Magnetic Resonance Imaging at 7T in Glasgow A unique opportunity!
An NHS MR Physicist's perspective... What is different about 7T scanners? What has already been achieved? Imaging Centre of Excellence (ICE) What's different about this site? Research opportunities available. Ensuring MR safety
What is different about 7T scanners? Over 4 times stronger than existing standard clinical scanners These are not routine systems. There are a limited number of manufacturers. Shajan Gunamony, now at UoG Imaging coils are often not standard and even bespoke. Stronger magnet, more energy, more signal.
Examples of what is possible from other clinical research sites Professor Chris Hess, UCSF School of Medicine GE 7T installed since 2006
Ultra high resolution
Early Work - Comparing 3T & 7T T2* GRE - 6.5 min scan, same parameters, 0.35 x 0.35 x 2.0 mm 3T 7T Chris Hess, UCSF
Early Work - Pushing Spatial Resolution 0.250 mm in-plane, 2 mm slice Line of Gennari Chris Hess, UCSF
Small vessel resolution Polemini, MGH
Contrast - phase differences
From Susceptibility to Phase Contrast Phase Yields 10-fold Improvement in CNR over Conventional MRI 3T 7T Chris Hess, UCSF
Nuclear Substructure depicted with 7T Phase 7T 3T Magnitude Phase Chris Hess, UCSF
Contrast - susceptibility differences
Microscopic Susceptibility T2* Contrast B0 Diamagnetic Paramagnetic B0 χ<0 χ>0 Phase Magnitude Phase Phase Magnitude Magnitude Phase Chris Hess, UCSF
Observations T2* Contrast + Resolution Chris Hess, UCSF
SWI of Radiation-Induced Microbleeds Anaplastic astrocytoma 9 years after EBRT Chris Hess, UCSF
Improved Depiction of Steno-occlusion Closer Approximation to Catheter Angiography 3T DSA 7T Chris Hess, UCSF
7T Multi-echo MRA+MRV Simultaneous Visualization of Arteries, Veins & Microbleeds Chris Hess, UCSF
Multi-band 7T NODDI: Low Grade Glioma Clinically feasible (5.5 minute) diffusion modeling of brain tissue OD Viso Vic Vec T1+ T2 FLAIR ADC FA Qiuting Li et al, UCSF
Getting the best out of 7T balance benefits with challenges Benefits of 7T: Signal (to noise ratio SNR), T1 and T2 relaxation, Chemical Shift (for spectroscopy) Challenges of 7T: Specific Absorption Rate (SAR), RF Uniformity Ergonomics, Motion correction/detection Susceptibility
Problem: RF Inhomogeneity Nonlinear SNR and Contrast, SAR Hotspots Chris Hess, UCSF
And then this came along
Siemens Magnetom Terra First research 7T system designed for future clinical use. Although weighing 25 tons it is about half the weight of previous designs!
Siemens Magnetom Terra After Erlangen, Wurzburg and Cambridge, Glasgow will have the fourth in the world of this new design system. It will be delivered on 27 th November 2016 just before St Andrew s Day!
Siemens Magnetom Terra specifications
Research and Development Introducing ICE
Clinical lead for research For my own specialism in stroke, the 7T MRI scanner will allow us to produce detailed images of the damage caused by stroke and give us the capability of visualising the very small vessels responsible for many strokes. Prof Keith Muir
Clinical lead for research What sets Glasgow s 7T scanner apart from those at other sites.. indeed internationally is that it will be housed at a hospital. Most other facilities.. handle patients who can walk into a university research building, but we ll..bring patients in their beds from the hospital into the ICE building to use the scanner. Prof Keith Muir
Direct from patient bed-side to scanner table The ICE building has been designed to ensure that the 7T imaging facility is completely integrated within a university hospital campus allowing direct access to the 7T from all patient groups. Other sites around the world are in separate research sites remote from the hospital or if nearby still requiring transport.
QEUH campus 7T will actually be sited at the very first location of MRI in Glasgow.
Connectivity... Imaging Centre of Excellence (ICE) Main Acute Hospital Clinical Research Facility Learning & Teaching Building, Innovation Floor
Unique partnerships on site This facility unlocks the potential for ultra high field MRI based clinical research within the hospital campus. This facility has been made possible by a triple helix approach of partnership between the University of Glasgow, NHSGGC and Siemens.
A truly national resource The Imaging Centre of Excellence will bring together teams of clinical researchers, industry and academics. It will build on strong collaborations already existing at 1.5T and 3.0T There is now a strong desire in the industry to drive 7T to clinical especially since the static field limit is now 8T. Initial focus will be head but this will develop to other areas.
Translational research Ensuring the research activity reaches the patient is a role that NHS Researchers are well placed for. The NHS MR Physics Group is part of this... It comes with the same software platform as clinical 3T and 1.5T models aiding translational research between field strengths.. The scanner is expected to be operational from April 2017
7T enables At a sub millimetre resolution; Structure Variations in myelin and iron content Function Grey matter and white matter Variations in signal across the cortex Connectivity rsfmri at 1mm isotropic Layer based fmri responses Provided subject motion correction or detection strategies can be utilised!
Ensuring MR Safety Accurate RF modelling is critical Importance of inter-site site comparison to confirm image quality and RF deposition.
Ensuring MR Safety The use of numerical simulations on generic models remains the most widely used SAR evaluation method. Different safety factors are typically added to account for coil modelling errors, anatomic variability and uncertainties associated with the monitoring hardware. SAR and temperature can now be explicitly taken into account in ptx RF pulse design. Thermal dose likely to prove to be even more useful metric.
Maintaining safety Establish live patient RF safety modelling and ptx optimisation to increase feasibility of clinical research neuro scanning at 7T and other body areas by collaborating with appropriate sites. Many MR conditional implants are not yet tested to 7T and so accurate modelling is required. Sites such as MDC in Berlin have done extensive work on this.
UK 7T This will provide a UK network with Glasgow taking a lead on patient safety. A standardised head imaging protocol will be set up. Develop exchange programmes with major 7T sites such as Oxford, Cambridge, Nottingham, Cardiff, as well as international sites.
Any questions? johnfoster2@nhs.net