An accurate biopsy is essential in the diagnostic workup of any neoplastic lesion. Open biopsy has been the gold standard for the diagnosis of musculoskeletal lesions. Recently, however, as imaging techniques have evolved and as time constraints and financial considerations have increased, percutaneous needle biopsy has gained in popularity. This is particularly true in the spine, where an open biopsy can be a difficult procedure—it must be performed in an operating room, and carries with it a substantial risk of complications. In contrast, percutaneous needle biopsy is a less invasive procedure and can be performed with the patient under local anesthesia and on an outpatient basis.
The choice of biopsy instrument (fine-needle aspiration or core-needle biopsy) remains controversial. When a fine-needle aspiration biopsy is performed, only a small sampling of tissue is obtained and the architecture of the tissue is rarely preserved; thus, only a cytological study may be possible, and obtaining a histological diagnosis is more difficult and less accurate. In addition, sampling errors may occur due to the small amount of material obtained. A recent review of fine-needle aspiration and core-needle biopsies in 359 patients with musculoskeletal lesions found that the accuracy of fine-needle percutaneous aspiration biopsies was significantly lower than that of core needle biopsies (p > 0.04)1. Larger-bore needle biopsies offer the potential benefit of larger sample size and maintenance of the architecture.
The authors have presented a meta-analysis study in which they examined the effects of the inner diameter of the biopsy needle and the method of imaging guidance on the adequacy and accuracy of tissue samples obtained in the spine. Intuitively (since adequacy is considered to be dependent on the accurate localization of the lesion, the size of the tissue biopsy core, and the lack of architectural distortion), one would expect that the larger-diameter needle biopsies, under computed tomographic guidance, would confer significantly better results. However, the results of the meta-analysis suggest that this may not be the case. Although the trend was for the adequacy and accuracy of biopsies to increase with the larger bore of the needle, the difference was not statistically significant and was offset by a significant increase in the complication rate (p = 0.01).
The articles included in this meta-analysis addressed both primary and metastatic lesions. Importantly, the histology of the lesion seems to influence the accuracy of the biopsy; for example, metastatic spinal lesions have a higher rate of diagnosis, irrespective of the method2. Nourbakhsh et al. attributed the lack of significant differences between techniques, with regard to adequacy and accuracy, to the fact that the majority of the spine lesions were metastatic lesions and thus easier to diagnose regardless of the method. It would have been interesting if the authors had analyzed the accuracy and adequacy of these biopsy methods (guidance and needle bore) on the basis of the definitive diagnosis—primary spinal lesion compared with metastatic spinal lesion. Does a larger-bore needle make a difference when assessing primary spinal lesions?
The three-dimensional view afforded by the computed tomography scanner not only allows for more accurate visualization of the surrounding structures but more precise localization of lesion within the vertebral body. This is especially helpful when the lesion does not occupy the entire vertebral body. In addition, the development of wide-aperture computed tomography scanners with ultra-fast imaging times and the advances in the design of specialized thin-walled biopsy needles has allowed for more precise localization of lesions under computed tomography guidance. It is for this reason that computed tomography guidance has become the preference of many interventional radiologists. It would have been interesting if the authors had included a comparison of the imaging methods in relation to the size or geometry of the lesion within the spine. Such precise localization is not possible with fluoroscopy.
Biopsy of spine lesions is increasingly being performed by interventional radiologists in an outpatient setting. Thus, although the authors make the point that it is easy to immediately address complications that arise during fluoroscopic biopsy, the trend is, in fact, for these procedures to be done outside the operating room.
Computed tomographically guided biopsy is fast, accurate, and economic and, as such, has become the procedure of choice for the assessment of spinal lesions3. However, Nourbakhsh et al. do raise the question of whether this trend is technology driven. The article may be biased toward fluoroscopic guidance as the majority of the articles in the meta-analysis were published prior to 2001—a time when experience and technological progress with the computed tomography procedure were in earlier stages. Several authors have maintained that diagnostic outcome is related to technique and experience3. A prospective case-controlled study would further serve to test this hypothesis.
*The author did not receive any outside funding or grants in support of her research for or preparation of this work. Neither she nor a member of her immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the author, or a member of her immediate family, is affiliated or associated.
1. Hau A, Kim I, Kattapuram S, Hornicek FJ, Rosenberg AE, Gebhardt MC, Mankin HJ. Accuracy of CT-guided biopsies in 359 patients with musculoskeletal lesions. Skeletal Radiol. 2002;31:349-53.
2. Kattapuram SV, Rosenthal DI. Percutaneous needle biopsy of the spine. In: Sundaresen N, editor. Tumor of the spine: diagnosis and clinical management. Philadelphia: WB Saunders; 1990. p 45-61.
3. Rimondi E, Staals EL, Errani C, Bianchi G, Casadei R, Alberghini M, Malaguti MC, Rossi G, Durante S, Mercuri M. Percutaneous CT-guided biopsy of the spine: results of 430 biopsies. Eur Spine J. 2008 May 8. [Epub ahead of print].