Ratio between carotid artery stiffness and blood flow – a new ultrasound index of ischemic leukoaraiosis

Figures & data

Table 1 Clinical and laboratory data of the patients with ILA and controls

Variable	ILA group	Control group	P-value
Patients (n)	52	44
Age (years)	54.90±8.27	52.39±7.34	0.118
Male:female	1.27±0.45	1.32±0.47	0.605
BMI (kg/m^2)	30.40±4.73	30.10±5.51	0.778
Arterial hypertension (%)	34 (0.65)	24 (0.55)	0.286
MAP (mmHg)	103.30±18.77	105.06±14.49	0.617
HR (beats/min)	61.09±11.00	62.92±9.98	0.415
Glucose (mmol/L)	5.31±0.75	5.20±0.87	0.530
Smoking (%)	9 (0.17)	8 (0.18)	0.912
Hypercholesterolemia	34 (0.65)	30 (0.68)	0.775
Cholesterol (mmol/L)	5.03±1.18	5.28±1.12	0.299
LDL (mmol/L)	3.11±1.01	3.27±0.99	0.441
HDL (mmol/L)	1.29±0.39	1.23±0.29	0.366
Triglycerides (mmol/L)	1.76±1.14	1.89±1.21	0.608
Antiaggregation therapy (%)	20 (0.38)	7 (0.16)	0.012
Antihypertensive therapy (%)	28 (0.54)	22 (0.50)	0.711
Statin therapy (%)	15 (0.29)	11 (0.25)	0.675

Notes: Data are presented as mean ± standard deviation for continuous variables and number of subjects (percentage) for categorical variables and P-value.

Abbreviations: ILA, ischemic leukoaraiosis; BMI, body mass index; LDL, low-density lipoprotein; HDL, high-density lipoprotein; HR, heart rate; MAP, mean arterial pressure.

Table 2 Ultrasound parameters of carotid arterial stiffness, carotid blood flow, and ratios of carotid stiffness and blood flow in the ILA group and the control group

Variable	ILA group	Control group	P-value
β	7.57±2.79	6.70±1.77	0.071
Ep (kPa)	115.91±49.07	97.97±29.73	0.038
PWVβ (m/s)	6.47±1.23	5.94±0.87	0.017
Q-ICAs (mm^3/s)	10.962±2.18	11.96±2.87	0.070
Q-ICAd (mm^3/s)	3.50±0.88	3.98±0.80	0.008
Q-ICAm (mm^3/s)	5.99±1.23	6.64±1.44	0.023
β/Q-ICAm (s/mm^3)	1.31±0.55	1.04±0.36	0.008
Ep/Q-ICAm (kPa s/mm^3)	20.20±9.66	15.50±5.89	0.006
PWVβ/Q-ICAm (mm^−2)	1.13±0.32	0.94±0.25	0.003
β/Q-ICAd (s/mm^3)	2.27±1.07	1.73±0.60	0.003
Ep/Q-ICAd (kPa s/mm^3)	35.04±18.59	25.73±9.65	0.003
PWVβ/Q-ICAd (mm^−2)	1.96±0.64	1.56±0.40	0.001

Notes: Data are presented as mean ± standard deviation, P-value, and 95% confidence interval of the difference.

Abbreviations: ILA, ischemic leukoaraiosis; Ep, pressure–strain elasticity modulus; PWVβ, pulse wave velocity beta; β, beta index; Q-ICAs, average systolic blood flow in internal carotid arteries; Q-ICAd, average diastolic blood flow in internal carotid arteries; Q-ICAm, average mean blood flow in internal carotid arteries.

