Monitoring movement in MRI by measuring changes in the EMF induced in head-mounted coilsTools Bhuiyan, E. H. (2017) Monitoring movement in MRI by measuring changes in the EMF induced in head-mounted coils. PhD thesis, University of Nottingham.
AbstractImage quality is degraded by involuntary movement of the subject in an MRI scanner. It is fairly challenging in MRI of the brain to monitor the involuntary head movement accurately. Though there are a few techniques to monitor head movement of the subject for prospective motion correction, it is still an unsolved problem in MRI. In this study, head movement inside an MR scanner is monitored via measurement of changes in the voltage induced in head mounted coils by switched magnetic field gradients. The motion of a rigid body such as the human head is decomposed into two components: namely translation and rotation. There are three degrees of freedom (DOFs) for translational motion i.e. translation along the x, y and z axes and three rotational degrees of freedom for rotational motion i.e. rotation about the x, y and z axes. Head movement is monitored in a gradient field by measuring the change in induced voltage in head mounted coils. To calculate the change in induced voltage I follow two approaches: circular loops simulation, analytical as well as numerical calculations. I show that by using a standard method one can form a linear model to identify the position and orientation of the coils.
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