Special Echo Applications - week 9

Voxel

geometrically cubed area (cm3) compared to the flat 2-D pixel in conventional echo

Longitudinal direction

the base moves toward the apex

Radial direction

walls thicken

Circumferential direction

cavity size decreases perpendicular to the long-axis of the chamber

Torsion

twisting motion: the apex and the base rotate in opposite direction during contraction

Displacement

the distance a cardiac structure or myocardial element moves between consecutive image frames, measured as a distance (cm)

Velocity

-the speed (displacement per time unit) of movement of a cardiac structure or myocardial element, reported as velocity (cm/s)

Strain

the fractional change in length of a myocardial segment; a unitless measure of myocardial deformation, reported as a positive or negative percentage

Strain rate

the rate of change in strain with units of 1 per second

Rotation

the circular motion of the LV myocardium around its long-axis measured in degrees

Twist

the absolute difference in rotation between the LV base and apex (degree)

Torsion

the gradient in rotation angle from base to apex, measured as degrees per cm

Doppler Flow Velocity

measurements are based on the backscatter of low-amplitude, high-velocity signals from moving blood cells

Doppler Tissue Velocity

Doppler Tissue Imaging (DTI) or Tissue Doppler Imaging (TDI)

- the measurements are based on the high-amplitude, low-velocity signals reflected from the myocardium; TDI measurements depend on a parallel alignment between the US beam and the direction of the myocardial motion

Tissue Doppler Strain Rate Imaging

is based on the difference in TDI velocity (V) between sample volumes divided by the distance (D) between them

SR (strain rate) =

(V1 - V2)/D

measured by seconds-1 or /s

Tissue Doppler Strain

is a measure of deformation defined as the difference between the final length (l) and the original length (l0) divided by the original length, as the percentage of length:

Strain =

(l - l0)/l0 x 100

Speckles

acoustic markers created by the interference patterns that are generated by the reflected ultrasound; they are relatively stable allowing the tracking of myocardial motion

Kernel

the region of speckles being tracked in a single frame, and represents the signature pattern of the reflected ultrasound

Longitudinal Strain or Global Longitudinal Strain (GLS)

measured from apical views:AP 4-Ch, AP 2-Ch and AP 3-Ch

Circumferential Strain (shortening)

measured from PSAX at mid ventricle

Radial Strain (thickening)

measured from PSAX

Right heart opacification

agitated saline followed by contrast agent mixed with non agitated saline for enhancement

Left heart and myocardium

contrast agents with trans pulmonary passage that consist of air or low-solubility fluorocarbon gas in stabilized micro bubbles encapsulated with denatured albumin or monosaccharides

Intracardiac Echocardiography (ICE)

an invasive, catheter-based, imaging modality that allows visualization of cardiac structures and blood flow with the use of Doppler imaging

• catheter-like US probe is passed into the IVC/ RA/RV from the femoral vein