NOTE
The gastric volume calculation uses the following two equations depending on the age:
Table 7. Gastric Volume Equations
Age range Equation
>= 18 years gastric volume (mL) = 27 + 14 * (MAD * MCD * pi / 4) - 1.28 * Age (in years)
4-18 years gastric volume (mL) = -7.8 + 3.5 * (MAD * MCD * pi / 4) + 0.127 * Age (in months)
8.4. Carotid Diameter Reduction Calculation
The Carotid Diameter Reduction calculation can be used to measure the percentage of the diameter reduction of the
carotid, or any other vessel, by measuring the full diameter of the carotid and the un-obstructed diameter.
1. From the scan screen select the "Vascular: Carotid" preset.
2. Select the Actions button
on the bottom right corner of the screen.
3. Under the “Calculations” heading, select either the Left Diameter Reduction or the Right Diameter
Reduction. Both tools operate in the same way, except one automatically labels the captured images with
“Left” and the other one with “Right”.
4. For best results it is recommended to acquire the image in the transverse view.
5. When you have frozen an appropriate view, select the Actions button
on the bottom of the screen.
6. You will have the option of selecting Artery Diameter (AD) to measure the full diameter of the artery or the
Lumen Diameter (LD) to measure the diameter of the un-obstructed part of the artery.
7. Adjust calipers as appropriate, then select “Confirm” once you are satisfied with caliper placement. Once you
confirm, an image will be automatically captured and the measurement will be added to the Notes section of
your current study.
a. To delete a measurement, select the label and select "x".
b. To edit a measurement, delete it from the report and re-add it by following the steps above.
8. Once you’ve added both measurements, the estimated diameter reduction will appear at the bottom of the
screen.
9. You will exit the diameter reduction calculation package when the study is uploaded. To exit the calculation
package before uploading a study, select the "x" next to “Left Diameter Reduction” or “Right Diameter
Reduction” on the bottom of the scan screen. You will be prompted to confirm exporting or deleting of captured
measurements if you exit before uploading your study.
NOTE
Once the carotid diameter reduction calculation package is exited, the inputs may not be
edited.
10. When the results of the diameter reduction calculation is exported, the output will be available in the Notes field
of the study. This can be retrieved and edited in the Study screen prior to study upload.
NOTE
The carotid diameter reduction uses the following formula:
Diameter reduction (percentage) = (1 - LD / AD)
Carotid Diameter Reduction Calculation
Manual Calculations Packages 45
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