Imaging Studies of the Heart & Vascular System: Cat Scan Technology
Guest: Dr. Joseph Schoepf - Radiology
Host: Dr. Linda Austin – Psychiatry
Dr. Linda Austin: I’m Dr. Linda Austin. I’m interviewing Dr. Joseph Schoepf who is Associate Professor of Radiology and he is an expert in the area of imaging studies of the heart and vascular system here at the Medical University of South Carolina. Dr. Schoepf, most people know that there are a number of ways that you can take images, look at images, of the heart, but let’s start with one that’s getting a lot of press these days, CT of the heart. What is a CT of the heart and what can it show?
Dr. Joseph Schoepf: Well, a CT of the heart basically works on the principle that everybody has at least some idea of how it works. It’s basically a CAT scan. That’s what most people outside of medicine would ordinarily refer to. A CAT scan, obviously, works with x-rays that penetrate the human body and form transverse, or axial, slices, if you will, of the human body that allows diagnosis of a variety of different diseases.
Computer tomography, or CAT scan, has become the workhorse of imaging around the country. It is the first and premier imaging modality that’s being utilized to diagnose a variety of different diseases, be it emergent or on a more elective basis. CT is the workhorse of trauma centers and emergency departments around the world to diagnose diseases such as stroke. Every patient who is admitted to the emergency department with a suspicion of stroke would get a CAT scan, or CT scan, of the head, for example. Trauma patients who have been involved in motor vehicle accidents, for example, typically get diagnosed for injuries to internal organs, injuries of the musculoskeletal system.
So, computer tomography really is the first line of defense that we have for a lot of emergency situations, but it is also used for patients with suspected diseases of the chest, for example, to evaluate lesions in the lungs, such as lung nodules, to check for cancers of all kinds throughout the body.
Dr. Linda Austin: Let’s start, though, with heart. What sort of patient is a candidate for getting a CT of the heart?
Dr. Joseph Schoepf: Typically, our criteria for accepting patients for a CT of the heart are patients who have some sort of chest pain. If patients have chest pain that is very typical for a heart attack, for example, that is usually not a candidate for a CT scan. Typically, if a patient has very clear cut symptoms of an acute heart attack and your doctor can tell by your EKG, or electrocardiogram, for example, or by some very simple blood work, if there are clear cut signs that a patient has had a heart attack, those patients need to go straight to the cath lab because, like with other organs, time is tissue. Those patients require immediate cardiac catheterization. Those patients require immediate tissue saving therapy, such as widening of the coronary arteries, lysis of blood clots that may be obstructing the blood flow.
So, typically, patients who have very typical signs of heart attacks are not candidates for a CT scan. However, we do utilize CT in such patients who have chest pain that may or may not be related to disease of the coronary arteries and the heart. There is any number of disease entities that can give you chest pain and oftentimes it’s very difficult to differentiate cardiac and noncardiac causes of chest pain.
Dr. Linda Austin: In other words, is it in the heart or is it in the tissue outside of the heart?
Dr. Joseph Schoepf: Exactly. And we’re trying to elucidate that further by doing a CT scan of the heart. What we’ve recently seen in scanner technology is really mind- numbing. We’re now able to create images of the beating heart in a living patient with a temper resolution, or shutter speed, of 83 milliseconds which allows us to get detailed crisp and clear images of the heart and the heart vessels. And we can do that with a spatial resolution that allows us to pinpoint very small problems down to a size of about .3 or .4 millimeters. So, speed and spatial resolution have come to a point that allows us to noninvasively look into the heart.
Typically, if there’s any suspicion that there’s anything wrong with the heart or the heart vessels, the traditional method of diagnosing that is an invasive catheterization which basically means that somebody snakes a tube up through a small incision in your groin, directly to your heart vessels, and injects contrast material, or dye, directly into the ostium of the coronary arteries to detect narrowings, or blockages, of those heart vessels.
Dr. Linda Austin: So, that traditional technique, then, is the angiography? At least traditional in the last, what, 10 or 15 years, I suppose?
