A protocol for assessing subtraction errors of arterial spin-tagging perfusion techniques in human brain

A protocol for assessing signal contributions from static tissue (subtracti on errors) in perfusion images acquired with arterial spin-labeling (ASL) t echniques in human brain is proposed. The method exploits the reduction of blood T-1 caused by the clinically available paramagnetic contrast agent, g adopentetate dimeglumine (Gd-DTPA), The protocol is demonstrated clinically with multislice FAIR images acquired before, during, and after Gd-DTPA adm inistration using a range of selective inversion widths. Perfusion images a cquired postcontrast for selective inversion widths targe enough (threshold ) to avoid interaction with the imaging slice had signal intensities reduce d to noise level, as opposed to subtraction errors manifested on images acq uired using inversion widths below the threshold. The need for these experi ments to be performed in vivo is further illustrated by comparison with pha ntom results. The protocol allows a one-time calibration of relevant ASL pa rameters (e.g., selective inversion widths) in vivo, which may otherwise ca use subtraction errors. Magn Reson Med 43: 896-900, 2000, Published 2000 Wi ley-Liss, Inc(dagger).