The recent developments in ultra-low-field brain MRI are reviewed, which enable imaging in open environments and demonstrate initial clinical applicability in point-of-care settings, and future developments are envisioned to address the current limitations of image quality and contrast in ultra-low-field brain MRI systems.
Abstract
Magnetic resonance imaging (MRI) is a cornerstone of neurological care, serving as the gold standard for diagnosing pathologies, such as brain tumors and, together with computed tomography, stroke. However, the high capital costs, specialized infrastructure requirements such as expensive and bulky radiofrequency-shielding cages, and the operational complexity of conventional high-field scanners (1.5T and 3T) largely confine MRI to centralized imaging facilities. This scenario often leads to reliance on brain computed tomography or ultrasound in point-of-care settings, despite MRI's superior soft-tissue contrast for diagnosis and prognosis. In the past decade, there has been renewed interest in compact and simplified ultra-low-field (under 0.1T) MRI scanners, fueled by advances in engineering and computing. Here, we review the recent developments in ultra-low-field brain MRI, which enable imaging in open environments and demonstrate initial clinical applicability in point-of-care settings. We also envision future developments along 3 focus areas (ie, hardware, imaging protocols, and data-driven image formation and analysis) to address the current limitations of image quality and contrast in ultra-low-field brain MRI systems.
The current clinical evidence base is reviewed, including the role of LF-MRI in supporting stroke-type classification and tissue confirmation, in wake-up and unknown-onset stroke for tissue-based triage, and in post-therapeutic settings to enable serial assessment after thrombolysis or thrombectomy.
A. Sorby-Adams, N. Pintér, Keith W. Muir et al.· Stroke· 0 citations
The emerging concept of "Green Radiology" aims to mitigate the environmental impact of medical imaging while maintaining high standards of patient care. Among various modalities, MRI is particularly resource-intensive. This review focuses on the clinical feasibility and significance of minimizing gadolinium-based contrast agent (GBCA) administration in neuroimaging, specifically for the longitudinal follow-up of brain tumors. Key points of this review are as follows: (1) Rationales for "Green" MRI: Beyond patient safety concerns such as adverse reactions and gadolinium retention in the brain and bone, GBCAs pose significant environmental risks due to their persistence in global water systems and potential eco-toxicity. (2) Feasibility in extra-axial tumors: For many extra-axial lesions, including meningiomas, schwannomas, and macro-PitNETs (≥ 10 mm), non-contrast MRI sequences-leveraging the inherent contrast of cerebrospinal fluid-provide sufficient diagnostic information for routine surveillance. (3) Strategies for intra-axial tumors: While GBCAs remain the gold standard for high-grade gliomas and metastases, a "non-contrast-first" strategy may be viable for tumors with indolent progression. In these cases, GBCAs can be reserved for instances where interval changes are first identified on unenhanced sequences. (4) Advanced contrast-free alternatives: Non-invasive techniques such as arterial spin labeling (ASL), chemical exchange saturation transfer (CEST) imaging, and advanced diffusion-weighted imaging (DWI) offer powerful metabolic and microstructural insights without the need for chemical agents. (5) Future perspectives: Deep learning-based technologies, including "virtual contrast" synthesis and dosage reduction algorithms, hold immense potential to harmonize diagnostic excellence with environmental sustainability. Transitioning toward "Green Neuroradiology" through the judicious use of GBCAs and the adoption of advanced non-contrast sequences is a practical and necessary step for sustainable radiological practice. This review highlights the concept of "Green MRI" for sustainable neuroimaging. We discuss the clinical and environmental rationales for minimizing the use of GBCAs, particularly in the follow-up of extra-axial tumors. Furthermore, we explore how advanced sequences and deep learning provide viable, contrast-free alternatives for future radiological practice.
Kazuhiro Tsuchiya, M. Gomyo, Shichiroh Katase et al.· Japanese Journal of Radiolog...· 0 citations
This work presents an open-source, optimized solenoid head coil tailored for the 50 mT open-source scanner (OSII ONE v2.1), set the basis for a fully reliable and reproducible component for the open-source OSII ONE MRI scanner.
Umberto Zanovello, Julia Pfitzer, Ariane Ernst et al.· 1 citation
Highlights What are the main findings? Portable MRI enabled safe bedside imaging in emergency and intensive care settings, although detection of very small (<5–6 mm) ischemic lesions remained less reliable than conventional high-field MRI. Diagnostic performance was influenced by lesion size and field strength, with low-field MRI reliably detecting most clinically relevant infarcts. What are the implications of the main findings? Low-field and portable MRI can expand timely access to stroke imaging where conventional MRI is unavailable, delayed, or unsafe, particularly in emergency departments, ICUs, and resource-limited settings. Continued improvements in hardware, imaging sequences, and multicenter validation studies are needed before low-field MRI can be adopted as a routine alternative to conventional high-field MRI for acute stroke evaluation. Abstract Background: Magnetic resonance imaging (MRI) has a central role in acute ischemic stroke (AIS) and transient ischemic attack (TIA) diagnosis; however, conventional high-field MRI remains limited by infrastructure requirements, patient transport, and restricted accessibility. Low-field and portable MRI systems have emerged as potential solutions for point-of-care neuroimaging in emergency, intensive care, and resource-limited settings. Methods: A systematic review was conducted according to PRISMA 2020 guidelines. PubMed, Scopus, Web of Science, and Cochrane Library databases were searched from inception through May 2026. Studies evaluating low-field or portable MRI systems (≤0.55 T) in adults with AIS, TIA, sub-acute ischemic stroke, or suspected stroke were included. Diagnostic accuracy, feasibility, safety, workflow, and clinical utility outcomes were extracted. Risk of bias was assessed using QUADAS-2. Results: Eleven studies encompassing portable and low-field MRI platforms ranging from 0.064 T to 0.55 T were included. Portable MRI demonstrated feasibility in bedside ICU and emergency department settings without major device-related adverse events. Diagnostic performance varied by field strength, lesion size, and imaging protocol. Conclusions: Low-field and portable MRI show promising diagnostic potential for AIS and TIA, particularly when conventional MRI is unavailable, delayed, or impractical. However, current evidence is limited by small, predominantly single-center studies with substantial risk of bias, and further prospective multicenter validation is required before these technologies can be incorporated into routine clinical decision-making.
Rachana R. Borkar, Sai Dhanush Reddy Jeggari, Kamal Kandel et al.· Brain Science· 0 citations
Qualitative similarities between volume measurements in adults and the questions of reproducibility through test-retest reliability and external validity using recent software updates to the Hyperfine Swoop system constitute a crucial foundation for the clinical utility of 64 mT MRI in monitoring brain volume loss over time.
M. Stockbridge, Rex Wang, V. Neal et al.· Aperture Neuro· 0 citations