Magnetic Resonance Coronary Angiography

Magnetic resonance coronary angiography

Currently the gold standard for assessment of coronary artery disease is coronary angiography using X-rays. As conventional coronary angiography is an invasive procedure with a small risk of significant complications, other modalities of imaging are being evaluated. Though multi-slice CT is a less invasive method of evaluating the coronary arteries, it still involves radiation exposure and the use of iodinated contrast material, with its attendant risks. Coronary magnetic resonance angiography is being considered as a potential noninvasive alternative for assessing the coronary anatomy.

Steady-state free precession whole-heart coronary magnetic resonance angiography has become the method of choice for coronary imaging with 1.5 Tesla magnetic resonance imaging systems. The intrinsically high blood signal intensity allows whole heart coronary MRA with SSFP sequence without using MR contrast medium. Myocardial and venous blood signals can be suppressed using T2 preparation. Diaphragmatic movements can be reduced by a tight fitting abdominal belt so that imaging can be done during free breathing.

A paper by Kato S and associates [1] had a negative predictive value of 88% with whole-heart coronary MRA which is useful in avoiding unnecessary X-ray coronary angiography. There is also a 99% negative predictive value for detecting left main stenosis or three vessel disease so that a 1.5 Tesla whole-heart coronary magnetic resonance angiography reliably rules out significant left main disease or three vessel disease. Total study time including the pre-scan was less than 30 minutes, while it was 70 minutes for the previous target volume coronary MRA, which had also a poor specificity of 42% when all vessels were analyzed.

Diagnostic images can be obtained even in patients with heart rates above 70 beats per minute without administration of beta blockers, in contrast from multidetector computed tomography. High density calcium does not cause beam-hardening artifacts in magnetic resonance angiography, which is one of the reasons for excluding patients with heavy calcification from MDCT evaluation studies. A review on magnetic resonance coronary angiography in 2022 noted that it has a well established role in coronary assessment in congenital heart disease and vasculitides like Kawasaki disease. But it is yet to be implemented as a clinical alternative in adult coronary artery disease. This is inspite of the fact that MRI is safe, non-radiating and even non-contrast technique compared to CT coronary angiography [2].

References

1. Kato S, Kitagawa K, Ishida N, Ishida M, Nagata M, Ichikawa Y, Katahira K, Matsumoto Y, Seo K, Ochiai R, Kobayashi Y, Sakuma H. Assessment of coronary artery disease using magnetic resonance coronary angiography: a national multicenter trial. J Am Coll Cardiol. 2010 Sep 14;56(12):983-91. doi: 10.1016/j.jacc.2010.01.071. PMID: 20828652.
2. Androulakis E, Mohiaddin R, Bratis K. Magnetic resonance coronary angiography in the era of multimodality imaging. Clin Radiol. 2022 Jul;77(7):e489-e499. doi: 10.1016/j.crad.2022.03.008. Epub 2022 Apr 9. PMID: 35414430.