Silent fMRI Acquisition Methods for Large Acoustic Noise during Scan

Abstract

Functional magnetic resonance imaging (fMRI) is now the method of choice for studying neural correlates of various tasks in normal subjects as well as patients. This method, however, is inevitably coupled with the acoustic noise produced during the image acquisition process. This is a problem not only in auditory experiments but also in other cognitive tasks in general. The problems caused by such noise are modulation of auditory activation, impaired perception of auditory stimuli, and deterioration of task performance possibly due to stress from the abnormal circumstances. While both hardware and software solutions have been reported, several methods are introduced here that focus on software solutions that can be implemented in scanners already installed. Their advantages and disadvantages diŠer depending on the kinds of tasks involved, i.e. whether block design or event-related design, and they are discussed with a view to better utilization.

Neuroimaging paradigms for tonotopic mapping (II): The influence of acquisition protocol

“…For experiments that involve sound presentations in particular, ASN may influence outcomes at an acoustic or neural level in the form of a direct masking of the delivered stimuli and interference with task performance, or at a metabolic or vascular level in the form of a sustained elevation of baseline activity and reduced activation due to non-linear ceiling effects (Talavage and Edmister, 2004). Various solutions have been proposed to overcome these detrimental effects (Okada and Nakai, 2003). Several strategies aim to make the acquisition sequence quieter, for instance by optimising the design of coil geometries (Bowtell and Mansfield, 1995), excitation pulses (Schmitter and Bock, 2010), readout gradient shapes (Loenneker et al, 2001; Zapp et al, 2012), switching frequencies (Chapman et al, 2003; Segbers et al, 2010), slew rates (de Zwart et al, 2002), and k -space trajectories (Oesterle et al, 2001).…”

Assessment of impacted and partially impacted lower third molars with panoramic radiography compared to MRI—a proof of principle study

“…These include the current acquisition times of more than 20 min, high costs and relatively low accessibility, as well as the discomfort to the patient of being a fixed position in a noisy machine for an extended period. 30,31 conclusion The presented study demonstrates that MRI not only provides much the same information that panoramic radiography usually does, but also has the advantages of a dose-free three-dimensional view. This may facilitate and shorten third molar surgery.…”

A Survey Analysis of Acoustic Trauma Related to MR Scans

“…Acquisition timing or gradient waveform optimization depending on the hardware characteristics was proposed. 27,28 Software techniques may additionally enhance silent hardware technologies; however, they are more application dependent and not necessarily a generic approach.…”