Cross sectional, test-retest and longitudinal changes of relative cerebral blood flow in Parkinson's disease

Background This study aimed to quantify relative cerebral blood flow (rCBF, R1) and dopamine transporter (DAT) availability in subjects with Parkinson’s disease (PD) using positron emission tomography (PET) with [ 18 F]FE-PE2I. We investigated group differences in R1, test–retest variability (TRV), associations with DAT availability, and annual longitudinal changes (ALC). Results Cross-sectional (38 PD, 35 age- and gender-matched controls), test-retest (9 PD) and longitudinal (19 PD) cohorts were included. R1 and binding potential (BP ND ) values were estimated in the striatum (STR), substantia nigra (SN), and cortical regions. Group differences in R1 and associations with DAT availability were assessed cross-sectionally. In PD subjects, TRV and ALC over 2 years were calculated. PD subjects showed significantly lower R1 in STR (0.94 ± 0.08 vs. 1.05 ± 0.11, p < 0.001) and occipital cortex (0.99 ± 0.07 vs. 1.04 ± 0.07, p = 0.006) compared with controls. Low to moderate positive correlations was found between R1 and DAT availability in STR and SN of PD subjects (r 2 = 0.41 and 0.3, p < 0.001) and controls (r 2 = 0.28 and 0.42, p < 0.001). TRV was 5.06% in STR [range:4.06;6.82], 5.41% in SN [4.38;9.33] and ranged from 1.47% [0.85;3.72] to 2.80 [1.23;4.42] across cortical regions. ALC in the STR and SN were 1.95% [0.48;4.21] and − 0.47 [-2.42;4.60] and ranged from 0.92% [-0.37;1.35] to 1.17% [0.41;3.46] across cortical regions. Conclusions rCBF is reduced in the striatum and occipital cortex in PD, correlated positively with DAT availability and exhibited adequate test-retest reproducibility. Longitudinal changes of rCBF within 2-y interval were smaller than the TRV, suggesting relative stability of rCBF despite progressive DAT loss. Trial registration number The study was prospectively registered in the EudraCT database (EudraCT No. 2011-002005-30, registered on 26 April 2011; 2017-001585-19, registered on 2 August 2017; and 2017-003327-29, registered on 8 October 2017).