Purpose: To assess correlations between the degree of dopaminergic depletion measured using single-photon emission computed tomography (SPECT) and different clinical parameters of disease progression in Parkinson's disease (PD).
Methods: This retrospective study included 970 consecutive patients undergoing (123)I-ioflupane SPECT scans in our institution between 2003 and 2013, from which we selected a study population of 411 patients according to their clinical diagnosis: 301 patients with PD (69.4 ± 11.0 years, of age, 163 men) and 110 patients with nondegenerative conditions included as controls (72.7 ± 8.0 years of age, 55 men). Comprehensive and operator-independent data analysis included spatial normalization into standard space, estimation of the mean uptake values in the striatum (caudate nucleus + putamen) and voxel-wise correlation between SPECT signal intensity and disease stage as well as disease duration in order to investigate the spatiotemporal pattern of the dopaminergic nigrostriatal degeneration. To compensate for potential interactions between disease stage and disease duration, one parameter was used as nonexplanatory coregressor for the other.
Results: Increasing disease stage was associated with an exponential decrease in (123)I-ioflupane uptake (R(2) = 0.1501) particularly in the head of the ipsilateral caudate nucleus (p < 0.0001), whereas increasing disease duration was associated with a linear decrease in (123)I-ioflupane uptake (p < 0.0001; R(2) = 0.1532) particularly in the contralateral anterior putamen (p < 0.0001).
Conclusion: We observed two distinct spatiotemporal patterns of posterior to anterior dopaminergic depletion associated with disease stage and disease duration in patients with PD. The developed operator-independent reference database of 411 (123)I-ioflupane SPECT scans can be used for clinical and research applications.
Keywords: 123I-ioflupane SPECT; Disease duration; Disease stage; Parkinson’s disease; Voxel-wise analysis.