Currently, heart imaging devices are used to look at how the heart functions and blood flows through it. University of Iowa Hospitals and Clinics is very fortunate to have state-of-the-art heart imaging techniques that can actually watch the heart while it beats to help in diagnosing heart ailments.
Ademola Abios, MBBS, MD, with UI Heart and Vascular Center, talks about heart imaging:
There are several types of heart imaging machines, what are some we may be familiar with?
The simplest heart imaging machine that most people are familiar with is the chest x-ray, which provides a gross imaging of the heart and the lungs. It gives an idea of the overall size of the heart, but doesn’t provide details about its structure and function. Some people may also be familiar with ultrasound of the heart—an echocardiogram. This uses high frequency sound waves to look at the structure of the heart. Other imaging modalities are cardiac catheterization or angiogram, a CT scan, and a cardiac MRI.
How is an MRI used to look at the heart?
An MRI uses a strong magnetic field rather than x-rays to provide detailed images of the structure and function of the heart. These basically involve the absorption of magnetic energy and emission of signals which are converted to a set of images of the heart. This is an advantage as it does not expose the patient to radiation from x-ray.
How does a CT scan of the heart differ from an MRI?
A CT scan is really an x-ray technique that uses a CT scanner, which is essentially a cyclo-tube housing the x-ray machine with a patient lying on a table that moves through this tube to take very thin slices of the heart.
It is different from an MRI in that it uses x-ray rather than magnetic energy. It also uses a different kind of dye, compared to the MRI. Utilizing state of the art technology, UI Hospitals and Clinics has specialized CT scanners able to obtain very detailed pictures of the blood vessels to the heart that were previously available only with invasive angiogram or cardiac catheterization.
Now the major advance is the ability to freeze the heart in all of its phases of contraction, so that the heart appears still, allowing us to look inside those arteries to identify blockages.
What determines the type of heart scan equipment used for each patient?
The type of scan depends on the clinical question being asked as well the kind of medical condition a patient may have. For example, the ultrasound or echocardiogram can generally answer questions about the pumping function of the heart and its valves. But it does not allow a visualization of the blood vessels to the heart. On the other hand, a CT scan and cardiac MRI can both provide this information. However, they may not be used in some patients with kidney disease or with pacemakers as in the case of cardiac MRIs.
Who is the typical person that needs or receives heart imaging?
A CT scan should not be used as a screening tool in the asymptomatic population. Now having said that, the patients who may benefit from this test include those with intermediate risk factors for coronary artery disease, and symptoms that are not very clear cut but somewhat suspicious of coronary artery disease. Also, some patients with inconclusive results from a stress test or patients who have had bypass surgery whose physicians wish to evaluate the bypassed vessels are all potential candidates for this test.
Can heart disease be detected by heart imaging before symptoms physically occur?
Absolutely! Heart imaging is able to detect heart disease prior to symptoms being present. Although the capabilities of our treatments are so great that we can detect even the smallest amount of calcium buildup in the arteries, we generally do not recommend using a CT scan as a screening tool in the asymptomatic patient, as I mentioned earlier. However, a CT scan can detect calcium buildup inside the coronary artery and may identify patients without symptoms that might benefit from aggressive risk factor modification. Other kinds of heart imaging may also be recommended for other groups of patients with risk factors but no symptoms in order to provide early detection and treatment.
Why would a seemingly healthy person consider a heart scan?
Well, as I mentioned, a seemingly healthy person who has several risk factors for coronary artery disease, including things like hypertension, diabetes, high cholesterol, and all family history of heart disease may be considered for heart scan by his or her physician, in order to provide early detection and treatment.
Is heart imaging also being used in the treatment of heart disease?
Absolutely! There are multiple heart imaging techniques that are used to treat heart disease. I think a fairly well-known example is the coronary angiogram, which is performed to localize blockages in the arteries to the heart. Now once the blockage has been identified, we can inflate a balloon catheter to open up the blockage and a stent, which is a tiny, wire mesh tube, can be inserted to keep it open.
Is UI Hospitals and Clinics involved in any research with regard to heart imaging?
Yes, there are multiple, ongoing clinical and research trials involving advanced heart imaging going on at the UI Hospitals and Clinics. More information can be obtained by calling the UI Heart and Vascular Center Center and asking about ongoing research in heart imaging. |
