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. Author manuscript; available in PMC: 2012 May 1.
Published in final edited form as: Neuroimaging Clin N Am. 2011 May;21(2):285–301. doi: 10.1016/j.nic.2011.01.003

Figure 2.

Figure 2

CBF quantitation is improved on long post-label delay (PLD) images using pcASL at 3 T in this patient with bilateral Moyamoya disease. On images with relatively short PLD’s, there is less ASL signal in the bilateral MCA territories (arrows). As PLD increases, these regions with arterial arrival delay “fill in,” indicating that CBF in these regions is normal. However, longer PLD images have lower SNR, requiring longer acquisition time. In practice, a compromise must be made between these two competing effects, with most clinical ASL images having PLD’s between 1.5 and 2 s.