Movement Disorder Society - Dublin, Ireland

Objective: To determine whether regional variations in brain microstructural integrity are associated with (a) dopaminergic integrity of the striatum and (b) movement deficits in Parkinson's disease (PD).

Background: Several diffusion tensor imaging (DTI) studies in PD reported regional alterations of brain microstructures. However, whether these alterations seen on DTI correlate with dopaminergic deficits in PD patients has not been determined. We report preliminary findings of joint DTI and dopamine transporter (DAT) imaging as part of the PPMI study.

Methods: DTI data and 123I-DAT SPECT data were acquired in 15 de-novo PD patients (age: 61.5 +/- 8.6 years) at 6 different international MRI sites and processed and analyzed centrally. The PD patients had on average 22+/-6 points on the MDS-UPDRS Part III scale and 40 +/- 14 points on the total UPDRS scale. Fractional anisotropy (FA) in DTI was evaluated voxel- by-voxel in relationship to the 123I-DAT uptake ratio in the putamen and caudate nucleus as well as to the severity of PD symptoms as measured using UPDRS scores.

Results: Reduced 123I-DAT measures of the putamen as well as of the caudate were associated most prominently with reduced FA values near the right supplementary motor areas (SMA) and medial part of the motor cortex (p < 0.001, at a cluster level of 100 voxels). In contrast, increasing symptom severity was associated primarily with reduced FA values bilaterally in the substantia nigra as well as in some regions in the brain stem (p < 0.001, at a cluster level of 100 voxels)

Authors: Norbert Schuff, Katherine Wu, Yu Zhang,  Shannon Buckley,  John Seibyl,  and Kenneth Marek