More novel radiotracers such as [11C]PHNO have been developed to quantify the relative differences in binding of DRD3 compared with dopamine D2 receptor (DRD2) in brain regions in order to improve the precision of neuroreceptor identification and gain a deeper understanding of addiction-related biomarkers in alcohol-dependent patients (149) and in stimulant use disorder (150). The gene discussed is DRD2; the disease is substance dependence.