Metastatic Spinal Tumors: MR Findings after Novalis Radiosurgery

PURPOSE: To assess the therapeutic effect of Novalis radiosurgery for metastatic spinal tumors and evaluate the changes after treatment using MR imaging. MATERIALS AND METHODS: Between November 2003 and June 2005, 21 patients with metastatic spinal tumors underwent Novalis radiosurgery. Of these patients, the 7 with 13 metastatic spinal tumors who had undergone follow-up MR imaging were included in this study. The tumor locations were cervical spine in three, thoracic spine in four, lumbar spine in five and sacrum in one. During the first three months after Novalis radiosurgery, follow-up MRI was performed monthly and subsequently at 3-6-month intervals. On MR imaging, the volume of the tumors, the changes of their signal intensities and any changes in adjacent spinal cord were evaluated. RESULTS: Among the 13 lesions, 9 were decreased in volume (69.2%), 2 were stable (15.4%) and 2 were slightly increased. Seven of 9 lesions showed decreased signal intensity on T2 weighted images and 4 had compressive deformity. Two of 9 lesions had increased T2 signal intensity and tumor necrosis were detected on contrast-enhanced MR imaging. No changes in spinal cord were noted in any of the lesions. Those changes were detected on MRI obtained 1 month after Novalis surgery and the lesion sizes were gradually changed up to 3 months. CONCLUSION: Novalis radiosurgery was effective for the treatment of metastatic spinal tumor and the suppression of tumor growth. The estimation of therapeutic effect and detecting complication were precisely evaluated on MR imaging.

MR Distinction between Multiple Myeloma and Metastasis Involving the Spine

PURPOSE: To differentiate multiple myeloma from metastasis involving the spine at MR imaging. MATERIALS AND METHODS: Twenty-five patients with multiple myeloma and 37 with vertebral metastasis were included in this study. MR images were retrospectively analyzed with regard to infiltration and enhancement patterns, signal intensity, the involvement of three consecutive vertebrae, the number of lesions within one vertebra, and paraspinal and epidural masses. Using a 1.5-T imager, we obtained sagittal and axial, unen-hanced and enhanced T1-weighted images, and fast spin-echo images. For statistical analysis, Fisher's exact test was used. RESULTS: All cases of multiple myeloma and metastasis showed low signal intensity on T1-weighted images, and there were no significant differences in signal intensities or enhancement patterns. Infiltration and enhancement patterns were classified as focal (52% in multiple myeloma vs 68% in metastasis, p> 0.05), diffuse (32% vs 32%, p > 0.05) or salt and pepper (16% vs 0%, p 0.05), isoin-tensity (36% vs 3%, p 0.05). Paraspinal and epidural masses played little part. CONCLUSION: The salt and pepper infiltration pattern, the presence of more than five lesions within one vertebra, and the involvement of more than three consecutive vertebrae were useful MR findings for differentiation between multiple myeloma and metastasis involving the spine. In most cases, however, it is difficult to distinguish between the two conditions.

Differentiation of Multiple Myeloma and Metastasis: Emphasis on Bone Marrow Invo l vement Pattern of Spine inSagittal MR Images

PURPOSE: To differentiate multiple myeloma and metastasis of the spine. MATERIALS AND METHODS: Retrospectiveanalysis of MR images of the patients with multifocal spinal involvement of multiple myeloma and metastasis wasdone. Analysis was done in viw points of bone marrow involvement pattern(focal, diffuse, and mixed), margin,number, size and uniformity of the focal lesions, involvement of pedicle and posterior element, and epidural andparavertebral mass formation. RESULTS: Multiple myeloma predominantly showed diffuse pattern (11/21, 52.4%) ofmarrow involvement, while metastasis showed mainly focal pattern (18/21, 85.7%). Margin of the focal lesions weredistinct in majority (8/10, 80%) of multiple myeloma and indistinct in majority (16/21, 76.2%) of metastasis. Sizeof the focal lesions were smaller in cases of multiple myeloma than those of metastasis, but number and standarddeviation of the size of the focal lesions did not show significant difference between the two diseases.Involvement of posterior element were more common in multiple myeloma, and epidural mass formation andparavertebral mass formation were more common in metastasis. CONCLUSION: The diffuse pattern of marrow involvementalone suggests multiple myeloma. When a focal or a mixed pattern is found, distinct margin and smaller focallesions are suggestive of multiple myeloma, and indistinct margin and larger focal lesions andepidural/paravertebral mass formation are suggestive of metastasis.

