Myocardial perfusion
Cardiac MR (magnetic resonance) perfusion techniques are sensitive for the detection of myocardial ischemia. It is proving to be a useful noninvasive modality for detecting significant stenoses in patients suspected of having coronary artery disease (CAD).
Perfusion imaging is performed using a dynamic first pass acquisition during a contrast bolus. We use an Inversion Recovery (IR) turbo FLASH technique, which allows for high T1 contrast imaging. The images are acquired during the administration of a “tight” contrast bolus in which the injection lasts four to five seconds.
Perfusion imaging is performed using the pharmacological stress agent adenosine, similar to the stress studies performed in nuclear cardiology. Adenosine is used to produce maximal vasodilatation in order to demonstrate hemodynamically significant stenoses. Ischemic regions show up as signal defects in the myocardium. Rest perfusion images are also obtained after the adenosine infusion has been terminated in order to evaluate fixed defects versus artifacts. Myocardial perfusion is always combined with cine and viability imaging. Given this capability, Cardiac MR has the potential to provide a comprehensive assessment of the heart in one single exam.