Robbert J.H. van Gorkum¹, Christian Guenthner¹, Andreas Koethe^1,2, Christian T. Stoeck^1,3, and Sebastian Kozerke^1
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, ²Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland, ³Division of Surgical Research, University Hospital Zurich, University Zurich, Zurich, Switzerland

Second-order motion-compensated diffusion encoding gradient waveforms cause substantial eddy currents (ECs), which can violate the linear-system assumption of a gradient impulse response function and thus require a dedicated measurement and reconstruction approach. Using a 3-dimensional spectroscopic imaging method, diffusion encoding gradient-induced ECs were characterized and non-linear effects were identified. When accounting for zeroth- and first-order diffusion encoding gradient-induced ECs besides off-resonance and trajectory-induced concomitant fields and ECs, image distortions could be adequately mitigated in echo-planar and spiral in vivo second-order motion-compensated cardiac diffusion tensor imaging sequences.

Chang-Hoon Choi¹, Suk-Min Hong¹, Jörg Felder^1,2, Christoph Lerche¹, and N. Jon Shah^1,3,4,5
1Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich, Juelich, Germany, ²RWTH Aachen University, Aachen, Germany, ³Institute of Neuroscience and Medicine - 11, Forschungszentrum Juelich, Juelich, Germany, ⁴JARA - BRAIN - Translational Medicine, Aachen, Germany, ⁵Department of Neurology, RWTH Aachen University, Aachen, Germany

Interest in simultaneously operating MR-PET systems as a means of accessing multiple biological parameters with high spatial and temporal resolution is increasing.  In a hybrid acquisition, the RF antenna is used inside the PET FOV generating potential photon loss and artefacts. A multi-channel J-pole antenna array, which does not include any high-density parts in the imaging FOV, has been recently introduced, and its outstanding performance has been demonstrated. To prevent interference between MR and PET, including an RF shield is necessary. Here, we conducted a simulation to compare the characteristics of the J-shape antenna array with and without the shield.  

Patrick Vogel¹, Martin A Rückert¹, Teresa Reichl¹, Johanna Günther¹, Christoph Greiner¹, Liana Mirzojan¹, Alexander von Böhn¹, Thomas Kampf², Thorsten A. Bley³, Volker C. Behr¹, and Stefan Herz^3
1Experimental Physics 5 (Biophysics), University of Würzburg, Würzburg, Germany, ²Diagnostic and Interventional Neuroradiology, University Hospital Würzburg, Würzburg, Germany, ³Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany

In this work a first human-sized Magnetic Particle Imaging (MPI) scanner designed and specifically engineered for experimental (cardio)vascular interventions is presented.

Based on a novel open design implementing the so called traveling wave MPI approach, the open iMPI system provides imaging of Tracers based on superparamagnetic iron oxide nanoparticles (SPIONs) with high sensitivity, optimal patient handling and would even allow hybrid imaging of magnetic tracers within gold standard x-ray based interventional angiography systems.

In initial experiments, the feasibility of a human-sized interventional MPI scanner with real-time data reconstruction and image visualization is demonstrated.

Mark Gosselink¹, Aris van Ieperen¹, Wout Schuth², Martino Borgo², Dimitri Welting¹, Edwin Versteeg¹, and Dennis Klomp^1
1Department of Radiology, University Medical Center Utrecht, Utrecht, Netherlands, ²Futura composites, Heerhugowaard, Netherlands

We propose a setup to boost spatiotemporal encoding for MRI in the human brain using a conventional receiver array (32ch) and fast gradients (6100T/m/s). Moreover, we demonstrate that the operation frequency of a high-end gradient-amplifier can be increased to ultrasonic frequencies so to avoid unpleasant acoustic noise. By using this amplifier with 8 RF transmitters, 32 receivers and a 2-channel gradient coil, a light-weight setup is constructed for operation in a 7 Tesla MRI system. The setup is demonstrated for operation in the human brain showing good FLAIR data and no peripheral nerve stimulation at the slew rate of 6100T/m/s.

Niklas Wehkamp¹, Philipp Rovedo², and Maxim Zaitsev^3
1Department of Radiology, Medical Physics, Medical Center – University of Freiburg, Freiburg, Germany, ²Neurozentrum, Medical Center – University of Freiburg, Freiburg, Germany, ³High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria

We present numerical optimization of variable winding pitch coil designs for miniature coils with respect to target field homogeneity. The optimization is based on a continuous coil winding layout that was used to simulate field homogeneity in the target volume via the Biot-Savart law. The example coil designs expand the range of applications for frequency adjustable field probes, as they increase the B₀ modification field’s homogeneity by factor of 7. Due to the specific requirements of miniature B₀ modification coils, the dimensions of the coil are restricted in length, width and wire diameter.

Bart Romke Steensma¹, Christina Anna Louka^1,2, Alexander Jurriaan Eberhardt Raaijmakers³, and Cornelis Antonius Theodorus van den Berg^1
1Center for Image Sciences, Computational Imaging Group, University Medical Center Utrecht, Utrecht, Netherlands, ²School of Applied Mathematical and Physical Sciences, Department of Physics, National Technical University of Athens, Athens, Greece, ³Biomedical Engineering, Medical Imaging Analysis, Eindhoven University of Technology, Eindhoven, Netherlands

We developed a wearable setup to detect heart motion and stroke volume with an RF antenna connected to a miniature network analyzer. EM simulations were used to demonstrate the possibility of measuring changes in stroke volume with an RF antenna and to investigate the spatial sensitivity of the antenna. A Valsalva manoeuver was used to provoke changes in stroke volume, which were observed with the RF antenna and in cine MRI acquisitions.

Devin Willey^1,2, Olivia Jo Dickinson^1,2, Devon Karl Overson^1,2, Trong-Kha Truong^1,2, Fraser Robb³, Allen W Song^1,2, Bruno Madore⁴, and Dean Darnell^1,2
1Brain Imaging And Analysis Center, Duke University, Durham, NC, United States, ²Medical Physics Graduate Program, Duke University, Durham, NC, United States, ³Brain Imaging And Analysis Center, GE Healthcare, Aurora, OH, United States, ⁴Radiology, Brigham and Women's, Harvard Medical School, Boston, MA, United States

A wireless MR-compatible ultrasound-based device consisting of an integrated RF/wireless coil, organ-configuration motion sensor, Raspberry Pi, pulser/receiver, and analog-to-digital converters was developed to acquire, digitize, and wirelessly transmit ultrasound data while simultaneously acquiring MR-images. Experiments were performed to demonstrate the system's 1)  mobility through continuously acquiring, digitizing, and wirelessly transmitting ultrasound data at multiple locations, and 2) ability to wirelessly monitor physiological motion during coughing/gasping. This integrated system enables the OCM sensor to travel with patients throughout the hospital while also demonstrating the ability of the iRFW coil and backend electronics to process and wirelessly transmit a high-fidelity signal.