The major aim of the National Heart, Lung and Blood Institute (NHLBI)/Suburban Hospital Cardiovascular MRI Research Project is to develop new approaches in assessing patients with cardiovascular disease with MRI technology. To date, we have focused on four specific aims. 1) Detection of acute coronary syndrome with MRI. The sensitivity and specificity for detecting acute coronary syndrome was 84% and 85% by MRI, 80% and 61% by an abnormal ECG, 16% and 95% for ST depression or T-wave inversion, 40% and 97% for peak troponin-I, and 48% and 85% for a TIMI risk score >3. The MRI was more sensitive than strict ECG criteria for ischemia (p<0.001), peak troponin-I (p<0.001), and the TIMI Risk Score (p=0.004). The MRI was more specific than an abnormal ECG (p<0.001). Multivariate logistic regression analysis showed an abnormal MRI was the strongest predictor of acute coronary syndrome and added statistically significant diagnostic value over clinical parameters (p<0.001). We concluded that the resting MRI scan exhibited diagnostic operating characteristics suitable for triage of patients with chest pain in the emergency department. 2) Characterizing myocardial viability with MRI. We developed a method that can differentiate infarcted myocardium, stunned myocardium, and normal myocardium one day after heart attack with a single acquisition [Radiology 2002, in press]. We also developed a ?phase sensitive reconstruction method? which improves the quality of heart attack images and minimizes the influence of user selected parameters on the apparent size of the heart attack [Kellman P, Arai AE, McVeigh ER, Aletras AH. Phase-sensitive inversion recovery for detecting myocardial infarction using gadolinium-delayed hyperenhancement. Magnetic Resonance in Medicine 2002 47(2):372-383]. Expanding upon this work, we have been able to use this new method to increase the speed of imaging a heart attack by a factor of 3-4 [Arai et al, International Society of Magnetic Resonance in Medicine May 2002, Honolulu]. Further acceleration by another factor of two is currently under active investigation. 3) First pass myocardial perfusion imaging. We developed and validated a faster method for imaging myocardial perfusion (blood supply) at the NIH [Epstein FH, London JF, Peters DC, Goncalves LM, Taylor J, Balaban RS, Arai AE. Multislice first-pass cardiac perfusion MRI: validation in a model of myocardial infarction. Magn Reson Med. 2002 Mar;47(3):482-91]. The advantages of this MRI method include very rapid, near real time detection of perfusion abnormalities at a resolution at least double that achieved by PET scans and 4 times the resolution of a standard thallium scan. There are a wide range of potential applications [Arai AE. Magnetic Resonance First Pass Myocardial Perfusion Imaging. Topics in MRI 2000:11(6):383-398]. During the last year at the NIH, we have shown that the MRI can measure myocardial perfusion as accurately as microsphere injections (a gold standard method only usable in animal models) [Christian et al. Scientific Sessions of the American Heart Association 2001 and in review for publication]. 4) MRI characterization of atherosclerotic plaque. We have correlated high-resolution MRI findings in the arterial wall of patients and volunteers with blood tests of inflammation, a process important in the development and progression of atherosclerosis [Weiss CR, Arai AE, Bui MN, Agyeman KO, Waclawiw MA, Balaban RS, Cannon RO 3rd. Arterial wall MRI characteristics are associated with elevated serum markers of inflammation in humans. J Magn Reson Imaging. 2001 Dec;14(6):698-704]. We were able to detect subtle abnormalities in the wall that predicted abnormal blood tests that seem unlikely to be detectable by current clinical methods. We have extended this work in patients with known significant blockages in the carotid arteries and find that the MRI contrast agent gadolinium nearly doubles the ability to discriminate different portions of the atherosclerotic plaque [Wasserman BA, Smith WI, Trout HH 3rd, Cannon RO 3rd, Balaban RS, Arai AE. Carotid Artery Atherosclerosis: In Vivo Morphologic Characterization with Gadolinium-enhanced Double-oblique MR Imaging Initial Results. Radiology. 2002 May;223(2):566-73].
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