Johnes Obungoloch1, Ivan Muhumuza1, Wouter Teeuwisse2, Joshua Harper3, Martin van Gijzen4, Steven Schiff5, Andrew Webb2, and Thomas O'Reilly2
1Mberara University of Science and Technology, Mberara, Uganda, 2Leiden University Medical Center, Leiden, Netherlands, 3Universidad Paraguayo Alemana, Asuncion, Paraguay, 4Delft Institute of Applied Mathematics, Delft, Netherlands, 5Yale University, New Haven, CT, United States
Synopsis
Keywords: Low-Field MRI, Low-Field MRI
Point-of-care
(POC) low-field MRI systems have a large potential to increase the
accessibility and sustainability of MRI in low- and middle-income countries
(LMICs). An important step in translating scientific developments from high-income
countries to LMICs is technology that can be assembled or constructed
locally. We describe the construction and testing of a POC system on site
in Africa. All components to assemble a 50 mT Halbach magnet based system,
together with the necessary tools, were air-freighted from The Netherlands to
Uganda. With four instructors and six untrained personnel, the complete project
from delivery to first image took approximately 11 days.
Introduction
The lack of MRI facilities, both clinical and
research, in the African continent has been highlighted in several recent
articles (1-3). In (3) four crucial challenges were highlighted: access and
availability, personnel training and education, research capacity and
sustainable technology. One approach that can potentially address many of these
recommendations is low-field MRI. In
order to fulfill these requirements, the system must be designed to be
affordable, but equally importantly to be understandable and repairable by, for
example, local medical physicists and/or electricians.
In September 2022, a team of researchers from
the Netherlands and Paraguay worked with local students and professionals at
the Mbarara University of Science and Technology (MUST) to construct, on site,
the first custom-built point-of-care MRI system in Africa. This work addresses
the question of how does one, in a practical manner, attempt to reproduce academic
developments in the area of low-field MRI design and construction (4-6) into a
practical product which can be manufactured and assembled on-site, in this case
in Uganda. Logistics, training, knowledge transfer, and infrastructural
capabilities are the focus of this paper, rather than device optimization and
design as in standard publications. We aim to give a realistic assessment of
the challenges in transferring knowledge from high-resource to lower-resource
environments.Construction and testing
Shipped components for magnet construction were
twenty-five PMMA rings produced via a computerized numerical control (CNC)
mill, M4 and M5 threaded brass rods (length 382 and 504 mm, respectively),
brass nuts and washers (M3, M4, M5), fifty 2 mm thick PMMA “lids” for the
magnet rings, glue, and 4089 12 x 12 x 12 mm3 NdFeB N-48 magnets. On
a practical level one should bear in mind that facilities for delivery after
shipping may be somewhat limited. As an example, the 325 kg crate was delivered
with a van that could just accommodate it, as shown in Figure 1, and did not
have a hydraulic lift. Because a fork lift was not available on site we ended
up opening the crate in the back of the van at night and carrying out items one
piece at a time into the laboratory.
The critical steps in magnet construction are ensuring
the correct orientations of the thousands of small magnets, and very accurate
spacing of the individual rings of mgets, as shown in Figure 2: typical
accuracies of 0.05 mm can be achieved using digital or analogue calipers.
An open
source (https://github.com/LUMC-LowFieldMRI/
GradientDesignTool)
was used to obtain three-dimensional wire patterns for the gradient coils.
These were printed using PLA formers with thickness 5-6 mm and groove depth 2.7
mm such that coated 2.1 mm2 wire could snugly be placed in the
grooves. In order to facilitate modularity the inner y- and z-coils were
fabricated in four different quadrants, with the outer x-coil fabricated as two
halves, as shown in Figure 3. Approximate printing times using an Raise3D
Pro2/3 Plus 3D printer were 5 or 8 days per segment for Z- and Y-gradient or
X-gradient respectively. In the laboratory in Uganda, the stages involved in
producing the gradient coils were removal of residual plastic in the grooves
(1.5 h per segment), placement of insulated wire and supergluing into place (1
hour per segment), as shown in Figure 3.
The MR spectrometer used to obtain initial
images, Figure 4, was the magnetic
resonance control system (MarCos) (14) developed by a consortium of
international researchers, details of which are available in open repositories
(https://github.com/yvives/PhysioMRI_GUI, https://github.com/vnegnev/marcos_extras/wiki).
The three-channel gradient amplifier is an open-source design
(https://github.com/LUMC-LowFieldMRI/GradientAmplifier) capable of providing up
to ~15 Amps with a peak voltage of 13 V. For the small solenoidal coil, a low
power RF amplifier can be used, in this case a Mini-Circuits zx60-100vh+ with a
maximum output power of 1 watt.
Figure 5
shows an approximate timeline for the build. This is intended as a guide, and
should be reconciled with the fact that two instructors were present the entire
time, with extensive experience of all aspects of the system construction. Six
untrained persons performed the majority of the construction. Discussion
This work
shows the feasibility and challenges associated with translating academic
advances in point-of-care MRI to locations in which accessibility and
sustainability are absolute enabling factors. Rather than simply shipping a
finished product, we believe that the fact that the assembly and testing
procedures took place entirely on location ensures a much greater transfer of
knowledge, and the possibility for this knowledge to be passed on. In addition
to being able to fabricate further systems, the ability to adjust, improve and
repair such a system is enormously enhanced by the from-ground construction
approach. Nevertheless, despite all of
the funding, support and organization that went into getting us to this point,
there are very substantial challenges that remain to successfully bring such a
technology to the point of regulatory approval, health-care evaluation and
commercial dissemination. These challenges are heightened within the largely
unexplored terrain of open-source technology such as this.Acknowledgements
This
work was funded by the National Institutes of Health (2R01HD085853), the Dutch
Science Foundation (NWO grants WOTRO Joint SDG Research Programme W 07.303.101,
Stevin Preis 14997), and the European Research Council (Horizon 2020 ERC
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