Catalysing the Clinical Application of High-Field Magnetic Resonance Imaging (MRI)
Submitting InstitutionUniversity of Nottingham
Unit of AssessmentPhysics
Summary Impact TypeTechnological
Research Subject Area(s)
Physical Sciences: Other Physical Sciences
Engineering: Biomedical Engineering
Medical and Health Sciences: Neurosciences
Summary of the impact
Nottingham researchers constructed the world's first 3T MRI scanner, thus
demonstrating the viability and benefits of high-field MRI. This provided
a stimulus for magnet and MRI system manufacturers to develop 3T scanners,
which have now become established as the standard platform for high-end
clinical MRI studies. We estimate that since 2008: 2500 3T scanners have
been installed, representing a global investment of $5 billion;and 30-40
million patient examinations have been performed with 3T MRI scanners.
Technical advances which underpinned the Nottingham 3T scanner also
impacted on the development of functional MRI, thus opening up a new field
of medical research and clinical application. In a subsequent phase of
research, the Nottingham group developed ultra-high (7T) magnetic MRI in
partnership with PhiIips; forty 7T MRI scanners (current unit cost
>$10M) have now been installed across the world.
The early development of MRI through the late 1970s and 1980s brought an
increase in the operating magnetic field strength, from the 0.05-0.15T of
the first systems, to 1.5T, which was considered to be high field at that
time. Despite the clear theoretical advantage of still higher fields,
namely improved signal-noise ratio resulting in higher spatial and
temporal resolution, attempts to introduce 4T systems were not successful
(see Section 4). The major manufacturers (Siemens, Philips and GE)
produced just a handful of these systems in the late 1980s and then
abandoned the project since the anticipated improvements were not
realised, primarily due to limitations in the performance of the scanner
hardware and software. A field of 1.5T then remained the clinical standard
for most of the next two decades.
It was against this background that the Nottingham MRI group commissioned
and took delivery of the world's first 3T whole-body magnet in October
1991. In a project funded by the Department of Health, British Technology
Group and the University of Nottingham (1991-1994), we developed a unique
MRI scanner around this magnet. This involved designing and building our
own control electronics, radio-frequency and gradient systems, as well as
developing our own scanner control software. The aim, and successful
outcome, of the project was to produce a high-field system with the
ability to run echo-planar imaging (EPI). EPI is a technique that was
developed in Nottingham, and whose importance was recognised in the award
to Sir Peter Mansfield of the 2003 Nobel Prize for Physiology or Medicine.
The extremely high quality that we demonstrated in our 3T EPI images was
particularly noteworthy [1,2;i,ii], given that at that time commercial
manufacturers were struggling to implement EPI even at 1.5T.
The application of EPI at 3T provided an important enabling technology
for the field of functional MRI (fMRI) [iii] in which brain function is
monitored through the detection of changes in local blood flow. fMRI is
heavily reliant on high temporal and spatial resolution, and our 3T
scanner was ideally suited to research in this area. From 1994 onwards,
fMRI formed a major focus of our research, and we made several significant
contributions to its early development including the first paper on Single
Event MRI, and indeed coined the term `Single (cognitive) Event' . In a
series of highly cited papers [4-5], we then demonstrated how fMRI could
be used to investigate the cortical encoding of sensory responses in the
auditory , somatosensory and olfactory cortices . Our work, funded
by the MRC in a series of special project and programme grants which have
run continuously since 1993, was a major factor contributing to the
establishment of 3T MRI as the new clinical standard for neuroimaging and
functional neuroimaging (see Section 4).
We continued with our strategy of delivering higher sensitivity through
increased magnetic field strength when, in 2005, we acquired one of the
first 7T scanners in the world (the first in the UK and the first to be
supplied by Philips) through a £3M award from the HEFCE Joint
Infrastructure Fund [iv]. This field strength posed new challenges as the
wavelength in tissues at 300MHz is commensurate with the dimensions of the
human head, leading to significant interference effects. Our work at 7T,
demonstrating the increased sensitivity of fMRI, the increased spatial
resolution of anatomical images, and the improved access to new contrast
(including chemical exchange saturation transfer sensitisation and
quantitative susceptibility maps), has demonstrated that these effects are
surmountable [6,7;v-viii]. Indeed we have used the improved susceptibility
contrast to develop a reliable method for differential diagnosis of
multiple sclerosis (MS) [6; vi,vii]. Moreover, the quality and robustness
of our 7T data have played a significant role in stimulating the growth of
the 7T MRI market worldwide.
