Motion Corrected Reconstruction for 3D Cardiac Simultaneous PET-MR Imaging: Towards Efficient Assessment of Coronary Artery Disease

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Coronary artery disease (CAD) is the leading single cause of morbidity and mortality in the Western world. CAD reduces the blood supply to the cardiac muscle and can lead to chest pain (angina) or heart attack. CAD diagnosis is currently performed by a wide range of invasive and non-invasive tests. However in current practice a non-negligible number of patients that may not need the intervention are referred to invasive, ionizing, and potentially harmful x-ray cardiac catheterization procedures. Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) are two very promising non-invasive imaging technologies for early risk assessment, guidance of therapy and treatment monitoring of CAD. Both technologies provide complementary information, thus the recent introduction of simultaneous PET-MR systems offers great potential for accurate interpretation of findings of PET and MR images and new perspectives for better CAD diagnosis and treatment. For example three-dimensional fusion of PET perfusion images with non-invasive coronary MR images may allow the exact localization of stenosis, causing ischemia, to guide required interventions. However, inevitable patient motion (such as that caused by breathing and heart beating) during the acquisition degrades the image quality of both PET and MR images. Currently, commercial simultaneous PET-MR scanners do not feature technology for efficient and accurate correction of such motion. Current research developments that deal with the motion problem in cardiovascular PET-MR concentrate mainly on improving the quality of PET images based on MR information. Moreover these approaches do not allow truly simultaneous PET and MR acquisitions leading to prolonged scan times, since diagnostic MR images need to be acquired after the simultaneous PET-MR acquisition. The reason is that dedicated MR acquisitions need to be performed concurrently with the PET imaging in order to correct for motion in the PET data. This means that MR is being used as an expensive motion-correction device limiting its diagnostic utility. In this proposal we aim to develop, implement and test the clinical feasibility of an efficient PET-MR acquisition and reconstruction framework that enables truly simultaneous acquisition of complementary PET and MR diagnostic information. We hypothesize that this can be achieved using synergistic information of both modalities i.e. functional, anatomic and motion MR information, and quantitative perfusion PET data in a motion corrected reconstruction approach. The proposed approach is foreseen as an important step towards clinical adoption of PET-MR cardiovascular imaging and lastly towards an efficient and accurate non-invasive assessment of CAD.