Fast Field-Cycling MRI

Fast Field-Cycling MRI

These pages describe our research project on Fast Field-Cycling Magnetic Resonance Imaging.

This research is being carried out in the School of Medicine, Medical Sciences and Nutrition at the University of Aberdeen, in the North-East of Scotland.

We are associated with the Aberdeen Biomedical Imaging Centre.

Overview

Aberdeen was lead partner in the EU-funded Horizon-2020 research project "IDentIFY" (Improving Diagnosis by Fast Field-Cycling MRI), which ran for four years from January 2016.

Our FFC-MRI project involves making a step change in magnetic resonance imaging (MRI) technology, by breaking one of its fundamental "laws" - that the applied magnetic field must be held constant during image acquisition. By deliberately switching the magnetic field during the collection of MR images, we are able to gain access to radically new types of endogenous contrast.

The project is generating the enabling technology to make FFC-MRI an invaluable tool for basic biomedical research, through to clinical research and diagnosis. We are also heavily involved with projects to investigate biological and medical applications of FFC-MRI.

 

The concept of FFC-MRI is explained in this animation:

 

In this video, Prof. David Lurie and team discuss their work: 

About

Rationale Behind Field-Cycling

Much of the "contrast" in MR images arises from differences in the T1 relaxation time between normal and diseased tissue. For example, tumours normally exhibit significantly longer T1 values than their surrounding normal tissue, making them stand out in MR images.

Studies over the years on small tissue samples have shown that the way in which a tissue's T1 varies with magnetic field could also be a potential indicator of disease. However, that information is completely invisible to conventional MRI scanners, because each scanner can only operate at its own magnetic field (e.g. 1.5 T or 3.0 T).

The aim of our project on "Fast Field-Cycling MRI" (FFC-MRI) is to build and use new, very special types of MRI scanner in which the magnetic field can be switched (or "cycled") during the scan, so that the pattern of how T1 varies with magnetic field can be measured. This new type of MRI should be even more sensitive to changes in tissues brought about by disease, potentially allowing earlier and more reliable diagnosis of some medical conditions.

We have built a range of FFC-MRI scanners which have allowed us to perform relaxometry studies and field-cycled MRI measurements of large samples, as well as human volunteers and patients. Our equipment can be seen on the Facilities panel below.

Fast Field-Cycling NMR Relaxometry

Fast Field-Cycling Nuclear Magnetic Resonance (NMR) has been used for decades in order to measure the variation of T1 with magnetic field strength of small samples. A field-cycling pulse sequence comprises three distinct periods, called "polarisation", "evolution" and "detection", each applied at a different magnetic field strength. The magnetic field during the evolution period can be changed, but the field applied during the detection period is always the same, so that the NMR signal is always at the same frequency.

FC pulse sequence
Field-cycling pulse sequence, showing the three periods. Relaxation takes place during the Evolution period, while signal detection occurs during the Detection period.

A field-cycling relaxometry experiment involves repeating a T1-measurement pulse sequence - e.g. Inversion Recovery - each repetition using the same Detection field but a different Evolution field strength. The result of the experiment is a set of NMR signals obtained after the spins have "evolved" at a range of field strengths, and these can be analysed to produce a graph of T1 versus field strength (the T1 dispersion curve). The diagram below shows an example of a field-cycling relaxometry pulse sequence, which has been adapted for MRI by the addition of magnetic field gradients during the detection period.

Field-Cycling Inversion-Recovery pulse sequence for relaxometric imaging measurements
Field-Cycling Inversion-Recovery pulse sequence for relaxometric imaging measurements

 

Quadrupole Dips

Whereas one might expect to see a gradual, smooth increase in T1 with field strength, with biological samples this increase is often superimposed by three pronounced "dips" where the T1 value drops by 10 to 15% over a small range of field strengths. These are known as "quadrupole dips" and are found at well-defined field strengths (16 mT, 49 mT and 65 mT) where the Nitrogen-14 nuclear quadrupole resonance (NQR) and the proton NMR frequencies are equal. T1 is reduced at these field strengths because the nuclear spins of hydrogen atoms on the "backbone" of protein molecules are strongly coupled to the nuclear spins of adjacent nitrogen atoms, and this enhances the efficiency of proton NMR relaxation at the NQR frequencies.

T1 dispersion curve
T1 dispersion curve measured from a volunteer's forearm. Quadrupole dips centred on 49 mT and 65 mT can clearly be seen.

 

In fact, the "depth" of the quadrupole dips provides information about the concentration of protein in the sample under study, and we are investigating the possibility of protein imaging by "quadrupole-dip" MRI. By implementing a field-cycling inversion-recovery imaging pulse sequence, it is possible to collect images "on" and "off" a quadrupole dip. In areas of the body with large protein concentrations these will exhibit markedly different signal intensity. This is demonstrated in the images shown below of a volunteer's thighs, obtained with the evolution field set on- and off- the quadrupole dip at 65 mT. Muscle regions appear significantly darker (i.e. lower NMR signal) in the 75 mT image compared to the 65 mT image, due to the differences in T1 of the tissue at the two field strengths.