The following members of our MRI group contributed to the development of
the world's first 3T scanner: Bowtell, Francis, Glover,
Gowland, Mansfield, Morris; this group together
with Brookes and Mullinger contributed to the 7T work.
References to the research
* denotes papers best indicating quality of research
1) *P. Mansfield, R. Coxon, P. Glover, `Echo-planar imaging
of the brain at 3.0T - first normal volunteer results.' J. Comput.
Assist. Tomogr. 18, 339 (1994).
2) P. Mansfield, R. Coxon, J. Hykin, `Echo-volumar imaging
(EVI) of the brain at 3.0 T - first normal volunteer and functional
imaging results', J. Comput. Assist. Tomogr. 19, 847 (1995).
3) *M. Humberstone, G. V. Sawle, S. Clare, J. Hykin, R. Coxon, R.
Bowtell, I. A. Macdonald, P. G. Morris, `Functional magnetic
resonance imaging of single motor events reveals human presupplementary
motor area', Ann. Neurol. 42, 632 (1997).
4) D. Hall, M. P. Haggard, M. A. Akeroyd, A. R. Palmer, A. Q.
Summerfield, M. R. Elliott, E. Gurney, R. W. Bowtell, `Sparse
temporal sampling in auditory fMRI', Human Brain Mapping 7,
5) S. Francis, E.T. Rolls, R. Bowtell, F. McGlone, J. O'Doherty, A.
Browning, S. Clare, E. Smith, `The representation of pleasant
touch in the brain and its relationship with taste and olfactory areas',
Neuroreport 10, 453 (1999). DOI: 10.1097/00001756-199902250-00003
6) *E.C. Tallantyre, M.J. Brookes, J.E. Dixon, P.S. Morgan, N.
Evangelou, P.G. Morris, `Demonstrating the perivascular
distribution of MS lesions in vivo with 7-tesla MRI', Neurology 70,
2076, (2008). Listed in REF2; DOI: 10.1212/01.wnl.0000313377.49555.2e
7) W. van der Zwaag, S. Francis, K. Head, A. Peters, P.A. Gowland,
P.G. Morris, R. Bowtell, `fMRI at 1.5, 3 and 7 T: Characterising
BOLD signal changes', Neuroimage 47 1425 (2009). Listed in
REF2 DOI: 10.1016/j.neuroimage.2009.05.015
Grants in support of MRI at high and ultra-high field
i. `Ultra High Speed Echo-Planar Imaging at 3.0T', P. Mansfield,
R. Bowtell, P.A. Gowland and B.S. Worthington, MRC Special Project Grant,
ii. `Techniques of functional MRI/S: Application to dystonia, hearing
and recovery from stroke', P.G. Morris, R.W. Bowtell, P.A. Gowland,
A. Moody, G.V. Sawle and B.S. Worthington, MRC, Special Project Grant,
iii. `Fundamental improvements to functional MRI and their
application to hearing, movement disorders and stroke', P.G. Morris,
R.W. Bowtell, P.A. Gowland, G.V. Sawle and A. Sunderland, MRC, Programme
Grant, (1999-2004) £1,280,844
iv. `An ultra-high frequency facility for functional magnetic
resonance', P.G. Morris, R.W. Bowtell, P.A. Gowland, P.M. Glover, S.
Francis, S.R. Jackson and P.F. Liddle., Joint Infrastructure Fund,
v. `Functional neuroimaging at ultra-high field', P.G.
Morris, R.W. Bowtell, P.A. Gowland, S.T. Francis, P.M. Glover, S. Jackson,
C. Rorden, P. Liddle, D. Hall, A.R. Palmer, MRC Programme Grant,
(G9900259), (2005-2010) £1,860,084
vi. `Investigation of MS lesion heterogeneity in vivo using
high field (7Tesla) MRI', P.G. Morris and P. Morgan, MS Society,
(01/04 /08 - 31/03/09) £39,745
vii. `Potential use of newly detected MRI features of lesions
to diagnose MS', N. Evangelou and P.G. Morris, MS Society, (02/08/09
- 02/08/11) £127,792
viii. `Realising the benefits of structural and functional MRI
at ultra-high-field', P.G. Morris, R.W. Bowtell, P.A. Gowland, S.T.
