Feasibility study Mid-Field (0.6 T) MRI system

Currently, access to MRI is limited due to costs (purchase, siting and
maintenance), the need for skilled personnel that is scarce, and safety issues
that require a hospital setting. The complexity and costs of MR scanners as
well as the safety issues are almost directly related to the magnetic field
strength. Mid-field (field strength between 0.1 T and 1 T) MRI scanners have
found renewed attention of industry and academia in the last years to reduce
costs and improve accessibility to MR. The improved hardware around the main
magnetic field and AI-powered reconstruction techniques provide ways to
mitigate the reduced signal from the lower main magnetic field. Mid-field
scanners have the potential to be placed in different environments such as a
community centre, closer to the GP, moving MR closer to the first line in
health care. Moreover, the lower magnetic field strength allows to make the
scanner more patient friendly, due to the possibility to widen the bore, more
silent imaging and fewer safety procedures.

A prototype 0.6 T MR scanner has been developed by Philips, based on a
commercially available 1.5 T MR scanner. A scanner of this type will be placed
in a side building of the LUMC by late 2024. Researchers of the LUMC already
gained experience and optimized standard sequences in healthy volunteers in the
past year at the same system as installed at the Philips plant in Best.

Through this study we further want to study what the potential role of a 0.6T
MR scanner could be in the Dutch healthcare system to increase the diagnostic
capacity of the first line of defence (GP practices) and to help triaging
patients for hospital referral. The prerequisite for assessing this role of
mid-field MRI is clinical research to study the clinical value of the obtained
images in comparison to imaging or non-imaging diagnostic methods that
currently are standard care, and technical research to optimize scan protocols
and new scan methods for mid-field partly based on the lessons from patient
scans. Technical research will include improved image quality and reduced
scan-time, multi-parametric mapping, fat suppression techniques, reduced
acoustic noise levels and lowered hardware requirements. In the translational,
clinical research we aim to study applications for brain, cardiac, lumbar
spine, knee, abdomen, (prosthetic) joints, whole body and lung.

Dissemination of technological findings will be performed via articles in world
leading journals on MR and radiology and the impact on the healthcare system
will be disseminated in medical journals. The technological developments we
pursue in this project are important to both the MR as well as the medical
community, since they open up avenues for new utilization of MRI in the
healthcare system.

Our overall aim is to develop mid-field MRI systems for low-threshold,
extramural service to GP practices that can contribute to making healthcare
more sustainable. In this study we want to perform the first steps towards
this general aim. On one hand, we aim to improve image quality and develop
several new techniques that improve patient comfort, reduce placing costs
and/or easy operability. Some of these techniques can directly be productized,
other insights will be used in future MR research and development. On the other
hand and in parallel, we aim to explore what types of pathology that GPs often
need additional diagnostic tests can reliably be detected with mid-field MR.
This will potentially lead to further, more specific clinical research studies.

In this study brain, cardiac, lumbar spine, (prosthetic) joint, knee, abdomen,
whole body and lung imaging will be performed. To get a broad sample of
potential applications, no specific diagnostic questions are filtered.
Therefore, we will include patients where one could expect mid-field MRI to
provide sufficient image quality, but also include patients in which poor
performance is expected to allow a realistic estimation the diagnostic value
over a wide range of application. After the scan we will perform a survey with
the patients to incorporate feedback on comfort and scan experience. The
diagnosis based on the acquired images will be compared to the standard
diagnostic approach to perform a qualitative feasibility assessment. For each
anatomical region 50 patients (making the total 400) will be scanned to
incorporate a wide range of pathology for each organ to get a proper impression
of the performance of the new MRI scanner.
MRI-protocol development will follow the usual roadmap of MR physics research
that consists of an iterative process of identification of new requirements or
artefacts in existing techniques, MRI-protocol optimization, sequence
development, pilot experiments, quality review meetings, and finally back to
identification of sources of artefacts. For each of the studies (image quality
improvement/reduced scan time per anatomical region, multi-parametric mapping,
fat suppression, acoustic noise reduction, lowered hardware requirements, total
12) a maximum of 40 healthy volunteers will be scanned (maximum total number
480).

The used scanner is based on a commercially available model (1.5T), brought
down to a lower field strength of 0.6T, reducing projectile forces with a
factor 2.5 and power deposition with a factor 6.25[1]. All normal safety
checks will be performed as for 1.5T, minimizing risks. Extensive tests and
scans, both on phantoms and in vivo have been performed by Philips.
LUMC-employees have participated in extensive scanning at the 0.6 T scanner in
the Philips factory, including scans of human volunteers and elderly subjects.
The questionnaire will take a short time.