This section of our website is dedicated to students interested in interventional radiology and is overseen by our Medical Student Council.
Under the drop-down menu at the top of the screen labeled "Medical Students" you will find an introduction to the specialty as well as great resources on how to get involved, explore IR, and become a competitive applicant for residency.
Get involved by Joining the Society of Interventional Radiology. Membership is FREE to students. Also consider applying for a position on the Medical Student Reserves, a group of medical students who work on short-term projects throughout the year.
Physician Spotlight: Dr. Grafe (Gray) Lyons
Assistant Professor of Radiology and Radiological Science
Complex IVC Filter Retrieval, Fibromuscular Dysplasia (FMD), Interventional Radiology, IVC Filter Placement, IVC Filter Retrievals, Limb Threatening Ischemia, Renal Artery Disease, Varicose Veins, Vascular Disease , Vascular Malformations, Venous Thromboembolism
Can you give us a brief overview of your background? How did you discover Interventional Radiology and what made you decide to pursue a career in this field?
I came into IR sort of late. I went through medical school trying out a couple of different specialties. I initially thought I would do a surgical subspecialty like ENT, Ortho, or Plastics. However, I was MD-PhD and after finishing the PhD component of my training program, my interests had changed somewhat and I was more focused on the anatomic components of disease. This led me towards eventually pursuing a diagnostic radiology residency at New York-Presbyterian/Weill Cornell Medical Center.
During residency, I also tried out a lot of different subspecialties in Radiology but I ended up liking Interventional Radiology the most. Ironically, this was the subspecialty that was the most surgical in nature. But I had previously done a surgical internship and had a great experience there. I appreciated the hands-on, procedural focus of the field, and enjoyed the patient contact it provided. Ultimately, I think it was a good mix of my interests in medical imaging, anatomy, and hand-on or surgical approach. I pursued my training in Vascular and Interventional Radiology at the Miami Cardiac & Vascular Institute, where I had a great experience.
What unique perspectives does being a physician-scientist provide? What are some additional rewards and challenges that come with that title?
My PhD was in the development of the sensory nervous system, however I utilized a lot of imaging to visualize the neural systems I was investigating. During this time, I developed and built a lot of new microscopic technologies and procedures. So this process taught me how to image and visualize complex systems. I consider IR to be the least standard of the imaging modalities. We have to be very dynamic and creative in the way we visualize disease processes intraoperatively so that we can successfully conduct our procedures.
As one of the new attendings at Hopkins, I appreciate the technology-driven approach of the institution and the IR division here. There is opportunity for research and advancements at all levels whether it be preclinical or clinical. There are challenges however in that the field often develops very quickly and this development at time can outpace our own ability to test our own methods. Because our technology is moving so quickly, we are often on to the next thing before we have completely proven the last one.
Can you speak to the opportunities available in IR as a career?
The way you mold your career in IR can be very diverse, it is one of the bigger draws of the field. You can do 100% IR with high complexity cases to almost all outpatient minor routine procedures. Some people mix interventional with diagnostic cases. So as an attending, you can really find the balance of complexity of procedures, lifestyle, and other interests like research that fits with your interests. I often liken this to being a neurosurgeon and neuropathologist at the same time: you can choose when you choose when you want to be operating and when you want to be doing diagnostics. Furthermore, you don’t have to be static in your practice and you can shape your practice as you mature in your career. IR affords that flexibility.
I know that you have a focus in treating venous diseases. Can you talk about the opportunities to work at vein clinics as an IR doctor?
Where I previously trained at Weill Cornell, they had developed a Vein Treatment Center that had become quite successful from both a clinical and commercial standpoint. This model has been replicated at a number of IR divisions at different university systems including Jefferson. Venous treatments really arose from IR and is a growing part of our field. Although the vein clinics often exist in the private space, I think it really needs to grow in the academic space. Often times, venous disease really affect a person’s quality of life and you can make a significant difference in treating these types of disorders.
What are your current clinical and research interests?
