RT Book, Section
A1 Paladini, Dario
A1 Sglavo, Gabriella
A1 Volpe, Paolo
A2 Fleischer, Arthur C.
A2 Toy, Eugene C.
A2 Lee, Wesley
A2 Manning, Frank A.
A2 Romero, Roberto J.
SR Print(0)
ID 1106705847
T1 COLOR DOPPLER SONOGRAPHY IN OBSTETRICS
T2 Sonography in Obstetrics and Gynecology: Principles & Practice, 7e
YR 2015
FD 2015
PB McGraw-Hill Education
PP New York, NY
SN 9780071547727
LK obgyn.mhmedical.com/content.aspx?aid=1106705847
RD 2024/04/24
AB DefinitionsAliasing:  aliasing  of  a  Doppler  signal  occurs  when  the  Nyquist  limit  has  been  exceeded.  This  resulting  "wrapped  around"  appearance  of  either  the  pulsed  Doppler  or  color  Doppler  signal  leads  to  ambiguity  in  the  direction  and  velocity  information  being  displayed.Angle  of  insonation:  the  angle  between  the  long  axis  of  a  vessel  and  direction  of  the  ultrasound  beam.  This  value  is  dependent  upon  fetal  position  in  relation  to  transducer  placement.B-flow:  an  angle-independent  technique  by  which  blood  flow  is  detected  by  analyzing  the  signal  amplitudes  of  moving  red  blood  cells  within  vessels.  This  technique  uses  a  subtraction  algorithm  that  displays  only  moving  blood  flow  but  does  not  display  stationary  structures  such  as  the  vessel  wall.CDUS/PDUS:  color  Doppler  ultrasonography/power  Doppler  ultrasonography.Glassbody  rendering:  a  three-dimensional  volume  rendering  technique  that  displays  vessels  using  color  or  power  Doppler  ultrasonography.  These  vascular  structures  are  simultaneously  displayed  with  surrounding  anatomic  structures  that  are  reconstructed  from  variably  transparent  gray-scale  voxels.Nyquist  limit:  the  theoretical  limit  to  the  rate  that  is  required  to  sample  an  ultrasound  signal  that  contains  data  with  a  specified  maximum  frequency.  It  represents  the  highest  frequency  that  can  be  coded  for  a  given  sampling  rate  (PRF)  in  order  to  fully  reconstruct  the  ultrasound  signal.  If  the  frequency  is  greater  than  half  the  sampling  frequency,  the  Nyquist  limit  is  exceeded.Pulse  repetition  frequency  (PRF):  the  number  of  transmitted  pulsed  Doppler  pulses  per  second.  The  greatest  velocity  that  can  be  measured  by  a  specific  transducer  depends  on  the  distance  between  the  probe  and  vessel,  as  well  as  the  PRF.Umbilical  coiling  index  (UCI):  the  UCI  is  obtained  by  dividing  the  total  number  of  complete  vascular  coils  by  the  umbilical  cord  length.  Hypercoiling  has  been  defined  as  a  UCI  >0.3  coils/cm,  whereas  hypocoiling  as  a  UCI  <0.1  coils/cm.