Different Clinical Implications of Substantia Nigra R2* and Diffusion Tenser Imaging Changes in Parkinson's Disease (P03.121)

Abstract

Objective: To investigate the clinical implications of MRI R2* relaxation rate and DTI fractional anisotropy (FA) in different areas of the SN in PD. Background R2* and FA values may reflect different pathophysiologies in the SN of Parkinson9s disease (PD) patients. The majority (>80%) of PD-related cell death is known to occur prior to the diagnosis and affect more ventral than dorsal parts of SN. Design/Methods: High resolution MRI (T2*, DTI) were obtained from 28 Controls and 40 PD subjects with 15 early (disease duration≤1 year), 14 medium (disease duration 2-5 years), and 11 later (disease duration>5 years) stage disease. FA and R2* in dorsal and ventral SN of all and each stage of PD subjects were compared to those of Controls, and correlated with clinical measures (UPDRS-III, akinetic/rigidity, and tremor scores “off” drug, disease duration, and levodopa equivalent dosage), after controlling for age and gender. Results: Compared to Controls, PD subjects demonstrated significantly increased R2* and reduced FA in the SN overall. R2* changes presented a similar pattern in both ventral and dorsal SN and correlated with all clinical measures except tremor scores. FA changes in ventral and dorsal SN were not correlated with clinical measurements, except for tremor score in dorsal SN. The pattern of change in the two regions, however, was different. Ventral SN changes occurred early and persisted through later stages of PD, whereas FA changes in dorsal SN seemed not to be present early in disease but became significant in later stages. Conclusions: The differential clinical correlation of R2* and FA measures in the SN supports the notion that FA changes in ventral SN at earlier stages may reflect existing PD-related cell death, but R2* may be gauging the changes of progression that are either pathoetiological or compensative related. Further studies are warranted. Supported by: NS060722 (GD, MML, QXY, and XH), and the HMC GCRC (NIH M01RR10732) and GCRC Construction Grant (C06RR016499). Disclosure: Dr. Du has nothing to disclose. Dr. Lewis has nothing to disclose. Dr. Sen has nothing to disclose. Dr. Shaffer has nothing to disclose. Dr. Styner has nothing to disclose. Dr. Wang has nothing to disclose. Dr. Yang has nothing to disclose. Dr. Huang has nothing to disclose.