Although interventional radiology (IR) is a relatively young and still evolving specialty, its minimally invasive approach to treatment for serious conditions, such as uterine fibroids and aortic aneurysms, has brought IR to the forefront of radiology. IR is stretching its wings with new procedures that offer patients shorter recovery periods and relief from symptoms without invasive surgery, but according to one of the fields experts, there are factors hindering IRs widespread use in the United States both in terms of public awareness and a lack of interventionalists.
At this years annual meeting of the Radiological Society of North America (RSNA), Gary J. Becker, M.D., FSCVIR, FACC, FACR, and 20-year practitioner of IR, gave the annual oration in which he addressed the future of interventional radiology. In addition to the pressing need for more radiologists in general, Becker presented data indicating that radiologists are becoming less involved in interventional procedures even as technology and science provide increasingly more effective ways to treat a number of disease states, including cancer, through interventional radiology.
Becker is the assistant medical director and director of research and medical outcomes at the Miami (Fla.) Cardiac & Vascular Institute. He spoke with Medical Imaging about what he sees on the horizon for IR and his history with IRs specialized procedures.
How long have you been involved in IR, and what are the earliest procedures you remember performing?
I was in my residency at Indiana University (Bloomington), and in 1978 one of the faculty and I did the first three biliary drainages in Indiana. Actually, it was sort of a turning point for me, because I talked to our chairman in radiology about what I was going to do when I finished my training. I stayed at Indiana with a vague idea that radiology might have a more significant role in treatment in the future, and I was interested in an admitting service and more. I was looking forward to things really having some kind of an impact, so I stayed on the faculty there after I finished my training and that was sort of the start of it for me.
What were some the procedures that followed once you decided to stay the course and explored IR?
I was always doing angiography throughout my training from 78 on. I had an internal medicine internship before that. We did a lot of angiography for trauma and diagnosis of visceral problems, for instance a lot of the work-ups that are done today for tumors with CT scanning and MRI used to be done with angiography. Also in the late 70s we began to do some angioplasty. Around that time, balloon angioplasty was really getting its start.
What specific procedures are being performed now and being developed within IR? And what procedures are they replacing, such as uterine fibroid embolization versus hysterectomy?
A lot of women who have had uterine fibroids in the past were offered only hysterectomy as a choice. Now they have embolization as a new alternative. The other things that are going on in the field include the treatment of abdominal aortic aneurysm and thoracic aortic aneurysm with endographs. They are all catheter-based procedures with fluoroscopic and angiographic guidance without doing open repairs. The idea with endographs is to avoid opening the abdomen to repair the aorta, or in the case of thoracic aneurysm, to avoid opening the chest to repair the aorta when you can do it transluminally using a catheter approach.
In our practice it has been an important thing for the past seven years. It has caught on and there are a couple of devices that have been approved by the FDA. There are quite a few doctors who are training in that field of practice and those would include interventional radiologists and surgeons primarily, a few cardiologists although I think the future says there will probably be a lot more cardiologists involved in that area as well. Another option in the U.S. is carotid stenting as an alternative to carotid endarterectomy for people with either very significant asymptomatic carotid stenosis or with symptomatic carotid stenosis, symptomatic meaning TIAs (transient ischemic attack) or stroke.
Who is performing interventional procedures, such as uterine fibroid embolization?
Uterine fibroid embolizations are almost exclusively being performed by interventional radiologists. There has been some interest on the part of a few of the more aggressive gynecologists, but admittedly and they would admit this, too they just do not have the background in angiography and radiology to begin on that sort of field of endeavor any more than we do to begin our own practice at hysterectomy.
With other procedures, such the carotid stenting, are those radiologists requirements changing?
Yes, I think thats an area where you are going to see a lot of overlap of practice. For years, when carotid arteriography was done, it was done by whoever was the dominant force in a hospital doing most of the diagnostic arteriography. In most hospitals across the U.S. that was the radiology department and that could either be a general angiographer or a neuro-angiographer or somebody with training in neuroradiology. In either case, it was usually in the hands of radiologists.
In the last few years there has been a lot more aggressive behavior on the part of the cardiologists who happen to have patients on the table for coronary catheterizations and then have just done a little bit more anatomic searching with or without a clinically symptomatic reason to do so. The result has been an increase in interest in catheter-based treatments for carotid disease instead of just subjecting everybody to carotid end arterectomy. That has gotten a lot of folks interested the neurosurgeons, the vascular surgeons, the cardiologists, the radiologists now everybody is sort of in the game.
What new technologies are fueling the growth in IR, and what procedures are possible now as a result of these technologies?
I would definitely say that about the endografts. If you go back seven or eight years, we definitely did not have any manufacturers providing us with the tools to do aortic repairs transluminally. In fact, the few aortic aneurysms that we did in those days were done by devices that we made at home at night at the kitchen table. I spent many a night sewing together stents and fabric and making endografts for my patients, because there were not alternatives. Manufacturers caught on pretty quickly though; it is a pretty intense area of competition.
We could postulate some things that are going to happen with regard to technology. Looking into the diagnostic realm, I think MRA is going to clearly replace catheter angiography for the diagnostic evaluation of vascular disease. Since we are vascular and interventional radiologists, we are going to maintain that interest and involvement in diagnosis. Beyond that I see potential in the marriage of technologies, such as MRI coupled with therapeutic ultrasound in the form of high-intensity focused ultrasound beams that could be used to completely non-invasively target and destroy tumors. There are a few companies that are working on this now, where you will be able to actually take the imaging data set from the MRI, send a sample ultrasound beam into an area, create a little bit of change in the tissue as a result of that and get a new MR signal. You then would take a refined high-intensity focused ultrasound beam and go right back at the target with a strong enough ultrasound [beam] basically to destroy the tissue. I think that is fascinating. That is technology that is going to change how we approach things. I dont know who is going to be doing that when it actually does happen, but I believe that it will happen.
