Table 3.

Ratios of left and right structures relative to non-PD peers.

		Structure	L-PD	R-PD	All PD
Volume only		Putamen	1.17	1.24	1.22
		Caudate nucleus	0.83	0.32	1.27
		Hippocampus	0.99	0.86	0.90
Shape considering volume		Putamen	1.36	0.39	0.68
		Caudate nucleus	1.71	0.00	0.44
		Hippocampus	–	–	0.54
Shape only		Putamen	2.84	2.30	0.84
		Caudate nucleus	2.23	0.00	0.91
		Hippocampus	–	–	–
	More left structure atrophy relative to right
	More right structure atrophy relative to left

All values >1 indicate more right side atrophy whereas all values <1 indicate more left side atrophy. For volume only, the value was calculated as the PD mean volume difference from non-PD mean volume as a ratio of mean non-PD volume (left mean non-PD structure volume—left mean PD structure volume/left mean non-PD volume) to (right mean non-PD structure volume —right mean PD structure volume/right mean non-PD volume); the ratio is thus left/right where a value >1 = smaller right structure than left and value <1 = smaller left than right. For both shape considering volume and shape only, the value was calculated as the ratio of [right number of significantly different voxels (PD relative to non-PD)/total structure voxels] to [left number of significantly different voxels (PD relative to non-PD)/total structure voxels]; the ratio is thus right/left where a value >1 = more atrophy on the right than left and <1 = more left atrophy than right. – indicates no group difference and thus no way to assess asymmetry.