PhD Defense: A plug-and-play gradient insert for fast and silent MRI

The main limitation of MRI-scanners is the speed at which images are acquired. This limitation is relevant for both clinical practice and fundamental brain research. In the clinic, a full MRI-exam can take up to 30 minutes during which the patient has to stay motionless while the scanner makes loud sounds that can cause anxiety and induce unwanted motion. In fundamental brain research, detailed images with a high resolution are needed (< 1 mm). The acquisition of such images with a conventional MRI-scanner is too slow and increasing the speed of acquisition is limited by the interaction of the MRI-scanner with the nerves through nerve stimulation.

Both the loud sound and the interaction with the nerves are caused by the same part of the MRI-scanner: the gradient coils. The goal of this thesis was to present a new local gradient coil, a so-called plug-and-play gradient insert. This coil can be used to image the brain faster and at a higher resolution as it has less interaction with the nerves. In addition, this thesis shows that this coil can be used to reduce the sound during MRI-scans by ultrasonically switching the currents in the coil which shifts the produced sound outside of the human hearing range. Lastly, we showed that this coil can be applied to both anatomical and metabolic imaging of the brain.