WHERE TO PLACE THE DOPPLER SAMPLE VOLUME IN THE HUMAN MAIN PULMONARY-ARTERY - EVALUATED FROM MAGNETIC-RESONANCE PHASE-VELOCITY MAPS

Objective: To give recommendations for the placement of Doppler sample volumes for blood flow assessment in the human main pulmonary artery. Methods: In 10 healthy volunteers MR-phase velocity measurements were obtained and computing of the mean temporal blood velocity data was p erformed to guide single Feint Doppler velocity recordings, Results: T he mean temporal brood velocity profiles were consistently skewed with the lowest blood Velocities towards the inferior/right vessel wall. B lood velocity indices (ratio of point to mean velocities, where a poin t equals a square of 4 pixels) varied considerably with the lowest ind ices located towards the inferior/right vessel wall. A centrally locat ed fictive sample volume revealed an average blood velocity index valu e (average of all IO subjects) of 1.08 (range 0.99-1.25; s.d. 0.08) wh ere the central point was defined at maximum systole, and a value of 1 .13 (range 0.97-1.34; s.d. 0.11) when the central point was defined in end-diastole. The mean of multiple sample volumes along the inferior/ right to superior/left diameter revealed a blood velocity index of 1.0 1 (range 0.87-1.21, s.d. 0.09) in systole and 1.03 (range 0.87-1.19; s .d. 0.09) in diastole. Conclusions: For practical clinical purposes, s ingle point estimation of the mean blood velocity in the pulmonary art ery should be performed centrally. The use of multiple sample volumes placed along the inferior/right to superior/left diameter improves the mean velocity estimate in healthy volunteers, Further studies should be conducted to reinforce the basis for Doppler velocity recording in the diseased human pulmonary artery as well as to investigate other im portant determinants of Doppler-derived CO, namely angle of insonation and assessment of the cross-sectional area.