Francis, W.A. Kockenberger, P.M. Glover, D. Auer, S.R. Jackson, P.F.
Liddle, T. Paus, A.R. Palmer, K. Krumbholz, MRC Programme Grant,
(G0901321), (01/01/2010 - 31/12/2015) £2,424,424
Details of the impact
Using the world's first 3T MRI scanner we demonstrated, in papers from
1994 onwards [1,2], that it was possible to generate high resolution,
artefact-free images. These results played a significant role in
convincing magnet and system manufacturers that the move to high field was
not only technically feasible, but could herald the new state-of-the-art
for clinical MRI systems.
The primary impact of high-field MRI on patient care has been through the
improvement in the quality of clinical diagnostic scans that high field
provides (see estimate of the number of patient examinations below), but
high field has also underpinned the new field of functional MRI (fMRI). As
described in section 2, the work of the Nottingham group was critical in
this development through their demonstration of EPI at 3T , and this
technique has subsequently been implemented in all commercial high-field
scanners. The stimulus to the new field of fMRI arose since EPI offers the
fastest mode of image acquisition, and was rapidly adopted as the
functional neuroimaging method of choice. EPI offered a viable alternative
to `FLASH', the fastest imaging technique then (mid- 1990s) commercially
available (FLASH proved inadequate to deal with the confounding effects of
motion on the small signal changes due to brain activity that must be
detected in fMRI).
The move to 3T gathered momentum and, by the mid-2000s, sales of 3T MR
scanners by all three major manufacturers (GE, Philips and Siemens) were
beginning to grow. At first, it was major MRI research centres who
installed 3T scanners (for example, in 1998 Oxford University's fMRIB
Laboratory were the first to follow the Nottingham example in the UK),
then clinical research facilities, and eventually larger hospitals, both
increasing capacity and replacing some of their older 1.5T systems.
The growth of high-field MRI has been sustained through the assessment
period (2008 onwards). Figures provided by a leading industrial source [A]
provide some key indicative data:
- The number of new scanner installations per annum (high- and
low-field) grew from approximately 2000 in the year 2003, to
approximately 3000 in 2010 (global figures);
- The fraction of these new installations designated as high field (3T)
grew from less than 2% before 2003, to 20% in 2010;
- The typical cost of a 3T MRI scanner is $2M [B]; the value of global
sales of high-field scanners in 2010 (the last year for which data are
available to us in a relevant form) was $1 billion;
- In the first half of the REF assessment period (2008-2010; data were
available only for this period) approximately 1400 high-field scanners
Extrapolating these data [A] we estimate that over 2500 high-field
scanners were installed from January 2008 - July 2013 (this is almost
certainly an underestimate since the rising trend in sales is neglected),
representing a global investment of $5 billion.
To evaluate the impact on patient care over the assessment period we
estimate the number of high-field examinations as follows: (i) the average
number of scans per scanner per year (averaged over both low- and
high-field scanners) in England is 6500 (using figures of 300 installed
scanners [C] and two million patient examinations [C]); the average number
of operational high-field scanners during the assessment period is taken
as 2250 (1000 installed prior to 2008 [A], plus half of the newly
installed scanners). This gives a global estimate of the capacity for 80
million patient examinations using high-field MRI from January 2008 to
July 2013. Taking into account the use of some of the high-field scanners
for research, and their application in more complex cases, we estimate
that 30 - 40 million high-field patient examinations were performed during
The role of the Nottingham research in underpinning these developments is
confirmed by leading industrialists:
`The development of a prototype 3T scanner at the Sir Peter Mansfield
Magnetic Resonance Centre in Nottingham demonstrated that the
theoretical benefits of high field could be realised in practice.'