Currently, I am dong a handful of clinical studies on all different aspects of IR. My particular clinical interests are in vascular disease and pain treatments. I do see a huge future in pain treatment. With the ongoing opioid crises, providers are trying to moving away from prescribing opioid medications. However, patients still have a lot of chronic pain. So I do believe that developing and improving treatments for pain is important. Being an IR, we can use image guidance to target particular nerves with good precision and then utilize a variety of interventions once we have reached our anatomic area of interest.
Can you talk about how IR’s management of pain interfaces with other specialties?
The treatment of chronic pain can also involve Anesthesiologists and PM&R doctors who specialize in pain management. I do believe that pain management requires a team centered approach involving these other fields caring for patients with pain diseases. But the particular advantage and contribution IR can provide to this domain is its intensive training with image and image-guidance. We have experience working with advanced imaging modalities like MRI and doing advanced targeted treatments. Some of our newer interventions include cryoablation of peripheral nerves and neurolysis techniques at the celiac plexus. A lot of the more advanced techniques do put patients at risk of complications, and another advantage as an IR in this space is that you can manage your own complications.
What are some of the rewarding parts of working in your field? Challenges?
The most rewarding part of my first year working as an attending have been working with the trainees. It is really nice working with and learning from people who are smart, dedicated, and have similar interests. However it can be challenging because teaching adds a layer of complexity on top of doing a procedure myself: verbalizing the process of conducting a procedure and explaining its complexities without physically being able to do them.
What is your favorite IR procedure, and why?
There are so many different procedures in IR that I enjoy, so it’s hard to pick a favorite. But I often enjoy a good dialysis case. I find them to be very rewarding and they usually lead to good outcomes for the patients.
There is also a lot of innovation in this space within IR. Here at Hopkins, I am the point person for the novel Endovascular Fistula creation. This is a very interesting and innovative technique where we can create a new site for fistula using our percutaneous techniques. The procedure has been shown to have a technical success rate and maturation comparable to surgical fistulas. And the time to fistula creation is faster than surgical fistulas. In the end, I do think long-term studies will show patients treated with this approach will survive longer and it will also provide an alternative option for patients who are not good candidates for surgical fistulas.
This newer procedure is not available at all centers though. Hopkins is currently only one of two centers in the state of Maryland to offer it. And some providers have been hesitant to refer patients out for this procedure based on its novelty and relative lack of long-term data. But I have tried to combat this by focusing on outreach and education targeted towards these referring providers. I also thinks it helps to be stakeholder in the disease process. As an IR doc, I do a lot of dialysis catheters, fistulagrams, and emergent dialysis access procedures while on call. So the specialists in the nephrology department have become familiar with me and my dedication towards patient care, which makes them more receptive when I offer a new procedure.
What do you think medical students should know about IR?
Don’t get psyched out. With IR training transitioning into the integrated residency, it is easy to look at the numbers and see how competitive the specialty has become. However, there are a lot of pathways to get into the field. And the field is always looking for interested and dedicated practitioners.
Furthermore, there are whole swaths of the country where there are no IRs or where people have to travel far to receive IR expertise. So there is a definite medical need in this specialty for more practitioners and you can make an impact.
I believe it is a very good specialty from a career standpoint. There is a lot of flexibility in how you guide your career as we have previously discussed, IR docs are good colleagues that are often a relaxed and happy bunch, and there is good job market for the specialty.
Finally, I find the field to be very rewarding with outcomes that can significantly impact patient’s lives.
Interviewed by: Ahmed Farhan
Physician Spotlight: Dr. Mina Makary
What are your personal and professional experiences and how it led to the position you currently hold?
I’m a Vascular and Interventional Radiologist and an Assistant Professor of Radiology at The Ohio State University (OSU) Wexner Medical Center in Columbus, Ohio, and I also serve as the Director of Scholarly Activity and Research in my department.
I’m from Ohio, and I did my training (medical school, diagnostic radiology residency, and interventional radiology training) at Ohio State – Go Bucks! I loved working at Ohio State because of its strong, clinically-oriented, and collegial IR department, so I also stayed on as faculty after my training.
