Percutaneous Biopsy of the Spine

Bone Metastases

A suspicion of bone metastasis represents the principal indication for percutaneous biopsy of the spine. It is especially helpful in patients with no known primary tumor who develop multiple lesions with imaging findings consistent with metastases, or in patients with a known primary malignancy who develop single or multiple lesions that are atypical for the stage of the malignancy or unlike the usual appearance of the metastases (e.g., sclerotic lesions in renal cancer). This procedure may also be helpful in patients who demonstrate bone changes after radiation therapy of the skeleton, as these changes may represent radiation-induced necrosis, metastasis, or local tumor extension.

Primary Bone Tumors

Primary bone tumors may represent an indication for percutaneous needle biopsy, at least in some specialized centers. The diagnostic accuracy of percutaneous biopsy is lower than for open biopsy because of the complex architecture of primary bone tumors. The analysis of such biopsy specimens requires a trained osteoarticular histopathologist, who should be involved in the decision as to which form of biopsy is appropriate. The puncture site and approach of the biopsy must be carefully selected in consultation with the referring surgeon to minimize the amount of biopsy tract to be removed at the time of definitive surgery (especially in cases of chondrosarcoma and chordoma) and to avoid contamination of other compartments.

Spinal Infections

Histopathology and microbiology analysis are usually required when the nature of the causative microorganism has not been determined. Samples for these two analyses are required because tuberculosis may be suggested only on the histopathologic analysis. Some organisms are difficult to culture, and some tumors or pseudotumors may mimic infection.

Other Indications

Percutaneous biopsy of the spine may also be indicated when other malignant lesions (osseous lymphoma, plasmacytoma) are suspected or when the benign nature of a lesion cannot be confirmed by clinical, biologic, or imaging features. For example, in cases of osteoporotic vertebral collapse or eosinophilic granuloma, there may be clinical doubt and a biopsy may determine the best management.

Radiologic Guidance

Percutaneous biopsy of the spine can be performed with fluoroscopic, CT, or MRI guidance, depending on the biopsy site, the radiographic appearance and size of the lesion, and the skills of the radiologist. CT fluoroscopy provides real-time CT images and is the method of choice for percutaneous biopsy of the spine. In contrast to conventional CT guidance, CT fluoroscopy exposes the patient to less radiation, with some studies citing a reduction of 94% in patient absorbed dose. Procedure time is also reduced, as the period between imaging and needle adjustment is eliminated or greatly shortened. However, the operator is present during the scan and therefore is subject to more radiation than the operator who leaves the room during routine CT scanning.

Currently, percutaneous biopsy of the spine with MR guidance is performed at only a limited number of institutions and usually requires a dedicated interventional MR unit. The superior contrast resolution and lack of ionizing radiation are a potential advantage of MR guidance.