Exploring Vessel Wall Biology In Vivo By Ultra-Sensitive Total-Body Positron Emission Tomography.

Ultra-sensitive, high-resolution extended field-of-view total-body positron emission tomography (PET) using the first-of-its kind 194 cm axial field-of-view uEXPLORER may facilitate the interrogation of biologic hallmarks of hitherto difficult to evaluate low-signal vessel wall pathology in cardiovascular disease. Methods: Healthy volunteers were imaged serially, for up to 12 hours after a standard dose of 18 F-fluorodeoxyglucose (FDG) ( n = 15) or for up to 3 hours after injection of a very low dose (about 5% of a standard dose; n = 15). A cohort undergoing standard 18 F-FDG PET ( n = 15) on a conventional scanner with a 22 cm axial field-of-view served for comparison. Arterial wall signal, crosstalk with hematopoietic and lymphoid organs and image quality were analyzed using standardized techniques. Results: Total-body PET depicted the large vessel walls with excellent quality. The arterial wall could be imaged with high contrast up to 12 h after tracer injection. Ultra-low dose total-body 18 F-FDG images yielded comparable vessel wall signal and target-to-background ratio compared to conventional dose, short axial field of view PET. Crosstalk between vessel wall and lymphoid organs was identified with superior accuracy in both total-body PET cohorts, compared to conventional PET. Conclusion: Total-body PET enables detailed assessment of in vivo vessel wall biology and its crosstalk with other organs, over an extended time window after tracer injection or at ultra-low tracer dose. These initial observations support the feasibility of serial imaging in low-risk populations, and they will stimulate future mechanistic studies or therapy monitoring in atherosclerosis and other vessel wall pathologies.