5-60 Image Optimization
The user must be sure that there is minimal movement of the participating persons (e.g., mother and
fetus), and that the probe is held absolutely still throughout the acquisition period.
Movement will cause a failure of the acquisition. If the user (trained operator) clearly recognizes a
disturbance during the acquisition period, the acquisition has to be cancelled.
One or more of the following artifacts in the data set indicate a disturbance during acquisition:
Sudden discontinuities in the reference image B
These are due to motion of the mother, the fetus or fetal arrhythmia during acquisition.
Sudden discontinuities in the color display
Motion of the mother, the fetus or fetal arrhythmia affects the color flow in the same way it affects the
gray image.
Fetal heart rate far too low or far too high
After acquisition the estimated fetal heart rate is displayed. If the value does not match the
estimations based on other diagnostic methods at all, the acquisition failed and has to be repeated.
Asynchronous movement in different parts of the image
e.g., the left part of the image is contracting and the right part is expanding at the same time.
The color does not match the structure in the display format of grey mode
The color displays above or beneath the actual vessels.
Color “moves” through the image in a certain direction:
This artifact is caused by a failure in detecting the heart rate due to low acquisition frame rate.
Use higher acquisition frame rate for better result.
CAUTION
:
1. In all of the above cases the data set has to be discarded and the acquisition
has to be repeated.
2. It is not allowed to perform the STIC fetal cardio acquisition if there is severe
fetal arrhythmia.
WARNING
:
Diagnoses made only by assessing this 3D/4D acquisition are not permitted.
Every diagnostic finding has to be evaluated in 2D as well.
NOTE
:
The user must be sure that no one of the participating persons (mother, fetus, and user)
moves during the acquisition. A movement of anyone will cause a failure of the
acquisition. If the user recognizes a movement during the scan, the acquisition has to be
cancelled!
5.11.6.1 Basic Procedures for STIC
1. Obtain a feasible 2D image (fetus heart).
To observe a small structure, zoom in the interested part (Usually Spot zooming is applied for good
image quality).
2. Toggle
konb to enter 3D/4D acquisition preparation mode.
3. Tap [STIC] to enter STIC acquisition preparation mode.
4. Set the acquisition, displaying related parameters.
Select the parameter package.
Set the acquiring time and angle according to the target size and the motion conditions.
For fetus of 20-30 weeks, the acquisition time range are: 10
～
12.5s, and the angle range are:
10-20°.
