Table 4.

Associations between eICA tortuosity index and subjects’ characteristics.

Characteristics	Right eICA					Left eICA
	ρa	p-Value	βb	p-Value	VIF	ρa	p-Value	βb	p-Value	VIF
Age (years)	0.138	0.141	0.108	0.241	1.092	0.068	0.467	−0.015	0.868	1.092
Male sex	−0.211	0.023	−0.227	0.021†	1.004	−0.215	0.021	−0.197	0.032†	1.004
BMI (kg/m2)	0.270	0.003	0.053c	0.003†	1.004	0.394	0.000	0.075c	<0.001†	1.004
Hypertension	0.113	0.227	0.003	0.976	1.095	0.161	0.084	0.076	0.394	1.095
DM	0.012	0.901	0.007	0.937	1.051	0.162	0.082	0.094	0.277	1.051
Dyslipidemia	0.097	0.301	0.033	0.712	1.029	0.165	0.076	0.071	0.407	1.029
CAD	−0.092	0.326	−0.060	0.501	1.016	−0.043	0.649	0.011	0.902	1.016
Smoking	−0.069	0.460	0.200	0.053	1.379	−0.026	0.780	0.113	0.256	1.379

^aSpearman’s rank correlation coefficient between eICA tortuosity index and each variable; ρ: Spearman’s correlation coefficient.

^bMultiple linear regression analysis, β: parameter estimate; eICA tortuosity index was converted into natural logarithmic equivalent value for statistical analysis. Right eICA tortuosity: exponentiated coefficient exp(β) for BMI was 1.054, exp(β) for male was 0.797. Left eICA tortuosity: exponentiated coefficient exp(β) for BMI was 1.078, exp(β) for male was 0.821.

^cData are presented as natural logarithmic tortuosity index per unit increase in BMI (kg/m²).

^†Significant variables.

DM, diabetes mellitus; CAD, coronary artery disease; eICA, extracranial internal carotid artery; VIF, variance inflation factor; BMI, body mass index.