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Measurement references 6-21
Percent Area Reduction
Taylor K.J.W., P.N. Burns, P. Breslau. Clinical Applications of Doppler Ultrasound , Raven Press, N.Y., (1988),
p.130-136.
Zwiebel W.J., J.A. Zagzebski, A.B. Crummy, et al. “Correlation of peak Doppler frequency with lumen
narrowing in carotid stenosis.”
Stroke , 3: (1982), p.386-391.
% Area Reduction = [1 - A2(cm
2
)/A1(cm
2
)] * 100
where:
A1 = original area of the vessel in square cm
A2 = reduced area of the vessel in square cm
Percent Diameter Reduction
Handa, Nobuo et al., “Echo-Doppler Velocimeter in the Diagnosis of Hypertensive Patients: The Renal
Artery Doppler Technique,”
Ultrasound in Medicine and Biology , 12:12 (1986), p.945-952.
% Diameter Reduction = [1 - D2(cm)/D1(cm)] * 100
where:
D1 = original diameter of the vessel in cm
D2 = reduced diameter of the vessel in cm
Pressure Gradient (PG) in mmHG
Oh, J.K., J.B. Seward, A.J. Tajik. The Echo Manual
.
2nd ed., Lippincott, Williams, and Wilkins, (1999), p.64.
PG = 4 * (Velocity)
2
(velocity units must be meters/second)
Peak E Pressure Gradient (E PG)
E PG = 4 * PE
2
Peak A Pressure Gradient (A PG)
A PG = 4 * PA
2
Peak Pressure Gradient (PGMax)
PGMax = 4 * VMax
2
Mean Pressure Gradient (PGMean)
PGMean = 4 * VMax
2
(average pressure gradient during the flow period)
Pulsatility Index (PI)
Kurtz, A.B., W.D. Middleton. Ultrasound-the Requisites . Mosby Year Book, Inc., (1996), p.469.
PI = (PSV – EDV)/V
where: