title: Comparison of real-time water proton spectroscopy and echo-planar imaging sensitivity to the BOLD effect at 3 T and at 7 T.
abstract: Gradient-echo echo-planar imaging (GE EPI) is the most commonly used approach to assess localized blood oxygen level dependent (BOLD) signal changes in real-time. Alternatively, real-time spin-echo single-voxel spectroscopy (SE SVS) has recently been introduced for spatially specific BOLD neurofeedback at 3 T and at 7 T. However, currently it is not known how neurofeedback based on real-time SE SVS compares to real-time GE EPI-based. We therefore compared both methods at high (3 T) and at ultra-high (7 T) magnetic field strengths. We evaluated standard quality measures of both methods for signals originating from the motor cortex, the visual cortex, and for a neurofeedback condition. At 3 T, the data quality of the real-time SE SVS and GE EPI R2* estimates were comparable. At 7 T, the data quality of the real-time GE EPI acquisitions was superior compared to those of the real-time SE SVS. Despite the somehow lower data quality of real-time SE SVS compared to GE EPI at 7 T, SE SVS acquisitions might still be an interesting alternative. Real-time SE SVS allows for a direct and subject-specific T2* estimation and thus for a physiologically more plausible neurofeedback signal.
authors.affiliation: Department of Radiology and Medical Informatics, University of Geneva, Geneva, Switzerland; Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, Aachen, Germany.
authors.forename: Yury
authors.initials: Y
authors.lastname: Koush
authors.affiliation: Center for Magnetic Resonance and Optical Imaging (CMROI), Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Elliott
authors.affiliation: Department of Radiology and Medical Informatics, University of Geneva, Geneva, Switzerland; Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
authors.forename: Frank
authors.initials: F
authors.lastname: Scharnowski
authors.affiliation: Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, Aachen, Germany; JARA Translational Brain Medicine, Jülich - Aachen, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Mathiak
mesh_terms: D000328:Adult; D003199:Computer Systems; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D008297:Male; D010100:Oxygen / Q000097:blood*; D011522:Protons; D012815:Signal Processing, Computer-Assisted; D059629:Signal-To-Noise Ratio; D013057:Spectrum Analysis / Q000379:methods*; D014867:Water
chemical_list: D011522:Protons; D014867:Water; D010100:Oxygen