Table 3 Correlations of ultrasound parameters of ILA with ILA

Variable	Spearman’s ρ	P-value
β	0.149	0.153
Ep (kPa)	0.166	0.122
PWVβ (m/s)	0.233	0.030
Q-ICAd (mm^3/s)	−0.286	0.005
Q-ICAm (mm^3/s)	−0.232	0.025
β/Q-ICAm (s/mm^3)	0.227	0.031
Ep/Q-ICAm (kPa s/mm^3)	0.233	0.030
PWVβ/Q-ICAm (mm^−2)	0.254	0.018
β/Q-ICAd (s/mm^3)	0.252	0.016
Ep/Q-ICAd (kPa s/mm^3)	0.257	0.016
PWVβ/Q-ICAd (mm^−2)	0.315	0.003

Notes: Data are presented as Spearman’s rho and P-value. Z-scores of variables were used in the analyses.

Abbreviations: ILA, ischemic leukoaraiosis; Ep, pressure–strain elasticity modulus; PWVβ, one-point pulse wave velocity beta; β, beta index; Q-ICAd, average diastolic blood flow in internal carotid arteries; Q-ICAm, average mean blood flow in internal carotid arteries.

Table 4 Associations of ultrasound parameters of ILA with ILA

Variable	OR	P-value	CI
			Lower	Upper
β	1.472	0.090	0.941	2.303
Ep (kPa)	1.607	0.055	0.990	2.610
PWVβ (m/s)	1.712	0.028	1.061	2.762
Q-ICAd (mm^3/s)	0.541	0.008	0.343	0.853
Q-ICAm (mm^3/s)	0.577	0.016	0.368	0.902
β/Q-ICAm (s/mm^3)	1.848	0.016	1.120	3.050
Ep/Q-ICAm (kPa s/mm^3)	1.946	0.015	1.140	3.323
PWVβ/Q-ICAm (mm^−2)	2.009	0.007	1.207	3.343
β/Q-ICAd (s/mm^3)	2.152	0.010	1.204	3.847
Ep/Q-ICAd (kPa s/mm^3)	2.249	0.010	1.214	4.167
PWVβ/Q-ICAd (mm^−2)	2.441	0.003	1.350	4.412

Notes: Logistic regression: ILA group as a dependent variable, standardized Z-scores of variables were used in the analyses. Data are presented as OR, P-value, and 95% CI of OR.

Abbreviations: ILA, ischemic leukoaraiosis; OR, odds ratio; CI, confidence interval of OR; Ep, pressure–strain elasticity modulus; PWVβ, one-point pulse wave velocity beta; β, beta index; Q-ICAd, average diastolic blood flow in internal carotid arteries; Q-ICAm, average mean blood flow in internal carotid artery.

Table 5 ROC analyses of ultrasound parameters of ILA

Variable	AUC	P-value	95% CI
			Lower	Upper
β	0.587	0.152	0.470	0.704
Ep (kPa)	0.597	0.121	0.478	0.715
PWVβ (m/s)	0.636	0.031	0.518	0.753
Q-ICAm (mm^3/s)	0.365	0.026	0.250	0.480
Q-ICAd (mm^3/s)	0.333	0.006	0.224	0.443
β/Q-ICAm (s/mm^3)	0.632	0.032	0.518	0.747
Ep/Q-ICAm (kPa s/mm^3)	0.635	0.031	0.519	0.752
PWVβ/Q-ICAm (mm^−2)	0.648	0.019	0.532	0.764
β/Q-ICAd (s/mm^3)	0.647	0.017	0.534	0.760
Ep/Q-ICAd (kPa s/mm^3)	0.650	0.017	0.535	0.764
PWVβ/Q-ICAd (mm^−2)	0.683	0.004	0.572	0.795

Notes: Data are presented as area under ROC curve, P-value, and 95% CI. Z-scores of variables were used in the analyses.

Abbreviations: ILA, ischemic leukoaraiosis; AUC, area under ROC curve; ROC, receiver operating characteristic; CI, confidence interval; Ep, pressure–strain elasticity modulus; PWVβ, one-point pulse wave velocity beta; β, beta index; Q-ICAd, average diastolic blood flow in internal carotid arteries; Q-ICAm, average mean blood flow in internal carotid arteries.