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.
Abstract
Portable, low-field (LF) magnetic resonance imaging (MRI) is emerging as a clinically relevant adjunct in acute stroke care, enabling MRI in environments where conventional neuroimaging access is delayed, unavailable, or impractical. Advances in permanent magnet design, compact gradient and radiofrequency hardware, and the use of contemporary reconstruction methods have improved LF image quality and operational feasibility, supporting deployment at the point-of-care in emergency department, intensive care unit, and resource-limited settings. This review summarizes the evolving role of LF-MRI for acute stroke. LF sequence principles most relevant to stroke evaluation are summarized, focusing on how constraints in signal-to-noise ratio, achievable diffusion weighting, acquisition time, and diffusion direction sampling at LF influence lesion conspicuity and the reliability of quantification. The current clinical evidence base is then 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. Practical implementation considerations emphasize use case-driven deployment that preserves time-critical computed tomography and angiography pathways and clearly defines when LF-MRI should be used as an adjunct rather than a substitute for established initial imaging. Future directions include pragmatic workflow studies to determine where LF-MRI changes management, continued advances in hardware and pulse sequence development, and careful application of artificial intelligence for reconstruction and enhancement with task-specific validation in acute stroke.
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
Low-field magnetic resonance imaging (LF-MRI) has recently emerged as a novel approach to extend MRI capability into critical care environments and offers a unique opportunity to support repeated imaging during periods when neurological examination is unreliable or limited.
Lina Zheng, Z. Law, X. Nie et al.· Stroke· 0 citations
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.
Ed X. Wu, Yujiao Zhao, Yilong Liu et al.· Stroke· 1 citation
It is shown that low-field portable MRI systems (<0.1T) offer point-of-care acquisition with reduced infrastructure requirements and have demonstrated concordance with conventional MRI for multiple acute brain pathologies.
A. DeHavenon, Matthew J Huentelmen· Stroke· 0 citations
Stroke is a leading cause of morbidity and mortality globally. Prehospital stroke care is a rapidly growing field to improve stroke outcomes. Methods to assess patients in the prehospital setting include clinical scales and portable neuroimaging that are usually restricted to mobile stroke unit computed tomography scanners, which are not widely available. Lightweight low-field magnetic resonance imaging devices at the <0.1T range offer an opportunity for portable lightweight imaging for the prehospital setting, with the advantage of greater tissue assessment to diagnose stroke. This review focuses on the current landscape and future direction for low-field magnetic resonance imaging in the prehospital setting, with a discussion of current and upcoming devices, and potential barriers to ambulance integration and how these may be overcome. Low-field magnetic resonance imaging provides an exciting opportunity for portable and safe imaging for the prehospital setting for the early diagnosis of stroke and the initiation of triage and treatment. These devices have the potential to be much more widely available and accessible than the current prehospital assessment model of mobile stroke units and provide additional detail for treatment decisions compared with non-imaging-supported telehealth prehospital assessments.
James L Barker, A. Balabanski, Angela Dos Santos et al.· Stroke· 0 citations
This review critically appraise how CT and MRI are integrated hierarchically across these scenarios, and how emerging fast MRI and quantitative biomarkers may reshape future selection paradigms.
Kai Xu, J. Lyu, Xin Lou· Journal of Magnetic Resonanc...· 0 citations
