Noninvasive vascular elastography for carotid artery characterization on subjects without previous history of atherosclerosis.

BACKGROUND

Noninvasive vascular ultrasound elastography (NIVE) was recently introduced to assess mechanical properties (strain or elasticity) of peripheral vessel walls. The goal of this study was to determine strain values in subjects with normal carotid arteries and the reproducibility of these measurements.

METHODS

Sixteen individuals without previous history of carotid atherosclerosis were recruited in four age categories [40-49], [50-59], [60-69], and [70-79] years old. The left and right common and internal carotids (LCC, LIC, RCC, and RIC, respectively) were independently scanned by two radiologists (RAD-A and RAD-B). The axial strain elastograms were computed with the Lagrangian speckle model estimator.

RESULTS

Supported by Bland-Altman analyses, strain values between LCC and RCC were found similar with a Pearson correlation coefficient (r) of 0.83 (p < 0.0001). Equivalently, a good correlation was found between RAD-A and RAD-B for common carotids with r=0.80 (p < 0.0001). Lower strain values (p < 0.001) were measured for male common carotids (1.62 +/- 0.32%) than females (2.21 +/- 0.76%). Regarding the internal carotid strain measurements, the correlation was lower between RAD-A and RAD-B with r=0.52 (p=0.01), but drastically decreased between LIC and RIC (r=0.16, nonsignificant). Male internal carotid strain estimates (p=0.03) were lower (1.48 +/- 0.44%) than in females (1.84 +/- 0.64%). Additionally, male common and internal carotid mean elastic moduli varied from 33-106 kPa, whereas it covered a range of 25-67 kPa for females. Female carotids were more elastic (44 +/- 17 kPa) than males (58 +/- 17 kPa, p <0.001).

CONCLUSION

Strain measurements in common carotids were found reproducible. However, less consistency was observed for the deeper internal carotids. The NIVE imaging method still remains to be validated with pathological cases, but it might provide a unique approach for stroke prevention and characterization of vascular stiffness.