Shuowen Hu1, Olumide Olulade1, Gregory G. Tamer2, Wen-ming Luh3, Thomas M. Talavage1,2
1School of Electrical and Computer
Engineering, Purdue University, West Lafayette, IN, USA; 2Weldon
School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA; 3National
Institute of Mental Health, Bethesda, MD, USA
The objective of this study is to assess signal fluctuations induced by non-T1-related confounds in variable repetition time fMRI and to develop a compensation procedure. Dummy acquisitions (gradient readout sequences with radio-frequency excitation disabled) were effected at variable offsets between actual acquisitions, allowing the study of non-T1-related confounds such as eddy currents and gradient coil heating that may arise in variable TR experiments. Three imaging sessions utilizing a phantom were conducted to assess the signal fluctuations, which were modeled as a second order system. A modified projection procedure was successfully implemented to correct for signal fluctuations arising from non-T1-related confounds.