Image-Guided Percutaneous Biopsy of Musculoskeletal Lesions

Yung-Hsin Chen, John A. Carrino and Laura M. Fayad

Image-guided percutaneous needle biopsy (PNB) has emerged as a safe, effective, and accurate tool for the diagnosis of musculoskeletal lesions.1–5 Information obtained from percutaneous biopsy helps determine appropriate therapy and disease prognosis. Whether a lesion is benign or malignant and its specific histologic type and grade (in the case of malignant lesions) is vital knowledge for treatment planning. Because diagnostic accuracy may be greatly influenced by the biopsy method used and location of sampling, a well-planned and well-executed percutaneous biopsy is essential for providing an accurate diagnosis and facilitating treatment. When a biopsy is performed poorly, the outcome may be disastrous from a number of standpoints. If an incorrect diagnosis is obtained, a delay in treatment may result, and complications may ensue. In addition, when the percutaneous route taken is badly planned, treatment options can become limited, thus endangering potential limb preservation surgery and creating a significant negative impact on ultimate survival.^6–10

Traditionally, open incisional biopsy was considered the gold standard for ensuring that adequate tissue was obtained from a musculoskeletal lesion for proper diagnosis. In conjunction with clinical and imaging characteristics, the final histologic diagnosis would then be made. However, open biopsies have a complication rate of 16%, and 8.2% of all patients who have undergone biopsy have their treatment plan affected by these complications.⁸ In addition, 1.2% of patients who have had a biopsy undergo unnecessary amputations because of diagnostic errors that are based on the results of an open biopsy.⁸

Historically it was believed that needle biopsy was ineffective for the diagnosis of some lesions, specifically primary mesenchymal musculoskeletal tumors, because such tumors are among the most difficult of pathologies to accurately diagnose. As such, in a survey of practices in the early 1980s, only 9% of patients reportedly underwent needle biopsy,¹¹ whereas approximately 40% of patients underwent needle biopsy in the late 1990s.¹² Today, PNB is thought to be the initial procedure of choice for establishing the diagnosis of a musculoskeletal lesion.^12,13

Well-established, consistently good results for core needle biopsy (CNB) have been reported.14–19 Welker et al. found no significant deleterious effects on patient outcome when diagnostic errors occurred after needle biopsy.¹² Needle track seeding has not been a relevant clinical issue, since en bloc resection of the biopsy track and local field radiation is commonly practiced. The reported accuracy of a needle biopsy procedure in distinguishing benign from malignant lesions, the exact grade, and the exact pathology was 92.4%, 88.6%, and 72.7%, respectively, with a major diagnostic error rate of 1.1%, none of which ultimately had an impact on patient outcome.¹² More recently, PNB was established as a highly accurate and clinically useful technique for characterizing musculoskeletal lesions, with often higher accuracy in soft-tissue masses than with bone lesions. Certain histologies such as lymphoma and histiocytosis may require a second biopsy for final diagnosis.¹⁹

In addition to having good diagnostic accuracy, additional benefits of PNB include a three- to fivefold increase in cost-effectiveness over traditional open biopsy,20–22 minimal limitation of activity after the procedure, rapid recovery time, quicker initiation of patient treatment, and assistance with operative planning.^7–9,16,23 Contrary to open biopsy, PNB does not significantly alter the strength of weight-bearing areas, thus avoiding the need for immobilization.^6,9,24

Indications

• Establish whether a musculoskeletal lesion is benign or malignant

• Obtain material for microbiologic analysis in patients with known or suspected infection

• Stage patients with known or suspected malignancy when local spread or distant metastasis is suspected

• Determine the nature and extent of systemic diseases (e.g., connective tissue diseases)

Histopathologic studies are often needed in patients with musculoskeletal lesions to establish a definitive diagnosis of tumor, infection, or systemic process. A lytic or blastic lesion may occur in a patient without a history of cancer and may appear malignant or indeterminate; PNB in this setting is requested for clarification. More commonly, however, a lytic or blastic bone lesion or soft-tissue mass appears in a patient with a history of malignancy. PNB is needed to establish the diagnosis of metastasis for staging and initiation of radiation or adjuvant therapy. In addition, in a patient with known cancer and a lesion developing more than 10 years after the initial diagnosis, PNB is needed to distinguish whether the lesion is the same histology as the original tumor or a new neoplasm. Another common indication for PNB is a bone or soft-tissue lesion in a patient whose history, physical examination, laboratory values, and imaging point to infection. Treatment in such a case relies on determining the cause of infection, and biopsy allows identification of the organism in question. The rarest indication for PNB is a systemic disease such as a connective tissue disorder; PNB is performed to exclude other more insidious processes.

