Table 4.

Correlation between FA, ADC Value and HI, Course^a

Pearson correlation coefficient	C2 DRG	C3 DRG	GON
FA value
vs. course	–0.019	–0.040	–0.096
vs. HI	0.015	–0.263	–0.420*
ADC value
vs. course	0.232	–0.299	–0.164
vs. HI	–0.075	0.136	0.531*

FA: fractional anisotropy, ADC: apparent diffusion coefficient, HI: headache index, DRG: dorsal root ganglia, GON: greater occipital nerve.

^aThe value = symptomatic value – asymptomatic value.

^*P < 0.05.