Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology Hybrid PET/CT and PET/MRI imaging of vulnerable coronary plaque and myocardial scar tissue in acute myocardial infarction Stephanie Marchesseau, Aruni Seneviratna, A. Therese Sjoholm, Daphne Liang Qin, Jamie X.M. Ho, Derek J. Hausenloy, David W. Townsend, A. Mark Richards, John J. Totman and Mark Y.Y. Chan Clinical Imaging Research Centre A*STAR-NUS Singapore Department of Cardiology, National University Heart Centre, Singapore Duke-National University of Singapore Medical School, Singapore Cardiovascular Research Institute, NUHS, Singapore Institution Picture/Logo Optional Copyright American Society of Nuclear Cardiology

Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology BACKGROUND 1- Acute myocardial infarction (AMI) occurs when rupture or erosion of coronary atheroma (vulnerable plaques) 2- Combined CT and PET with 18F-NaF can identify coronary atherosclerotic plaques that have ruptured or eroded. 3- What are the processes behind 18F-NaF uptake in vulnerable plaques ? 4- Does 18F-NaF also uptake in myocardial scar tissue ? Copyright American Society of Nuclear Cardiology

Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology METHODS Study type: Prospective cohort Study subjects: Ten patients with STEMI were scanned after 18F-NaF injection, for 75 minutes in a Siemens PET/MR scanner using delayed enhancement (LGE). They were then scanned in a Siemens PET/CT scanner for 10 minutes. Study endpoints: Primary end point: Reproducibility of previous detection accuracy of culprit plaques Secondary end point: Increase of uptake in myocardial scar Study variables Tissue to background Ratios of 18F-NaF uptake between culprit and non-culprit plaques Tissue to background Ratios of 18F-NaF uptake between scar tissue and remote healthy myocardium Copyright American Society of Nuclear Cardiology

Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology RESULTS Confirming previous findings, culprit lesions uptake was significantly higher than non-culprit lesions uptake. Additionally, scar uptake was higher than healthy myocardium uptake as measured by PET/CT and PET/MR data. (Left) Boxplot representation of the 2 groups of lesions showing a significant difference in TBR between the culprit and the non-culprit lesions. (Right) Boxplot representation of the myocardium uptake using both the PET/CT and the PET/MR modalities Copyright American Society of Nuclear Cardiology

Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology CONCLUSIONS 1- Our study results first confirm previous findings of successful 18F-NaF differentiation of culprit coronary atheromata in the IRA of patients with recent STEMI. 2- However, more research is still required before 18F-NaF PET imaging can be used as a diagnostic tool for vulnerable plaques. 3- For the first time, we identified simultaneous 18F-NaF uptake in myocardial scar in the territory supplied by the IRA using both PET/CT and PET/MRI. 4- Pathobiological processes involving microcalcification may be common to both atherosclerotic plaque disruption and myocardial infarction. 5- Potential use of 18F-NaF to image both vulnerable plaque burden and myocardial scar tissue. Copyright American Society of Nuclear Cardiology