Interventional radiological procedures are performed under imaging guidance to treat a lesion, prevent its progression, or obtain a pathological diagnosis. These procedures protect patients from the potential risks of surgery and general anesthesia. Their success rate is comparable to surgical procedures, but they have fewer associated side effects. Since large surgical incisions are not required and the need for general anesthesia is minimized, serious postoperative complications are avoided, leading to shorter hospital stays. As a natural consequence, the total cost of the procedure is also reduced.

Unlike other treatment methods, interventional radiological procedures are repeatable. Additionally, for some patient groups, these procedures may be the only option. When surgical or medical treatment options are no longer viable, interventional radiological procedures remain the sole choice.

Interventional procedures can be broadly categorized into vascular interventional procedures, which are performed within blood vessels, and non-vascular interventional procedures, which are conducted outside the blood vessels. Non-vascular interventional procedures include treatments for conditions affecting the abdominal cavity, thoracic cavity, respiratory system, biliary system, urinary tract, gastrointestinal system, and musculoskeletal system. Vascular interventional procedures, on the other hand, focus on diseases related to arteries and veins.

Non-Vascular Interventional Radiological Procedures

• Percutaneous biopsies: Imaging-guided biopsies are performed on lesions in various tissues to determine their characteristics (fine-needle aspiration biopsy and core needle biopsy).

• Percutaneous abscess and fluid collection drainage: Abscesses (pus-filled collections) and non-infectious fluid collections in the abdominal and thoracic cavities are drained using specially designed thin catheter-like instruments under imaging guidance.

• Percutaneous simple cyst and hydatid cyst treatments: Simple cystic structures originating from tissues in the abdominal and thoracic cavities or cysts caused by parasites are drained. The condition known as "Hydatid Cyst," which is commonly believed to be transmitted from cats and dogs, can be treated using non-surgical interventional radiology techniques.

• Percutaneous biliary drainage and biliary stent placement: In cases of bile duct obstruction, bile may be drained externally through a catheter. Alternatively, small metallic tubes called "stents" can be placed in the narrowed bile ducts to ensure normal bile flow into the small intestine. If the bile duct narrowing is benign, balloon dilation can be performed to widen the narrowed area.

• Percutaneous cholecystostomy: For patients who cannot undergo gallbladder surgery or need a temporary alternative, a catheter is used to drain the thickened and infected bile from the gallbladder.

• Percutaneous nephrostomy: When an obstruction prevents normal urine flow and causes urine to accumulate in the kidney's collecting system, special catheters are used to drain the urine externally, preventing kidney damage.

Percutaneous double-J stent placement: In patients with a narrowing between the kidney and the bladder (who are not candidates for surgery), a double-J stent is placed to ensure continuous urine flow between the kidney and the bladder.

• Percutaneous stone removal: Kidney stones are removed through the same percutaneous method.

• Esophageal and colonic stent placement: In patients with esophageal, small bowel, or colorectal cancer who are not candidates for surgery, stents are placed in the narrowed areas to relieve obstruction and maintain physiological passage.

• Percutaneous gastrostomy: In patients who cannot take food orally, a catheter is inserted through the skin into the stomach, allowing for enteral feeding.

• Percutaneous celiac ganglion block: In cancer patients, imaging-guided injection of medication into the abdominal pain centers reduces pain and the need for analgesics.

• Tracheal stent placement: In patients with airway obstruction who are not candidates for surgery, a stent is placed in the narrowed area to open the airway.

• Percutaneous tumor ablation (RFA and microwave ablation): In cancer patients, tumors are destroyed using high heat for control. This method is applied to primary and secondary tumors of the liver and lungs, as well as kidney and certain bone tumors, playing a crucial role in cancer treatment.

• Percutaneous IRE (Irreversible Electroporation: Nanoknife) therapy: A newly developed method for treating inoperable pancreatic cancers, also used for localized treatment of certain liver and prostate tumors.

• Vertebroplasty, kyphoplasty: In cases of vertebral compression fractures due to osteoporosis or hemangiomas, bone cement is injected into the collapsed vertebra through a needle, preventing further damage to bone integrity and surrounding tissues.

