Using Ultrasonography, Shear Wave Elastography, Strain Imaging, and 3-D Volume Ultrasonography on Cardiovascular Disease

The subject will be asked to lay on a hospital bed for ultrasound imaging of the arteries. The subject will have an automatic blood pressure cuff put on to measure blood pressure. The subject will also have a three-lead ECG taken during the experiment. The artery will be visualized using ultrasound imaging, and the depth of the arterial wall will be noted. The focal depth on the device will be set to measure shear wave propagation in the walls of the artery. Measurements will be made at multiple locations along the artery's length and at different phases of the cardiac cycle determined by ECG gating. Either or both the Verasonics or GE Logiq systems will be used for measurements. Measurements made with these systems use acoustic output within the FDA regulatory limits of diagnostic imaging.

Researchers will use the Verasonics device to acquire data for measurement of wave velocity in the tissue of interest (arterial walls and surrounding tissue) due to the pressure pulse from ejection of blood by the heart into the systemic circulation. Using ECG gating we can regulate the timing of the individual acquisitions. In each acquisition, high frame rate ultrasound imaging is used to acquire data to measure the motion of the propagating waves. Multiple measurements on different heartbeats are made with varying delays to obtain measurements throughout the heart cycle assuming at that the behavior during consecutive heartbeats is similar. Multiple measurements will be made in a given artery and multiple locations in the arterial wall.

Will be done using Lumason (Bracco Diagnostics, Inc) administered intravenously via slow hand infusion. Real-time contrast-enhanced carotid cine-loop (longitudinal and short axis) images obtained at least 3 seconds before and 5 minutes after the appearance of the contrast effect in the lumen of the determined artery will be acquired and digitally stored for off line analysis. Up to two vials will be used for a study.

Measurements will be performed offline on the workstation using Echo PAC software (GE Healthcare Inc., Princeton, NJ). The media-adventitia interface of the arterial wall will be manually traced from a still frame image. The circumferential and radial strain curves will be automatically obtained. Measurements of the peak radial and circumferential strain, strain rate will be obtained. If arterial plaque is identified: A region of interest will be placed at the plaque in 3 different regions: 2 shoulder regions and the fibrous cap top, the measurement results of the peak longitudinal, radial and circumferential strain, strain rate will be acquired by the software.

When generating a 3D volume the ultrasound data can be collected in 4 common ways. Freehand, which involves tilting the probe and capturing a series of ultrasound images and recording the transducer orientation for each slice. Mechanically, where the internal linear probe tilt is handled by a motor inside the probe. Using an endoprobe, which generates the volume by inserting a probe and then removing the transducer in a controlled manner. The fourth technology is the matrix array transducer that uses beam steering to sample points throughout a pyramid shaped volume