AUTHOR=Cowin Gary J , Mardon Karine , Houston Zachary H. , Bhalla Rajiv , Stimson Damion H. R. , Thurecht Kristofer J. , Brereton Ian M. 

TITLE=Simultaneous Dual Echo Gadolinium Enhanced MR-PET for Evaluation of PET Tracer Delivery in Altered Pathophysiology

JOURNAL=Frontiers in Physics

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2022.759749

DOI=10.3389/fphy.2022.759749

ISSN=2296-424X

ABSTRACT=Efficacy of diagnostics and therapeutics for brain tumours can be modulated by vascular delivery and blood brain barrier permeability. Simultaneous dynamic gadolinium MR-PET  enables independent assessment of vascular delivery and blood brain barrier integrity in a brain tumour animal model in the presence of a PET tracer. 
Dual echo dynamic gadolinium enhanced gradient echo imaging allows simultaneous calculation of T2* and T1 images from the TE image pairs. Relaxivity values then enabled determination of independent T2*- and T1-derived gadolinium concentrations simultaneously with measurement of [18F]DPA-714 radiotracer delivery. 
Separate T2*- and T1-derived gadolinium concentrations curves were derived in a selection of tumours and normal tissue, reflecting vascular delivery and tissue uptake. Changes in the PET activity curves were seen in tumours. The dramatic changes in the MR-derived vascular delivery and tissue uptake estimates, may improve the understanding of the alteration of delivery and uptake of new theranostic agents.