Siemens ACUSON Cypress

ACUSON Cypress™ Operator’s Manual 7-15
Vascular Formulas and References
Doppler Formulas
TABLE 36. Doppler Formulas (Vascular)
Type Formula Units
Resistance
Index (RI)
Maximum Velocity is the peak Systolic velocity.
Minimum Velocity is the end Diastolic velocity.
—
Pulsatility
Index (PI)
Maximum Velocity is the peak Systolic velocity.
Minimum Velocity is the end Diastolic velocity.
TAV Maximum is the time-averaged Maximum velocity. Time
Averaged Velocity Maximum is the averaged (mean) value of
the maximum Doppler shift frequency.
—
Volume Flow
TAVMax is the time-averaged maximum velocity (m/s). Time
Averaged Velocity Maximum is the averaged (mean) value of
the maximum Doppler shift frequency.
CSA is Cross Sectional Area (cm2).
Factor 60 converts to ml/min.
l/min
(liters/
minute)
Ratio
—
Systolic/
Diastolic
(S/D)
—
Internal
Carotid/
Common
Carotid Ratio
(IC/CC)
ICA velocity is the highest Internal Carotid Artery Peak Sys-
tolic velocity.
CCA velocity is the mid Common Carotid Artery Peak Systolic
velocity.
—
Maximum Velocity Minimum Velocity–()
Maximum Velocity
--------------------------------------------------------------------------------------------------------
Maximum Velocity Minimum Velocity–()
TAV Maximum
--------------------------------------------------------------------------------------------------------
TAVMax CSA×
60
10
4
-------- 10
3
××
Velocity A
Velocity B
--------------------------
Systolic Velocity
Diastolic Velocity
-------------------------------------------
Highest ICA Velocity
Mid CCA Velocity
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