I really enjoy my job for a variety of reasons. We have a very clinically centered practice where we do a variety of interventions from simple to complex while taking care of patients in both the inpatient consult service as the well as the outpatient clinic environments. It is very rewarding to work with patients to improve their quality of care. I also enjoy working with medical students, residents, and fellows, and I get to be a part of their journey and see them develop over time. Lastly, innovation is key focus of our division, whether through research and discovery or through direct advancement as we take care of exceedingly complex and sick patients in IR. I consider myself extremely lucky to have found IR because I can’t imagine a better specialty with a more exciting amount of opportunity, and the chance to have a huge positive impact on patients.
How did you find Interventional Radiology (IR) as a specialty? Is that something you always knew you wanted to go into or is that something you found later on?
OSU has always had a strong history of IR and the college of medicine had a strong IR interest group. I didn’t really find out about IR until third year of medical school. When I was in my diagnostic and interventional radiology rotation as a medical student, I saw the exciting work being done in the field. Back then, IR was a fellowship after diagnostic radiology residency, so I didn’t have to make a decision early on at that point.
I further gained a deeper appreciation throughout my intern year and in my diagnostic radiology residency when I had more responsibility on my IR rotations, confirming the belief that it was the coolest thing ever. Radiology in general and IR specifically – the more you learn about it, the more you appreciate it. From the outside, someone looking in may not know all of what you’re thinking and your thought process/problem solving. But the specialty is exciting beyond imagination – the more you learn, the more exciting it becomes.
Also, I’m a doer so I like to use my hands and problem solve, but I’m also a thinker. In medicine there’s a certain dichotomy that if you’re a thinker you go into certain types of specialties and if you’re a doer you go into other types of specialties. But I enjoyed both – I enjoyed being creative and using my problem-solving skills to make a diagnosis, but then also act on it. What strikes me about IR is that it is very broad (you get to deal with a lot of systems), it’s very cutting edge (you get to interact with a lot of technology), you get to deal with a lot of problem solving and you get to improve outcomes by doing procedures that are minimally invasive and have a shorter length of stay, quicker recovery, and lower cost to the system.
For example, I was in clinic the other day explaining to a patient about the Transjugular Intrahepatic Portosystemic Shunt (TIPS) procedure and how the procedure creates a new blood vessel in the liver to decrease the blood pressure in the portal system. After hearing my explanation, the patient looked at me and asked “you’re going to do all of this with just this pinhole?” And i said “yes!” But after looking at how big the stent was, the patient didn’t believe me.
IR is the future!
Do you have a favorite clinical procedure?
There are three parts of my practice that I really enjoy.
Interventional Oncology (IO) is an area that is very rewarding as an interventional radiologist as we are central part of the cancer patient’s journey from the very beginning of their oncological care through biopsies & ports. We also therapeutic locoregional therapy like transarterial chemoembolization (TACE), Y90 radioembolization, and ablations as well. Ablations for treatment of early-stage hepatocellular carcinoma (HCC), for example, can be curative. The patient comes in the morning; you ablate their tumor and the patient goes home free with a band-aid. There is no other therapy in medicine that literally cure cancer in this definitive and quick way. Additionally, later on in the patient’s oncological care, IR is involved from a palliative care and pain standpoint.
I also have a strong clinical presence doing venous interventions (acute and chronic). Those patients are very grateful – the outcomes are really striking when you treat somebody’s veins and the swelling goes away and it changes their quality of life significantly. Many of these patients are underdiagnosed or have been told in the past that there are no treatment options. So, the impact of a successful endovascular therapy is huge and it’s very rewarding.
Finally, I’ve also focused my practice on performing advanced portal interventions, such as TIPS/Balloon Occluded Retrograde Transvenous Obliteration (BRTO)/balloon-occluded antegrade transvenous (BATO)…etc. OSU is a major transplant center and we have the privilege of taking care of these patients, so it’s very rewarding to help them out and provide a good outcome for these often critically-ill group of patients.
What are your ongoing research projects?
My research interests are very broad as well – and they mirror my clinical interests. I’ve done research on interventional oncology & venous interventions. One project that comes to mind is locoregional therapies for neuroendocrine tumors. Neuroendocrine tumors are very rare but we treat a large number of patients as OSU is a big tertiary care center for these patients. I’ve published an exciting study evaluating the outcomes of drug eluting beads (DEB) vs conventional TACE for neuroendocrine tumors.
