Pulsed arterial spin labeling parameter optimization for an elderly population

Purpose: To optimize pulsed arterial spin labeling (PASL) parameters for the elderly to take into account possible perfusion changes that occur in the brain with age. Materials and Methods: Healthy young (N = 14. age range = 21-27 years) and elderly (N = 12, age range 61-67 years) subjects were scanned using Q2TIPS (QUIPSS II with thin-slice Tl periodic saturation) with varying inversion times (TI2) at 1.5T. The difference signal (Delta M), transit time (delta t). and cerebral blood flow (CBF) were calculated in segmented gray matter (GM). Results:The young displayed more perfusion-weighted signal difference than the elderly at all TI2'S. The peak AM occurred at TI2 similar to 1300 msec and 1500 msec in the young and elderly groups, respectively. Qualitatively, intravascular signal was minimal in the younger group by TI2 = 1500 msec, whereas a longer TI2 of 1800 msec was needed to minimize this signal in the elderly. The transit time was similar to 100 msec longer in the elderly, and CBF was in the range of literature values. Conclusion: For acquiring perfusion-weighted images with minimal intravascular signal and adequate tissue signal for PASL studies of cerebral perfusion in the elderly, a longer Inversion time is advantageous.