“[18F]PR04.MZ PET/CT Imaging for Evaluation of Nigrostriatal Neuron Integrity in Patients With Parkinson Disease
” by Juri and colleagues is the editor’s favorite for this issue. Dopaminergic, nigrostriatal neuron degeneration is causal for Parkinson disease (PD) and PET quantification of dopamine transporters is a widely accepted method for differential diagnosis between idiopathic PD and essential tremor. [18F]PR04.MZ is a new PET tracer for precise quantification of striatal and extra-striatal dopamine transporter. The authors described their initial experience with [18F]PR04.MZ PET/CT in 18 healthy volunteers, 19 early PD patients (Hoehn-Yahr I–II), and 13 moderate-advanced PD patients (Hoehn-Yahr III–IV). PET/CT was performed 60 to 90 minutes after injection of 5 mCi of [18F]PR04.MZ. Specific binding ratios (SBRs)were calculated for caudate nucleus, anterior putamen, posterior putamen, substantia nigra (SNpc), compared between different groups and correlated with clinical ratings. [18F]PR04.MZ showed very high and specific uptake in the putamen, caudate, and substantia nigra pars compacta and very low nonspecific binding in other brain regions, and SBR values for the control group were 22.3 ± 4.1, 19.1 ± 3.5, and 5.4 ± 1.2, respectively. SBR reductions were observed in all regions both initial and moderate PD, ranging from 35% to 89% (P < 0.001). The observed pattern of reduction was posterior putamen > anterior putamen > substantia nigra pars compacta > caudate, with contralateral posterior putamen being the most affected region. Rostro-caudal depletion gradient was evident in all PD patients and progression correlated with motor manifestations. [18F]PR04.MZ PET/CT is highly sensitive for the detection of dopaminergic deficit in nigrostriatal pathways in PD.