Imaging cell injury and death

Although there has been much emphasis on detecting myocardial viability over the past decade, there is a growing interest in finding a marker for myocyte injury and death. There has been limited clinical utility for infarct-avid imaging with (99m)Technetium ((99m)Tc) pyrophosphate and (111)Indium antimyosin, but recent experience with (99m)Tc-labeled annexin V and contrast-enhanced magnetic resonance imaging has stimulated cell death detection. In the effort to image myocyte damage, it is crucial to understand the pathologic finding and cell signals that can be used as critical in vivo markers for the transition from viable to dead tissue. It may not be possible to capture an image at the precise moment when a myocyte dies, but we need to know the different processes that can occur. Specifically, it is important to understand that oncosis and apoptosis are two distinctly different methods of cell death, and both ultimately result in myocyte necrosis. As we approach the more complex problems of myocyte injury during inflammation, cardiomyopathy, ischemia, reperfusion, and transplant rejection, we realize that more specific markers of real-time tissue injury are needed. This review focuses on the pathophysiology of myocyte injury necrosis and repair as a method to guide newer developments in myocardial imaging.