Instead of basking in the sun, second-year Northeast Ohio Medical University College of Medicine student Sriharsha (Harsha) Voleti recently spent time in Hawaii soaking up all things radiology.
Voleti was recognized with the Magna Cum Laude Award for the best oral scientific presentation in neuroradiology at the American Roentgen Ray Society Annual Meeting, held in Honolulu in May.
“It was really fun to be able to meet people who are leaders in the field and are essentially pushing radiology forward. It was nice to be able to sit down and talk to them, get their insights on what direction radiology’s going in and what medical students, like me, can do to get more involved,” says Voleti.
Taking an interest
Radiology has always been a consideration for Voleti, but it’s not an easy field to get to know, he says.
“Shadowing radiologists isn’t too exciting, because you just sit there and watch the radiologists do their work. Basically, the work in radiology happens in your head,” says Voleti.
“It’s kind of like watching somebody else watch a movie. The person watching the movie is going to enjoy it, but watching that person, you aren’t going to get a whole lot out of that unless you actually know what’s going on,” he explains.
Luckily, Voleti took the initiative to email several Cincinnati-based physicians in hopes of exploring his interests before matriculating to NEOMED.
Achala Vagal, M.D., the vice chair of research for the Department of Radiology at the University of Cincinnati, took Voleti under her wing and has been mentoring the student ever since.
“She was very accommodating and provided me a lot of opportunities to get involved, even though I wasn’t even in medical school at the time. I didn’t really have a whole lot of knowledge, but she took a chance on me and gave me a lot of projects to do. It was a huge learning curve, but I’ve really enjoyed it. I’m very grateful to have her as a mentor,” says Voleti.
For two years now, Voleti has been working with Dr. Vagal to study the imaging of acute ischemic strokes.
Voleti reflects on his most recent, award-winning research:
There are three types of imaging that can be used to diagnose stroke patients. The first is a non-contrast CT, which rules out a hemorrhage or a bleed in the brain and could show what part of the brain is affected by the stroke. The second type of imaging is a CT angiogram, which essentially tells you which vessel in the brain is occluded — where the clot is in the brain.
The next type of imaging the patient could receive is a CT perfusion, which tells you how much brain has died and how much brain can potentially be saved with treatment. CT perfusion is really useful because then doctors can say, for example, this patient has so much brain that can be saved and not a lot has died yet — so this patient is probably going to benefit from being treated. Those three imaging modalities help guide the treatment selection for these patients.
Recently, the guidelines changed for what treatment and imaging patients should receive if they come into the hospital with a stroke. Before 2018, patients who came into the hospital with a stroke were only supposed to be treated with a thrombectomy (procedure that removes the clot in the brain) if they presented under six hours from the time they first had the stroke. But in 2018, the guidelines for treatment and imaging changed to potentially allow stroke patients presenting up to 24 hours to receive thrombectomy treatment.
My research specifically looked at collateral flow. That’s when, if a major blood vessel is occluded, a patient could have other blood vessels supplying that area of the brain that doesn’t have full blood flow. It’s kind of like backup power. If the power goes out, then you have a backup generator to provide you some power until it’s restored. Collateral flow is probably not going to be as good as the primary source of blood flow, but it might be enough to hopefully keep that part of the brain alive until the clot is removed.
We studied the relationship between collateral flow and CT perfusion and found that patients with better collateral (supplemental) flow have a higher volume of brain that can be saved and a lower volume of brain that is already dead when they present to the hospital between 6-24 hours.
This is clinically relevant since not much research has been done in stroke patients presenting between 6-24 hours and our study looked at the real-world applications of the recent 2018 guidelines. Stroke patients who present in later time windows of up to 24 hours may have enough collateral flow for them to be eligible for treatment. By expanding the time window, so many more patients can be included for treatment than ever before.
Some hospitals around the country don’t actually have the capability to do a CT perfusion scan, so it’s hard for them to truly assess the volume of the brain that can be saved or the volume that is already dead. But, a lot of the hospitals can do a CT angiogram, where they can actually locate the clot and assess the blood flow in the brain.
As a workaround, maybe hospitals could use CT angiograms to look at the collateral flow of the brain and possibly even estimate how much brain can be saved. After all, time is brain, and maybe that can decrease the time before a patient is treated and more importantly, aid in the selection process for treating patients who arrive at the hospital after six hours from when they first had the stroke.
Appreciative of opportunities
Bottom line, says Voleti: Research experience puts the first two years of medical education into perspective.
“You can see images of the brain in textbooks, but unless you’re actually doing the research and observing how everything happens in the real world, you don’t know how important that image is. The imaging has a huge influence on how stroke patients are treated.”