Improving the accuracy of cardiac PET with motion-free imaging.

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Cardiac positron emission tomography (PET) uses a minute amount of radioactive labelled compound, called a tracer, to image the heart. Dynamic PET uses a specialized scanner to image the patient over several minutes, taking a series of snap shots of the injected tracer as it distributes through the patient's body. The dynamic images can then be processed by specialized software to measure the rates at which the tracer interacts with the tissues in the body. These rates can be used to assess physiologic function. In cardiac PET we use these methods to measure functions such as myocardial (heart muscle) blood flow (MBF), which can be used to detect reduced blood supply to the heart. PET MBF measurement is a leading tool in basic research for understanding disease and measuring therapy effectiveness, and is emerging as an important clinical tool. For dynamic PET to be accurate, the subject must remain perfectly still during image acquisition. However, in cardiac PET, patient motion is observed in over 40% of scans due to patient discomfort, coughing, or non-compliance. Even in animal studies, where the animal anaesthetized, motion is common as the animal settles on the bed. Another common and uncontrollable source of motion is "heart creep", settling of the heart in the chest, over the duration of the scan. This program aims to address heart motion, by automatically detecting it, and correcting the images before measuring MBF. The program will expand on existing state-of-the-art imaging technologies and a vast amount of existing data at the University of Ottawa Heart Institute (UOHI) to develop motion detection techniques. These techniques will be integrated into existing commercial software developed at UOHI (FlowQuant©) to correct patient motion during MBF measurement. The program will also explore correction for motion during image reconstruction by the camera, to obtain motion-free images that are also free of other motion related errors, thus resulting in even more accurate MBF measurements.