Effects of Levodopa Therapy on Cerebral Arteries and Perfusion in Parkinson's Disease Patients

Background Levodopa is the most-commonly used therapy for Parkinson's Disease (PD). Imaging findings show increased cerebral blood flow (CBF) response to levodopa, but the artery morphological change is less studied. Purpose To investigate the effect of levodopa on cerebral arteries and CBF. Study Type Prospective. Population 57 PD patients (56 +/- 10 years, 26 males) and 17 age-matched healthy controls (AMC, 57 +/- 9 years, 9 males) were scanned at baseline (OFF). Patients were rescanned 50 minutes after taking levodopa (ON). Field strength and sequence 3 T; Simultaneous noncontrast angiography intraplaque imaging (SNAP) based on turbo field echo; Pseudo-continuous arterial spin labeling (PCASL) based on echo-planner imaging. Assessment The Unified Parkinson's Disease Rating Scale (UPDRS-III) was used to assess the disease severity. Length and radius of arteries were measured from SNAP images. CBF was calculated from PCASL images globally and regionally. Statistical tests Mann Whitney U tests were conducted in comparing PD vs. AMC. Wilcoxon matched-pairs signed rank tests were used in comparing OFF vs. ON, and the more-affected vs. the less-affected hemisphere in PD. Linear regressions were performed to test the correlations of neuroimaging findings with behavioral changes. Significance threshold was P < 0.05 with Bonferroni correction. Results PD patients were identified with significantly lower CBF (PD OFF Mean = 40.15 +/- 5.99, AMC Mean = 43.48 +/- 6.21 mL/100 g/min) and shortened total artery length (PD OFF Mean = 5851.07 +/- 1393.45, AMC Mean = 7479.16 +/- 1335.93 mm). Levodopa elevated CBF of PD brains (PD ON Mean = 41.48 +/- 6.32 mL/100 g/min) and expanded radius of proximal arteries. Artery radius change significantly correlated with CBF change in corresponding territories (r = 0.559 for Internal Carotid Arteries, r = 0.448 for Basilar Artery, and r = 0.464 for Middle Cerebral Artery M1). Global CBF significantly related to UPDRS-III (r = -0.391) post-levodopa. Data conclusion Levodopa can increase CBF by dilating proximal arteries. Level of Evidence 1 Technical Efficacy Stage 4