MGH Martinos Center for Biomedical Imaging 2017 | Page 21

groups around the world pursuing
development of MPI. The research-
ers in these groups have been
focused on a variety of possible
applications, including applications
in oncology; cell tracking; and
cardiovascular, gastrointestinal and
lung imaging. Notably, though, with
all of the activity surrounding MPI,
the researchers have neglected one
particular area of interest: that is,
the brain.
this grant, he and his group set
to work assessing the potential
of MPI, examining the barriers
to its use for neuroimaging in
humans and, through simulations,
testing the performance of various
MPI scanner designs. (An MGH
Research Scholar Award, which
Wald received the following year
for the project “Magnetic Particle
Imaging for Breast Cancer Screen-
ing and Monitoring,” afforded
further opportunities to explore the
Wald was struck by this. He watched potential of the technology.)
the groups setting often lofty goals
for the technology while studiously The results of the work were
avoiding the application directly in encouraging. Wald and colleagues
front of them. “I thought, ‘Everyone concluded that a first-generation
is ignoring the easy stuff,’” he says. human-size MPI scanner could
“If these magnetic particles stay in offer tenfold higher sensitivity than
the blood, and if you then directly conventional functional MRI with
detect the particle concentration, similar spatial resolution, with the
you are detecting blood. We have possibility of improvement with
lots of interesting stuff to do with further development.
a blood detector in the brain: func-
tional brain imaging!”
In the wake of the research, they
knew that a human-size MPI
Deciding to dig a little deeper, Wald scanner with the potential to revo-
in 2014 applied for and was awarded lutionize neuroimaging was in fact
one of the first BRAIN Initiative achievable. Now all that remained
grants by the National Institutes for them was to make it.
of Health. With the support of
Building a bigger mousetrap
The opportunity to construct the
scanner came in 2017, when Wald
applied for and was awarded his
second BRAIN Initiative grant. This
grant will support the construction
and validation of an MPI device for
use in humans, as outlined during
the earlier research. Wald knows
there will be challenges to face.
“There is currently no human MPI
scanner,” he reminds us. “And there
is a reason for this: It’s hard.” But he
has no doubt that the team he has
assembled—which also includes
Clarissa Cooley, Ken Kwong, Emiri
Mandeville, Joe Mandeville, Erica
Mason and Wim Vanduffel—will be
able to address them.
What sorts of c hallenges will they
need to tackle? The greatest difficul-
ties may lie in translating the tech-
nology for human-size imaging—
scaling up the field generation and
detection, for example. Wald also
anticipates a variety of “industrial
type” challenges in designing and
building the scanner. Not least:
figuring out how to keep a two-ton,
water-cooled
electromagnet
spinning around the subject’s head.
If successful, the new scanner will
open up a range of applications for
MPI, both in the lab and otherwise.
“We are betting that it will be a
valuable tool for neuroscience,”
Wald says. “But also, in the clinic,
it could monitor for hemorrhage
or, with targeted agents, look for
tumors. We are hoping to have a
solid proof of principle for these at
the end of our five-year grant.”
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