Brad H. Thompson, MD
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
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
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
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.