Improved quantification of brain perfusion using FAIR with active suppression of superior tagging (FAIR ASST).

ABSTRACT

PURPOSE: To address two problems for perfusion studies in the middle or inferior brain regions (1) to reduce venous artifacts due to the intrinsic superior labeling of FAIR; (2) to alleviate the discrepancy of the existence of both superior and inferior boluses, but with only the inferior bolus having a temporally defined bolus width with Q2TIPs or QUIPSS. MATERIALS AND METHODS: Superior tagging suppression methods for FAIR with different combinations of pre- and postinversion superior saturation pulses were evaluated and compared with FAIR with Q2TIPS for producing perfusion maps of superior, middle, and inferior brain regions. RESULTS: One preinversion plus two postinversion superior saturation radio frequency pulses effectively suppressed the superior tagging of FAIR and sufficiently eliminated venous artifacts without negative effects, avoiding the overestimations of cerebral blood flow that can occur in FAIR. CONCLUSION: FAIR ASST improves FAIR with Q2TIPS and provides more reliable and accurate blood flow estimations for perfusion studies of middle and lower brain regions. FAIR ASST confers the advantages of asymmetric PASL techniques, such as PICORE, in which only the inferiorly labeled blood is used for perfusion quantification, to the symmetric PASL technique FAIR, while preserving the robustness of FAIR against MT effects.