General Measurement 3-13
Parameters Descriptions
Average
Pressure
Gradient
/
Average pressure gradient in the whole traced Doppler
spectrum.
MPG: Maximum Pressure Gradient.
()() ( )
ab
Tb
Ta
TTdttVmmHg −=
∫
2
4)(MPG
Where V(t) is the peak systolic velocity.
MMPG: Mean velocity Mean Pressure Gradient.
(Obtained during auto-spectrum calculation.)
()() ( )
ab
Tb
Ta
TTdttVmmHg −=
∫
2
4)(MMPG
Where V(t) is the mean systolic velocity.
VTI Velocity-Time Integral
Velocity-time Integral. It is the integral of the product of
Doppler instantaneous velocity and the total time interval.
()
∫
b
a
T
T
dttVmVTI ＝)(
AT Acceleration Time
It is the time of the blood velocity accelerating from the
end of diastole to the systolic peak. Generally, it's the
time interval between the end of the first cardiac cycle
and the peak of the next cardiac cycle. Choose the first
peak when two peaks existing the systolic cycle.
DT Deceleration Time Deceleration Time.
HR Heart Rate
Calculates the heart rate per minute by measuring the
time interval of one cardiac cycle.
S/D /
PS/ED.
S/D (No unit) = PS (m/s) / ED (m/s)
D/S /
ED/PS.
D/S (No unit) = ED (m/s) / PS (m/s)
PI Pulsatility Index
Pulsatility Index.
PI (No unit) = |(PS (m/s) – ED (m/s)) / TAMAX (m/s)|
RI Resistive Index
Resistance index. RI (No unit) = |(PS (m/s) – ED (m/s)) /
PS (m/s)|
θ /
Correction angle is the spectrum angle during
measurement, which is a result obtained from a non D
trace measurement tool and usually is displayed together
with the spectral measurement results.
PV Peak Velocity
The peak velocity in systolic or diastolic cycle (with no
difference), which is the highest velocity of the red blood
cell(s) that cross the sample volume, and it can be used
to examine the venous vessel.
NOTE:
1. In the formulae above, T means time, the unit is s; V means the velocity at each point during T,
the unit is cm/s; a is the traced starting point, while b is the traced end point.
2. The above parameters are all the information obtained in D trace, while in application, the
system only displays part of them according to operation and preset.
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