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L. Nelson "Nick" Hopkins III, MD -- Part One

Angioplasty.Org recently talked with Dr. L. Nelson "Nick" Hopkins, Chairman of Neurosurgery, Professor of Radiology, and Director of the Toshiba Stroke Research Center at the University at Buffalo, State University of New York. Truly one of the pioneers in the treatment of stroke, as well as the non-surgical therapies developed to treat both stroke and carotid disease, Dr. Hopkins provides a unique perspective into the growing area of cross-specialty and multidisciplinary collaboration between and among medical specialities.

This three-part interview covers a range of topics:

  • Part One discusses the diagnosis and treatment of stroke;
  • Part Two deals with carotid artery disease;
  • Part Three discusses how imaging may impact future treatment, and how reimbursement questions must be resolved for this field to move forward.



L. Nelson "Nick" Hopkins III, MD
L. Nelson Hopkins, MD
University of Buffalo

Q: The role of imaging has always been critical in the detection and prevention of stroke. In recent years newer imaging techniques have become available, but would these constitute “a sea change”?
Dr. Hopkins: Absolutely, yes. First we got MR diffusion and perfusion studies which helped us to better differentiate what tissues actually had ischemia and infarction versus the areas that were that were under-perfused, but not yet infarcted. So the MR studies helped us to better understand the pathophysiology of stroke a little better. But just in the last couple of years, with the new 64-slice CT scanners, we’ve had a major advance in our ability to very quickly diagnose and treat acute strokes.

With a 64-slice CT scanner you can get a CT scan, which tells you whether or not the patient has a hemorrhage or not, and you can get a CT angiogram very quickly with a relatively small amount of contrast. 40-50cc will give you a reasonable CT angiogram, as well as a CT perfusion study.

Aquilion 64-slice CT scanner
Aquilion™ 64-slice CT scanner
(courtesy Toshiba America Medical Systems)

And we now have been working with Toshiba Corporation to develop some new algorithms using the Vital Images Vitrea® workstation to enable us to more accurately measure CT perfusion, cerebral blood flow, cerebral blood volume and time-to-peak contrast accumulation.

Using these parameters we can very accurately and very, very quickly predict which areas of the brain are infarcted versus those areas that are just ischemic. In a scan that lasts only 5-7 minutes total, we can get a pretty clear picture of what’s going in the patient’s brain and it gives us very, very clear directives as to whether or not we need to intervene.

Q: So 64-slice CT is has implications in emergency treatment of stroke?
Dr. Hopkins: Definitely. This has really revolutionized the way we’re treating acute strokes. Because the big fear used to be that we would revascularize an area of the brain that was already dead and cause a major hemorrhage. If you reperfuse an area of dead brain, then there is a significant likelihood that you’re going to have a reperfusion hemorrhage. So these new imaging studies have helped us to better understand which areas of brain are in danger versus the areas of the brain that are already infarcted or dead tissue. If we have a large area of infarcted tissue and dead brain, then we usually do not try to revascularize that area of brain because we’re not going to accomplish anything and we’re likely to turn it into a hemorrhage.

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The ideal candidate is, if we see a patient with a major neurologic deficit and we see a large area of brain at risk without a large area of dead brain. That’s the kind of patient where we know there is going to be a very major vessel occluded and we know that we’ve got to get that vessel open if we’re going to prevent that patient from having a major stroke.

Q: You’re talking about CT a lot. Do you still use MRI?
Dr. Hopkins: MR and MRI and all the other variants of MRI, perfusion, diffusion and so on, are still very, very important to us. We get much better resolution of brain tissue with an MRI. But in acute stroke, where time is of the essence, we can learn as much as we need to learn from the CT studies. MRI takes more time, and we want to avoid that if at all possible.

MRI is still very important in the evaluation of patients with impending stroke, or patients who have cerebrovascular disease and who have not yet had a stroke. MRI is extremely valuable. I don’t mean to discount MRI. I just mean to simply say that in the acute phase, we’re finding with the newer, higher-resolution, better, faster CT scanners, we can learn what we need to know to allow us to make a decision - whether or not we need to intervene and remove a clot - much more quickly with just the one study, and so we’re not using MRI so much in acute stroke anymore.

Q: Once you done the imaging, what are the tools used to treat acute stroke?
Dr. Hopkins: There are basically two major tools that we have available to us. One is intravenous tPA (tissue plasminogen activator), and that drug has been approved for a number of years for the treatment of acute stroke. IV tPA can be very helpful. We find that it is quite helpful in patients with lesser degrees of stroke. For example, if somebody has a more minor stroke, that means you probably don’t have one of the major trunk arteries shut down. And in that situation, IV tPA can be very helpful. That means you’re dealing with smaller branches that are probably occluded.

If somebody has a major stroke, with major branch occlusion, then the likelihood of tPA giving you a good result goes way down. If you look at patients with NIH stroke scales, which gauge the degree of severity of the stroke from 0-40 (0 is a normal patient and 40 would be a fatal stroke) -- if you have a stroke that’s NIH scale 10 or greater, then the odds of recovery with IV tPA go down a significant degree, like 75%. That’s because if you have a major stroke with major deficit, then there’s probably a major artery occluded and it’s not likely for IV tPA to be successful in reopening a major artery. In that situation, we tend to migrate more towards the use of a more aggressive approach, and the other FDA-approved tool at this point is a clot retrieval device called the MERCI Clot Retriever. So if we have a major stroke with a major branch occluded, we would lean more toward removing that with a clot retrieval device such as the MERCI device.

Q: And that’s done using endovascular techniques?
Dr. Hopkins: That’s right. Usually the femoral artery is used as an access point and micro catheters are then navigated into the intracranial circulation. And the clot retrieval device is then navigated through the micro catheter into the clot, and is then used to capture the clot and remove it.

Q: So surgical removal of clot isn’t done?
Dr. Hopkins: It wouldn’t work. We’ve never had good results with surgical removal of clots inside the brain, that is, the kind of clots that form in arteries and cause acute stroke. First of all, it takes too long to get there. Second of all, the brain is very, very sick, and all the trauma of getting there seems to be more than the brain can handle. So, the way to attack an acute stroke where you have a clot that’s occluding a major cerebral is to use the endovascular approach, using the vascular highway to approach and then remove the clot.

(continue to Part Two)

This interview was conducted by Burt Cohen of Angioplasty.Org.