Contraindications

There is no absolute contraindication to PNB, but several factors can be considered relative contraindications because they render PNB unsafe to perform:

• Known coagulopathy that cannot be corrected adequately

• Inability of the patient to cooperate or be positioned for the procedure

• Known adverse reaction to potential medication given during the procedure

• Hemodynamic instability

• Lack of a safe pathway to the lesion

• Pregnancy

Biopsy should be delayed until critical parameters are satisfied, including coagulopathy, infection, and hemodynamic instability. Technical considerations such as lack of a safe pathway to the lesion, adverse reaction to potential medications given during the procedure, and inability of the patient to cooperate or be positioned for the procedure, as well as pregnancy, have to be addressed before initiating or proceeding with PNB. Careful review of imaging and clinical correlation are critical to avoid unnecessary biopsy of a classic “do-not-touch” lesion such as traumatic avulsion of an apophysis in young patients, evolving myositis ossificans, and subchondral geodes that may appear histologically aggressive and confuse clinical management.

Equipment

Percutaneous needle biopsy may be performed under fluoroscopic,25–27 ultrasound,^25–28 computed tomography (CT),^3,25–26 or magnetic resonance imaging (MRI) guidance.^29–31 The imaging choice is primarily dependent on the location and imaging characteristics of a lesion and, to a lesser degree, on the available imaging modalities and patient positioning.

For a superficial soft-tissue lesion or a lesion with cortical disruption that allows an acoustic window for passage of a needle, ultrasound may be used (Figs. 157-1 and 157-2). Ultrasound provides real-time visualization, minimal patient and preprocedure preparation, and no radiation exposure to the patient. Obviously, poor sound penetration or a hard surface precludes the use of ultrasound for deep medullary bone lesions. Moreover, deep soft-tissue lesions also preclude ultrasound use because poor sound penetration may lead to unknowing disruption of critical soft-tissue compartments.

FIGURE 157-1 A, This 64-year-old woman noticed fullness and discrepancy in her thigh diameters, right being larger than left for several months. Magnetic resonance imaging axial short tau inversion recovery shows hyperintense lobular lesion. B, Ultrasound shows heterogeneous echogenic 10.5 × 16.7 × 10.5 cm posterior thigh mass with areas of color Doppler flow. C, One of four sequential biopsies with 18-gauge core biopsy needle. High-grade myxoid liposarcoma was found on pathologic examination.

For a radiographically identifiable lesion that does not require careful negotiation of neurovascular structures, fluoroscopy allows fast multidirectional real-time visualization with ease of use and less cost than CT or MRI (Fig. 157-3). However, low soft-tissue contrast makes fluoroscopy less ideal for lesions with large cystic or necrotic areas.

FIGURE 157-3 A, Metastatic lung cancer in 78-year-old man; fluoroscopically guided transpedicular L1 biopsy was performed. B, Intravertebral core biopsy. C, Fine-needle aspiration with 25-gauge needle.

For a deep lesion or a lesion adjacent to neurovascular bundles, CT and MRI are ideal for creating high-resolution road maps of compartmental anatomy. In practice, CT is routinely used for lytic or blastic lesions with or without a soft-tissue component, whereas MRI is often used for lesions that are not identified on other imaging modalities and for targeting a focal marrow abnormality (Figs. 157-4 and 157-5). However, conventional CT can occasionally be a slow, arduous modality because of the lack of real-time visualization and the requirement for repeated scanning during needle manipulation and positioning. CT-fluoroscopy allows the combined convenience of real-time guidance and instantaneous cross-sectional anatomy. Although MRI guidance requires MRI-compatible (high nickel content) needles (E-Z-EM Inc., Westbury, N.Y.; Somatex, Berlin, Germany; MD Tech, Gainesville, Fla.; InVivo, Berlin, Germany), imaging with frequency encoding parallel to the needle path reduces susceptibility artifact, and specialized monitor devices and platforms are being developed for MRI-guided procedures^32,33 (Figs. 157-6 and 157-7).