The imaging specialist who performs invasive procedures is an interventional radiologist. These physicians use real-time imaging tools like X-ray, ultrasound, CT, and MRI to guide needles, catheters, and other instruments through the body, treating conditions that once required open surgery. Two closely related subspecialists, interventional cardiologists and interventional neuroradiologists, do similar work focused specifically on the heart and brain.
What an Interventional Radiologist Does
An interventional radiologist is a medical doctor who combines deep expertise in medical imaging with hands-on procedural skills. Unlike a diagnostic radiologist, who reads scans and reports findings to other doctors, an interventional radiologist directly treats patients. They evaluate patients before procedures, perform the procedures themselves, and manage follow-up care afterward. In academic medical centers, a diagnostic radiologist who also interprets imaging studies is the exception rather than the rule; interventional radiologists spend most of their time evaluating and managing patients in a clinical role.
Their procedures are minimally invasive, typically requiring only a needle puncture or a small catheter insertion rather than a surgical incision. This distinction matters for recovery. A procedure like treating a small kidney tumor, which once meant a weeklong hospital stay after open surgery, can now be handled as an outpatient visit through imaging-guided techniques.
Common Procedures
The range of procedures interventional radiologists perform is broad. Some of the most common include:
- Needle biopsy: A small needle is guided into nearly any part of the body to collect a tissue sample. Fine needles extract cells for analysis, while larger core-biopsy needles cut a small piece of tissue for more detailed examination.
- Angioplasty and stent placement: A balloon-tipped catheter is threaded into a blocked blood vessel, inflated to open the blockage, and often followed by placing a tiny mesh tube (stent) to keep the vessel open.
- Catheter insertion: Tubes are placed into large veins to deliver chemotherapy, nutrition, or dialysis access.
- Drainage procedures: Fluid collections like abscesses are drained through a needle or a small catheter placed through the skin, largely replacing what used to require surgery.
- Angiography: An X-ray exam of arteries and veins that maps blockages, narrowing, or other vascular problems.
- Feeding tube placement: A tube is inserted directly into the stomach for patients who cannot eat by mouth.
- Clot-dissolving treatment: Medications that break up blood clots are delivered directly to the site of the clot through a catheter.
Imaging Tools Used During Procedures
Interventional radiologists choose their imaging tool based on the procedure and the part of the body involved. Fluoroscopy, which produces a continuous X-ray video, is the most common. It lets the physician watch in real time as a catheter or wire moves through blood vessels. The procedure suite typically has a C-arm machine with the X-ray source below the patient and the image receptor above, along with an ultrasound machine positioned for easy access.
CT scanning provides detailed cross-sectional images and is particularly useful for guiding biopsies of deep organs or draining fluid collections. Ultrasound is portable, uses no radiation, and works well for guiding needles into superficial structures or blood vessels. MRI offers exceptional soft-tissue contrast and is increasingly used for certain biopsies and tumor treatments, with specially designed MRI-compatible needles and probes now available for procedures like microwave ablation and radiofrequency ablation.
In some advanced centers, multiple imaging tools are fused together. A physician might overlay a prior MRI onto live fluoroscopy to pinpoint a tumor’s exact location while threading a catheter toward it. PET/CT, which highlights metabolically active cancer cells, is also being used during procedures to confirm that a tumor has been fully treated.
Cancer Treatment Through Interventional Radiology
Interventional oncology has become a growing part of the field. For liver tumors, both primary cancers and metastases from other organs, interventional radiologists use several established techniques. Transarterial embolization blocks the blood supply feeding a tumor, starving it of oxygen and nutrients. Variations of this approach deliver chemotherapy drugs or radioactive particles directly into the tumor’s blood supply, concentrating treatment at the site while limiting exposure to the rest of the body. These techniques are now included in major cancer treatment guidelines.
Percutaneous thermal ablation is another option. A thin probe is inserted through the skin and into the tumor, then heated using radiofrequency energy or microwave energy to destroy the cancerous tissue. This approach works best for tumors under 3 centimeters in diameter and can be curative for small liver cancers and colorectal liver metastases. Cryoablation, which freezes tumors instead of heating them, is used in similar situations.
Related Specialists Who Use Imaging for Invasive Work
Two other specialties overlap with interventional radiology in significant ways. Interventional cardiologists focus on the heart and its blood vessels. They perform balloon angioplasty and stenting to open blocked coronary arteries, treat heart valve problems, and increasingly work on peripheral blood vessels like the renal and carotid arteries.
Interventional neuroradiologists (also called endovascular surgical neuroradiologists) specialize in the brain, spine, head, and neck. They perform cerebral angiograms, treat brain aneurysms and abnormal tangles of blood vessels, place stents in narrowed arteries supplying the brain, and embolize tumors in the head and neck like glomus tumors and meningiomas. Many of their biopsies can be done under local anesthesia and light sedation, though procedures targeting deep structures near the upper spine may require general anesthesia.
Interventional radiologists themselves also treat vascular problems throughout the body, including opening and stenting carotid arteries, treating aortic aneurysms, and working on arteries in the legs and kidneys. The boundaries between these three specialties sometimes overlap, and which specialist performs a given procedure often depends on the institution and the specific clinical situation.
Training Requirements
Becoming an interventional radiologist requires extensive training. After medical school, physicians enter a five-year residency program that includes three years focused on diagnostic imaging and two years dedicated to interventional procedures. The American Board of Medical Specialties recognizes interventional radiology as its own distinct clinical discipline, separate from diagnostic radiology. After completing residency, physicians can pursue additional fellowship training in areas like neurointerventional work or interventional oncology.
This training path reflects how the specialty has evolved. Interventional radiologists are not simply radiologists who occasionally perform procedures. They are clinicians who see patients in clinic, make treatment decisions, perform complex procedures, and manage patients through recovery, functioning much like surgeons who happen to use imaging instead of open incisions.