Introduction
Interventional radiology is the technique used in the diagnosis and treatment of diseases. This branch of radiology has been playing a key role in the diagnosis and management of oncological patients. The procedure involves the insertion of small catheters or wires from outside the body. Imaging techniques such as X-ray, CT (computed tomography), or ultrasound are utilized to guide radiologists. Interventional radiology includes embolization and ablation techniques. Embolization is a minimally invasive technique that involves the closure of specific blood vessels. Ablation is a minimally invasive technique used to destroy abnormal tissue.
What Is Embolization?
Embolization is a technique using catheters or coils that are useful in blocking tumor vessels or preventing acute bleeding. Tumors require constant blood for their nourishment. A lack of which can cause tumor cell death. It is a common procedure to restrict tumor growth. Embolization stops the blood flow to prevent tumor growth. A large number of fluids, along with minute particles, are flushed through vessels to induce blockage. This is effective in treating lung, liver, kidney, or bone tumors. However, the procedure can damage other organs and blood vessels.
What Is Ablation?
The procedure includes the utilization of a catheter or needle along with thermal energy like microwave, radiofrequency, or cryoablation to treat varicose and tumors. Extreme heat or cold is applied to the affected area. Heat radiation is termed radiofrequency ablation, and cold application is termed cryoablation. The treatment can have an adverse impact on the heart, like abnormal braking circuits (irregular heart rhythm). The tissues close to heart muscles are destroyed, leading to arrhythmias (irregular heartbeats).
What Role Does Embolization Play in the Future of Interventional Radiology?
Embolization is an important aspect of interventional radiology that can be performed as an endovascular or percutaneous approach. Embolization can induce occlusion or reduction in the blood flow of the targeted vessel. Embolization has been routinely used in arterial or venous bleeding, vascular or lymphatic malformation, visceral or renal aneurysms (enlargement caused by the weakened arterial wall), variceal diseases (dilated veins), presurgical treatment, and oncological treatments. Embolic agents that are used in embolization have specific strengths and weaknesses. They can be used singularly or in combination to improve efficacy.
The embolization procedure is one hour long and requires the administration of local anesthesia. Followed by the radiologist puncturing the thigh to pass catheters and guidewires into the patient's arteries. A contrast agent is administered into the catheter to obtain a clearer image. A 0.5 mm (millimeter) embolic particle is administered through a microcatheter. The particles contain chemotherapy or radiation to block the blood flow. Some patients may experience the adverse effects of nausea or pain following the procedure.
Embolization was earlier used in the following conditions:
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Uterine Artery Embolization: Tiny particles are injected into blood vessels supplying the uterus. It stops the blood flow to fibroids resulting in their shrinkage.
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Prostate Artery Embolization: It is a minimally invasive treatment that improves lower urinary tract symptoms caused by benign prostatic hyperplasia (age-related prostate enlargement).
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Pulmonary Arteriovenous Malformation Embolization: Embolization is the procedure of choice in the treatment of the abnormal connection between the artery and the venous.
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Chemoembolization: This is a refined form of embolization therapy. In this technique, the radiologist will place a microcatheter in the blood vessel to supply locally targeted high-dose chemotherapy into arteries that supply tumors. The method is helpful in treating tumors such as hepatoma (liver cancer), primary liver cancer metastasis, tumor spreading to the liver from colon cancer, carcinoid (slow-growing cancerous tumor), sarcoma (cancer developing in bone and soft tissue), ocular melanoma (eye cancer), and other tumors spread.
What Is the New Field of Application in Embolization Therapy?
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Emborrhoid Technique: In recent years, hemorrhoids (piles) have been treated with transarterial embolization of superior rectal arteries. Emergency cases of bleeding are being treated with embolization as an alternative to surgery. The technique is non-invasive and targets the rectal arteries for occlusion.
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Bariatric Embolization: Embolization treatment is used to treat gastrointestinal conditions like obesity. Obesity can cause type 2 diabetes, diseases of the liver, heart, joints, lungs, and tumors. Studies are underway on the effectiveness of embolization of gastric arteries and gastroepiploic arteries, or bariatric embolization.
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Embolization of Inflammatory Joint Disease: Embolization therapy has been used in recent times to treat musculoskeletal diseases like osteoarthritis, frozen shoulder, and joint overuse injuries. The procedure acts by reducing inflammatory new blood vessels that cause chronic pain. In addition, the growth of unmyelinated sensory nerves is induced along the path.
Embolization techniques are being used for prostate, gastric, and hemorrhoidal arteries.
What Is the Role of Ablation in Interventional Radiology?
Ablation techniques are being used in the treatment of prostate cancer, uterine fibroids, and atrial fibrillation, or treat tumors in the lung, breast, thyroid, liver, and other body parts. Ablation has become an important tool in oncology. At present, the ablation techniques face limitations from improper visualization of target lesions, longer treatment time, and artifacts in imaging from patient movement. With the advancement of ablation technology occurring at a rapid pace, the technique is utilized in treating the thyroid, prostate, and pancreas. The navigation system and ablation confirmation techniques are newer additions to the existing technology. The inclusion of image-guidance tools, image registration, fusion software, and semi-automated robotic needle guidance could optimize ablation procedures.
Ablation therapy is of the following types:
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Radiofrequency Ablation: High energy electric current is transmitted through a needle to produce heat to destroy damaged cells. The current heats the needle above 60 centigrades which can cause protein degeneration and tissue damage.
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Cryoablation: In this technique, argon and helium gas are circulated through the needle to lower the temperature of damaged tissue below minus 40 centigrades for several minutes
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Microwave Ablation: Electromagnetic waves are transmitted through needles causing agitation of water molecules in damaged cells, producing sufficient heat to destroy them. The technique has potential in the treatment of liver disease, lung malignancies, renal and adrenal tumors, and bone metastasis.
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Percutaneous Ethanol Ablation: This is a type of alcohol ablation that uses ethanol that is injected into damaged tissue. The technique is useful in the treatment of cancer as alcohol is toxic to tumor cells and their blood vessels. The technique can treat small tumors efficiently. However, the ablation technique can cause discomfort.
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Laser Ablation: The technique in which a laser beam is directed on the affected tissue to remove the damaged tissue.
Conclusion
Various systemic illnesses that may require surgery are being treated with minimally invasive techniques of embolization and ablation. These interventional procedures enable direct access to the required areas and avoid side effects from surgery. The procedure of embolization and ablation is being increasingly used in the treatment of cancer. There are ongoing studies on the application of the procedure in the treatment of difficult-to-assess tumors.
