Accurate Gray Matter CBF Mapping in Whole Brain IR 3D PULSAR Imaging Through Flip Angle Modulation

Neville Dali Gai¹, Sardha Lalith Talagala², John Butman¹

3D IR-PULSAR provides whole brain perfusion imaging in about 5 minutes. Data acquisition is through use of centric-ordered slice encoding (along kz) followed by single-shot gradient-echo EPI acquisition. In addition to tagged blood signal decay during extended data acquisition, modulation of k-space during non-steady state constant flip angle acquisition results in blurring. This introduces inaccuracies in gray matter and white matter perfusion values. Here we correct for blurring by modulating the flip angle train so that magnetization in gray matter remains almost constant across all 3D-TFEPI shots. Optimization for tagged blood signal is used to select the modulated pulse angle train. Results in five volunteers show significantly increased gray matter CBF values due to a marked reduction in blurring.