New Developments in Heart Imaging: Frequently Asked Questions

Brad H. Thompson, M.D.
Department of Radiology
University of Iowa Hospitals and Clinics

Creation Date: March 2000
Last Revision Date: March 2000
Peer Review Status: Internally Peer Reviewed

What is heart imaging used for, and what are the new developments of which we are speaking?

Heart imaging right now is to look at cardiac function and blood flow non-invasively. At the University of Iowa, we are fortunate to have a state of the art ultrafast CT scanner, which allows us to perform movie studies of the heart while it beats. This allows us to look how well the heart beats and the overall size and shape of the heart. We also use this modality to investigate the heart for structural problems like congenital defects or cardiac tumors. We are using the same machine non-invasively to look at the coronary arteries to screen patients who are at risk for cardiac cardiovascular disease (atherosclerosis). The same test can be essentially used on MR, looking at morphology, size, and function. We don't have the capability to look at coronary calcification with MR, but there is quite a bit of research trying to figure out a way to perform coronary angiography using both CT and MR. For the CT, it has very fast acquisition times, which allow us to capture images of the heart while it beats. We paste these images together to create a movie. This allows us to watch the heart beat in near real time. Once we have done that, we can actually sit down at a workstation or computer terminal and measure how well the heart contracts and look at the overall volume and the cardiac function. We are currently performing these same measurements with our new cardiovascular MR scanner. There are some advantages for using MR compared to CT. Specifically, we have the capability to image the heart in any plane, and we don't need to give contrast material as you do in CT. Plus, the other additional benefit is that patients don't have any radiation exposure with MR.

Would it be a good idea for a person with family history of heart disease to undergo this procedure to see how the heart is doing in order to get a head start on any potential problems?

Yes. One of the accepted tests in patients with a family history of heart disease as far as imaging is concerned is a coronary calcification test, which is being used at multiple centers in the United States. This test screens for hardening of the arteries. It is a very simple test requiring about 10 minutes, performed on a CINE CT machine. We use this here to diagnose excessive or early calcification of the coronary arteries. Once this is identified, then appropriate steps can be taken by the family physician or cardiologist to reduce risk factors. We have patients as young as 23 who have already developed hardening of the arteries. In one of our studies of males under the age of 36, we have found a surprisingly high prevalence of calcification in this population. As the examination needs to be performed on a CINE CT or ultrafast machine, it is unfortunate that there aren't many of these around the country. They can be found only in major metropolitan areas such as Chicago or Los Angeles. New technology with other more conventional scanners have improved their ability to acquire images fast enough to allow those machines to serve as screening for early atherosclerotic heart disease. Several of the lay magazines have, over the last four or five years, published quite a bit on coronary calcification screening. There was an article last year in Parade Magazine on a certain senator who had undergone this test, and his experiences were published how he felt it had impacted his health care. That was Senator Paul Simon from Illinois.

How old is the average heart imaging patient?

It depends on the disease that we are looking at. We have pediatric patients who are being imaged for congenital anomalies. These patients may be as young as a year or even younger. An MR is a very good imaging tool for patients up to their 20Ős. The other cohort tend to be patients in the 50 plus range who are coming for workup of suspected cardiovascular disease, namely related to atheroslcerosis and myocardial infarctions. Coronary artery disease is a major killer in the US, and there is a substantial patient population in need of cardiac imaging so that appropriate medical therapy management can be instituted. Additionally, cardiologists using echocardiography have performed most imaging for older cardiac patients. That is a very good screening device to look at overall cardiac function, and it is done without radiation. Typical patients that we see in radiology are patients who have specific clinical concerns, or they are patients where the echocardiography study was not very diagnostic or the quality was relatively poor. These patients are referred to us to investigate their heart and/or to substantiate or confirm findings seen on echocardiography. Over the years, nuclear medicine is also a widely used examination looking at cardiac function and blood flow. I think that with the newer CT and MR machines, that overall volume of nuclear medicine studies have probably decreased, particularly with regard to the test that measure cardiac function. The thallium study still continues to be used quite heavily to look at cardiac blood flow, particularly in patients who have suspected angina where the doctor feels there is a likely area of impaired blood flow to a certain part of the heart.

Will health insurance cover the test if there is no other reason to have the test other than family history?

I presume you are talking about the coronary calcification study. The answer is a mixed yes and no. When we originally started doing the test in Iowa, it was not covered. Over the last couple of years, I have heard of patients making inquiring to their insurance company, and, in some cases, the exam has been covered. It is pretty much up to the carrier. I really don't know any more about the particulars other than that some people have managed to get it covered. I think that the medical community and insurance companies will get to the point where they realize that this exam is a cost-effective tool to screen for heart disease.

What would cause hardening in the arteries of a 23 year old?

These patients have usually two problems: they have obviously a familial problem with their blood fats (lipids), or they have diabetes mellitus. There are a few patients who don't have any real risk factors! Obviously, anybody who has more than one factor compounded with obesity and smoking is also more likely to have atherosclerotic calcification. The benefit of doing screening on younger patients would be to pick up and identify this early atherosclerotic calcification so that the patient can be treated to help prevent a bad outcome, i.e., early heart attack.

What are the new developments in heart imaging? How useful are these techniques?

