Report from SCMR: Salvage imaging offers fresh insight on benefits of heart therapy

Cardiac researchers assessing the benefits of revascularization therapies will operate a little less in the dark, thanks to salvage imaging, a new cardiac MR technique.

Using T2-weighted pulse sequences, salvage imaging identifies the location and extent of edema that accumulates in the myocardium after an ischemic event such as myocardial infarction.

The areas where edema accumulates correlate with heart muscle that is at risk for permanent damage after infarction, according to Dr. Eike Nagel, director of cardiovascular MRI at the German Heart Institute in Berlin.

"With salvage imaging, we can see after revascularization how much muscle would have died if we had not performed the intervention," Nagel said in an interview with Diagnostic Imaging.

Before the advent of salvage imaging, the effect of therapy could be measured only by using large two-armed trials in which therapy was applied to one group and withheld from the other. The amount of myocardial damage after the trial would be calculated for each individual. The averages for each group would then be compared to measure how much damage would have been incurred if therapy had not been performed.

Salvage imaging allows each patient to serve the function of both an experimental subject and a control to make that determination.

"Within one patient, you can tell how much difference I actually made by doing my therapy," Nagel said. "You can then find out with relatively small groups if one therapy is better than another."

Dr. Holger Thiele, a cardiac MRI researcher at the University of Leipzig in Germany, demonstrated at the 2009 Society for Cardiovascular Magnetic Resonance meeting last week how salvage imaging affects a clinical trial. In a study involving 220 subjects, she showed that therapy in patients after myocardial infarction can be optimized by adding antioxidative agents to standard therapy.

"We had known this from animal data before and are now able to demonstrate this effect in patients using MRI as an endpoint," she said.

Salvage imaging will ultimately help evaluate the clinical efficacy of hundreds of techniques designed to optimize revascularization therapy, Nagel said.

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