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Measurement Formulas
2
-
14
LOGIQ 7/LOGIQ 7 Pro Advanced Reference Manual
Direction 5116269-100 Rev. 2
Measurement Formulas
Formulas–Generic
Table 2-2: Generic Calculation Formulas
Calc
Mnemonic
Calc Name
Input Measurements
Formula
MaxPG
Maximum Pressure
Gradient
two Doppler blood flow
peak velocities
MaxPG[mmHg]=4x(v1^2-
v2^2)
MeanPG
Mean Pressure Gradient
flow velocities from one
time marker to another
time marker in a Doppler
display
MeanPG[mmHg]=
n
4x (Vi^2)/n
i=1
% Stenosis
Stenosis Ratio
two areas (by ellipse,
trace, circle or distance)
% Stenosis= [1-(A
residual
/
A
lumen
)]x100
PI
Pulsatility Index
two Doppler blood flow
peak velocities and
TAMAX
PI=(V
max
-V
diastole
)/
TAMAX
a
a.Vdiastole = Vmin or Vend-diastole (depends on preset selection)
RI
Resistivity Index
two Doppler blood flow
peak velocities
RI=(V
max
-V
diastole
)/V
max
or
RI=(V
max
-V
min
)/V
max
HR
Heart Rate (beats/minute)
one 2 beat time interval
HR[BPM]=120[sec]/
2beat time [sec]
A/B Ratio
Velocities Ratio
two Doppler blood flow
peak velocities
A/B=V
1
/V
2
TAMAX
Time Averaged Maximum
Velocity (Trace Method is
Peak or manual)
two time marks in a
Doppler display
TAMAX=sum{Vt} from t1
to t2/(t2-t1) [cm/s or m/s]
TAMIN
Time Averaged Minimum
Velocity (Trace method is
Floor)
two time marks in a
Doppler display
TAMIN=sum{V
t
} from t1
to t2/(t2-t1) [cm/s or m/s]
TAMEAN
Time Averaged Mean Velocity
(Trace method is Mean)
two time marks in a
Doppler display
TAMEAN=sum{V
t
} from t1
to t2/(t2-t1) [cm/s or m/s]