Right now as sort of an intermediate step to that we have patients who have cancer and they have lesions that are metastatic in the liver and the colon, as an example. You have a colon cancer and there are new lesions showing up in the liver and lets say they are in a difficult place or an impossible place to resect surgically. There are ways now to go percutaneously with the needle and guide it by ultrasound or CT, get the needle tip in a position and then place a radiofrequency probe and actually destroy the tumor with radiofrequency ablation. That is a nice intermediate step, because it is non-operative, it is percutaneous, and it involves an interventional technique. And in thinking about the most invasive, completely surgical approach to a lesion, we have that as our intermediate step. I think we will have in the future completely non-invasive tumor ablation, which would be done via the MR-guided, high-intensity focused ultrasound.
During your presentation at RSNA, you mentioned that there is a lack of appropriately trained interventionalists. Why do you think there is a lack of emphasis on IR?
We are part of a bigger problem, and the problem stems from poor estimation of manpower. There are a lot of facets of that. One of them is that you can go back to the 1980 GMENAC (Graduate Medical Education National Advisory Committee) report that I referred to at RSNA. This commission was looking at the manpower needs in medicine in the future and they made a very poor estimate. They grossly underestimated the needs for radiologists in the year 2000. You could say a lot of things have transpired in the meantime that they would not have been able to predict. But the real problem that is more current is that in the 1997 Balanced Budget Act there were some major Medicare cutbacks. As a result, we see an automatic and an immediate impact on the ability to fund graduate medical education, because graduate medical education at teaching hospitals is funded in large part out of the Medicare budget.
Since 1997, we have seen a 7 percent reduction in the number of training slots overall in radiology. Thats a big number, because in terms of that impact on interventional radiology, it is great, because IR overall is only amounted to about 8 percent of radiology trainees. In the field of interventional radiology, the number of positions available is just about double the number of radiologists finishing training who are really interventional radiologists. Plus, when you start looking at the impact of encroachment issues, specialties are always encroaching on each other. When you dont know the impact of that encroachment and you dont know what new procedures or new activities are going to require more of a certain kind of specialist, then the manpower needs assessment becomes even more complicated. I think for the magnitude of the job that is out there for interventionalists, it is a very large percentage of what used to be done surgically. It is amazing that there are only a couple thousand certified interventional radiologists in the country.
Which imaging modalities will be used more as interventional radiology expands?
I think all of the above. I think MR is just getting its start and is going to be very important. Fluoroscopy, CT and ultrasound we use pretty routinely in our day-to-day work in IR. We move somewhat fluidly between them throughout the day, just depending upon what the needs are of the individual case.
Is flat-panel digital fluoroscopy going to be a major area of growth?
It is going to be extremely important in all of our day-to-day procedures. The diagnostic angiography we do, the angioplasty and stenting we do, all will be flat-panel, Im sure. I dont know whether we are talking about two years or five years, but there is no question it is going to happen.
There are some great studies going on, particularly in the area of fibroid embolization, to document the degree of radiation exposure and it has been shown to be pretty low, fortunately. There is no general answer that is going to satisfy everybody, but basically if you have training and you have experience, we can show that the dosage rates for a procedure like fibroid embolization are quite low. It is important because a number of the people that get fibroid embolization are doing that as an alternative, because they want to maintain fertility. So, we are assuming that they are going to want to get pregnant and we want to keep the radiation dosage down. We also are starting to document fluoro times for all interventional procedures. That is becoming part of what we do, and it is probably going to be required in the future. I think it is just good practice, you can document learning curves, and behavioral changes in procedures that make for less radiation dose.
The manufacturers are working on ways to reduce radiation exposure. They are working with the FDA and I am on a committee of the SCVIR (Society of Cardiovascular and Interventional Radiology) that interfaces with the FDA about three of four times a year in an advisory capacity. Radiation exposure is one of the areas that we delve into quite a bit. Last time we met, there was a presentation by one of the FDA staff on progress in the area of radiation reduction. They have a new set of specific initiatives in conjunction with manufacturers that includes automatic features that will be included on new machinery, such as improved methods of collimation. Those of us who are in the field manufacturers, the FDA, interventionalists, all of the staff support in the rooms we constantly have that on our minds. Although it may not appear that way, when you are in the middle of a complex interventional procedure, that is really the truth. We concentrate on keeping the radiation dose down.
With regard to awareness of interventional radiology, is the general public aware that these procedures are available?
In our experience, people are doing a lot more to self-help than they used to. I dont think that their doctors are necessarily announcing all the alternatives in the office, not yet, but what is happening as a result of doctors not providing the information, is patients are becoming suspicious and they are getting antsy and doing their own thing. The bottom line is, if youre a doctor in the year 2000 and you are seeing patients in your office with any kind of problem, youd better be prepared to go over all of the alternatives. As I mentioned during my talk at RSNA, in our own practice, about two-thirds of the patients who came in for possible fibroid embolization had made it to the office through non-traditional pathways, basically on their own. I think that is really important and maybe it is because patients with fibroids are in the Baby Boomer generation. They are not in the oldest group or the seniors, those people still arent using computers to the extent that the younger folks are, but I can only see it increasing. The children of the Boomers will be a lot more computer savvy than we were and I can only imagine that their use of computers is going to be greater and they are going to find their way to innovative therapies much easier than their parents.