Endovascular Interventional Radiology Procedures
Interventional radiological procedures performed in body vessels

• Balloon angioplasty and stenting: Treatment of arterial or venous stenosis using balloon dilation alone, a combination of balloon dilation and stenting, or stent placement alone.

• Mass embolization: Blood supply to highly vascularized masses is blocked using special embolic agents, leading to mass shrinkage and symptom relief. In some cases, embolization is performed before surgery to minimize intraoperative blood loss.

• Aneurysm embolization: Treatment of arterial or venous aneurysms using special embolic materials, avoiding open surgery.

• Inferior vena cava filter placement: Placement of a specialized filter in the inferior vena cava to prevent embolization of thrombi from the deep veins of the legs to the lungs.

• Arteriovenous malformation (AVM) and fistula treatment: Congenital or acquired vascular malformations (AVMs) and abnormal arteriovenous fistulas are treated using embolic agents.

• Transarterial chemoembolization (TACE): Targeted delivery of chemotherapy to highly vascularized tumors while simultaneously embolizing their feeding arteries, aiming to shrink the tumor and reduce systemic chemotherapy side effects.

• Radioembolization: In collaboration with the nuclear medicine department, intra-arterial radionuclide therapy using Yttrium-90 microspheres is successfully applied for the treatment of primary liver tumors (HCC and cholangiocarcinoma) and metastases.

• Transjugular intrahepatic portosystemic shunt (TIPS): A shunt is created by placing a stent between the hepatic and portal venous systems via a transjugular approach to reduce portal hypertension.

• Endovenous laser ablation: Treatment of varicose veins caused by venous insufficiency using laser probes inserted into the affected veins under imaging guidance.

Interventional Procedures in Cerebral (Brain) Vessels

• Cerebral aneurysm embolization: Occlusion of aneurysmal sacs in cerebral vessels using microcatheters to deploy mechanical metal coils or liquid embolic agents.

• Cerebral arteriovenous malformation (AVM) treatment: Targeted embolization of AVMs by advancing a microcatheter to the nidus and occluding the malformation with liquid embolic agents.

• Cerebral stroke treatment: Thrombolysis using clot-dissolving agents for acute thrombi in cervical and cerebral arteries, with balloon angioplasty and/or stenting if underlying stenosis is present.

• Stent placement for cerebral vascular stenosis: Stenting of critical stenosis in the carotid arteries (carotid artery stenting), with selective stent placement in other cerebral arteries as needed based on specific indications.

• Venous sampling: A diagnostic procedure to determine the localization and hormone secretion of pituitary and parathyroid adenomas.

Local Tumor Ablation Applications and Innovations

Tumor ablation can be performed using thermal (freezing: cryoablation; heating: radiofrequency ablation [RFA], microwave ablation [MWA], laser, high-intensity focused ultrasound [HIFU]) or chemical methods (acetic acid, ethanol). Additionally, irreversible electroporation (IRE), known as Nanoknife technology, induces cell membrane permeability between two electrodes, creating pores that lead to tissue ablation without thermal injury, thereby preserving adjacent critical structures.

Percutaneous Tumor Ablation
Percutaneous tumor ablation is an essential treatment option for primary and secondary liver tumors, as well as non-small cell lung cancer metastases. It is also effectively used in the treatment of kidney, bone, breast, and adrenal gland tumors.

Liver Cancer Treatment

Primary Liver Tumors (Hepatocellular Carcinoma - HCC)

As medical advancements progress, treatment guidelines continue to evolve. According to the Barcelona Clinic Liver Cancer (BCLC) staging system, percutaneous local ablation is increasingly preferred for early-stage liver cancer in patients who are not eligible for liver transplantation.

• For hepatocellular carcinoma (HCC) lesions <2 cm, percutaneous thermal ablation is considered a first-line treatment.
• For lesions <3 cm, both liver resection and ablation are viable options if the patient is a surgical candidate.
• Local ablation (RFA or MWA) is a safe and effective treatment for patients with up to three lesions, each ≤3 cm in diameter.
• In larger tumors, RFA can be combined with transarterial chemoembolization (TACE) or transarterial radioembolization (TARE) to achieve tumor downstaging, potentially allowing for liver resection or transplantation.
• In suitable patients, ablation provides a >50% five-year survival rate.

