Figure 1. Clinical improvement and changes in [¹⁸F]-dopa uptake following GDNF infusion.

(A) Changes in Unified Parkinson's Disease Rating Scale (UPDRS) scores (Total, Motor, and Activities of Daily Living [ADL] scores) following 39 months of bilateral glial cell line–derived neurotrophic factor (GDNF) infusion and over the subsequent 36-month withdrawal period. (B) [¹⁸F]-dopa uptake constant (Ki) maps at baseline, following 24 months of GDNF infusion, and following 6 and 36 months of GDNF withdrawal, respectively.