Quantitative Measurement of Circumferential Carotid Arterial Strain by Two-dimensional Speckle Tracking Imaging in Healthy Subjects

Background: Two-dimensional speckle tracking imaging (2DS) enables quantitative measurement of left ventricular strain. However, application of 2DS for measurement of circumferential carotid arterial strain (CAS) is not fully elucidated. We investigated the feasibility and reproducibility of measuring CAS by 2DS and determinants of CAS in healthy subjects.

Methods: Fifty-one healthy subjects (20 men and 31 women) with a mean age of 29 ± 11 years were enrolled. Ultrasound examination of bilateral common carotid arteries (CCAs) was performed and short axial views were recorded. The mean intima-media thickness (IMT) of bilateral CCAs was measured using semiautomated edge-detection software. Bilateral peak CAS at systole and time to peak CAS in each region were measured by 2DS. Stiffness parameter β of bilateral CCAs was measured and bilateral cardio-ankle vascular index (CAVI) was recorded. Intraobserver and interobserver variabilities for mean CAS were calculated in 15 subjects.

Results: Of the 612 regions, 577 (94%) had adequate waveforms for measurement of CAS. The mean value of CAS was 6.7 ± 2.1%. Required time for CAS analysis was 128 ± 12 seconds per subject. Multiple regression analysis identified age (P < 0.001) and pulse pressure (P < 0.05) as independent significant determinants of mean CAS. Corrected CAS, which was calculated as mean CAS/pulse pressure, correlated with age, mean IMT, and stiffness parameter β and systolic pressure (P < 0.001), age (P < 0.01), and stiffness parameter β (P = 0.02) were identified as independent significant determinants of corrected CAS. Coefficient of variance (CV) of intraobserver and interobserver variabilities for mean CAS were 8.8% and 5.9%, respectively.

Conclusions: 2DS in the CCAs is simply and quickly performed with high feasibility and excellent reproducibility. In healthy subjects, age and pulse pressure are the most important determinants of mean CAS.