What does it entail?
Arterial embolization is a method of interventional radiology whose purpose is to suppress the vascular supply of a tumour by provoking the occlusion of the nearby vessels with consequent ischemic necrosis of the lesion. The occlusion must occur as distally as possible: terminal arterioles deprived of collaterals only source of blood supply to the area where ischemia is to be induced. The vascular occlusion is provoked by material that stops the blood flow and facilitates thrombogenesis. The embolizing material is selectively inserted by catheterising the arterial vessels afferent to the tumour.
In brief, this procedure, in the treatment of hypervascularizing benign lesions is currently considered to be the only treatment available. In surgical lesions it reduces the surgical risk and is able to improve the results of surgery. The primary aim of embolizing for palliative treatment is to control pain.
Applications in the scope of musculoskeletal oncology
The indication for embolization is made after a correct histological diagnosis and the subsequent staging of the tumour that will allow us to define its morphology, size, and its relationship with nearby structures. A biopsy must always be performed before embolization, because after this procedure the diffusedly necrotic tissue could produce some problems of histopathological diagnosis.
Having defined the correct indication for embolization an angiograph of the region is performed to highlight the pathological vascularization of the lesion.
Subsequently, by selective and super-selective catheterisation embolization of the lesion vessels that supply the tumoral mass is performed.
At the end of the procedure an angiograph allows us to assess the territorial distribution and the quality of vascular occlusion.
Arterial embolization in the treatment of tumours and pseudo-tumoral lesions of the bone and the soft tissues has been shown to arrest the growth of the lesion, facilitate a possible surgical operation, decrease the pain, control a possible hemorrhage of the tumour, and perhaps to stimulate an immune response "unmasking" by necrosis a part of the antigens of the tumour.
The directions for application are:
- curative embolization that is used in the treatment of all benign, pseudo-tumoral and low-grade malignant lesions, such as aneurismal cysts, angiomas and hemangioendotheliomas to heal the aforesaid lesions;
- adjuvant embolization to facilitate locally the surgical treatment of aggressive benign and malignant lesions, such as OBL, TGC, neurinoma, chordoma and metastasis. The preoperative phase involves a reduction of the bleeding during the surgical operation and the reduction is size of the lesion, thus facilitating its removal. In the postoperative phase the procedure is useful for the control of possible hemorrhages and to complete the results of surgery;
- palliative embolization is used in the treatment of lesions that are not responsive to a suitable oncological surgical treatment due to their site, dimensions or diffusion. The object is the local control of the aggressiveness and pain.
The analgesic effect is correlated closely with the ischemic necrosis that determines a reduction in the size of the tumor and thus less compression on the periosteum whose fibres are responsible for pain, and a deceleration in the processes of neoplastic osteolysis and reduced risk of pathological fracture. In addition, the analgesic effect is greater than that produced by radiotherapy, since it is less influenced by the size of the tumoral mass.
Arterial embolization is a method not without risks that should be performed only at specialized centers to reduce possible complications, that in certain segments, such as the spine, can be extremely disabling. The main complication is the embolization of non-lesional areas.
Technique of the operation
The procedure is performed in local anesthesia (in general anesthesia in pediatric patients); after puncture of the common femoral artery at the groin (alternative approaches: humeral or axillary). The catheter is inserted under fluoroscopic control by retrograde approach to reach the lesion to be embolized. The diagnostic examination (angiograph) for the precise evaluation of the type and degree of vascularization of the lesion is therefore performed, by the introduction of contrast medium through the catheter. If this study shows the feasibility of the procedure, an embolizing material is inserted that will obstruct the pathological vessels. The procedure can be repeated several times for long periods of time. In the absence of complications hospitalization for 24-48 hours is enough.
The embolizing material
The embolizing material differs in physical-chemical characteristics (liquids and solid) and type of occlusion (permanent or temporary). The liquid embolizing materials are: 1) N-Butyl (2) cyanoacrylate; 2) pure alcohol. The solid embolizing materials are: 1) Microspheres; 2) metal spirals; 3) Spongostan.