Joint written statement from the Premium & Portfolio MR Manager and
the 7T & High Field MR Product Segment Marketing Manager, GE
`The 3T scanner constructed at the Sir Peter Mansfield Magnetic
Resonance Centre (SPMMRC) demonstrated that ....... the high speed
imaging technique of echo-planar imaging, developed in Nottingham by Sir
Peter Mansfield, could be implemented at high field. The combination of
high field and imaging speed was crucial in the development of
functional MRI, now the mostly widely used functional neuro-imaging
technique.' MRI Clinical Science Director, Philips Healthcare [E].
The success of the Nottingham group also led to a change in the strategy
of magnet manufacturers such as Oxford Instruments and motivated a
decision to re-invest in the manufacture of wide-bore superconducting 3T
magnets. Morris (Director of the Sir Peter Mansfield Magnetic
Resonance Centre (SPMMRC), part of the School of Physics & Astronomy)
held a consultancy with Oxford Instruments during the period when the
first 3T scanner was built (early 1990s - 1998) and provided advice
regarding the technical challenges of implementing MRI at 3T and the new
market opportunities for high-field scanners. His contact at Oxford
Instruments was a senior magnet designer who was a member of the main
Board during this period and states:
`The failure of 4T systems to 'take off' had made the Board of Oxford
Instruments nervous about investment in high field systems, but you
helped to convince us that there would be a new market for such
systems,...' ex-Board Member of Oxford Instruments now working as a
In addition, fMRI, which was initially used primarily as a research tool
in basic neuroscience and clinical studies, now supports clinical and
commercial applications which impact directly on the diagnosis and
treatment of patients. Clinically, fMRI is used in pre-surgical mapping of
the eloquent cortex, and in some institutions this has become standard
procedure [G]. It is also contributing to the diagnosis of
neurodevelopmental, psychiatric and neurodegenerative disorders. In
addition, fMRI provides a basis for monitoring the actions of new
therapeutic agents, enabling their mechanisms of action to be identified
and/or confirmed. It is also being taken up by companies offering
diagnostic and other services, including the elucidation of pain pathways
The same drivers that led to the development of high-field 3T MRI systems
apply a fortiori to the development of ultra-high field (7T) MRI
systems. However, the barriers to delivering the additional improvements
were substantial, and it was unclear whether such systems were a viable
proposition, even in a purely research environment. In 2005, we took
delivery of the first 7T MRI system to be supplied by Philips. Our work in
developing structural and functional MRI on this system stimulated take-up
by several prestigious research institutions, as confirmed by a statement
`The SPMMRC was one of the first in the world to undertake human
studies at ultra-high field (7T). It took delivery of the first 7T MRI
system to be constructed by Philips Healthcare and the pioneering work
of the SPMMRC at 7T encouraged investment in this technology and rapid
uptake by the user community.' MRI Clinical Science Director,
Philips Healthcare [E].
It is estimated that forty 7T instruments have now been sold [I], with
further growth anticipated. The current cost of a 7T scanner is over $10M.
Sources to corroborate the impact
(available on request)
A. MR Business Manager, Philips Healthcare.
B. `Advances in Whole-Body MRI Magnets', T. C. Cosmus and M. Parizh, IEEE
Trans. On Appl. Supercond. 21 2104 (2011); see top of page 3.
C. National Audit Office report `Managing High Value Equipment in the NHS
in England' http://www.nao.org.uk/report/managing-high-value-capital-equipment-in-the-nhs-in-england/;
Figure 2, page 13 for number of MRI scans, for number of scanners see
Figure 1e on page 5.
D. Letter signed jointly by the Premium & Portfolio MR Manager and
the 7T & High Field MR Product Segment Marketing Manager GE
E. Letter from MRI Clinical Science Director, Philips Healthcare.
F. Letter from ex-Board Member of Oxford Instruments.
G. `The Evolution of Clinical Functional Imaging during the Past 2
Decades and its Current Impact on Neurosurgical Planning', J.J. Pillai,
Am. J. Neuroradiol. 31 219 (2010); DOI: 10.3174/ajnr.A1845
H. See for example the services offered by Chronic Pain Diagnostics, http://chronicpd.com/.
I. Reference B gives a figure of 30 units installed by 2010; the estimate
of 40 comes from the DOTmed online publication http://www.dotmed.com/news/story/17820.