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Perfusion/coronary artery disease

Although currently only used as a research protocol, Cardiac MR (magnetic resonance) stress perfusion imaging is demonstrating its capability to non-invasively diagnose coronary artery disease (CAD) in patients with suspected CAD. The preliminary studies show promising results.

Short-axis images on 1st Pass perfusion study demonstrates a defect in the anteroseptal wall

CAD is now evaluated in clinical practice using imaging techniques from Nuclear Medicine, such as stress thallium SPECT studies or positron emission tomography (PET). Stress echo is also frequently used. The purpose of such stress tests is to reveal a stenotic coronary artery’s relative inability to augment flow upon stress to the myocardium it supplies.

The stress agent most frequently used is adenosine, a naturally occurring mediator of coronary vasodilation. Administered intravenously (IV) via continuous infusion, adenosine augments the resting coronary flow three to five times above baseline. Limited flow augmentation in the presence of a significant coronary stenosis results in heterogeneous myocardial perfusion. The relative lack of flow to the myocardium supplied by the stenotic vessel causes a ‘defect’ of decreased enhancement on the images or results in a wall motion abnormality.

Key Points

  • Cardiac MR perfusion imaging can be combined with cine and viability studies to provide a comprehensive examination of the heart for coronary artery disease.
  • Stress perfusion imaging with Cardiac MR is now used only as a research protocol.

Case in Point

Short-axis images on 1st Pass perfusion study demonstrates a defect in the anteroseptal wall Short-axis viability study showing hyperenhancement in the anteroseptal wall

68 year old male with congestive heart failure and hemodynamically significant stenosis in the left anterior descending artery on coronary angiography.

For Further Reading