Interventional Radiology (abbreviated IR or sometimes VIR for vascular and interventional radiology) is a subspecialty of radiology in which minimally invasive procedures are performed using image guidance. Some of these procedures are done for purely diagnostic purposes (e.g., angiogram), while others are done for treatment purposes (e.g., angioplasty).
Images are used to direct these procedures, which are usually done with needles or other tiny instruments like small tubes called catheters. The images provide road maps that allow the Interventional Radiologist to guide these instruments through the body to the areas containing diseases.
Imaging Modalities: Common interventional imaging modalities include fluoroscopy, computed tomography (CT), ultrasound (US), and magnetic resonance imaging (MRI). Fluoroscopy and computed tomography use ionizing radiation that may be potentially harmful to the patient and the interventional radiologist. However, both methods have the advantages of being fast and geometrically accurate.
Ultrasound suffers from image quality and tissue contrast problems but is also fast and inexpensive. Magnetic resonance imaging provides superior tissue contrast, at the cost of being expensive and requiring specialised instruments that will not interact with the magnetic fields present in the imaging volume.
Procedures: Common IR procedures are:
Angiography: imaging the blood vessels to look for abnormalities with the use of various contrast media, including iodinated contrast, gadolinium based agents, and CO2 gas.
Balloon angioplasty/stent: opening of narrow or blocked blood vessels using a balloon; may include placement of metallic stents as well (both self-expanding and balloon expandable).
Drain insertions: placement of tubes into different parts of the body to drain fluids (e.g., abscess drains to remove pus, pleural drains)
Thrombolysis: treatment aimed at dissolving blood clots (e.g., pulmonary emboli, leg vein thrombi, thrombosed hemodialysis accesses) with both pharmaceutical (TPA) and mechanical means. This procedure is also used for stroke patients.
Biopsy: taking of a tissue sample from the area of interest for pathological examination from a percutaneous or transjugular approach
Radiofrequency ablation (RF/RFA): localized destruction of tissue (e.g., tumours) by heating.
Line insertion: Vascular access and management of specialized kinds of intravenous devices (IVs) (e.g. PIC lines, Hickman lines, subcutaneous ports including trans-lumbar and trans-hepatic venous lines)
IVC filters: - metallic filters placed in the inferior vena cava to prevent propagation of deep venous thrombus, both temporary and permanent.
Vertebroplasty: percutaneous injection of biocompatible bone cement inside fractured vertebrae
Nephrostomy placement: Placing a catheter directly into the kidney to drain urine in situations where normal flow of urine is obstructed. NUS catheters are nephroureteral stents which are placed through the ureter and into the bladder.
Dialysis access and related intervention: Placement of tunneled hemodialysis catheters, peritoneal dialysis catheters, and revision/thrombolysis of poorly functioning surgically placed AV fistulas and grafts.
Biliary intervention - Placement of catheters in the biliary system to bypass biliary obstructions and decompress the biliary system. Also placement of permanent indwelling biliary stents.
Stroke Management and Neuro Intervention:
A few of our hospitals provide a stroke management service, whereby we provide neuro imaging and intervention.