CT-guided Percutaneous Biopsy of the Spine: Transpedicular approach

PURPOSE: To evaluate the efficiency of CT-guided transpedicular biopsy in obtaining diagnostic tissue fromvertebral body lesion. MATERIALS AND METHODS: The authors evaluated 25 patients(27 cases) who underwent CT-guidedtranspedicular biopsy for thoracic and lumbar vertebral lesions. Specimens were obtained from 27 lesions, sevenfrom thoracic spine and others from lumbar spine. Nine patients were men and 16 were women ; their ages rangedfrom 20 to 80 years. A 17-gauge "Osty-Cut" bone biopsy needle(Angiomed) with a hand-grip was used, and the patientwas placed in the prone position. For the analysis of results, pathologic reports were reviewed and follow-upstudies were checked. RESULTS: In all patients, the biopsy needle could be passed under CT guidance through thepedicle to the site of the disease. Pathologic reports indicated 11 malignancies, 11 normal trabecular bones andtwo cases of infectious spondylitis. Three cases were not diagnosed because of insufficient biopsy specimen. Eightcases of normal trabecular bone described in pathologic reports were confirmed by follow-up study. There were nocomplications during and after biopsy, and for pathologic diagnosis this was successful in 24 of 27 cases(88.9%). CONCLUSION: CT-guided transpedicular biopsy of vertebral lesion was safe and efficacious, especially in cases inwhich the posterolateral approach was difficult.

Differentiation between Osteoporotic and Metastatic Vertebral Compression Fractures by MRI

PURPOSE: To evaluate the MRI findings helpful in differentiating between osteoporosis and metastatic vertebral compression fracture. MATERIALS AND METHODS: This study involved 52 patients with nontraumaticvertebral compression fracture; 23 had osteoporosis and 29, metastatic diseases. We retrospectively analyzed signal abnormality and the extent to which bone marrow was seen within the involved vertebral body, sharpness of margin of abnormal signal intensity, morphological characteristics of the vertebral endplate, and the presence or absence of posterior element involvement and paraspinal mass, as seen on T1- and T2*-weighted MR images. For statistical analysis, the chi-square test was used. RESULTS: In 14 of 23 patients (61%) with osteoporotic benign compression, and 27 of 29 (93%) with metastatic compression fracture, the bone marrow of the compressed vertebral body showed both low signal intensity on T1-weighted image and high signal intensity on T2-weighted image. In 13 of 14 osteoporotic compression fractures, the extent of abnornal bone marrow signal was incomplete, but in 20 of 27 metastatic compression fractures, this was complete. In all 13 cases of osteoporosis, incomplete abnormal signal showed a sharp margin, whereas in five of seven metastatic compression fractures, this margin was ill-defined. Morphologically, the endplate was concave in 20 of 23 osteoporosis cases (87%), but was angled in 13 of 29 metastatic compression fractures (45%). Only the latter showed vertebral posterior element involvement (21/29) and paraspinal mass (16/29). CONCLUSION: The extent of signal abnormality, margin of compressed bone marrow, morphologic characteristics of the endplate, and the presence or absence of posterior element involvement and paraspinal mass on T1- and T2*-weighted MR images, as described above, may be helpful in differentiating between benign osteoporotic and malignant metastatic compression fractures.

Differential Diagnosis of Vertebral Lesions with paraspinal Mass with MRI

PURPOSE: To assess the characteristic features of MR findings which would be useful for the differentiation of various spinal diseases involving paraspinal soft tissue mass. MATERIALS AND METHODS: We retrospectively reviewed MR findings in 31 cases(M:F=20:11) of spinal disease in which paraspinal mass was involved. The breakdown of cases was as follows : spinal tuberculosis, 12; spinal metastasis, 13; multiple myeloma, 3; pyogenic spondylitis, 2; spinal aspergillosis; 1. RESULTS: The pattern of bone marrow invasion in spinal metastasis, multiple myeloma, spinal tuberculosis and aspergillosis was mixed ; focal, homogeneously diffuse and inhomogeneously patterns were seen. Pyogenic spondylitis showed inhomogeneously diffuse invasion; an intravertebral abscess was seen in the only five cases of spinal tuberculosis. Vertebral posterior compartment invasion was observed in seven cases of spinal tuberculosis, two of multiple myeloma, the one case of spinal aspergillosis and in all 13 cases of spinal metastasis. This and multiple myeloma showed no disc space invasion, in any case, but all cases of infectious spondylitis showed such invasion. Peripheral rim-enhancement in the paravertebral mass was seen in 11 cases of spinal tuberculosis, one case of pyogenic spondylitis and the case of aspergillosis. Bilobate anterior epidural mass was noted in 60% of spinal tuberculosis cases, 36% of spinal metastasis and one case of pyogenic spondylitis. CONCLUSION: MR findings of spinal disease involving a paraspinal soft tissue mass were useful for differentiation.