In vivo carotid strain imaging using principal strains in longitudinal view

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Cardiovascular Research

Background:

• Carotid plaque rupture is a major cause of stroke.
• Ultrasound strain imaging offers a noninvasive method to assess plaque instability.
• Axial, lateral, and shear strains are angle-dependent measures of plaque strain.

Purpose of the Study:

• To compare angle-dependent (axial, lateral, shear) and angle-independent (principal) strains in carotid plaque.
• To evaluate the relationship between different strain measures and plaque instability using defined indices.
• To investigate the influence of insonification angle on strain measurements.

Main Methods:

• Ultrasound strain imaging was performed on 76 patients with carotid plaque.
• Angle-dependent (axial, lateral, shear) and angle-independent (principal) strains were analyzed.
• Three strain indices (AMS, MMS, MSD) were calculated to quantify strain characteristics.

Main Results:

• Maximum principal strain demonstrated higher values compared to axial strain (AMS: slope=1.6, intercept=2.4%).
• Maximum shear strain also showed higher values compared to shear strain (AMS: slope=1.15, intercept=0.21%).
• Insonification angle did not significantly affect the relationship between angle-dependent and independent strain values across different patient subgroups.

Conclusions:

• Principal strains offer a more robust measure of carotid plaque instability compared to angle-dependent strains.
• These findings support the use of principal strains in ultrasound imaging for better prediction of plaque rupture risk.
• Insonification angle has a limited impact on the comparative analysis of principal versus conventional strain measures.