Dr. Joseph Schoepf: Exactly. That is the most conventional and most widely used way to diagnose diseases of the heart vessels in general, in this country and throughout the world.
Now, the improvements in scanner technology that I alluded to, allow us to do the very same thing with an injection of dye in an arm vein, so there is no big incision required, there is no catheter required. So, compared to traditional catheterization, this is a very noninvasive test
Dr. Linda Austin: So, then, here at the medical university, we have, as I understand, a 64-Slice CT scanner, correct? Will that be replacing traditional angiography?
Dr. Joseph Schoepf: As a matter of fact, I’ve already advanced to the next generation of multi-slice CT scanners. What we have been operating since October of last year is referred to as a dual-source CT scanner which makes things even faster and more accurate, as compared to the previous generation of 64-Slice CT scanners. So, we can do everything that the 64-Slice CT can, just significantly better than other centers. And MUSC, again, was very much ahead of the curve. We were actually the sixth center in the nation where that particular technology became available. So, we’re very cutting edge. We really operate the most advanced technological machinery that’s currently available.
Dr. Linda Austin: That’s fantastic. So when, then, would a patient be a candidate for that kind of an imaging study, and which patients would still get the traditional angiography with the catheter?
Dr. Joseph Schoepf: As I already pointed out, if you develop sudden acute chest pain, which is hard to bear, out of the blue, or if you had chest pain that felt similar before, you need to see your doctor immediately. The doctor will perform an electrocardiogram and simple blood tests that will determine if you’ve had a heart attack. If, however, you talk to your doctor and your physician is not sure if your symptoms, your chest pain, are related to any diseases of the heart then you’re a good candidate to undergo a CT study of the heart.
Dr. Linda Austin: So, then, who would get angiography, as it’s traditionally been done? Are there patients who fall between those two groups?
Dr. Joseph Schoepf: Typically, the most common way to diagnose diseases of the heart vessels, these days, is catheter angiography. So, the majority of the patients out there who have sort of iffy chest pain that is not associated with clear cut signs of a myocardial infarction would still get an invasive, traditional, catheterization. And that is exactly the patient population that we focus on. And we believe that our noninvasive CT scan, in that particular patient population, can replace a vast majority of the invasive, traditional, catheterizations.
There are a lot of imaging facilities out there that may be more on the commercial and less restrictive side that do offer CT coronary angiograms as sort of a general health checkup in patients who do not have symptoms, as a screening modality. However, we do not believe that’s the right way to go.
Dr. Linda Austin: So, we’re not doing those here anymore?
Dr. Joseph Schoepf: We’re not offering that type of exam at MUSC. We require that all our patients are symptomatic, have some sort of symptoms, and that they’re referred by their primary care physician, their cardiologist, or by some other physician who discusses the benefit of that particular test with the patient.
Dr. Linda Austin: So, then, here at MUSC, are there any patients, let’s say, where you’re certain that they’re not having a heart attack, EKGs are not showing that, but you get a traditional angiogram here rather than the new CT scan, is anybody getting that?
Dr. Joseph Schoepf: Yes. Simply because the CT scan is kind of the new kid on the block, we and others are very active in evaluating this technology and defining its strength and the ideal patient populations that benefit from that test. So, this is very new.
Dr. Linda Austin: I see.
Dr. Joseph Schoepf: Coronary CT angiography, as it’s commonly referred to, has been around, maybe, for 10 years. Initially, for a limited technology, and I have been doing this particular test for the last 10 years, so I have seen all the generations and iterations of that particular test, and only with the introduction of the 64-Slice CT in 2004, has this test come to a point where it can be routinely used with results robust enough to use it outside of research and as an actual tool for diagnosing patients with suspected coronary artery disease. So, patients will still have catheter angiography, and there’s nothing wrong with that. But I do foresee that, in many patients who are appropriate, CT coronary angiography, as a noninvasive test, will replace invasive cardiac catheterization.
Dr. Linda Austin: Dr. Schoepf, thank you so much.
If you have any questions about the services or programs offered at the Medical University of South Carolina or if you would like to schedule an appointment with one of our physicians, please call MUSC Health Connection: (843) 792-1414.