Special Echo Applications

3D echo advantages

• Elimination of geometrical assumptions when evaluating cardiac chamber volumes and mass

• Quantification of complex geometric shape volumes with accurate volumetric evaluation of regurgitant lesions and shunts with color Doppler

•  Viewing structures from any perspective with a realistic presentation of the heart valves

•  Assessment of lesions in simultaneous multiplanes and multi-slice mode

•  Assessment of regional LV wall motion and quantification of systolic dyssynchrony

All 3-D echo images are acquired in what is termed “volumes” derived from thousands of ____

voxels

voxels

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

operating frequencies of 3D echo

2.5-5 MHz as high as 7 MHz for TEE

Real-time narrow 3D section

beat by beat view with a wider image plane than standard 2-D imaging that can be rotated to view from different perspectives; looks like a thick slice

Real-time 3D zoom volume-rendered images

 full volume image of an enlarged area of interest that is rotated to show the structure of interest in a “surgical' view

3D Full volume

multiple beat volumetric imaging stitches together narrow volumes of data over several cardiac cycles; primarily used for accurate software-assisted 3-D quantification of chamber size and volume displacement (EF)

Simultaneous multple plane method

simultaneous display of two 2-D image planes has the ability to adjust the rotation angle, tilt, and elevation of the second image

3D color doppler imaging 

 uses real-time or full-volume color Doppler data acquisition, but at frame rates lower than for imaging data; new higher voxel rate capabilities using HVR (high volume rate) settings enable the capture of better images during flow cycles like regurgitation, and the possibility to quantify regurgitant jets from 3-D dataset

3-D image displays,

• Volume rendered 3-D images

• Surface-rendered images

• Wireframe images

• Simultaneous display of multiple 2-D images

• Graphic display of 3-D parameters versus time

Focused or limited 3D echo scanning protocol

TTE

Complete 3D evalution scanning protocol

TTE

Clinical Applications of 3-D Echocardiography

• Chamber quantification; LV volumes and EF, RV volume, LA volume

• Cardiac valves evaluation for stenosis and regurgitation

• Guidance of transcatheter procedures

How is LV function described? 

measures of EF, regional wall motion changes, and assessment of diastolic filling

longitudinal direction

the base moves toward the apex

radial direction

walls thicken

circumferential direction

cavity size decreases perpendicular to long axis of the chamber

Torsion

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 (cm)

velocity

the speed of movement of a cardiac structure or myocardial element (m/S)

strain

the fractional change in length of a myocardial segment (+/- %)

strain rate

the rate of change in strain (unit per 1 sec)

rotation

the circular motion of the LV myocardium around its long axis (°)

twist

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

torsion

the gradient in rotation angle from base to apex (°/cm)

Doppler Flow Velocity (PW)

measures low-amplitude, high velocity signals from moving blood cell

Doppler tissue velocity (DTI/TDI)

measures high-amplitude, low velocity signals from myocardium

Tissue doppler strain rate

based on difference in TDI velocity between sample volumes divided by distance between them 

formula for strain rate

SR =(V1- V2)/D (s^-1)

Tissue doppler strain

a measure of deformation - the difference between the final length and original length divided by the original length, as a %

formula for strain

Strain =(l - l_o) / l_o x 100

negative strain

shortening = contraction

positive strain

lengthening = relaxation

During systole, strain ____ rapidly until end-systole is reached 

decreases ↓

During diastole, a rapid ____ in strain occurs during early phase of diastolic filling followed by a plateau in diastasis, then another increase with atrial contraction

increase ↑

there zero strain (baseline) at ______

end-diastole = ventricle is fully relaxed, no deformation 

maximum negative strain occurs at _____

end-systole

Speckle tracking strain imaging

tracks the motion of “speckles” on myocardium

speckles

markers created by the interference patterns that are generated by the reflected ultrasound; stable, allowing the tracking of myocardial motion.

kernel

the region of speckles being tracked in a single frame

advantages of speckle tracking over DTI

• simpler data acquisition

• lack of angle dependence

• direct measurement of strain 

• multiple simultaneous measurements

• ability to perform analysis after image aquisition

Longitudinal strain (GLS) 

AP4, AP2, AP3

circumferential strain (shortening)

PSAX at mid ventricle

Radial strain (thickening)

PSAX

contrast echocardiography

the injection of an agent into the bloodstream that increases the echogenicity of the blood or myocardium, improving visualization of cardiac chambers and myocardial tissue.

main purpose of contrast echo

To enhance ultrasound images by producing opacification of cardiac chambers or increasing the density of the myocardium.

contrast agents are used for right-heart opacification

Agitated saline, followed by a contrast agent mixed with non-agitated saline for improved enhancement.

contrast agents are used for left-heart and myocardial opacification

solubility fluorocarbon gas in stabilized microbubbles encapsulated with denatured albumin or monosaccharides

ultrasound instrument settings during contrast imaging

• Lower mechanical index (MI) to about 0.5

• Set focal depth to middle/near field

• Use a lower transducer frequency

• Increase overall gain and dynamic range

*helps minimize microbubble destruction

applications of contrast echo

1. Detection of intracardiac shunts

2. Enhancement of Doppler signals

3. Left-ventricular (LV) opacification

4. Myocardial perfusion assessment

intracardiac echocardiography (ICE)

invasive, catheter-based imaging modality that allows visualization of cardiac structures and blood flow with doppler

instrumentation of ICE

catheter-like probe inserted through IVC, RA, RV from femoral vein

Applications

• guiding device closure of IAS 

• guiding radio frequency Pv ablation 

• monitoring transcatheter valve replacement

• peri-interventional imaging of AoV/MV