Sentara RMH has offeredmagnetic resonance imaging (MRI) for several decades, but only since January 2018 has the hospital leveraged the advanced imaging capabilities of MRI specifically for the diagnosis and treatment of heart conditions. This new use of the technology represents a significant advance for heart services at Sentara RMH—one that’s in keeping with the hospital’s goal of providing leading-edge cardiovascular care to the community.
Cardiac MRI (CMRI) is a powerful, noninvasive cardiac imaging modality that can be used to diagnose many types of cardiac conditions—including assessing problems involving the structure and function of the left and right ventricles (lower chambers) and the heart valves; quantifying the volumes of the heart chambers; evaluating the muscular walls of the heart; and detecting inflammation, edema and fibrosis (scarring) within the heart.
Currently, CMRI is the gold-standard noninvasive cardiac imaging modality for measuring the thickness of the heart’s walls; the chamber sizes and volumes of the left and right ventricular chambers; and for measuring the ejection fraction, which is the percent of volume of blood the ventricles can pump to supply vital nutrients and oxygen to each of the body’s organ systems. Knowledge of these key metrics is crucial because it guides the management of patients with several types of heart disease, including but not limited to those with severe high blood pressure, heart failure, heart valve disease and hypertrophic cardiomyopathy (thickening of the heart muscles), among others.
For cancer patients preparing to undergo certain types of chemotherapy, the use of CMRI to determine left and right ventricular function and ejection fraction is especially important, since certain chemotherapy drugs can adversely affect the heart’s function. CMRI can be used prior to chemotherapy to establish a baseline heart function and then be repeated throughout chemotherapy treatment to check for any significant changes in ventricular function. This type of monitoring can help cancer doctors decide among certain chemotherapy treatments and make any necessary adjustments during a course of treatment. Furthermore, the long-term adverse cardiovascular outcome of radiation therapy and certain chemotherapy drugs can be evaluated with CMRI.
CMRI also can be used to help diagnose abnormalities of the aorta—the largest artery in the body, which comes directly out of the heart—as well as the pulmonary arteries that connect the heart and lungs. Each of these vessels can be affected by stenosis (narrowing) or dilation, as well as other conditions, all of which can be revealed by CMRI.
CMRI and Heart Attack
Cardiovascular disease continues to be the leading cause of death in developed countries around the world and is now overtaking infectious diseases as a major cause of death in developing countries as well. For those unfortunate individuals who suffer an acute heart attack, CMRI is a powerful means of determining how much damage has occurred to the heart, and also can be used to assess the damage resulting from a prior heart attack. The information CMRI provides in these cases far surpasses what we could obtain through an echocardiogram or stress test.
CMRI can identify mechanical complications resulting from a heart attack, such as ventricular aneurysm or valve dysfunction. With the aid of a contrast medium and a pharmacological stress agent, a stress CMRI can be performed to provide additional robust information that indicates, for example, the presence and severity of ischemia (inadequate blood supply) or scar tissue in the heart. At present, Sentara RMH is not performing the stress CMRI because we don’t yet have in place the cardiac monitoring system required by the testing. However, the Sentara RMH administration team is generously working to acquire the needed system, and we expect to be performing CMRI stress tests at the hospital soon.
Assessing Valve and Rhythm Problems
Currently, the cardiovascular societies that establish guidelines for managing patients with heart valve disease recommend that such patients undergo CMRI when an echocardiogram is unable to provide sufficient data about a patient’s condition. Without the use of contrast, CMRI can provide information about heart valve anatomy such as valve prolapse, in which the valve bulges into a heart cavity, as well as the degree of valve stenosis (narrowing of the valve) or regurgitation (leaking of blood through a faulty heart valve).
