18F-FDG accumulation in atherosclerosis: use of CT and MR co-registration of thoracic and carotid arteries

The purpose of this study was to depict18F-fluoro-2-deoxy-D-glucose (FDG) accumulation in atherosclerotic lesions of the thoracic and carotid arteries on CT and MR images by means of automatic co-registration software. Fifteen hospitalised men suffering cerebral infarction or severe carotid stenosis requiring surgical treatment participated in this study. Automatic co-registration of neck MR images and FDG-PET images and of contrast-enhanced CT images and FDG-PET images was achieved with co-registration software. We calculated the count ratio, which was standardised to the blood pool count of the superior vena cava, for three arteries that branch from the aorta, i.e. the brachial artery, the left common carotid artery and the subclavian artery (n=15), for atherosclerotic plaques in the thoracic aorta (n=10) and for internal carotid arteries with and without plaque (n=13). FDG accumulated to a significantly higher level in the brachial artery, left common carotid artery and left subclavian artery at their sites of origin than in the superior vena cava (p=0.000, p=0.000 and p=0.002, respectively). Chest CT showed no atherosclerotic plaque at these sites. Furthermore, the average count ratio of thoracic aortic atherosclerotic plaques was not higher than that of the superior vena cava. The maximum count ratio of carotid atherosclerotic plaques was significantly higher than that of the superior vena cava but was not significantly different from that of the carotid artery without plaque. The results of our study suggest that not all atherosclerotic plaques show high FDG accumulation. FDG-PET studies of plaques with the use of fused images can potentially provide detailed information about atherosclerosis. (orig.)