agenda

Signal Processing Seminar

Jeroen van Gemert

Strong magnetic background fields are of great interest in Magnetic Resonance Imaging (MRI), since images with high spatial resolution can be obtained at reduced scanning times. Strong background fields may cause RF interference effects, however, and these effects can severely degrade the quality of an MR image. This problem can be partly resolved using various advanced and mostly expensive techniques, but there is also a cheap and practical solution, namely, dielectric pads. The design of such a pad is not trivial. Normally, finding the “optimal” pad for a specific region of interest involves evaluating many different pad designs using electromagnetic field simulations. This is a very time-consuming approach taking hours to days of computation time. We propose a nonlinear optimization method based on model order reduction that allows us to design high-permittivity pads in less than 30 seconds.

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MSc SS Thesis Presentation

Enhancement of the Spatial Resolution for the Temperature Sensing System of the 7 Tesla Magnetic Resonance Imaging Scanner

Tariq Saboerali

The MRI scanner with an ultrahigh magnetic field of 7T not only increases the image resolution but it also increases the Specific Absorption Rate (SAR) of the patient. In other words, the body temperature of the patient increases due to the absorption of heat produced by the 7T MRI scanner. This is dangerous for the health of the patient. In order to ensure that the SAR level of the patient does not exceed the acceptable limit, the body temperature of the patient should be monitored during the scan with a spatial resolution as small as possible. This way safety measures can be taken immediately if the body temperature increases. In order to monitor the temperature during the MRI scan, fiber optic sensors (FOS) can be used. The fiber optic sensors (FOS) are immune from electromagnetic interference and there is no electrical connection to the patient and thus it is safe to monitor the temperature during an MRI scan by using FOS [1]. However, the FOS may have a spatial resolution which is not acceptable for medical purposes. This study focuses on methods to increase the spatial resolution of an existing fiber optic temperature sensing system of a 7T MRI scanner. To increase the spatial resolution of the existing temperature sensing system two methods are evaluated, namely the total variation deconvolution method and the blind deconvolution method. This study shows that the total variation deconvolution method gives the best results for the input temperature estimate. The blind deconvolution method strongly depends on the initial guess of the impulse response of the temperature sensing system, which is difficult to find. Therefore the results of the input temperature and the impulse response are less reliable when using the blind deconvolution method. Also it is shown that the machine resolution gets worse when increasing the spatial resolution by interpolating the input temperature in the Fourier domain.


Signal Processing Seminar

Thomas Sherson

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MS3 seminar

MS3 Master Event

Come to learn about our group and current Master Thesis Projects...

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Signal Processing Seminar

Christos Tzagkarakis

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Signal Processing Seminar

Jorn Zimmerling

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