Imaging principles and instrumentation
Radiation navigation is used for precise tissue sampling from small lesions in complex anatomical zones. The choice of method depends on the localization of the lesion:
- Fluoroscopy (fluoroscopy) — provides real-time guidance oriented to bone structures.
- Computed tomography (CT) — provides high soft-tissue and bone resolution, but does not allow real-time tracking of needle advancement.
Access is performed using cutting (cutting) or trephine (trephine) needles. The patient is placed in the prone (prone) or lateral decubitus (lateral decubitus) position. Recently, routine practice has been improved by the introduction of battery-powered reusable power drills. They increase the diagnostic yield of obtained samples, facilitate passage through hard osteosclerotic lesions, and make the procedure less painful.
Indications for bone biopsy
The decision to intervene is made by a multidisciplinary team including a spinal neurosurgeon, oncologist, cytopathologist, and radiologist. Data must be cross-referenced with radiographs and MRIs beforehand to avoid inadvertently puncturing typical benign formations.
Main indications:
- Identification of an infectious process (e.g., disc aspiration in spondylodiscitis).
- Suspended bone metastasis (intervention is justified only if its result will change patient management).
- Staging of a known tumor.
- Diagnosis of primary tumors of the musculoskeletal system to determine the degree of malignancy (grading) and perform cytogenetic analysis.
- Histological comparison in synchronous or metachronous cancer.
If the patient has multiple metastases, the largest and anatomically most accessible lesion is selected for puncture. For complex locations, the risk-benefit ratio is always evaluated.
Preparation: hemostasis correction
The only absolute contraindication to spinal biopsy is hemorrhagic diathesis. Bleeding in this area can lead to epidural hematoma formation and spinal cord compression. Therefore, correction of coagulopathy is critically important:
- Antiplatelet agents: discontinued at least 5 days before the spinal intervention for full platelet function recovery.
- Platelets: count must be above 50,000/μL. Transfusion is indicated in case of deficiency.
- INR: values above 1.3–1.5 require transfusion of fresh frozen plasma (FFP) or cryoprecipitate.
- Anticoagulants (heparin, warfarin, direct oral anticoagulants) are discontinued strictly according to local clinical protocols.
Technique and risks
The procedure is painful as it involves passing through the periosteum and bone tissue. Conscious sedation (conscious sedation) is routinely used, most commonly a combination of fentanyl and midazolam. General anesthesia is indicated in rare cases. Continuous monitoring of vital signs is mandatory during the procedure.
Important nuances and risks:
- When osteosarcoma or soft tissue sarcoma is suspected, the needle must not extend beyond the allowed anatomical compartment (capsule). This is necessary to reduce the risk of local recurrence after the tumor is surgically removed.
- The risk of iatrogenic fracture of a weight-bearing bone after sampling is extremely low.
- If the biopsy is performed in the setting of a painful pathological vertebral fracture, it makes sense to perform palliative cementoplasty (palliative cementoplasty) immediately after successful tissue sampling to relieve pain.
Clinical case: During transpedicular biopsy of the C7 vertebra (e.g., in collapse due to adenocarcinoma metastasis) under CT guidance, a 10-G bevel trocar is used and a 12-G trephine needle is coaxially introduced. The needle is advanced along an oblique trajectory (oblique needle tract), strictly avoiding penetration into the spinal canal, ipsilateral transverse foramen, and adjacent intervertebral foramina.
Briefly: answers to topical questions
What complications, besides epidural hematoma and iatrogenic fracture, can occur during percutaneous vertebral biopsy?
During percutaneous vertebral biopsy, in addition to epidural hematoma and iatrogenic fracture, hemorrhagic and oncological complications may develop. These include:
- Massive hemorrhage — occurs during puncture of highly vascularized formations (renal cell carcinoma metastases, hemangiomas).
- Spinal cord compression — is a consequence of severe hemorrhagic complications.
- Needle tract seeding (tract seeding) — a rare complication after fine-needle aspiration biopsy, with an incidence of 3–5 cases per 100,000.
The «Fifty, one and a half, five» rule for a safe biopsy: Platelets > 50,000, INR < 1.5, discontinuation of antiplatelet agents 5 days prior.
Class and exam questions
What anesthesia is required for percutaneous vertebral biopsy?
Conscious sedation using fentanyl and midazolam is usually sufficient. General anesthesia may be used in individual cases.
Why is it important not to cross the anatomical compartment boundaries during sarcoma biopsy?
This prevents the spread of tumor cells beyond the fascial bed, which is critical for preventing local recurrence after subsequent radical resection.
What else to study on this topic
- Spinal infiltration and neuromodulation procedures
- Radiofrequency ablation for skeletal pain
- Percutaneous vertebroplasty and osteoplasty
- Bone tumor embolization
- Percutaneous discectomy
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