Cardiovascular Magnetic Resonance Imaging
The USC Division of Cardiovascular Medicine is particularly proud of its pioneering program in high-field cardiovascular magnetic resonance (CMR) imaging. While most cardiac centers use lower-field imaging devices, our division has invested in devices capable of high-field diagnostic studies. With this novel technology, the heart can be captured in three dimensions with amazing clarity. Our two new 3T MRI systems produce optimal-resolution images of the heart muscle, the structure of the heart (for congenital and valvular heart disease detection), and the coronary arteries. They also allow us to observe scarred heart muscle, blood flow through the muscle of the heart, and heart muscle metabolism to detect and study inadequate blood flow to the heart. CMR additionally allows for clinical visualization of the peripheral and renal arterial systems as well as the carotid arteries. With CMR, conditions such as aortic aneurysms and aortic dissections can be detected at their earliest phases, and the presence and extent of pulmonary hypertension can be reliably determined. Other vessels can also be imaged and disease detected such as narrowing of the arteries to the kidneys that can produce severe hypertension.
USC cardiovascular medicine faculty are involved in several research projects that employ CMR imaging. Using CMR?s ability to accurately evaluate left ventricular size, shape, and function, USC acts as a core laboratory for the international NIH (NHLBI)-supported Surgical Treatment for Ischemic Heart Failure (STICH) trial, which examines surgical treatment for heart failure after heart attack. The STICH trial compares medical, bypass surgical, and surgical ventricular restoration. In a second NIH (NHLBI)-supported research grant, our researchers study the heart muscle in patients with type I diabetes. Using phosphorus and blood flow CMR assessment to assess ATP and phosphocreatine levels in the heart muscle at rest and during stress, the study aims to determine the biochemical basis for the abnormal heart function commonly found in diabetics. Finally, a third NIH (NHLBI)-supported program?the Women?s Ischemia Syndrome Evaluation (WISE)?uses phosphorus CMR assessment at rest and with stress to determine the basis for chest pain in women who show no evidence of coronary artery obstruction. Many women suffer from this syndrome, sometimes called ?Cardiac Syndrome X.?
CMR imaging is non-invasive and allows evaluation of heart and vascular function using a single modality and without the risks associated with ionizing radiation or x-ray dye. 3T CMR imaging can be described as a ?one-stop shop? for the comprehensive analysis, including severity and prognosis, of virtually any form of cardiovascular disease.
Commonly asked questions:1. What does the "T" in 3T MRI stand for?
Answer: T stands for "Tesla" a unit that indicates the strength of the magnetic field. Widely available MRI systems have a field strength of 1.5 Tesla. The newest systems are 3T, twice the magnetic field compared with the common MRI systems.2. Can people with with pacemakers undergo cardiovascular magnetic resonance imaging?
Answer: At the present time, such imaging studies are not performed routinely due to the fact that the magnetic and radio wave fields can have a harmful effect on the pacemaker and/or an implantable cardioverter defibrillator(ICD). However, it may be performed if it is essential for life threatening disease.3. Will the 3T MRI detect a blockage?
Answer: The 3T MRI can sometimes detect blockage in the coronary arteries (the arteries that supply blood to the heart). Blockages may be routinely detected in the larger blood vessels, such as the arteries to the brain, kidneys or legs.4. Is this in the experimental stages?
Answer: The procedure used is called myocardial perfusion imaging. It detects the blood supply to the heart muscle (myocardium). This type of imaging has been used in association with the injection of radioisotopes such as thallium or technetium scanning. Several studies have demonstrated that this type of scanning used with MRI can detect abnormalities of blood supply to heart muscle in women with chest pain that is not demonstrable with radioisotopes. The procedure with MRI might still be considered research.5. What exactly does the 3T MRI do?
Answer: 3T MRI is useful for general MRI imaging of any organ. Regarding the heart, it demonstrates the blood supply and distribution, the presence of heart muscle scarring, the contraction ability of the heart, the coronary arteries and the metabolism in heart muscle. 3T MRI is generally superior to MRI at lower magnetic fields. When MRI scanning is performed with cold pressor testing (when the hand is dipped into a bucket of ice water) or during the infusion of a drug, adenosine, that normally causes the smaller arteries in the heart to dilate with an increase in blood supply to the heart, the IV injection of the MRI contrast agent gadolinium traces the blood supply to the heart muscle. In patients with disease of the coronary arteries, the blood supply is found to be limited. This is the case with coronary artery disease involving the large vessels or with coronary artery disease involving the small coronary arteries, i.e., those that cannot be seen even by coronary angiography performed during cardiac catheterization.6. Can MRI replace the CT scan?
Answer: CT scanning of the heart can depict the coronary arteries with the administration of relatively large doses of x-ray contrast agents that can have a detrimental effect on the kidneys. MRI, especially at 3T can also depict the coronary arteries, albeit not yet as well as CT.7. Is the 3T MRI free?
Answer: No. 3T MR1 is the same price as standard MRI at the present time.8. Can I pay cash for this procedure if I do not have health insurance?
Answer: Once you have a consultation, the physician?s office will work with the hospital?s financial counselor to secure a quote for the services your physician prescribes. You can pay cash for those services on the day your services are rendered.9. Does this system detect small vein blockage?
Answer: The 3T MRI shows blockages involving the very small coronary arteries using perfusion imaging.10. If I am coming from out of state can I have the consultation and 3T MRI scan on the same day?
Answer: Yes.11. How long does the imaging last?
Answer: The imaging takes less than one hour.12. Is the quality of the imaging better to see than the CT scan or the angiogram?
Answer: MRI uniquely depicts the blood flow abnormalities to the heart muscle consistent with small vessel coronary artery disease.