Spin-labeling imaging of cerebral perfusion at 1.5 and 3.0 Tesla

Purpose: Two sequences have been compared for estimation of cerebral blood perfusion in areas of strong magnetic susceptibility changes at 1.5 and 3.0 Tesla: flow sensitive alternating inversion recovery (FAIR) true fast imaging in steady precession (TrueFISP) and FAIR echo-planar imaging (EPI).

Methods: An arterial spin labeling (ASL) method was implemented, which is capable of perfusion imaging in areas of high magnetic susceptibility changes by combination of the FAIR spin preparation with a TrueFISP data acquisition strategy. Quantitative perfusion images were recorded at 1.5 Tesla and 3.0 Tesla on twelve healthy volunteers (24 to 42 years old) and one patient (23 years old). FAIR-TrueFISP perfusion images were compared to FAIR-EPI.

Results: The FAIR-TrueFISP sequence showed no significant distortions and markedly reduced signal void artifacts in areas of high susceptibility changes as compared to FAIR-EPI. At 3 Tesla, highly resolved FAIR-TrueFISP perfusion images could be acquired with an in-plane resolution of up to 1.3mm. Cerebral perfusion of gray matter areas was 105.7±5.2ml/100g/min in FAIR-TrueFISP and 88.8±14.6ml/100g/min in FAIR-EPI imaging at 1.5 Tesla, and 70.4±7.1ml/100g/min in FAIR-TrueFISP and 63.5±6.9ml/100g/min in FAIR-EPI imaging at 3.0 Tesla. Higher perfusion values at 1.5 Tesla were due to more pronounced partial volume effects of fast moving spins at lower spatial resolution.

Conclusion: FAIR-TrueFISP allows for assessment of cerebral perfusion in areas of critically high susceptibility changes for conventional ASL methods at 1.5 and 3.0 Tesla.