GE LOGIQ E9 Service Manual page 182

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5535208-100, R

Tissue Velocity Imaging (TVI) Checks

Introduction

TVI calculates and color codes the velocities in tissue. The tissue velocity information is acquired by

sampling of tissue Doppler velocity values at discrete points. The information is stored in a combined

format with grey scale imaging during one or several cardiac cycles with high temporal resolution.

Preparations

1.) Connect one of the probes, to the scanner's left-most probe connector.

2.) Turn ON the scanner

The 2D Mode window is displayed (default mode).

3.) If needed, adjust the Display's Brightness and Contrast setting.

4.) Press TVI.

5.) Use the trackball (assigned function: Pos) to position the ROI frame over the area to be examined.

6.) Press Select. The instruction Size should be highlighted in the trackball status bar.

If the trackball control pointer is selected, press trackball key to be able to select between

Position and Size controls.

7.) Use the trackball to adjust the dimension of the ROI.

Adjust the TVI Controls

To reduce quantification noise (variance), the Nyquist limit should be as low as possible, without

creating aliasing. To reduce the Nyquist limit: Reduce the Scale value.

The Scale value also affects the frame rate. There is a trade off between the frame rate and

quantification noise.

TVI provides velocity information only in the beam direction. The apical view typically provides the

best window since the beams are then approximately aligned to the longitudinal direction of the

myocardium (except near the apex). To obtain radial or circumferential tissue velocities, a

parasternal view must be used. However, from this window the beam cannot be aligned to the

muscle for all the parts of the ventricle.

PW will be optimized for Tissue Velocities when activated from inside TVI.

Section 3-6-6 "Connecting Probes" on page 3-20

probesSection 9-18 "Probes" on page 9-104

Section 4-3 - Functional checks

for info about connecting the