Jarle Ladstein1, Hallvard Re Evensmoen2, Asta Kristine Hberg2, Anders Kristoffersen3, Dominic Holland4, Anders M. Dale4, 5, Pl Erik Goa3
1MI Lab and Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway; 2Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway; 3Clinic of Radiology, St. Olavs University Hospital, Trondheim, Norway; 4Department of Neurosciences, The University of California, San Diego, United States; 5Department of Radiology, The University of California, San Diego, United States
Geometric distortions in functional EPI scans cause local misregistration between functional and anatomical images. This can decrease the power of functional group level analysis in regions with much distortion. To evaluate the effect of applying a distortion correction to the functional data, 25 subjects were scanned during a special encoding paradigme and the data analyzed both with and without applying a correction estimated from reverse gradient scans. In regions of interest in the entorhinal cortex the degree of distortion was high and using distortion corrected data had a positive effect in terms of increased activation volume and peak z-volume.