M Eschelbach

An Active Transmit/Receive NMR Magnetometer for Field Monitoring in Ultra High Field MRI Scanners.

We present a miniaturized active nuclear magnetic resonance (NMR) magnetometer consisting of a susceptibility matched field probe and a PCB based RF transceiver. Thanks to its transmit-receive (TX/RX) capabilities, the system can be used to monitor the spatio-temporal field evolution during a magnetic resonance imaging (MRI) scan and thereby allows for a correction of gradient field imperfections to improve image quality. The magnetometer can be tuned for magnetic fields ranging from 7 T to 15.5 T and achieves a resolution of 14.8 nT measured in a 9.4 T whole body scanner.

Comparison of prospective head motion correction with NMR field probes and an optical tracking system

The aim of this study was to compare prospective head motion correction and motion tracking abilities of two tracking systems: Active NMR field probes and a Moiré phase tracking camera system using an optical marker.

Constrained optimization for position calibration of an NMR field camera: Position Calibration of an NMR Field Camera

Knowledge of the positions of field probes in an NMR field camera is necessary for monitoring the B0 field. The typical method of estimating these positions is by switching the gradients with known strengths and calculating the positions using the phases of the FIDs. We investigated improving the accuracy of estimating the probe positions and analyzed the effect of inaccurate estimations on field monitoring.

An MR-Compatible Haptic Interface With Seven Degrees of Freedom

Functional magnetic resonance imaging (fMRI) is a powerful tool for neuroscience. It allows the visualization of active areas in the human brain. Combining this method with haptic interfaces allows one to conduct human motor control studies with an opportunity for standardized experimental conditions. However, only a small number of specialized MR-compatible haptic interfaces exist that were mostly built around specific research questions. The devices are designed for pure translational, rotational, or grasping movements. In this work, we present a novel MR-compatible haptic interface with seven degrees of freedom (DoF), which allows for both translations and rotations in three DoF each, as well as a two-finger precision grasp. The presented haptic interface is the first one with these capabilities and is designed as a universal tool for human motor control studies involving fMRI. It allows for the switching of the paradigm to reprogramming rather than redesigning when moving on to a new research question. We introduce its kinematics and control, along with results of MR compatibility tests and a preliminary fMRI study, showing the applicability of the device.