MGH Martinos Center for Biomedical Imaging 2016 | Page 7

in previously unreachable places,”
said Mathieu Sarracanie, a research
fellow in the Low-Field Imaging
Laboratory in the Martinos Center
and lead author of the newly published results.

This creates a number of new opportunities for MRI. Not least: Without the need for massive, cryogencooled superconducting magnets,
the scanners can be sited and operated in a range of unconventional
environments. For example, ultraThe technology described in the low-field scanners operating with
paper operates at a magnetic field this new technology could complestrength of 6.5 millitesla—more ment traditional MRI by relieving
than 450 times lower than with hospital congestion and reducing
clinical MRI scanners. The authors triage delays in the neuro-intensive
of the study, including Sarracanie, care unit.
Cristen LaPierre, Najat Salameh,
David Waddington, Thomas Witzel Also, mobile standalone scanners
and Matthew Rosen, achieved high- could be implemented in resourceperformance MRI at this ultra-low poor environments and in situafield strength through innovative tions where MRI systems are not
engineering, acquisition strategies, traditionally available—for examand signal processing. In the paper, ple, during military conflicts, natuthey report 3D MRI of the living ral disasters or sports events.
human brain with heretofore unattainable speed and resolution in the “This novel non-cryogenic ultra-low
ultra-low-field MRI regime.
field MRI technology will be smaller,
lighter, less expensive, more robust

and more transportable than conventional MRI systems,” said Rosen,
Director of the Low-Field Imaging
Laboratory, an Assistant Professor
of Radiology at Harvard Medical
School and the senior author of the
work, “allowing for operation in, for
example, battlefield hospitals—near
to where injuries are most likely to
occur—and enabling assessment of
brain injury within the first hours of
the primary injury.”
Importantly, the ultra-low-field
technology is also considerably less
expensive than traditional MRI.
Conventional scanners can cost
upwards of $1.5 million for the
high-field (1.5-Tesla) devices most
commonly used today. The scanner
described in the Nature Scientific
Reports paper, in contrast, could
cost less than $50,000.

A Scanner So Small It Could Fit In The Back Of An Ambulance
In a 2015 paper, Clarissa Zimmer- Jason Stockmann is the lead author Matt Rosen and senior author Larry
man Cooley and colleagues reported of the 2016 paper. Other contribu- Wald.
the construction and validation of a tors include Cooley, Bastien Guerin,
prototype of another portable MR
system. This scanner, which weighs
in at less than 100 kg, works by replacing conventional gradient encoding with a rotating, lightweight,
cryogen-free, low-field magnet
(called a “Halbach” magnet). In a
Journal of Magnetic Resonance paper
published in June 2016, the researchers described a study in which they
extended the capabilities of the MR
encoding method Transmit Array
Spatial Encoding (TRASE) to enable
its use in portable imaging systems
with inhomogeneous B0 fields—like
the one they developed. This work
moves the prototype scanner ever
closer to realization.
Clarissa Zimmerman Cooley, Jason Stockmann and Larry Wald