Benign versus malignant osseous lesions in the lumbar vertebrae: differentiation by means of bone SPET

Bone scanning is a well-accepted and frequently performed diagnostic proced ure with a high sensitivity, especially when single-photon emission tomogra phy (SPET) acquisitions are added. However, the differentiation of benign f rom malignant osseous lesions often poses difficulty. The purpose of this s tudy was to find out whether the particular localisation of an intraosseous lesion in a lumbar vertebra is an indicator of its aetiology. Bone scintig raphy including planar whole-body scans as well as SPET imaging of the lumb ar spine was performed in 109 patients. The diagnoses of osseous lesions in the lumbar vertebrae were made strictly on the basis of the findings of ma gnetic resonance imaging, computed tomography or plain radiography. Sixteen patients had to be excluded from the study because they did not undergo ad equate radiological examination. To determine the particular localisation o f vertebral lesions in the bone scan, two experienced nuclear medicine phys icians examined the studies independently while blinded to the radiological results. Four anatomical regions were differentiated within the vertebra: the vertebral body, the pedicle, the facet joints and the spinous process. Clopper-Pearson analysis, which takes into account the number of examinatio ns, yielded the following probability intervals for the malignancy of intra osseous lesions in the lumbar spine: vertebral body 36.8%-57.3%, pedicle 87 .7%-100%, facet joints 0.8%-21.4% and spinous process 18.7%-81.3%. It was c oncluded that lesions affecting the pedicle are a strong indicator for mali gnancy, whereas involvement of the facet joints is usually related to benig n disease. Lesions affecting the vertebral body or the spinous process do n ot show a clear tendency towards either malignancy or benignity. In contras t to other studies, a significant probability of malignancy (35.6%) was obs erved in lesions affecting exclusively the vertebral body.