Additionally, I’ve also published on educational resources for residents and medical students, such as the IR symposia. I’ve published on informatics and wrote a paper on applying an informatics solution to improve the workflow for radiologists. Finally, one of the dearest areas of interest to my heart right now is ethics in IR. When working with evolving technologies, you always have to ask how to deal with it and discuss issues like utility, conflict of interest, and turf wars. All these issues come to mind and we’ve done really good work with my good friend Eric Keller who is a great inspiration to me.
What are you most interested in the future of IR?
In my view, research in IR, like any specialty, is split up into two ways: optimization of existing procedures/interventions and developing new interventions/innovations. Procedures like Y90 radioembolization have been done for a long time. We started with lobar and have progressively gone more selective. With the Legacy trial coming out, we are now able to achieve great outcomes with higher dose radiation segmentectomy. These are all new advancements and approaches that allow us to get pathological necrosis and go from a palliative approach to a curative approach.
The other area for research focuses on new procedures such as geniculate artery embolization, prostate artery embolization, and interventional pain procedures. We may also be able to apply existing technology to new fields. For example, there are ideas on using Y90 for treatment of prostate cancer, thrombocytopenia, and potentially glioblastoma, a radiosensitive tumor in the brain. Between all these developments, we’ll have a huge impact in patient care.
What advice would you give medical students, residents, or early career IR attendings interested in an academic career?
The advice I’ll give applies whether they plan to go into academics or not – work hard, learn as much as you can, and treat every rotation as if you are going into that field. Don’t say “I’m going into IR so I don’t need to learn about this as much” Everything you learn in medicine will help you become the best physician you can be.
Practice as a clinically centered physician-in-training – don’t say this is just a procedure. It’s not just about the procedure – the procedure is the smallest thing you can do. It’s about the patient, including periprocedural care, management, and the even decision to intervene or not. Patients really appreciate this approach. This process is how you achieve great outcomes in patient care.
Always ask questions – there are no stupid questions. Even if you don’t know the answer – find out why. Sometimes the experts don’t know.
For those going into academics, start research early. Research takes a long time. For every project you do, you’ll learn a lot: the process of research, how to write papers, how to do statistics, how to interpret results, how to do the review process, and how journals work. The more you do, the better you’ll be. It is an enjoyable process – the fun of discovery is very real and alive. When you discover something and you contribute to the literature, you are helping not just one patient, but everyone else coming after you. You are contributing a small piece to the bigger puzzle – so keep that excitement going!
The future is extremely bright because of the medical students of today. Every time a medical student asks me for work on a project and I see their excitement and we discover something together – it makes me realize that this generation will take us to the next level!
Interviewed by: Vedant Acharya
Medical Student – 4th Year
University of Miami Miller School of Medicine
Physician Spotlight: Dr. Jordan Tasse
Assistant Professor of Radiology, Vascular & Interventional Radiology
Director of Interventional Oncology
Program Director, Integrated VIR residency and independent VIR residency programs
Rush University Medical Center
Hometown: Cleveland, Ohio
Undergrad: Ohio University
Medical School: Chicago Medical School, Rosalind Franklin University
Diagnostic Radiology Residency: Stritch School of Medicine, Loyola University
Vascular & Interventional Radiology Fellowship: Rush University
How/when did you decide to pursue a career in IR and what do you think are the most important considerations for students who are considering a career in IR or any other medical field?
My Dad was trauma surgeon and growing up he thought based on my personality and the fact that I was really into sports that I should consider orthopedics, so that was the initial plan. Fourth year of medical school however, I rotated through ortho and felt that it wasn’t the right fit, so I started scrambling. While on surgery, I remember having a GI bleed patient; I followed the patient to IR, watched them stop the bleed through a tiny pinhole in the groin, and I was amazed – I did more research into what IR is, talked to as many IRs as I could find, shadowed and went all in after that and went into DR residency knowing 100% that I wanted to do IR.
The process of choosing a medical specialty for students is a certainly a challenge. The best advice that I can give to students is give everything a chance and then become exposed to any field that they are considering. IR is typically not a core rotation for students, so most have limited exposure during medical school. We have tried to get the word out earlier by helping with IR interest groups and giving lectures to early medical students to at least put it on their radar. Once a student has interest, my recommendation is to gain exposure. Seek out the IRs at your hospital, get involved in research, join the SIR RFS community, etc. That is the only way to see what it is IRs do and decide if it’s what you want your career to be in.
