PARTIAL FOURIER RECONSTRUCTION FOR 3-DIMENSIONAL GRADIENT-ECHO FUNCTIONAL MRI - COMPARISON OF PHASE CORRECTION METHODS

Partial Fourier (PF) methods take advantage of data symmetry to allow for either faster image acquisition or increased image resolution. Fas ter acquisition and increased spatial resolution are advantageous for fMRI because of increased temporal resolution and/or reduced partial v olume effects, respectively. Standard PF methods, which use a phase re ference obtained from a low resolution image, are adequate for the rec onstruction of time-stationary images acquired using either spin echoe s or short TE gradient echoes. In fMRI, however, multiple images are a cquired using long TE gradient echoes, which introduces possible phase drifts in the fMRI data and high spatial frequencies in the phase ref erence, This work investigates several techniques developed to reconst ruct fMRI data obtained with PF acquisitions. PF methods that account for both high-frequency spatial variations and time-dependent drifts i n the phase reference are discussed and are quantitatively evaluated u sing receiver operator characteristic curve analysis.