BK Medical bkSpecto, Руководство для продвинутых пользователей

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88 Chapter 8 August 2018 bkSpecto Advanced User Guide (16-01642-01)
Table 8-2. Formulas for the main Doppler indices.
The correct placement of markers for measuring RI and PI is indicated in Fig 8-3.
“Mean” in the Pulsatility index formula is the averaged max flow velocity.
All main Doppler indices are measured together.
PS, ED, RI, PI, S/D
You can measure the Doppler indices in different ways:
•
Automatic – the Doppler curve is drawn automatically and you position markers
on it.
•
Manual – you draw the Doppler curve manually (freehand).
•
Real-time – the system calculates and displays the indices automatically in real
time.
To measure the Doppler indices automatically:
1
Tap Measure and select Auto.
2
Position one marker at the start systolic (SS) frequency.
3
Position the second marker at the end diastolic (ED) frequency.
The Ps, Ed, PI, RI and S/D measurements are displayed to the left of the image.
Minimum two cycles must be included between the time cursors, and the calculated
index is an average over the cycles.
NOTE:
Make sure that the trace appears to be a good fit to the spectrum so that the
basis for the automatic calculation is correct.
To measure PI manually:
1
Select Doppler Trace Freehand .
2
Position the marker on the start systolic (SS) frequency and tap.
3
Draw a curve that traces a line along the whole maximum spectrum through the
peak systolic (PS) frequency, the minimum diastolic (MD), and onto the end
diastolic (ED) frequency.
4
Tap.
The Ps, Ed, PI, RI and S/D measurements are displayed.
If the traced curve covers more than one cycle, the PI is calculated as the average of
each cycle.
Index Formula
A/B ratio PS/ED
Resistance index (PS-ED)/PS
Pulsatility index (PS-MD)/Mean