The seeds of the discipline that would become interventional radiology, the use of medical imaging to guide minimally-invasive procedures, were sowed in 1923, when the first successful angiography was done. Thirty years later, the development of the Seldinger technique—how to insert chest drains, PEG tubes, and other instruments needed for interventional radiology—drastically reduced complications for such procedures. The heightened level of safety allowed the development of processes that would become interventional radiology. In 1964, an accidental operation performed by Charles Dotter earned him the title of "father of intervention," and launched the formation of the discipline of interventional radiology.
In the decades that followed, this clinical specialty, broadly termed just angioplasty, acquired more applications, and by the 1980s interventional radiology had a foot in two worlds: diagnostic and therapeutic. At this point, a number of advances changed the treatment landscape and technology began pushing interventional radiology into a therapeutic model. As the tools of imaging became more sophisticated, cross-sectional imaging methods made once highly invasive procedures significantly less invasive and, as a result, safer.
Interventional radiology and oncology: an optimal combination
Currently, almost all oncology patients will interact with an interventional radiologist. Depending on the type of cancer, the interventional radiologist may be a consultant or one of the patient's primary physicians. Interventional radiology procedures in the treatment of cancer include:
- Transarterial chemoembolization (TACE)
- Radioembolization
- Radiofrequency ablation
- Cryoablation
Interventional radiology allows medication to be delivered precisely where it is needed. For example, in treating liver cancer, the TACE procedure consists of a small catheter inserted into a blood vessel of the groin and then threaded into a blood vessel in the liver guided by a real-time X-ray called video fluoroscopy. After contrast dye is injected through the catheter to define and locate the tumor and map the blood vessels, chemotherapy can be delivered directly into the blood vessels that feed the tumor. Finally, microspheres are injected into tumor-feeding blood vessels to block them. This both traps the chemotherapy in the tumor and deprives the tumor of blood and nutrients.
Radioembolization, or SIRspheres or THERAPspheres, differs from TACE in that tiny glass or resin beads filled with a radioactive particle are injected rather than a chemotherapy agent. Also, a patient getting TACE would stay in the hospital overnight, while radioembolization does not require an overnight stay. For radiofrequency ablation, which is usually employed as a secondary treatment for discomfort, the radiologist uses imaging to guide a thin needle into cancer tissue. Then high-frequency energy is sent through the needle to heat and kill cancer cells. Cryoablation is a similar procedure using extreme cold to destroy cancer cells.
All of these procedures deliver highly-targeted therapy with minimal surgery or time in the hospital, which is a cornerstone of interventional radiology. In fact, the three tenets of interventional radiology, in oncology and other therapeutic areas, have remained constant since that first angiography in 1923:
- Imagination/innovation
- Lower impact on the patient
- Minimally invasive procedures
Immuno-oncology and more
The latest innovations in oncology are focused on immuno-oncology, or IO. These procedures build on practices like TACE or cryoablation, but target an immune response that can be specific to the particular patient. One exciting area of study is focused on the "abscopal effect," in which localized radiation initiates an antitumor response in cells distant from the actual target. Similar investigations around cryosurgery are underway, as well as a number of other avenues linking immunotherapy to interventional radiology.
Minimizing impact on patients and shortening hospital stays are more important than ever today, and interventional radiology has been shown to be a sure way forward. Ongoing and developing clinical trials are helping to determine how this subspecialty can best be used to meet a host of 21st century healthcare objectives. Stay tuned. We’ll keep you posted.
For more on the capabilities of interventional radiology right now, download the Keosys eBook on peptide receptor radionuclide therapy.
