Image Guided Bone Marrow Biopsy

Image Guided Bone Marrow Biopsy Overview

  • Authors: Claire S. Kaufman, MD; Keith T. Kuo, BS; Keshav Anand, MD, MPH.

  • Focus: Diagnostic procedures for bone marrow aspiration and biopsy, utilizing advanced imaging guidance (e.g., CT or fluoroscopy) to significantly improve safety, accuracy, and efficacy, particularly in challenging anatomical locations or in patients with altered marrow architecture.

Background and Indications for Procedure

  • Bone marrow aspirate and trephine biopsies (BMBx) are fundamental diagnostic tools, providing crucial insight into the hematopoietic system and other systemic diseases. They are essential for diagnosing, staging, and monitoring various conditions, notably hematologic malignancies, a spectrum of infections, and a range of non-hematologic diseases by allowing direct examination of marrow cellularity and architecture.

  • Common indications for BMBx include:

    • Anemia: persistent, unexplained anemia to identify underlying bone marrow failure, myelodysplastic syndrome, or infiltrative processes.

    • Pancytopenia: evaluation for aplastic anemia, myelofibrosis, or leukemia.

    • Thrombocytopenia: diagnosis of immune thrombocytopenia (ITP), drug-induced thrombocytopenia, or primary bone marrow disorders.

    • Fever of unknown origin (FUO): to detect occult infections (e.g., fungal, mycobacterial) or neoplastic processes within the bone marrow.

    • Abnormal peripheral blood smear with concern for bone marrow pathology: presence of blasts, immature cells, or unexplained cytopenias strongly suggests a primary marrow disorder.

    • Malignant hematologic disorders: essential for initial diagnosis, staging, and assessment of treatment response in leukemias, lymphomas (e.g., Hodgkin and non-Hodgkin), multiple myeloma, and myeloproliferative neoplasms.

    • Focal lesions on imaging: presence of suspicious lytic or sclerotic lesions within bone, which may represent metastasis, infection, or primary bone lesions, where imaging guidance ensures precise targeting.

    • Suspected bone marrow metastasis: in patients with known solid tumors, BMBx can confirm metastatic spread to the marrow.

  • It is essential that a complete hematologic work-up precedes BMBx, including a full blood count to assess cell lines, and a thorough evaluation of coagulation status to minimize bleeding risks.

Patient Work-Up and Clinical Evaluation

  • Prior to BMBx, a comprehensive work-up should generally include:

    • Complete blood count (CBC): to quantify hemoglobin, white blood cell count (and differential), and platelet count, which provides baseline information on hematologic status.

    • International normalized ratio (INR): a measure of extrinsic coagulation pathway function, important for assessing bleeding risk, especially for patients on anticoagulants or with liver dysfunction. A PTT (Partial Thromboplastin Time) may also be considered to assess the intrinsic pathway.

  • No absolute contraindications to BMBx exist that would unequivocally prevent the procedure; however, relative contraindications necessitate careful risk-benefit assessment and potential corrective measures:

    • Severe hemophilia or other severe inherited bleeding disorders: requires factor replacement therapy prior to the procedure.

    • Severe disseminated intravascular coagulopathy (DIC): a life-threatening condition associated with widespread clotting and bleeding; BMBx should be performed only after aggressive correction of coagulopathy.

  • Thrombocytopenia and its implications:

    • Patients may present with thrombocytopenia from various etiologies, including underlying hematologic conditions. The decision to transfuse platelets is often individualized.

    • Consensus regarding prophylactic platelet transfusion prior to the procedure is inconsistent; generally, transfusion is often unnecessary and can be avoided for patients with platelet counts greater than 20,000\text{/}\mu\text{L} in the absence of other bleeding risk factors.

    • Imaging-guided BMBx is considered inherently safer even in thrombocytopenic patients compared to landmark-guided procedures, due to its precision in avoiding critical structures.

Techniques for Bone Marrow Biopsies

General Procedure

  • Traditionally, BMBx can be performed in inpatient or outpatient settings, often without sedation using manual palpation of anatomical landmarks (e.g., posterior superior iliac spine, PSIS).

  • However, image guidance (CT or fluoroscopy) is increasingly preferred, especially for difficult anatomical sites, focal lesions, or obese patients, offering increased safety by direct visualization of needle trajectory, reduced attempts, and improved diagnostic yield.

Equipment Needed

  • Specialized bone marrow biopsy kits and needles are required, typically comprising:

    • Jamshidi-type needle: a classic manually inserted needle designed to obtain both aspirate and a core biopsy, known for its sharp tip and side port for aspirate collection.

    • OnControl power drill (FDA-approved in 2007): a powered device that facilitates needle advancement through dense cortical bone, significantly improving patient comfort, reducing operator fatigue, and often yielding higher quality, less fragmented specimens, particularly in patients with sclerotic marrow or dense bone.

Procedural Steps: CT-guided BMBx

  1. Preparation:

    • Patient typically positioned prone to maximize access to the posterior iliac crest, but may be lateral or oblique if unable to lie prone due to pain or other medical conditions.

    • A radiopaque grid is applied on the lower back to assist in initial localization and subsequent precise alignment with the CT scanner table.

    • A scout CT scan is performed to identify the target bone marrow site (e.g., posterior iliac crest, vertebral body, sternum in specific cases) and to determine the optimal, safest needle trajectory, avoiding vessels, nerves, and organs.

  2. Anesthesia:

    • Local infiltration using 1% lidocaine is administered at the access site, carefully anesthetizing the skin, subcutaneous tissue, muscle, and crucially, the periosteum covering the bone, which is highly pain-sensitive.

