Abstract:
:Perfusion imaging with pulsed arterial spin labeling techniques, like flow-sensitive alternating inversion recovery (FAIR), may suffer from inflow of fresh, i.e., unlabeled, spins. Inflow of fresh spins is caused by the arrival of unlabeled spins in the image slice and can lead to underestimation of the perfusion if not taken into account. In this study it was shown that a decrease in B(1) field strength toward the edge of the transmit coil and the consequent reduction in the inversion efficiency leads to a narrowing of the arterial delivery function and a reduction in FAIR signal. Increasing the B(1) amplitude of the adiabatic inversion pulse from 2.3 to 5.7 times its minimum amplitude requirement resulted in an observed increase of 40 to 80% in the rat brain FAIR signal at inflow times longer than 0.65 s. For coils with limited dimensions and significant B(1) inhomogeneity over the perfusion labeling slab, the application of an excessively large B(1) amplitude in combination with adiabatic inversion is recommended to optimize the FAIR perfusion contrast.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Schepers J,van Osch MJ,Bartels LW,Heukels SN,Viergever MA,Nicolay Kdoi
10.1002/mrm.20480subject
Has Abstractpub_date
2005-06-01 00:00:00pages
1355-62issue
6eissn
0740-3194issn
1522-2594journal_volume
53pub_type
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