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Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Positron Emission Tomography and Magnetic Resonance Imaging scanner; photo courtesy of the Center for Clinical Imaging Research in the Mallinckrodt Institute of Radiology at Washington University School of Medicine in St. Louis.