RT Book, Section
A1 Noori, Shahab
A2 Siassi, Bijan
A2 Noori, Shahab
A2 Acherman, Ruben J.
A2 Wong, Pierre C.
SR Print(0)
ID 1161424003
T1 Application of Pulsed Wave and Continuous-Wave Doppler in the Assessment and Measurement of Cardiac and Systemic Blood Flow*
T2 Practical Neonatal Echocardiography
YR 2018
FD 2018
PB McGraw-Hill Education
PP New York, NY
SN 9781260123135
LK accesspediatrics.mhmedical.com/content.aspx?aid=1161424003
RD 2024/04/20
AB The  measurement  of  blood  flow  through  any  vascular  structure  using  ultrasound  requires  two  basic  pieces  of  information:  the  velocity  of  blood  flow  and  the  cross-sectional  area  of  the  vessel.  The  velocity  of  blood  flow  can  be  measured  using  spectral  Doppler.  As  pulsed  wave  (PW)  Doppler  allows  for  measurement  of  velocity  at  a  specific  point  in  the  vessel  (ie,  range  resolution),  it  is  the  preferred  mode  of  spectral  Doppler.  When  measuring  the  velocity,  the  echocardiographer  must  take  care  to  use  an  angle  of  insonation  as  parallel  as  possible  to  the  direction  of  flow.  If  the  ultrasound  beam  is  intercepting  the  blood  flow  at  an  angle,  the  velocity  will  be  underestimated  (see  Chapter  6).  In  clinical  practice,  an  angle  of  less  than  20°  is  generally  considered  acceptable,  as  the  effect  on  velocity  is  negligible.  An  angle  greater  than  20°  will  require  angle  correction,  which  often  produces  inconsistent  results.  Another  important  point  in  measuring  the  velocity  is  that,  in  the  presence  of  a  turbulent  flow,  the  measured  velocity  by  PW  Doppler  cannot  be  used  to  estimate  the  flow  because  of  aliasing  that  occurs  with  higher  velocities  (see  Chapters  1  and  4).  Therefore,  the  operator  should  assess  the  flow  by  color  Doppler  first  to  ensure  that  the  flow  is  laminar  before  attempting  to  obtain  the  velocity  by  PW  Doppler.