Cardiac MRI is excellent at quantifying ventricular volumes, function, and tissue characterization. Ten-to-twelve slice T2 weighted imaging is frequently performed to assess myocardial oedema and area at risk (AAR) following an acute myocardial infarction, but image acquisition can result in long acquisition times and multiple breath-holds by a patient. Researchers from Barts Heart Centre at St. Bartholomew’s Hospital in London have determined that a much shorter three-slice technique is just as effective, according to a study published in the January issue of the Journal of Cardiovascular Magnetic Resonance.
The most commonly used protocol for assessing the AAR, defined as the area of ischaemic myocardium that occurs distally to a coronary artery occlusion, is to acquire images of the whole left ventricle with 10 to 12 continuous myocardial short axis slices. Each slide is acquired with a single breath hold of 10-15 seconds, a process that may be difficult for patients, according to lead author Stephen Hamshere, M.D. of the Department of Cardiology and colleagues. They conducted a study to determine if three non-contiguous slices would provide enough clinical information to assess the AAR.
The study included 167 patients who had a myocardial infarction successfully reperfusioned through primary percutaneous coronary intervention between April 2008 and November 2012 at St. Bartholemew’s Hospital. The patients had either a three or ten-slice T-2 short tau inversion recovery(STIR) imaging within the first week after reperfusion.
The protocol included balanced stead-state free precision cine imaging to acquire 10-12 short axis slices with one slice per breath-hold. This was followed by either 10-slice or 3-slice fat-suppressed T-2 weighted triple inversion turbo spin echo STIR imaging, with one slice per breath-hold. Then 10-12 short axis slice images matched with short-axis cine images were acquired, with one slice per breath-hold.
All studies were evaluated by two cardiologists specializing in cardiac imaging and two interventional cardiologists. They determined that the findings from the 3-slice sequence and the 10-slice sequence were comparable, and that both showed statistically significant correlations with angiographic risk scores.
The primary benefit of the 3-slice imaging protocol was a quicker acquisition and analysis time. The authors reported that the overall scan time was nearly five minutes shorter than the 10-slice, advising that this shorter time would benefit patients who were unable to lie flat for extended periods or who were claustrophobic. A shorter acquisition time might also enable additional MRI scans to be performed in the MRI suite of a busy radiology department, thus making better use of resources and potentially increasing revenue. Similarly, a shorter analysis time could potentially improve staff productivity.
Three-slice cardiac MRI can accurately detect myocardial oedema. Appl Radiol.