Spinal cord compression due to metastatic disease: diagnosis with MR imaging versus myelography

Epidural and subdural contrast in myelography and CT myelography

A retrospective study of 624 lumbar myelographic and CT myelographic procedures was undertaken to evaluate the frequency, radiographic and clinical relevance of contrast medium outside the dural sac. Our findings indicate that epidural contrast is frequently identified on CT scans with highly sensitive window settings (in 35.4% of all CT myelographic studies). Standard myelographic films are less sensitive for the detection of epidural contrast (9.6%). Subdural contrast is far less often encountered (in 2.4% of CT myelographic studies and in 3.2% of standard myelographic films). We believe leakage of contrast to occur through the puncture site into the epidural and subdural space.

Spinal cord compression secondary to prostate carcinoma: treatment and prognosis

Of 35 patients with prostate carcinoma and suspected spinal cord compression 26 (74%) had myelograms and/or magnetic resonance imaging studies demonstrating epidural spinal cord compression. In 5 of 26 patients (19%) spinal cord compression was the first indication of prostate cancer. All patients were initially treated with radiation, steroids and androgen deprivation therapy. Three patients underwent laminectomy. Of 12 patients (100%) ambulatory at presentation 12 remained ambulatory. Of 12 patients (83%) who were paraparetic at presentation 10 were ambulatory after treatment. However, 2 of these patients subsequently had recurrent compression and became paraplegic. Overall, 7 of 26 patients (27%) had recurrent compression. Of 5 patients who either presented with paraplegia or in whom paraplegia developed secondary to recurrent spinal cord compression 4 remained paraplegic despite treatment. The average survival of these 5 patients after treatment was 3.9 months versus 18 months for the group as a whole. In ambulatory or paraparetic patients radiation, androgen deprivation therapy and steroids are effective palliative therapy. However, patients who present with paraplegia or in whom paraplegia developed secondary to recurrent compression are often not palliated by this combination therapy. Prophylactic radiation of vertebral metastases discovered concurrently with compressive metastases may be valuable in preventing paraplegia.

MRI of extradural spinal tumours at 0.3 T

Ninety-one patients with extradural spinal tumours were examined by magnetic resonance imaging. There were 76 metastases (6 from unknown primary tumours). Seven patients had primary spinal tumours and 8 had multiple myeloma. Sixteen had bulging, diseased vertebral bodies compressing the subarachnoid space and 67 had extradural tumour compressing the spinal cord. Sixty patients had paravertebral involvement. Intraspinal involvement did not correlate with the extent of spinal lesions. All patients had vertebral destruction, with hypointense or combined hypo- and isointense signal relative to bone marrow on T1-weighted images. In most of the 22 patients with T2-weighted images the tumours were isointense or slightly hyperintense. It was usually impossible to differentiate the various tumours on the basis of signal intensity and morphology. However, metastases from carcinoma of the prostate were often more hypointense than other tumours on T1- and T2-weighted images. An inhomogeneous pattern in which diffusely low signal is combined with focal lower signal on T1-weighted images may suggest myeloma. In the 22 patients examined with both T1- and T2-weighted images, T1-weighted images gave the best information in 18; in 3 they were equivalent and in 1 inferior to T2-weighted images; they are therefore recommended for routine imaging of epidural spinal tumours.

Magnetic resonance imaging in rheumatology

Images

Pathologic vertebral compression in spinal malignancy secondary to intervertebral disk expansion

A retrospective analysis of the MR appearance of the intervertebral disks in 17 patients with spinal malignancy was performed. Disk expansion, related to neoplastic structural weakening of the bone in the face of unaltered disk biomechanics, was present in 20% of all visualized disks in association with a 77% incidence of malignant involvement of the vertebral bodies studied. This compared with a frequency in benign disk expansion (i.e., osteoporosis) of 2% in the age-matched, but randomly selected, control group. On careful review, there was no strict correlation between disk expansion and patient symptoms. Although this finding may be seen in non-neoplastic conditions, it is felt that the higher incidence of disk expansion associated with osseous vertebral malignancy nevertheless reflects the underlying gravity of the pathologic changes accompanying neoplasia.

Magnetic resonance imaging in the evaluation of spinal tumors

Magnetic resonance imaging (MRI), which has recently begun to replace myelography, postmyelography computed tomography (CT), and to some extent, bone scans, has become the procedure of choice in the evaluation of spinal tumors; the applications of MRI in this role are reviewed. In the extradural space, MRI is the most sensitive technique for the detection of tumors in the vertebral bodies. At the same time, it provides superb delineation of suspected thecal sac impingement. In the intradural extramedullary space, MRI is generally as accurate as myelography and postmyelography CT while being noninvasive. Finally, in the intramedullary space, MRI is unquestionably the procedure of choice in the evaluation of suspected cord tumors. In general, MRI has become the best initial procedure in the evaluation of suspected tumors of the spine, regardless of the space in which they may lie; frequently, it is the only required examination.