Abstract
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Objectives: 68Ga-DOTATOC has been reported to be taken up by activated macrophages, which accumulate in active inflammatory lesions including atherosclerotic plaques. The purpose of this study was to investigate the correlation between aortic uptake of 68Ga-DOTATOC and cardiovascular risk factors, by using various measurement indexes.
Methods: Fifty patients with neuroendocrine tumors who underwent 68Ga-DOTATOC PET/CT were retrospectively enrolled. On axial PET images, regions-of-interest were drawn for the ascending thoracic aorta (ATA) and descending thoracic aorta (DTA) on every slice with a fixed interval. Standardized uptake value (SUV) was measured in the aorta, and also in the superior vena cava as a background. The maximum SUV (SUVmax) and mean SUV (SUVmean) of targets, and target-to-background ratio (TBRmax or TBRmean; the ratio between SUVmax or SUVmean of a target and SUVmean of the background) were measured. Clinical information was obtained from medical record review, and correlations between uptake measurements and Framingham risk score (FRS) were evaluated.
Results: TBRmax of the ATA exhibited a significant correlation with FRS (r = 0.459, P = 0.001). TBRmax of the DTA also exhibited a significant but relatively lower correlation (r = 0.392; P = 0.005 for DTA). In contrast, TBRmean of both the ATA and the DTA did not exhibit a significant correlation with FRS. When patients were divided into two groups of high and low FRS (n = 15 and 35, respectively), there were significant differences in TBRmax (1.45 ± 0.21 vs. 1.73 ± 0.23, P <0.001) and TBRmean (0.99 ± 0.11 vs. 1.10 ± 0.09, P = 0.003) between the two groups.
Conclusion: 68Ga-DOTATOC uptake in the thoracic aorta exhibited a significant correlation with cardiovascular risk factors, which suggests probable 68Ga-DOTATOC uptake in vascular inflammation. Among various measuring indexes, TBRmax of the ATA exhibited the highest statistical significance. Further studies are warranted regarding clinical efficacy of 68Ga-DOTATOC PET/CT in vascular inflammation and its correlation with cardiovascular events. Research Support: