SIMPLE WAY TO RESOLVE THE RANGE AMBIGUITY

Purpose: The purpose of this study was to test the hypothesis that wit h the range gate fixed, random adjustment of the pulse repetition freq uency will offer a rapid and accurate way to avoid misinterpretation o f range ambiguity. Background: Traditionally, to avoid the misdiagnosi s of Doppler artifacts caused by range ambiguity, time must be spent o n checking the flow patterns in the calculated phantom range gates. Me thods: Twenty-four patients (mean age 64 +/- 15 years, 15 men, and nin e women) with mitral regurgitation were included in the study. Pulsed Doppler evaluation teas performed with sample volume initially at the shallow left ventricle and then, along the direction of ultrasonic bea m, at the calculated range gate distal to the mitral valve to search f or the high velocity Doppler signal. The highest velocity scale was in itially selected. After detection of high velocity signal, the velocit y scale was lowered to achieve the lower pulse repetition frequency. R esults: For all patients, a high velocity regurgitant Doppler signal c ould be recorded both distal to the mitral valve and at the shallow le ft ventricle. Such signal persisted at the range gate distal to the mi tral valve but disappeared at the range gate at the shallow left ventr icle after manual adjustment of the velocity scale. The sensitivity, s pecificity, and accuracy of disappearance of the high velocity Doppler signal after adjustment of the pulse repetition frequency for confirm ation of a phantom phenomenon are 100% 100%, and 100% respectively. Co nclusions: Without the necessity of exact information about the pulse repetition frequency used, random adjustment of the pulse repetition f requency for the selected gate range is a rapid and exact method for i nitial differentiation of in, situ from phantom, signal in pulsed Dopp ler echocardiography.