Silent BOLD imaging

Pulsed magnetic field gradients in magnetic resonance imaging produce high levels of acoustic noise. In functional magnetic resonance imaging, acousti c scanner noise causes unwanted masking effects. Recently, we proposed a me thod to perform magnetic resonance imaging experiments undisturbed by acous tic scanner noise by utilizing the property of standard gradient coils to p oorly submit acoustic noise in the low frequency range. The silent gradient scheme is now incorporated into a standard T-2*-weighted sequence. Additio nally, simultaneous multi-slice excitation (SIMEX) pulses were implemented to improve the intrinsic low volume coverage of the silent sequence. The pr oposed silent SIMEX technique was tested and compared with a standard noisy technique using auditory and visual stimulation paradigms. The scanner noi se during the silent experiments could be reduced below the range of the am bient noise of the ma.-net room. This feasibility study shows a trend of de creased activated areas in the noisy experiment for both, the visual and au ditory paradigm. (C) 2001 Elsevier Science B.V. All rights reserved.