Embolization of musculoskeletal bone tumors

Abstract

Bone tumors may present as incidental findings, with pain or loss of function, or as fractures. There is a broad range of indications for transarterial embolization (TAE) in primary or metastatic bone tumors: to reduce operative hemorrhagic risks, to simplify or allow more definitive surgery, or in the context of pain palliation, fever, bleeding, or hypercalcemic and other rheological factors. Embolization may also increase tumor sensitivity to chemotherapy or radiation therapy. The procedure itself is often complex with significant risk to adjacent structures and is usually part of a wider treatment strategy. There are many options of embolic agent, techniques, and end points but all aim to devascularize the tumor. Catheter angiography at the time of TAE is used to determine the correct embolic agent and technique with care taken to isolate at risk structures. Many factors determine the best choice of embolic material, probably the most important of which is operator experience. In life-threatening situations or in preoperative embolizations of metastatic tumors, many operators opt for a combination of particulate emboli and stainless steel or platinum coils. Agents discussed include polyvinyl alcohol particles, trisacryl microspheres, gelatin sponge, liquid embolic agents, and embolization coils. Tumor types treated include vascular metastatic lesions, commonly renal cell or thyroid, particularly in locations prone to fracture; giant cell tumors; aneurysmal bone cysts; vertebral hemangiomas, osteosarcomas; arteriovenous malformations; and osteoblastomas. TAE should be considered in the treatment algorithm of primary or secondary bone tumors. Specific benefit is present where there is a high risk of bleeding at surgery, where there is spinal involvement and neural encroachment, where active bleeding is present or in awkward surgical locations where prolonged surgery is anticipated.

Keywords: Embolization; bone tumors; metastases.

Figures

Figure 1

(A) Pathological fracture through a renal cell metastases in the left humoral diaphysis. (B) Brachial angiogram demonstrating multiple arterial feeders from brachial and profunda brachii. (C,D) Selective catheterization and angiographic imaging of multiple arterial feeding vessels. (E) Distal catheterization of feeding vessel with particulate embolization. (F) Angiogram following embolization with single embolization coil in proximal feeding vessel. (G) Completion angiogram demonstrating effective devascularization; patient proceeded to intramedullary nail placement without incident and minimal blood loss.

Figure 2

(A) Renal cell metastases in left femoral head, preoperative appearances. (B) Appearances at angiography with a hypervascular lesion in the greater trochanter. (C) Embolization with 2.3-French microcatheter in a circumflex femoral feeding vessel; the lesion is partly embolized. (D) Post–gamma nail placement, multiple embolization coils can be seen; these were placed following particulate embolization with polyvinyl alcohol to completely occlude the vessels.

Figure 3

Transarterial embolization (TAE) in a functional phosphaturic mesenchymal tumor causing oncogenic osteomalacia. The patient presented with pelvic pain with a 10-year history of a lytic lesion in the pelvis (A) thought originally to represent a brown tumor. Three separate embolization procedures were performed. Temporary improvement in fibroblast growth factor 23 occurred, but the tumor rapidly revascularized. (B) Coronal computed tomography (CT) pre- and postcontrast and axial contrast-enhanced CT demonstrating the hypervascular lesion in the left ileum extending to the acetabular surface. (C) Second embolization visit: flush aortogram demonstrates multiple coils in the superior gluteal artery with persistent arterial blush in the ileum; selective internal iliac angiogram demonstrates remaining arterial feeders. (D) Superior gluteal artery embolization: superior gluteal artery is occluded, with residual tumor blush from unnamed ileal artery. (E,F) CT 6 weeks after third TAE. Early arterial image demonstrated reduced vascularity but this fills in in late arterial phase (F).

Figure 4

(A, B) Sagittal T2-weighted magnetic resonance images pre- and postcontrast demonstrating tumor within two midthoracic vertebral bodies; impingement on the spinal cord is demonstrated with loss of integrity of the posterior wall of the two vertebrae. Postcontrast images demonstrate involvement of the posterior processes. (C) Simmonds two-catheter injection of right sixth intercostal artery demonstrates the intercostal vessels. Note crowding of T7 and T8 vessels in keeping with vertebral body collapse at these levels. (D) Right T7 intercostal angiogram; tumor blush seen in right side of the vertebral body. (E) Same level as Fig. 4D following coil deposition to protect the distal intercostal circulation. Particulate embolization followed with 150- to 250-μm particles; finally the vessel origin was coil embolized. (F) Flush aortogram following bilateral T7, 8, and 9 intercostal artery embolization with a combination of coils and polyvinyl alcohol particles. (G) Postoperative appearances with T7 and T8 corpectomies.

Figure 5

(A) Angiogram in a case of giant cell tumor, with curettage and packing of the resultant cavity with postoperative bleeding. The buttress plate had been placed previously to avoid fracture. (B) Selective catheterization of a superior geniculate arterial feeder to the aneurysmal bone cyst demonstrates hemorrhage into the cavity. (C) Following polyvinyl alcohol embolization, the distal vessel is occluded. (D) The vessel is finally occluded with a coil. (E) Femoral arteriogram demonstrates cessation of hemorrhage.