Cardiac Shear Wave Elastography Using a Clinical Ultrasound System

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Cardiovascular Ultrasound

Background:

• Tissue stiffness is a critical factor in cardiovascular health and disease.
• Shear wave velocity (SWV) is a direct measure of tissue stiffness.
• Accurate and accessible methods for measuring SWV in cardiac applications are needed.

Purpose of the Study:

• To demonstrate that a standard clinical cardiac ultrasound system can accurately measure shear wave velocity.
• To validate the use of conventional, unmodified tissue Doppler imaging (TDI) for SWV assessment.
• To evaluate the feasibility of this technique in both phantom and in vivo models.

Main Methods:

• Utilized a research ultrasound platform for inducing and tracking shear waves as a reference.
• Employed a clinical cardiac ultrasound system (Philips iE33) with tissue Doppler imaging (TDI) at high frame rates (400-700 Hz).
• Tested the method on five tissue phantoms of varying stiffness and in vivo on a healthy individual and patients with cardiac pathologies.

Main Results:

• Shear wave velocities measured by the clinical TDI system closely matched those from the research platform (mean difference 0.18 ± 0.22 m/s).
• The limits of agreement between the systems were -0.27 to +0.63 m/s.
• In vivo, increased SWV was observed in the interventricular septum during aortic valve closure in patients with expected increased myocardial stiffness.

Conclusions:

• Conventional clinical cardiac ultrasound with TDI can reliably determine shear wave velocity.
• This non-invasive method offers a practical approach to assess cardiac tissue stiffness.
• The technique holds potential for diagnosing and monitoring cardiovascular diseases related to altered myocardial stiffness.