PMID- 12541264
OWN - NLM
STAT- MEDLINE
DCOM- 20030508
LR  - 20150525
IS  - 0740-3194 (Print)
IS  - 0740-3194 (Linking)
VI  - 49
IP  - 2
DP  - 2003 Feb
TI  - Velocity-driven adiabatic fast passage for arterial spin labeling: results from a 
      computer model.
PG  - 398-401
AB  - Velocity-driven adiabatic fast passage (AFP) is commonly employed for perfusion 
      imaging by continuous arterial spin labeling (CASL). The degree of inversion of 
      protons in blood determines the sensitivity of CASL to perfusion. For this study, 
      a computer model of the modified Bloch equations was developed to establish the 
      optimum conditions for velocity-driven AFP. Natural variations in blood velocity 
      over the course of the cardiac cycle were found to result in significant 
      variations in the degree of inversion. However, the mean degree of inversion was 
      similar to that for blood moving at a constant velocity, equal to the 
      time-averaged mean, at peak velocities and heart rates within normal ranges. A 
      train of RF pulses instead of a continuous RF pulse for labeling was found to 
      result in a highly nonlinear dependence of the degree of inversion on RF duty 
      cycle. This may have serious implications for the quantification of perfusion.
CI  - Copyright 2003 Wiley-Liss, Inc.
FAU - Utting, Jane F
AU  - Utting JF
AD  - Medical Physics and Bioengineering Department, University College London, London, 
      UK.
FAU - Thomas, David L
AU  - Thomas DL
FAU - Gadian, David G
AU  - Gadian DG
FAU - Ordidge, Roger J
AU  - Ordidge RJ
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Magn Reson Med
JT  - Magnetic resonance in medicine
JID - 8505245
RN  - 0 (Spin Labels)
SB  - IM
EIN - Magn Reson Med. 2003 Dec;50(6):1322
MH  - Animals
MH  - *Blood Flow Velocity
MH  - *Cerebrovascular Circulation
MH  - *Computer Simulation
MH  - Humans
MH  - Magnetic Resonance Imaging/*methods
MH  - Pulsatile Flow
MH  - Rats
MH  - Spin Labels
EDAT- 2003/01/24 04:00
MHDA- 2003/05/09 05:00
CRDT- 2003/01/24 04:00
PHST- 2003/01/24 04:00 [pubmed]
PHST- 2003/05/09 05:00 [medline]
PHST- 2003/01/24 04:00 [entrez]
AID - 10.1002/mrm.10363 [doi]
PST - ppublish
SO  - Magn Reson Med. 2003 Feb;49(2):398-401. doi: 10.1002/mrm.10363.