullary and 10 intramedullary) and 11 patients had thecal sac compression without evidence of spinal cord compression. 25% of patients with MSCC had two or more levels of compression, 69% of these involving more than one region of the spine. A paraspinal mass was noted at the site of extradural spinal cord compression in 28%, and only one-third of these were detected on plain radiography. Focal radiographic changes and consistent neurology were present in 91 (33%) patients who had not had previous radiotherapy. MRI confirmed the presence of MSCC in 89/91 patients (specificity and positive predictive value of radiographic/clinical findings 98%) and the level of disease in all. MRI led to a change in the radiotherapy plan in 53% of patients (21% major change). The sensory level when present was four or more segments below the MRI level in 25/121 (21%) patients, and two or more levels above in 8/121 (7%) patients. Although focal radiographic abnormalities with consistent neurological findings, when present, accurately predicted the presence and level of MSCC, whole spine MRI is indicated in most patients with suspected MSCC because the additional information may alter the management plan. Treatment may be appropriately initiated on the basis of focal radiographic changes and consistent neurology if MRI is contraindicated or delayed, and in patients with a poor prognosis. In patients in whom there are no focal radiographic abnormalities and consistent neurological findings, urgent MRI is mandatory before radiotherapy is commenced.