FC-IR image
FC-IR images of a volunteer's thighs, obtained at evolution fields of 65 mT
FC-IR image 75mT
FC-IR images of a volunteer's thighs, obtained at evolution fields of 75 mT
Facilities

We have developed novel equipment to carry out our research on fast field-cycling MRI (FFC-MRI). Many of these MR systems are unique in the world, and offer unprecedented facilities for research, and for their use in applications. The techniques themselves are described elsewhere on this site.

In our first-generation whole-body field-cycling MRI system (shown below), the detection magnetic field was provided by a permanent magnet which generated a vertical field of 59 mT. Just inside the bore of the permanent magnet was a resistive magnet, made from copper conductor in a saddle configuration. When electric current was sent through the resistive magnet windings they generated a field of up to 59 mT,  in opposition to the permanent magnet's field. In this way, switching on and off the current switched the total field in the centre of the magnet down and up in value, and the precise field value could be selected by choosing the correct current to send through the resistive magnet coils.

The typical switching time between magnetic field levels was 20-30 ms, significantly shorter than the T1 relaxation times found in most biological samples or in the human body.

59 mT whole-body FFC-MRI

The original 59 mT whole-body FFC-MRI system (with its copper RF screening removed)

 

More recently, we have built a whole-body FFC-MRI scanner based on a single-magnet design. The use of a single resistive magnet makes the pulse sequence more flexible, as the detection field can be altered as well as the polarisation and evolution magnetic fields. However, this flexibility comes at the expense of potential instability of the magnetic field during the detection period. Therefore, particular attention must be paid to the design and implementation of the control circuitry and the magnet power supplies.

0.2 T whole-body FFC-MRI magnet
0.2 T whole-body magnet for FFC-MRI
0.2 T whole-body FFC-MRI magnet
0.2 T FFC-MRI system, including 3-axis square Helmoltz coils for environmental field correction
0.5T FFC-MRI scanner
Service end of 0.2 T FFC-MRI magnet, showing water and electrical connections
Power supplies
Power supply cabinets (3 x 650 A) for 0.2 T FFC-MRI scanner (International Electric Co., Finland)

 

In addition to the home-built scanners described above, we have a commercial bench-top field-cycling relaxometer (Stelar SMARtracer), capable of making T1 dispersion measurements from 10 kHz to 10 MHz proton Larmor frequency on small (~1 ml) samples.

Stelar SMARtracer relaxometer
Our lab's benchtop field-cycling relaxometer
Funding

Funding for the FFC-MRI project has come from a number of sources, including the following:


Our current and recent funders include:

British Heart Foundation
British Heart Foundation
CSO logo
Chief Scientist Office

EPSRC
EPSRC
 
ARUK
Arthritis Research UK

EU H2020
European Commision

The Sirt Jules Thorn Charitable trust
The SIr Jules Thorn

Our industrial collaborators include:

Stelar
Stelar
International Electric Company
IECO
People

Core Research Group

Lionel Broche
Dr Lionel Broche
FFC team leader
The Hall Family Lectureship in Medical Physics
Dr Gareth Davies
Dr Gareth Davies
Research Fellow
David Lurie
Professor David Lurie
Emeritus Professor
Vasiliki Mallikourti
Dr Vasiliki Mallikourti
Research Fellow
 
James Ross
Dr James Ross
Lecturer
 
Robert Stormont
Mr Robert Stormont
Research Postgraduate Student (part-time)

 


Local Research Collaborators

 

George Ashcroft
Mr George Ashcroft
Senior Clinical Lecturer
 
Prof Dana Dawson
Professor Dana Dawson
Chair in Cardiovascular Medicine
 
Mr Yazan Masannat
Mr Yazan Masannat
Consultant Oncoplastic Breast Surgeon
and Honorary Clinical Senior Lecturer
Dr Nicola Mutch
Dr Nicola Mutch
Reader in Applied Medicine
Dr George Ramsay
Dr Justin Rochford
Reader
Justin Rochford 
Dr Justin Rochford
Reader

Former PhD Students on FFC-related projects

  • Dr Marcello Alecci
  • Dr Chang-Hoon Choi
  • Dr Dara Ó hÓgáin
  • Dr Ian Nicholson
  • Dr. Nicholas Payne
  • Dr Kerrin Pine
  • Dr Chittakorn Polyon
  • Dr Patana Puwanich
  • Dr Fraser Robb
  • Dr James Ross
  • Dr David Yeung
  • Dr Wiwat Youngdee
  • Dr Vasileios Zampetoulas
  • Dr. Nicholas Payne
Public Engagement and Publicity

Here you can find information about recent activities aimed at informing the public about our research. You can also find details of the public engagement activities that took place during our EU Horizon-2020 project "IDentIFY"


General Engagements

11th July 2019 - Professor David Lurie and Dr James Ross lead a series of workshops exploring magnetism, MRI and FFC in HMP Grampian, aspart of the Cell Block Science programme.