In addition, CMRI is crucial in establishing a diagnosis of certain cardiac conditions known to cause cardiac arrhythmias. For instance, we can use CMRI to help identify patients with markedly depressed left ventricular systolic function. Once identified, patients whose heart function does not recover after optimal medical therapy can benefit greatly from an implantable cardioverter defibrillator, a device that can abort dangerous cardiac arrhythmias and prevent sudden cardiac death.
Further Advantages of CMRI
While CMRI is a powerful complement to both invasive and noninvasive cardiac imaging, it does not currently replace any other cardiac imaging technique. It can, however, help establish an accurate diagnosis in those cases when other cardiac imaging techniques may fall short. It’s also particularly useful in enabling cardiologists to assess the risk of sudden cardiac death in patients with heart conditions such as hypertrophic cardiomyopathy, a genetic condition that causes the heart muscle to be very thick and can predispose some patients to sudden cardiac death.
Perhaps the greatest advantage of CMRI over other imaging modalities, however, is its capability to produce unmatched, robust data without the use of ionizing radiation. Whereas regular X-rays and computed tomography (CT) scanning rely on ionizing radiation to produce images, MRI manipulates the alignment of protons within an electromagnetic field to produce its highly detailed images without ionizing radiation. For patients who need a nuclear medicine stress test but for whom ionizing radiation is a concern—for example, young women of child-bearing age and young patients in general—stress CMRI can play an important role, since no ionizing radiation is involved.
By the same token, for those patients who need repeated cardiac imaging to monitor the progression of certain heart diseases, such as those with pulmonary stenosis or other forms of congenital heart disease, CMRI serves an important role in their heart care by providing the most comprehensive data without repeated exposure to radiation.
Magnetic resonance imaging gets its name from the fact that it uses a powerful magnet to manipulate proton alignments within the body, which in turn produces the images. Thus, care must be taken to screen CMRI patients for any metal in the body that may pose a safety hazard. Patients who have certain metal plates or implants, for instance, should not have an MRI procedure. Similarly, patients who work with welding or whose job involves grinding metals should have regular orbital X-rays prior to MRI if there is a concern that small metal fragments may have become embedded in the soft tissue around their eyes. The technologists who obtain MRI images are trained to screen patients carefully beforehand to avoid any harm to patients.
Another challenge related to imaging involves patients who cannot tolerate getting a CT or MRI due to claustrophobia, or the fear of being enclosed in a small or tight space. Fortunately, certain newer MRI machines have been designed with claustrophobic patients in mind. These types of MRI machines, including the one at Sentara RMH, are designed with a wider opening to reduce the risk of claustrophobia for many patients. Despite this wider design feature, however, a small number of patients do still experience claustrophobia. For such patients, their referring physicians can prescribe a small dose of antianxiety medication to be taken before the test to help relieve anxiety and prevent the experience of claustrophobia during a CMRI procedure.
A Growing Trend That is Helping to Save Lives
As you may imagine, CMRI is more complex than routine MRI imaging. Since the heart is constantly moving, imaging this organ requires advanced software and complex sets of protocols for each cardiac condition under investigation. Before the development of special software and computers with the requisite speed and processing power, in fact, CMRI was not possible.
At present, CMRI is well established in most major academic health centers, and its use outside of academic settings is beginning to grow, but it is not currently widespread among community hospitals. Like Sentara RMH, however, many community hospitals are recognizing the need for CMRI, and they are starting to catch up rapidly with their academic peers.
We’re fortunate that our hospital has been able to bring this important capability to our community. Between January 2018, when we started offering CMRI at Sentara RMH, and the end of May, more than 75 patients have benefited from this powerful imaging tool. Among those patients, CMRI has helped to prevent unnecessary heart valve surgery in some patients and appropriately guided caregivers to recommend heart surgery for others. Because we now offer CMRI, we are better able to serve patients who come to us with complex cardiovascular conditions for which other cardiac imaging approaches are not able to establish a firm diagnosis.
Thanks to this technology, that can only mean a better quality of life for many of these patients—and more lives saved—in our community.