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Abstract #1590

Physiological Origin of Low Frequency Drift in BOLD FMRI

Lirong Yan1, Yan Zhuo1, Yongquan Ye1, Sharon Xie2, Jing An3, Geoffrey Aguirre4, Jiongjiong Wang5

1State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, CAS, Beijing, China; 2Department of Biostatistics & Epidemiology, University of Pennsylvania, Philadelphia, PA, USA; 3Siemens Mindit Magnetic Resonance Ltd., Shenzhen, China; 4Neurology, University of Pennsylvania, Philadelphia, PA, USA; 5Radiology, University of Pennsylvania, Philadelphia, PA, USA

We investigated the biophysical mechanism of low frequency drift in BOLD fMRI (0~0.01Hz), by exploring its dependence on TE and image intensity as well as relationship with task-induced BOLD activation. Cardiac and respiratory signals were concurrently recorded during MRI scanning and subsequently removed. Drifts followed a characteristic dependence on TE and signal intensity that was similar to the BOLD contrast. There was a strong positive correlation between drift effects at baseline and tasked induced BOLD activation. Our study supports brain physiology, as opposed to scanner instabilities or cardiac/respiratory pulsations, as the main source of low frequency drifts in BOLD fMRI.