Positron Emission Tomography

Positron emission tomography (PET) was clinically introduced in the 1970s and has since become one of the most important diagnostic imaging modalities in oncology. Today, it is exclusively used as a hybrid imaging modality in conjunction with either computed tomography (CT) as PET/CT, introduced in 2001, or magnetic resonance (MR) imaging as PET/MR, introduced in 2011 (Beyer et al., J Nucl Med 41:1369–1379, 2000; Ng et al., Med Phys 37:1995–2003, 2010). The anatomic imaging component (CT or MR) complements PET with the spatial location of structures and morphological features of tissues, such as the texture of parenchymal organs or the contrast enhancement of vessels, which essentially depends on the electron density of the tissue (CT) or its proton density and relaxation properties (MR).