If you could go back and do it all over again, would you still choose IR, if yes, what is it you love about IR so much that you couldn’t see yourself doing anything else?
Yes 100%, and that’s grown on me more as the years go by. I’ve realized that I chose the perfect specialty for me. The clinical side is always engaging, challenging and rewarding. I enjoy the breadth of what we do in IR, from seeing patients in consult, to treating a huge array of disease processes, to following patients in clinic, research, working with trainees and constantly interacting with physicians of almost every other medical specialty. I interact with people at conferences and love to see the personality of IRs. It’s so much fun getting involved in the society, going to meetings and seeing familiar faces. Talking with other folks in IR, I know almost all of them would say the same thing; there are a lot of people that switch into IR, but not very many that ever switch out. One suggestion I give medical students is with any field that you are considering, talk to someone that is 5 or more years out of training in that field. Ask them if they enjoy their job and would choose the same specialty if they had to do it over again. I think that with most IRs, the answer is a resounding yes.
Do you specialize in a particular procedure or set of procedures? Do you have a favorite procedure?
I work as the director of interventional oncology at Rush, and so my practice primarily focuses on oncologic interventions. At academic centers and specifically at Rush, there is nothing that we don’t do (except cerebral). We all do a wide variety of procedures, but the future of IR will be more specialized; there is such a wide range of disease processes that we treat, so it is important to specialize. I have worked hard to build our interventional oncology practice and would say that category is my most rewarding type of procedures. Specifically, curative intent interventions such as percutaneous ablation of tumor or “radioablation” with Y-90 are my favorite type of interventions as they give me the opportunity to make a patient cancer free.
What is the most challenging aspect about being an interventional radiologist?
It’s a busy, busy field. Shuffling time for clinical, academic, administrative work and family is the most challenging part of the profession. I once had a med student tell me once that we work more than any other specialist they saw throughout their years in medical school. I was surprised to hear this, but I really enjoy what I do and wouldn’t have it any other way.
What is your outlook on the future of IR in the coming years?
The sky is the limit. As for the training pathways, the relatively new IR/DR residency has been a very positive change. Integration increases quality of training and clinical exposure. Our program became categorical a few years back with an intern year in surgery at Rush linked to our IR/DR residency program. This has been a huge plus for the program. We have been able to work with the surgical PD to tailor the intern year to rotations that will benefit our IR residents most. And they love our residents! An IR resident has won the “intern of the year” award now 3 years in a row. Residents come right into our program knowing all of the specialists and residents throughout the hospital that they are going to be working/interacting with over the next 5 years. Med students have recently been getting really involved in SIR and this reinforces that the best and brightest medical students are joining our specialty with enthusiasm. It’s unreal seeing what the medical students are doing in SIR and I think that is going to correlate beyond graduation and continue progression of the field. Right now the strength of trainees is the best it’s ever been.
And as for IR itself, everything is moving towards minimally invasive, there is probably going to be a shortage of IRs because the number of procedures is skyrocketing right now and I think that will continue. If you can have a minimally invasive option, with comparable or better outcomes and less morbidity, it’s pretty much a no-brainer for a patient to choose that. I think IR practices are going to continue to thrive and grow.
How did you end up at Rush and what has kept you at this particular institution?
With the old training paradigm, we applied to IR fellowship as a PGY4 DR resident, which I did. I applied broadly as I really wanted to get a feel for programs across the country, as opposed to relying on what you hear about word of mouth or online. I think that this was a great experience for me, visiting such a large number of programs and meeting faculty and trainees at these institutions. I tell students that there are so many amazing programs out there. So many great minds in our field. For me, I liked that Rush had a great mix of complex cases. There was nothing they didn’t do in high volume from oncology to aortic/peripheral arterial disease, to hepatobiliary and venous work and beyond. And the fellows were busy! I wanted a fellowship where I would work as much as possible; it was only one year so I wanted exposure to an extremely robust academic environment where I would be exposed to all types of procedures. There were only a handful of programs I visited that had the volume and variety that Rush did. That volume and variety has continued to grow at Rush since fellowship and it’s the same reason I’ve stayed 7+ years so far as an attending. We have a great group of faculty at Rush that are a pleasure to work with. Everyone is a team player. The medical students, residents and ancillary staff are also a really great group to be around and so there is no place I’d rather be.
