PHASE NAVIGATOR CORRECTION IN 3D FMRI IMPROVES DETECTION OF BRAIN ACTIVATION - QUANTITATIVE ASSESSMENT WITH A GRADED MOTOR ACTIVATION PROCEDURE

Motion poses severe problems for BOLD fMRI, particularly in clinical s tudies, as patients exhibit more involuntary movements than controls. This study focuses on the merits of a motion correction technique inco rporated in multishot fMRI scans, so-called phase navigator correction . The technique entails real-time assessment and off-line elimination of signal fluctuations caused by subject motion. The purpose of this s tudy was to quantify and characterize the effect of this type of impro vement on 3D fMRI brain activity maps. For imaging, the 3D PRESTO meth od was used, with a relatively simple finger opposition task. The foll owed strategy was guided by the notion that application of any fMRI im aging tool in clinical studies requires several qualities, such as hig h and spatially homogeneous sensitivity to brain activity, and low sen sitivity to motion. A graded motor activation protocol in 10 healthy s ubjects revealed that image stability was improved by approximately 20 %, by the use of phase navigator correction. As a result, sensitivity for task-related BOLD signal change was enhanced considerably in the b rain activity maps. Implications for use of this fMRI technique in pat ient studies are discussed. (C) 1998 Academic Press.