RT Journal Article SR Electronic T1 [68Ga]Pentixafor-PET/MRI for detection of Chemokine Receptor 4 expression in atherosclerotic plaque JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 297 OP 297 VO 58 IS supplement 1 A1 Xiang Li A1 Daniel Heber A1 Xiaoli Zhang A1 Markus Mitterhauser A1 Wolfgang Wadsak A1 Alexander Haug A1 Marcus Hacker YR 2017 UL http://jnm.snmjournals.org/content/58/supplement_1/297.abstract AB 297Objectives: Chemokines are expressed on the cells of the atherosclerotic vessel wall and participate in the initial emigration of leukocytes to the sites of inflammation. The expression of chemokine receptor type 4 protein (CXCR4) was found to be co-localized with monocytes/macrophages. A novel PET tracer, Gallium-68 (68Ga) Pentixafor, with an affinity to CXCR4, has recently been introduced for the imaging of atherosclerosis. We sought to evaluate human atherosclerotic lesions using 68Ga-Pentixafor PET/MRI.Methods: Thirty-four oncology patients underwent 68Ga-Pentixafor PET/MR imaging at baseline. The reproducibility of 68Ga-Pentixafor PET/MRI and atherosclerosis progression was assessed in seven patients with a follow-up exanimation. Eight arterial segments were analyzed. The maximum standard uptake (SUVmax) values were determined; target-to-blood ratios (TBR) were calculated. The Spearman correlation and the unpaired t test were used for statistical comparison between uptake ratios and cardiovascular risk factors. Immunohistology of atherosclerotic plaque lesions was obtained to detect CXCR4 expression.Results: A pattern of focal 68Ga-Pentixafor uptake that followed the curve of the vessel was observed. Increased arterial uptake was observed at 602 sites in 34 patients with 68Ga-Pentixafor PET/MRI. The descending aorta showed the highest plaque counts of 225 and TBR values (1.9±0.4). There were significantly higher uptake ratios in men (men: 1.9±0.3 vs women: 1.7±0.2); Spearman correlation R = 0.4; P < 0.05), but, 68Ga-Pentaxifor uptake was not associated with any risk factors for cardiovascular disease. 68Ga-Pentixafor PET/MRI showed high reproducibility during two examinations. There was no significant difference between the mean TBRmax values of plaque lesions (n=72) (TBRbaseline1.8±0.3 vs TBRfollow-up1.8±0.3) (p=0.9). The Pearson linear regression correlation coefficients for the uptake values obtained from the two times scans were 0.6 for TBRmax. Bland Altman analysis was used to assess agreement between the baseline and follow-up exanimations, with a lower bias for TBRmean (-0.03), which corresponded to a zero difference. Specific CXCR4 expression in human carotid plaques were detected.Conclusion: This study shows a pattern of focal 68Ga-Pentixafor focal uptake at atherosclerotic arterial segments. However, uptake ratios did not correlate with conventional cardiovascular risk factors. 68Ga-Pentaxifor had a high reproducibility with PET. Consequently, quantifications of 68Ga-Pentaxifor uptake, with dedicated MRI analyses of the vessel wall, might be useful in the characterization of atherosclerosis. Research Support: 1, Zernecke A, Weber C. Chemokines in the vascular inflammatory response of atherosclerosis. Cardiovasc Res. 2010;86:192-2012, Hyafil F, Pelisek J, Laitinen I, et al. Imaging the cytokine receptor CXCR4 in atherosclerotic plaques with the radiotracer 68Ga-pentixafor for positron emission tomography. J Nucl Med. 2016