What is it like being a physician amidst a global pandemic?
Obviously, it’s been a challenge. IR has been one of the specialties that has been full go throughout the pandemic because we treat patients who are critically ill. One problem a lot of these covid patients have is blood clotting disorders (PE, arterial thrombus, etc.). When we hit the spike last spring, we were treating a lot of covid patients. You don’t want to be exposed, you don’t want your trainees to be exposed, and you don’t want to expose those around you; but the whole point of everything we do is help patients. Luckily we had enough PPE throughout the entire process, we had residents helping out in the ICUs, and I think the whole situation at Rush was run from the top down really well to the degree that we all felt part of a team with a common goal. A lot of our patients are underprivileged, coming from areas that are underserved and the data shows that there are worse outcomes in covid patients with low SES. As physicians it is our job to treat all patients as if they were a family member. The pandemic has been really scary, but it has also been eye-opening. We are just trying to do our part and help in any possible way that we can and overall, that has been really rewarding.
Thinking of the students & residents you’ve worked with, what qualities, both personal and professional, would you use to describe those who are the most successful?
Hard work, determination and being a team player. In non-pandemic times, IR rotations are really important fourth year…To do well in an IR rotation, you don’t need to know the ins and outs of everything an IR does. We may ask you some anatomic questions, you certainly should read up on procedures you’re going into and disease processes we’re treating, but in general, your evaluation is not going to be based solely off of your IR knowledge. Get there early and stay until the end of the day, show enthusiasm, stay engaged, help out as much as you possibly can and get along with the staff. Also, getting to know the residents will go a really long way. We want people that will fit in as part of the team, work hard, and will excel in the field after graduation
Do you have any advice for medical students to make themselves stand out when it comes time to apply to IR residency programs?
As program director I want someone to show me that they have enough exposure to IR that I can be confident that they know enough about the field to know it’s 100% what they want to do and that they’re all in. Like I mentioned earlier, in the old days, people didn’t apply to IR fellowship until later on during their DR residency. So they had more time to decide during early DR residency that IR was right for them. That timeline has completely shifted forward and now medical students have to decide 4th year or probably earlier that they want to do IR. As a program director, we want people that have enough exposure to know that this is what they want to do, as matching into an IR/DR program locks them into a 6-year track with predominantly IR training during the PGY-5 and 6 years. The way to do that is rotations, talking to IRs, research, IR interest groups, shadowing and getting involved in SIR early. Another really important thing we look for in applicants is we want to make sure they really have an interest in DR as well. It is easy to look past the DR portion of the training when applying to an IR/DR program, but if you really look at it, there are a couple factors that make the DR part of it very important. Our training in DR is what separates us from other proceduralists in other fields; we really have a grasp of the complex anatomy and imaging necessary to do our procedures. Secondly, residents will spend the majority of their early years of training with DR. It is really important to find trainees that are interested in DR so that they are engaged and part of the team so that they can contribute and grow with the diagnostic residents before they join us for their IR predominant years at the end of their training.
Interviewed by: Brandon Golant
The First Foley
Written By: Jacob Poliskey
Interventional Radiologists use catheters nearly every day. A useful tool for many procedures, you might say we take their availability for granted: we pick up a sterile tube that looks like a million others and carefully position it in the patient. Standard procedure, right? But can you imagine having to fashion and assemble a catheter on your own every time a patient was in need? Dr. Frederic Foley (1891-1966) certainly was not satisfied with this system.
The curious and innovative Dr. Foley first fashioned his famous catheter to control bleeding after removal of the prostate. Urinary catheters of the 1920s had been used for years for the same purpose, but each individual urologist had to cement the parts together in a homemade style: catheter, bag, and the duct to swell the bag to hold the catheter in place in the bladder. Constructing a catheter by this method was time-consuming and designs weren’t the same from doctor to doctor. Then Dr. Foley stepped in.