  3. Needle Insertion:

    • A small skin incision (approximately 2-3 mm) is made to allow easy entry of the 11-gauge co-axial needle system. The co-axial needle acts as a protective sheath.

    • The co-axial needle is advanced through soft tissues until it reaches the bone cortex. Confirm precise position via an intermittent CT scan before advancing the inner stylet (or outer cannula for the core biopsy needle) through the cortical bone, minimizing risk of trajectory errors.

  4. Aspirate Collection:

    • Once the needle tip is securely within the bone marrow cavity, the inner stylet is removed.

    • A 10\text{ mL} or 20\text{ mL} syringe is attached, and vigorous aspiration is performed, collecting multiple samples (typically 0.2-0.5\text{ mL} each) of bone marrow aspirate into anticoagulant-containing tubes. These samples are crucial for cytological examination, flow cytometry, cytogenetics, and molecular studies.

  5. Biopsy:

    • Following aspirate collection, the biopsy needle (either manual Jamshidi or the OnControl power drill needle) is advanced through the co-axial outer cannula.

    • The needle is carefully advanced under imaging guidance through the cortex into the medullary cavity, rotating as it advances to secure a core sample of appropriate length (typically 1.5-2 cm for diagnostic adequacy). The power drill ensures a controlled and less traumatic biopsy.

  6. Deployment of Core:

    • After obtaining the core, the biopsy needle is withdrawn. A blunt pushing stylet is then utilized to gently release the bone marrow core from the needle lumen onto a sterile gauze pad. The core is then immediately fixed in formalin for histopathological examination.

Procedural Steps: Fluoroscopic-guided BMBx

  1. Patient Positioning:

    • Patient is positioned prone, or lateral if required, providing optimal access to the target area while allowing for lateral or oblique views during fluoroscopy. Positioning is often adjusted dynamically during the procedure.

  2. Preparation:

    • The lower back or other target area is meticulously prepared and draped in the usual sterile manner, maintaining an aseptic field to prevent infection.

    • The fluoroscopic image intensifier (C-arm) is positioned to provide real-time, bi-plane visualization of the needle advancement, allowing for continuous monitoring of its path relative to bony structures and critical soft tissues.

  3. Local Anesthesia:

    • Local anesthetic (e.g., lidocaine) is thoroughly administered in the target area, tracking the anticipated needle path to ensure adequate pain control before actual needle insertion. This involves anesthetizing skin, subcutaneous tissue, muscle, and periosteum.

  4. Needle Advancement:

    • The co-axial needle is carefully advanced under continuous or intermittent fluoroscopic guidance. This real-time visualization is particularly advantageous for precise needle placement, especially when targeting small or anatomically challenging areas.

    • Position is confirmed with fluoroscopic images (often in two orthogonal planes) before advancing through the cortex, very similarly to the principles of CT guidance, to ensure correct and safe entry into the marrow cavity.

Overcoming Technical Challenges

  • Alternative positions (lateral decubitus or oblique) can be effectively utilized if patients are unable to comfortably or safely lie prone, ensuring access to the iliac crest.

  • If a dry tap occurs (no aspirate retrieved despite successful access to the marrow cavity), this often suggests marrow fibrosis, packing of the marrow cavity with malignant cells, or an issue with needle placement/technique. In such cases, repositioning the needle within the marrow cavity or adjusting the angle may be necessary.

  • If the initial attempt is unsuccessful in obtaining an adequate core biopsy, additional core biopsies from a slightly different location within the same bone or even a contralateral site may be indicated to ensure diagnostic yield.

Recognizing and Treating Complications

  • Major complications from BMBx are exceedingly rare. Hemorrhage is the most common complication, typically localized to the biopsy site and usually self-limiting, managed with manual compression.

  • Risks of targeting an incorrect anatomical location are significantly reduced with imaging guidance. However, if such an error occurs, it can lead to injury to adjacent soft tissues, nerves, or vessels. Severe vascular injury may necessitate interventions such as emergent angiogram and subsequent embolization to control bleeding.

  • Special care should be taken when performing sternal aspirations due to their proximity to vital organs, carrying low but definite risks such as cardiac injury (e.g., pericardial tamponade) or pneumothorax if the needle penetrates too deeply through the sternum into the mediastinum.

Clinical Follow-Up

  • Immediately after the procedure, firm manual compression is applied to the biopsy site for several minutes (typically 5-10 minutes) to achieve hemostasis. Patients are subsequently monitored for a period (e.g., 30-60 minutes) for potential complications such as increasing pain, swelling, or active bleeding at the site.

  • Patients are given clear, detailed instructions for post-procedure care, including wound care, activity restrictions (e.g., avoiding strenuous activity for 24-48 hours), and signs to watch for, such as increasing pain, redness, warmth, discharge, or recurrent bleeding at the site, which would warrant immediate medical attention.

Expected Outcomes

  • Bone marrow biopsy results provide invaluable biological samples for accurate diagnosis, staging, and crucial treatment monitoring across a wide spectrum of hematologic and systemic diseases, particularly when guided by advanced imaging techniques.

  • When conducted correctly with appropriate imaging guidance, it consistently proves to be a low-risk procedure that patients generally tolerate well, with a high diagnostic yield, thereby significantly impacting patient management and prognosis.

References

  • Series of cited studies and articles related to complication rates, comparative analysis of different techniques (manual vs. image-guided), safety in special populations (e.g., thrombocytopenic patients), and overall efficacy of imaging guidance in improving the diagnostic accuracy and safety of BMBx.