Table 1.

Values of the correlation coefficient for the explored image metrics.^a

Image metrics	DTBZ-MRI					RAC-MRI
	α max	DD		UPDRS		α max	DD		UPDRS
Value
Log(BPND)	0.4	0.82** T0.94**	(−0.90**)	0.61** T0.62**	(−0.86**)	–	0.06	(0.21)	0.06	(0.22)
ASD	1.0	0.88**	(−0.91**)	0.63**	(−0.84**)	–	0.07	(0.23)	0.05	(0.24)
AID	1.0	0.72**	(−0.83**)	0.39**	(−0.65**)	–	0.07	(0.26)	0.09	(0.30)
Geometry
VOL	0.2	0.57**	(−0.69**)	0.48**	(−0.68**)	–	0.10	(0.38)	0.06	(0.29)
SAR	0.2	0.56**	(−0.68**)	0.51**	(−0.70**)	–	0.09	(0.32)	0.06	(0.24)
RVD	0.3	0.53**	(−0.70**)	0.46**	(−0.69**)	–	0.11	(0.32)	0.17	(0.29)
VOE	0.2	0.60**	(0.76**)	0.52**	(0.77**)	–	0.12	(0.30)	0.06	(0.28)
RCM	0.3	0.48**	(0.64**)	0.38**	(0.60**)	0.3	0.29*	(0.51*)	0.21	(0.39)
ECM	0.0	0.65*	(−0.75**)	0.59*	(−0.74**)	–	0.16	(0.32)	0.09	(0.27)
CMP	0.5	0.32*	(−0.49*)	0.36**	(−0.53*)	–	0.13	(0.28)	0.12	(0.31)
EXT	0.5	0.31*	(−0.51*)	0.36*	(−0.69**)	0.3	0.36*	(0.51*)	0.40**	(0.50*)
MBR	0.3	0.51**	(−0.62**)	0.53**	(−0.68**)	–	0.09	(0.26)	0.07	(0.25)
Texture
J1V	1.0	0.94**	(0.94**)	0.79**	(0.90**)	–	0.07	(0.24)	0.08	(0.26)
J2V	1.0	0.91**	(0.93**)	0.77**	(0.91**)	–	0.08	(0.25)	0.07	(0.23)

BP_ND, non-displaceable binding potential; AID, index of dispersion of activity values; VOL, region volume; SAR, region surface area; RVD, relative volume difference; VOE, volumetric overlap error; RCM, relative center of mass distance; ECM, region eccentricity; CMP, region compactness; EXT, region extent; MBR, mean breadth; J1V, first moment invariant of activity values; J2V, second moment invariant of activity values.

^aMaximum values of $\overline{R^2}$ and ρ (given in parentheses) between image metrics and clinical metrics, obtained in the DTBZ-MRI and RAC-MRI ROI spaces (using less affected side of putamen). All subjects were included in the analysis. The $\overline{R^2}(\alpha )$ values were obtained by fitting the image metrics with the two-term linear functions of UPDRS and DD. A two-term exponential function was used with BP_ND. Absent $\alpha \text{max}$ indicates that no trend in the correlation strength was observed. The star glyph indicates the significance level: **$P<0.01$, *$P<0.05$, and no glyph for $P>0.05$. ^T Value obtained with three-term exponential fit (BP_ND only).