His design was innovative: it used a stretchy rubber — latex — made from one piece, a serious step forward. This “latex” method simultaneously allowed a portion of the catheter to balloon outward while having the rest of the catheter be sturdy. A single-piece catheter stopped variability in between physicians’ use because they did not have to build or assemble the pieces themselves.
The project was not without its hurdles. It took Dr. Foley three years of experimentation — often with a boiling pot of latex on his wife’s stove — and a brief time of abandoning the project before a breakthrough came when he partnered with a rubber chemist. With that partnership in place, the first Foley appeared in 1935.
The inventors did not patent their product and an identical invention was patented a year later by the Davol Rubber Company. While they tried but failed to get the patent back, the name Foley stuck. Aside from no longer being made of latex, the Foley catheter in use today is very similar to the original innovation of Dr. Frederic Foley.1
1. Tatem, Alexander J., et al. “Frederick Eugene Basil Foley: His Life and Innovations.” Urology, vol. 81, no. 5, 2013, pp. 927–931., doi:10.1016/j.urology.2012.12.035.
2. Figure 1 Jacob Poliskey
Unraveling the History and Development of Endovascular Coils
Written By: Ravish Patel
Brain aneurysms are outpouchings of blood vessels in the brain. These balloon-like outpouchings can grow over time and eventually rupture, resulting in a subarachnoid hemorrhage, a serious form of brain bleed. One of the options for prophylactic treatment of a high-risk aneurysm is endovascular coiling, a minimally invasive technique that fills the aneurysm with small, flexible coils which effectively seal it off, reducing its risk of rupture significantly. The development of this technique was the result of a conglomeration of efforts from various pioneers since the 1960s (Figure 1).
The brain’s vasculature is tortuous, making it a notoriously hazardous highway to navigate with a catheter. In 1964, Luessenhop and Velasquez reported the first catheterization of brain vessels using an early glass chamber apparatus, surgically connected to the external carotid artery. This milestone revealed that the brain’s blood vessels could be catheterized, but they still didn’t have a way of navigating the treacherous turns of the brain’s vessels safely. To address this problem, Frei and colleagues designed a catheter with a silicone rubber tip that housed a micromagnet. By manipulating external magnetic fields, they were able to steer the catheter around more effectively and safely. Various blood flow-dependent catheters were also designed around this time.
In 1967, Yodh and colleagues used the system developed by Frei to design a type of catheter that could include a detachable tip. The tip was tethered to the rest of the catheter by paraffin wax, which was embedded with copper wire. An external electric current could be applied to the copper wire, causing the wax to heat up, resulting in the jettisoning of the tip of the catheter. They predicted three potential uses for the catheters: (1) to block feeding vessels of certain vascular malformations with congealable plastic, (2) to thrombose certain aneurysms by injection of a congealable plastic or detaching the tip of the catheter into the aneurysm and then injecting iron particles that would stick to the magnet in the tip and fill the aneurysm, and (3) for very selective injection of chemotherapeutic drugs in high concentrations for the treatment of a tumor.
With the realization of our intimate connection with the cerebral vasculature and equipped with the ability to deploy various tools within catheters, it wasn’t long before new tools were developed to try to treat brain aneurysms. One of the early nominees was a detachable balloon by Montgomery et al. They developed a balloon made of latex surrounded by a carbon steel cylinder that could be inflated and detached from the catheter by injecting an albumin-containing solution into the balloon and then heating the carbon steel cylinder using an external radiofrequency induction coil. When the temperature of the cylinder reached 55°C, the albumin coagulated and sealed the opening of the balloon. Injection of a little bit of additional albumin solution expanded the delivery microcatheter and detached the balloon.
While the navigation systems that relied upon external magnetic fields and blood flow were substantial, there was still room for improvement before widespread adoption. This improvement came when Engelson, a biomechanical engineer, had an idea to modify and improve the existing microcatheter. He attached a portion to the tip of the catheter that was flexible enough to be molded but stiff enough to hold its shape when navigating the vasculature. Thus, the “tracker” microcatheter came to be. This new catheter allowed for advancement of the microcatheter over a microguidewire that made it easier to steer through the vasculature without relying heavily on blood flow or an external magnetic field. This solution opened the door to widespread use of intracranial navigation with a safe and simple system.