The big and newest developments are in cardiovascular magnetic resonance. Even though MR imaging of the heart has been around for many years, it hasn't been until just recently that software development has enabled us to acquire images of the heart quickly enough and with sufficient quality to make this a valid tool to look at cardiovascular diseases. We have been doing cardiovascular imaging here since 1992, but our new scanner allows dramatic improvements in quality and time of the study. For instance, in 1992 it may have taken over an hour to perform a basic scan on MR; now we can get that in well under 1/2 an hour. The big problems with both CT and MR are that some patients aren't candidates for either one of these, particularly patients who don't have a regular heart rhythm, or patients who are claustrophobic.

We are in the process of using our scanner to provide qualitative and quantitative measurements of overall heart function. We use it commonly in pediatric patients now with suspected congenital anomalies, both pre and postoperatively. One of the big developments that will occur in the next several years as the software becomes refined is noninvasive imaging of the coronary arteries. I strongly believe that with some refinements and advancements in both CT and MR, it will be commonplace for a patient with suspected angina to come in and have a CT or MR rather than cardiac catherization. Ideally, we would like to get to the point where we could determine patency with CT or MR. There are some institutions already that have had a good experience with CT angiography, particularly over in Germany. The biggest problem we have right now is that the constant motion of the heart makes it difficult to visualize the coronary arteries sufficiently to allow us to evaluate them fully.

So, the cardiac imaging can show blockages?

Right now, the coronary calcification scan by CT shows us calcifications. It does not show specific sites of blockages. But, researchers have pretty much found that the heavier the atherosclerotic calcification, the more likely you are to have a blockage or vessel narrowing somewhere along that artery. What we are looking at is the total burden of calcium which is present. If you happen to be 60 and have no calcification, then there is a pretty strong likelihood that you don't have any significant narrowing. However, there is a small population of patients who do not have any calcification who will still have a significant blockage. As a general screening tool, the burden of calcification seems to equate fairly well to one's likelihood of having a narrowing somewhere. Conversely, we have a young adult, let say the age of 27 or 30, who should normally not have any coronary calcification findings. In these patients an alarming finding would indicate very premature hardening of the arteries and would also necessitate additional testing.

How do you know if you are at risk for heart problems?

Unfortunately a lot of people don't. Some of the obvious risk factors of high blood pressure, smoking, age, family history of heart attacks, gender and elevated blood lipids. Unfortunately, many people don't know what their BP is, their cholesterol is, and may not know of their family history . I think a big predictor can be identified through family history. Commonly, patients mimic the same historic heart patterns that their parents may have experienced. I have several friends with that identical history. These patients must be very cautions and watch their dietary intake and exercise. The best thing is to have frequent checkups with the doctor, particularly if you are at risk. If you smoke - stop. If you don't exercise - you should start.

Sometimes I experience a pain on my left side, under my ribs. I am in my 20's and wonder if this could be serious?

If it persists, clearly you should seek medical attention.

What can be done to prevent calcification of the arteries?

It is an inevitable process with aging. Typically by the time you reach 60 - 70, almost everyone has coronary calcifications as part of the aging process. Screening these patients therefore is problematic because you would expect some coronary calcification. Nevertheless, very extensive calcification disproportionate to age may indicate a problem and probably would need to be investigated further with angiography, particularly if the patient was having symptoms. Typically, atherosclerotic calcification in men begins at 50 years of age and slowly progresses. In women, it begins about 5 to 15 years later. The listener should understand that coronary calcification is a definite marker for atherosclerotic disease. The big limitation, however, is that is a marker for end-stage disease or atherosclerotic plaque development. Autopsy studies and military studies have shown that atherosclerotic vascular disease begins in individuals as early as 8 or 9 years old. These early plaques are considered fatty streaks or soft plaques. Unfortunately, a CT cannot identify them. The take home message there is that you can have a significant narrowing due to a soft plaque and not be able to identify that without coronary arteriography.

Must a patient have a cardiac "episode" to have the insurance company pay for imaging tests?

I think it is largely predicated on what the local physician finds. For instance, if the local doctor feels this person is at risk due to high lipid levels, i.e., cholesterol and, or family history, it may be entirely appropriate for the patient to undergo some form of cardiac testing. Unfortunately, as is the case for most screening exams, nobody wants to pay for them and most medical intervention takes place after the patient has experienced problems. The big problem with screening is that while it is a good idea, it is expensive and not very cost-effective.

Are there usually symptoms of heart disease prior to heart attack, or is that usually the first indicator?

Yes, usually a lot of patients will have symptoms. These may be anything from shortness of breath to decreased exercise tolerance; perhaps swelling of their ankles, palpitations, and fatigue; and, of course, the obvious chest pain which is referred to as angina. Unfortunately, there are some people who are perfectly healthy up to the day that they have their heart attack and have no warning symptoms whatsoever. A classic example of course would be Dan Reeves of the Atlanta Falcons who experienced what he thought was heartburn and consulted with the team physician and was taken for immediate bypass surgery. If you have any kind of symptoms that are commonly ascribed to heart problems, you should seek medical attention immediately.

If people have heart problems, is it safe for them to exercise?

They should do that in conjunction with their local physician. It depends on what the heart disease is, of course, but any exercise program should be cleared by your physician before beginning, particularly if you are an older patient, 45 years or older.

See related Patient Topics Diagnostic Imaging or Procedures and Therapies.

See related Provider Topics Diagnostic Imaging or Procedures and Therapies.

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