title: Where to place the Doppler sample volume in the human main pulmonary artery: evaluated from magnetic resonance phase velocity maps.
abstract: 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 performed to guide single point Doppler velocity recordings.
  
  
  RESULTS
  The mean temporal blood velocity profiles were consistently skewed with the lowest blood velocities towards the inferior/right vessel wall. Blood velocity indices (ratio of point to mean velocities, where a point equals a square of 4 pixels) varied considerably with the lowest indices located towards the inferior/right vessel wall. A centrally located fictive sample volume revealed an average blood velocity index value (average of all 10 subjects) of 1.08 (range 0.99-1.25; s.d. 0.08) where 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 1.01 (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, single point estimation of the mean blood velocity in the pulmonary artery 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 important determinants of Doppler-derived CO, namely angle of insonation and assessment of the cross-sectional area.
authors.affiliation: Department of Anaesthesia, Skejby Sygehus, Aarhus University Hospital, Denmark.
authors.forename: E
authors.initials: E
authors.lastname: Sloth
authors.forename: K C
authors.initials: KC
authors.lastname: Houlind
authors.forename: E M
authors.initials: EM
authors.lastname: Pedersen
authors.forename: J M
authors.initials: JM
authors.lastname: Hasenkam
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D002302:Cardiac Output; D003198:Computer Simulation; D015150:Echocardiography, Doppler; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011651:Pulmonary Artery / Q000502:physiology*