With newfound increased ability to navigate the vasculature, several people tried to use different styles of detachable balloons to occlude aneurysms in the brain. However, another challenge presented. Balloons did not adopt the shape of the aneurysm; rather, they forced the aneurysm to stretch out to the shape of the balloon within. This caused more stress on the already weak walls of the aneurysm, increasing their risk of rupture. Additionally, the balloons, which were filled with a solidifying agent, acted as conduits that transmitted energy from the systolic pulse of blood flow to the aneurysm’s walls, further increasing their risk of rupture. The high rates of morbidity and mortality from this solution beckoned for a new solution, one that wasn’t as unforgiving as the balloon in terms of rigidity but one that could still effectively occlude the aneurysm.
In 1988, Hilal reported the first use of pushable coils for packing of an aneurysm (Figure 1). Initial iterations of the coil were too stiff and therefore they did not adequately conform to the shape of the aneurysm. Additionally, they were also detachable but not retrievable, which posed a problem when coils drifted down an incorrect artery. The original design was improved upon to produce smaller, more flexible, and retrievable platinum coils. These new coils could be retrieved and redeployed if their positioning was unsatisfactory. Once the positioning was satisfactory, a positive direct electrical current could be applied to the delivery wire which then electrolytically dissolved the delivery wire just proximal to the platinum coil, detaching it into the aneurysm. Numerous coils could be deployed using this method until the aneurysm was completely and tightly packed. They conformed to the shape of the aneurysm and did not exert as much pressure on the fragile walls of the aneurysm as the inflatable balloons. Thus, endovascular coiling was born, a minimally invasive technique to treat brain aneurysms that resulted from incremental improvements in design that will likely continue to undergo incremental improvements in the future.1
1. Guglielmi G. History of endovascular endosaccular occlusion of brain aneurysms: 1965-1990. Interv Neuroradiol. 2007;13(3):217-224. doi:10.1177/159101990701300301
Figure 1 created with the help of canva.com
Figure 2 created with the help of Danielle Lanier
Guitar Strings and Guide Wires
Written By: Stephanie Kazi
Forget to bring your blowtorch to the Radiological Society of North America (RSNA) Annual Meeting? So did Charles Dotter in 1963. However, no need to worry, because fortunately Bill Cook at the booth for Cook Incorporated was willing to loan one to Dotter for use in his hotel room that evening, in addition to some Teflon tubing to go with it.
The creation of Teflon catheters with a blowtorch in a hotel room is one example of the ingenious, although unconventional, nature of the pioneering interventional radiologist Dr. Charles Dotter. He, like many pioneers in IR, utilized great resourcefulness for the development of standard tools used today.
For example, consider guidewires. Straight edged, angled, or ‘J’ shaped, stiff or flexible, hydrophilic or non-hydrophilic—the types of guidewires available today are expansive. However, the early angiographers were slightly more limited in their ready-made options. Some, such as Sven Seldinger, used wire purchased from machine shops and coiled it by hand to make their own guides. Others, such as Dotter, used guitar strings, piano wires, and speedometer cables.1
In addition to resourcefulness, “heat and patience” were other necessary components to Dotter’s wire development. While finding the stiffness and length of a particular type of guitar string satisfactory, certain time consuming modifications were required in order to achieve its desired function. The guitar string contained a central wire core that he would remove and replace with a No. 8 piano wire, thus forming a wire with a moveable core. The retractable inner piano wire permitted increased flexibility, making catheterization of tortuous vessels and the aortic valve possible.2
Thankfully, IR’s today do not need to construct their own guide wires out of musical instrument parts. However, the resourceful and creative history behind even the most standard tools utilized in IR serves as an inspiration for further advancements.
1. Geddes LA, Geddes LE. The Catheter Introducers. Chicago, IL: Mobium Press; 1993:18, 54.
2. Roberts, AC. The 2004 Dr. Charles T. Dotter Lecture: Interventional Radiology Today — What Would Charles Dotter Say? J Vasc Interv Radiol. 2004; 15:1357-1361.