Background
Percutaneous image-guided musculoskeletal biopsy provides an accurate, rapid, and cost-effective method for helping clinicians diagnose benign and malignant musculoskeletal lesions. [1, 2] In patients who present with nonspecific physical findings, imaging studies, and laboratory values, percutaneous biopsy can lead to a rapid and accurate diagnosis and allow implementation of the most appropriate therapy. Most biopsies can be performed with local anesthesia, with conscious sedation added if necessary.
Various imaging modalities can be used to target the lesion, including computed tomography (CT), [3] fluoroscopy, [4] ultrasonography (US), [5] and magnetic resonance imaging (MRI). [6] The procedure is safe, with major complications uncommonly reported. When proper techniques are used, nondiagnostic or insufficient specimens are obtained in only approximately 8-10% of biopsies. Accuracy is expected to be 70-100% and is improved with expert cytopathologic interpretation. [7, 8, 9, 10, 3, 11]
A 2009 review of 309 biopsies noted that image-guided core needle biopsy (CNB) was particularly effective in diagnosing homogenous soft-tissue tumors. [12] Rimondi et al also noted the reliability of percutaneous CT-guided biopsy after analyzing 2027 cases over a period of 18 years. [13] A study of 196 CT- or US-guided percutaneous CNBs by Crenn et al reported a diagnostic yield of 84.7% and a diagnostic accuracy of 91.7%, with an overall complication rate of only 1.0%. [14]
Contraindications
Certain limitations or contraindications apply to musculoskeletal biopsy, as follows.
Coagulation disorders should be corrected prior to biopsy; fresh-frozen plasma (FFP) can be administered immediately beforehand to temporarily correct the prothrombin time (PT), the activated partial thromboplastin time (aPTT), and the international normalized ratio (INR).
Some sites are not accessible to this procedure, including the following [15] :
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Sclerotic lesions next to major arteries
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Bone surrounded by infected soft tissues
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C1 and the odontoid process of C2 lesions
Biopsy of hemorrhagic lesions frequently is less accurate, even with CNB. Prebiopsy imaging can help guide needles to areas with less vascularization. A fine needle should be used if a path is in close proximity to vessels or if a hemorrhagic lesion is suspected.
An uncooperative patient precludes biopsy; however, general anesthesia, particularly in children, should be considered. [16]
Technical Considerations
Best practices
Biopsy of the correct lesion is imperative for accurate and timely patient care. In one study, biopsy was performed at an incorrect vertebral level in one of 94 patients. [17] The patient did not have a reported complication; however, this case underscores the need for thorough review of preprocedural imaging studies. The authors in that case also recommended obtaining a visual CT scan or MRI of the lesion that is consistent with the suggested lesion prior to biopsy.
Procedural planning
Choice of imaging guidance
The choice of imaging guidance depends to some degree on operator preference; options include US, CT, fluoroscopy, and MRI. [18] In general, biplane fluoroscopy can be used for superficial bony lesions, whereas CT is preferred for deeper lesions and lesions in anatomically complex areas. US obviates the need for ionizing radiation and can be used if an accompanying soft-tissue mass or cortical destruction is present.
On rare occasions, MRI may be used to visualize lesions occult to CT and to visualize the procedure in real time. However, MRI is of limited use in sclerotic lesions, in a relatively small number of interventional MRI systems, and with less cumulative operator experience. In a 2007 study of 45 biopsies, MRI was better for diagnosing bone lesions than soft-tissue lesions. [19]
Choice of biopsy route
The choice of biopsy route is crucial to success. The transpedicular approach prevents the leaking of cerebrospinal fluid (CSF) or the spread of infection or tumor, as long as the medial pedicular wall remains intact. Paraspinal approaches may be technically difficult secondary to a lack of purchase obtained with an angled approach to the vertebral body.
Some lesions may not be good candidates for percutaneous biopsy. Specifically, hypervascular metastases, such as renal cell carcinoma with posterior vertebral body or spinal canal extension, pose an increased risk of cord compression if biopsy is performed. Biopsy of a compression fracture should be performed under CT guidance; if the compression is too great, a percutaneous biopsy may not be appropriate.
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Core biopsy of subtle iliac bone lesion in a patient with pain and a history of breast cancer. Core specimens obtained with 14-gauge Ostycut needle. Pathologic results showed metastatic breast adenocarcinoma.
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Fine-needle aspiration biopsy specimen from a destructive thoracic vertebral lesion. Sample was obtained using a 21-gauge Rotex needle. Pathology showed metastatic renal cell carcinoma. Core biopsy with a larger-bore needle could have resulted in bleeding and cord compression as a result of the hypervascular nature of the tumor.
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Biopsy of the left ilium in a patient with a history of lung cancer. A 14-gauge Ostycut needle was advanced following local anesthesia. Pathology results showed metastatic disease.
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Image obtained following biopsy of the left ilium shows no evidence of complications. The needle tract is visible. The patient tolerated the procedure well.
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Computed tomography (CT)–guided fine-needle aspiration of a destructive intervertebral process. An 18-gauge Cuatico needle was used. Cultures confirmed discitis.
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Biopsy specimen from metastasis in the femur. The needle course was selected to allow easy access to the lesion without traversing the solid bony cortex.
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Coaxial insertion of a 21-gauge Rotex needle through an outer bone biopsy needle. Additional core needle specimens also were obtained. Pathologic diagnosis was fibroma.
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Computed tomography (CT)–guided biopsy for a lesion associated with the first rib. Diagnosis was a low-grade chondrosarcoma.
