Case study: Sven Jaeschke

Contact-Free Cardiac and Respiratory Gating and Motion Tracking using RF-Scatter for Ultra High Field Magnetic Resonance Imaging

Host Institution: Oxford University

Supervisors: Prof. Matthew Robson (Centre for Clinical Magnetic Resonance Research); Dr. Aaron Hess (OCMR), Dr Robin Heidemann (Siemens Healthineers)

As a Biomedical Engineering undergraduate and postgraduate, Sven had undertaken imaging-related, industry-sponsored projects, before working for a while in the medical devices industry, so it is perhaps not surprising that he chose an industry project for his doctoral project. His research project aims to develop new methods for cardiac gating and motion tracking using only power reflections of the transceiver MRI coils. The current gold standard for cardiac gating in the scanner, the electrocardiogram (ECG), can be affected by the high magnetic field strength in 7 Tesla MRI, resulting in missed or false trigger results that can increase scan time or significantly degrade image quality in cardiovascular MRI. Sven’s novel approach is to use parallel transmit imaging RF coils, and other parts of the commercial MRI scanner that are already available, to detect subtle changes in the coupling between the RF coil and the patient. This eliminates the need for additional hardware or any expert setup, and enables simultaneous real-time measurement of the scattering values of the RF coils.

The basic principle behind the scattering of the coils is that any returned voltage will arise from a combination of different sources, including mismatching of the antennae. Displacement of tissue or blood will change the complex conductivity and permittivity distribution which influences the imaging pulse as it travels from one antenna to another or back to its source. The changes in scattering over time can then be used to assess cardiac and respiratory motion. This approach has the potential to improve cardiac imaging at ultra-high magnetic field by providing robust triggering in periods of breath-hold and free-breathing, yielding additional gating information and an optimized workflow with no additional set-up.

CINE sequence of the heart reconstructed

The project is also linked and supported by an industry partner (Siemens Healthineers, Erlangen, Germany). Together with the industry partner, it is also planned to test the feasibility of the method at lower magnetic field strengths which are used in wide clinical practice. Further, Sven is also working with Oxford University Innovation to submit an invention report which could be licensed to industry partners.

He has already submitted two scientific abstracts on his work, for presentation at international scientific meetings, despite only having started his project in the summer of 2016.