Table 2.

CEST/APT and DTI parameters values in the substantia nigra for normal controls and PD patients at different stages.

		Normal (n = 23)	Early-stage PD (n = 12)	Advanced-stage PD (n = 11)	Tests of homogeneity of variances P values	ANOVA			Multiple comparisons P values (95% confidence interval)
						df	F	P values
CEST/APT	MTRasym(3.5 ppm)	1.25 ± 0.18	0.96 ± 0.14	0.81 ± 0.29	0.035	2	5.248	0.007	0.032 (0.02, 0.54), 0.599 (−0.23, 0.54), 0.032 (0.03, 0.84)
	${\text{MTR}}_{\text{asym}}^{\text{total}}$	3.45 ± 0.44	2.68 ± 0.50	2.21 ± 0.95	0.097	2	4.980	0.009	0.141 (−0.19, 1.73), 0.576 (−0.65, 1.59), 0.010 (0.26, 2.23)
DTI	FA	0.36 ± 0.02	0.34 ± 0.02	0.31 ± 0.03	0.790	2	9.630	<0.001	0.149 (−0.01, 0.05), 0.072 (−0.01, 0.07), <0.001 (0.03, 0.09)
	MD	0.68 ± 0.02	0.69 ± 0.03	0.70 ± 0.05	0.003	2	0.429	0.653	0.837 (−0.06, 0.04), 0.943 (−0.09, 0.07), 0.750 (−0.10, 0.05)

MTR_asym(3.5 ppm) was quantified by % water signal intensity. ${\mathit{\text{MTR}}}_{\mathit{\text{asym}}}^{\mathit{\text{total}}}$ was defined as the integral of the MTR_asym spectrum in the range of 0–4 ppm. FA, fractional anisotropy; MD, mean diffusivity. Three P values in multiple comparisons corresponded to the results between normal controls and early-stage PD patients, between early-stage and advanced-stage PD patients, as well as between normal controls and advanced-stage PD patients, respectively. Bold indicates significant change.