Coupling of CT and PET-18F-FDG Imaging in Arteries with Calcification

PET imaging of arteries is drastically dominated by the emission of activity from blood. In addition, the artery wall (2.3 mm) is thin in comparison to the whole artery section and is thus subject to partial volume effect (PVE). In fact, the whole artery area which has a diameter of 38 mm for the abdominal aorta is affected by PVE. Currently, 18F-FDG uptake in the artery is evaluated by means of standard uptake value (SUV) and tissue-to-blood ratio (TBR). In the case of TBR, the activity in blood is defined from an image of a vein. In the present work, the dynamic 18F-FDG images were decomposed with factor analysis (FA) in images of blood and tissue. Artery images were corrected for PVE with recovery factors deduced from a phantom. Eight subjects were imaged with CT and PET in dynamic mode. Five subjects were under medication for atherosclerosis. The tissue and blood images were used for SUV and TBR calculation and compared to the usual values obtained from the measured images. SUV and TBR were classified based on five levels of intensity of the artery calcifications on CT images and on the extent of the calcifications. SUV and TBR extracted from the decomposed images provided more accurate values than those deduced from the measured images. The method can be used in staging of atherosclerosis disease in elderly and it can be useful in the clinic with imaging in reduced time.