Evaluation of SNR with different type of MR coil(TX/RX,20 flexible coil) in concurrent TMS-fMRI studies

Background and Aim : Neuroimaging tools are a significant area of interest within the field of functional magnetic resonance imaging (fMRI). Traditionally, fMRI has subscribed to the belief that research on localization, recent evidence suggests the role of cortical specialization with the ultimate goal of obtaining a cognitively precise parts list for the human brain and that complex cognitive brain functions must result from the collaborative interplay between distributed and interconnected brain regions. Many fMRI studies took advantage of its high spatial resolution to identify functionally specialized brain areas. In contrast, by reversibly perturbing ongoing neural processing, Transcranial Magnetic Stimulation (TMS) is a non-invasive brain stimulation tool extensively used in clinical and cognitive neuroscience research can causally implicate the stimulated region, TMS-induced changes in neural activity need to be monitored directly by combining during functional magnetic resonance imaging (i.e., concurrent/interleaved TMS-fMRI) to understand neural mechanisms underlying cognitive functions. However, no advanced commercial multi-channel whole-brain array MR coils can fit the large TMS coil. This paper attempt to developed a low-cost and easy-to-configure setup that takes advantage of the superior signal-to-noise ratio (SNR) performance of commercially available flexible body array coils that can accommodate the TMS coilMethods : Concurrent TMS-fMRI is a technically challenging methodology that needs to overcome problems arising from the interference between the magnetic fields inherent to each technique. In this study, flexible MRI body array coils (i.e.,8coil; medium flexy coil and head 20coil) were fitted on TMS compatible 8coil that fixed with a TMS-coil holder. Case study images acquired using the flexible coil with sham and active TMS were compared with those from a product 2-channel (2CH)TX/RX coilResults : The first set of analyses examined the impact of 2CH head coil(TX/RX), images acquired using the flexible coil were of similar quality, but with increased noise levels, leading to moderately reduced temporal SNR values. Comparison with existing method: A previous study reported that the temporal SNR of a product 2CH head coil was twice that of a transmit/receive volume birdcage coil commonly used in combined TMS-fMRI. Taken together, these results suggest that the flexible-coil(20CH) setup improves SNR performance for combined TMS-fMRI acquisition.Conclusion : This paper has given an account of and the reasons for the widespread use of the inexpensive and easy-to-configure flexible-coil setup, which a practical and likely superior alternative to transmit/receive coil for combined TMS-fMRI studies.

کلیدواژه ها:

Brain ، Transcranial magnetic stimulation ، Functional magnetic resonance imaging ، signal-noise-ratio