Secondary Liver Tumors (Metastases)

RFA and MWA are frequently used for the treatment of secondary liver tumors, particularly colorectal cancer metastases.

• RFA or MWA is highly effective for metastases ≤3 cm.
• MWA is preferred for metastases measuring 3–5 cm.
• In cases of multiple colorectal liver metastases, a combination of surgical resection and ablation may be performed intraoperatively.
• Studies indicate that ablation combined with chemotherapy offers better outcomes than chemotherapy alone in colorectal cancer patients with liver metastases.
• Beyond colorectal metastases, the same techniques are applied for liver metastases from other malignancies, including breast, pancreatic, gastric, lung, and skin cancers, when appropriate indications exist.

Treatment of Lung Tumors

Radiofrequency ablation (RFA), microwave ablation (MWA), or cryoablation can be used in these procedures. Local ablation significantly improves survival in both primary and metastatic lung cancer patients.

Non-Small Cell Lung Cancer (NSCLC)

The standard treatment for NSCLC is surgery. However, in cases where patients are inoperable due to various reasons and have no lymph node involvement or metastasis, percutaneous ablation can be considered as an alternative treatment.

Lung Metastases

The lungs are the second most common site of metastasis. Ablation techniques are particularly effective in lung metastases, especially from colorectal cancer and other primary tumors.

Up to 4–5 lesions, each <3 cm in diameter, can be treated in both lungs.

Treatment of Kidney Tumors

For kidney tumors classified as T1a (>4 cm) and T1b (4–7 cm), local ablation offers an alternative to surgery.

• Tumors extending outward from the kidney can be treated with heating (RFA or MWA) or cooling (cryoablation).
• Cryoablation is a safer option for tumors located near the collecting system.

Treatment of Pancreatic Tumors

Pancreatic adenocarcinoma (PAC) is an aggressive cancer with a 5-year survival rate of less than 5%. Surgery remains the most effective treatment, but 80–85% of pancreatic cancer cases are inoperable at diagnosis due to metastasis or locally advanced disease.

• Locally advanced pancreatic adenocarcinoma (Stage 3) is defined by tumor encasement of the superior mesenteric artery, celiac axis, and/or a long segment of the hepatic artery (>180°) or occlusion of the superior mesenteric or portal vein without distant metastasis.
• Neoadjuvant chemotherapy (CT) and/or radiotherapy (RT) provide sufficient tumor regression for curative resection in less than 40% of patients.
• Given the limited effectiveness of systemic therapy for Stage 3 pancreatic cancer, local ablation techniques serve as a promising alternative.

Irreversible Electroporation (IRE) in Pancreatic Cancer
IRE is used for ablating tumors in Stage 3 patients who remain inoperable after chemotherapy.

• IRE creates micropores in the cell membranes, inducing apoptosis without disrupting vascular flow.
• It can be performed percutaneously or intraoperatively.
• The ideal tumor size for IRE is <4 cm in diameter.
• By the third month post-IRE, tumors typically transform into fibrotic scars with no contrast enhancement.
• Recurrence is suspected if contrast enhancement reappears.
• PET imaging is useful for functional assessment of ablated tumors.
• Follow-up includes imaging and tumor markers every three months.
• Studies indicate improved overall survival when IRE is combined with standard chemotherapy.

Treatment of Bone Tumors

Benign Bone Tumors

• Primary benign bone tumors, such as osteoid osteoma and chondroblastoma, are effectively treated with RFA under CT guidance.
• Technical success rates are 95–100%, with clinical success rates around 90%.

Bone Metastases

• RFA or cryoablation is used to reduce pain in patients with bone metastases.
• In some cases, ablation is combined with cement augmentation to reinforce the bone and prevent fractures.

Treatment of Prostate Tumors

• Multiparametric MRI has improved the accuracy of prostate cancer detection.
• Suspicious lesions identified on MRI undergo "fusion biopsy" for diagnosis.
• Local ablative therapies are emerging as an alternative treatment in select prostate cancer cases.
• IRE and high-intensity focused ultrasound (HIFU) are the most commonly used techniques.

Prof. Dr. Okan Akhan
Bayındır Söğütözü Hospital Head of Radiology Department