Dr James Ross lead a series of workshops exploring magnetismcreating electromagnets
The pair explained the fundamentals of MRI, and of electromagnetism. They helped inmates build their own electromagnets. The engagement was superb and the feedback excellent.

 17th June 2019 - CORDIS coverage of the IDentIFY project, in six languages 

 


11th June 2019 - Professor David Lurie gives the IPEM John Mallard Lecture at the UK Imaging and Oncology Congress (UKIO)

Professor David Lurie gives the IPEM John Mallard Lecture at the UK Imaging and Oncology Congress
President Professor Mark Tooley presented Professor David Lurie with his certificate for the John Mallard lecture at

20th April – 16th June 2019 - Immobile Choreography, by Beverley Hood.

Edinburgh based artist Beverley Hood has been commissioned to work with The University of Aberdeen team who are leading the research project, IDentIFY.

23rd April – 16th June 2019 - From Where Do We See? Craft Skills and Aesthetics in MRI: Public Exhibition by Dr Silvia Casini

The Small Gallery, Aberdeen Royal Infirmary - The art of MRI

 


29th January 2019 - The History, Physics, Applications and Future of Magnetic Resonance Imaging: talk by David Lurie

 


April 18th 2019 - Stuff Worth Knowing: The Science of Magnetic Resonance Imaging.

Professor David Lurie gave an interactive lecture, hosted by the Aberdeen Science Centre

Related image
Aberdeen Science Centre

Saturday 8th September 2018 - James Ross showed groups from the public the prototype FFC-MRI scanner, provided details of the prototype and answered questions.

Lionel Broche explained posters that were on display in the Suttie Centre and answered questions

British Science Week

2018

  • The IDentIFY team held an event inviting the public to visit the new FFC MRI scanner, and were on hand to answer questions. 
     
  • Dr Lionel Broche (IdentIFY Project) and Dr Mary Joan MacLeod (Stroke Specialist) led an event explaining MRI and FFC MRI 
Cafe Scientifique Talk

Cafe Scientifique Talk 

David Lurie gave a public lecture on MRI and FFC-MRI at Waterstones Bookshop, Aberdeen, on 25th October 2017


 "MRI scanning: a magnetic window to the body":

(Note - FFC-MRI part starts at 37 minutes.)


Question and Answer Session:

Publicity
 
TV and Radio

BBC Radio Scotland

21 November 2017

Interview with Prof David Lurie about FFC-MRI on the "Good Morning Scotland" news programme (audio file © BBC 2017). There was also an item on the BBC News web site:  New scanner "like 100 MRIs in one" developed in Aberdeen


STV news

21 November 2017

Item about FFC-MRI and the first patient scans, including an interview with a patient; broadcast on the STV evening news (video file © STV 2017). There was also an online item on the STV News site: Patients in Scotland first to use new powerful scanner.


Original 106 radio news item

21 November 2017

Radio news item on FFC MRI including interview with a patient (audio file © Original 106 2017).


SHMU-FM radio interview

24 October 2017

David Lurie was interviewed on Aberdeen local radio station SHMU-FM about MRI and FFC-MRI, during their weekly "Talking Science" programme.


18 February 2013 - Radio Castle (online station)

Castle Radio
David Lurie was interviewed on "
The Password Show with Peter Warren & Jane Whyatt".

7 February 2013 - STV news

STV news
The news programme featured an item about the FFC-MRI project
News Articles

May 11th 2019 - Press and Journal feature on FFC MRI

interview with Prof David Lurie. Full PDf here


4th May 2019 - The Press and Journal


5th July 2018 - The Evening Express 


1 December 2017 - The Scotsman newspaper

  • PDF of the article is here - The Times newspaper (online)

21 November 2017


22 November 2017 - Citizen newspaper (Aberdeen)


8 February 2013 - Press and Journal Newspaper

P&J article

Article

7 February 2013 - The Scotsman Newspaper

Scotsman article

 

23 March 2007 - The Scotsman Newspaper

Scotsman article

Front Page, Page 2
 

23 March 2007 - Press and Journal Newspaper

P&J article

Front Page

Online articles

3rd May 2019 - BBC News (online)


21 November 2017 - BBC News (online)


21 November 2017 - Twitter Feed - Nicola Sturgeon (First Minister of Scotland)

Radiology "Trade" Articles

February 2013 - Aunt Minnie Europe article

Aunt Minnie

AuntMinnie Europe radiology web site article on ZF-MRI project.


March 2013 - RAD Magazine article

RAD  Magazine

RAD Magazine medical imaging periodical article on ZF-MRI project.

General-Interest Articles

Spring/Summer 2008 - Innovate Magazine (Aberdeen University)

Innovate Magazine

An article on the project appeared in Issue 2
of the University of Aberdeen's "Innovate" magazine.


August 2007 - Science Scotland article

Science Scotland

Article in the Royal Society of Edinburgh's magazine -
see pages 21 and 22 of Issue 6.
Also available as Simplified Chinese script
Scientific Publications

These can be found on our Publications page.

 

Contact us

Biomedical Physics Building

University of Aberdeen
Foresterhill
Aberdeen
AB25 2ZD
United Kingdom