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.
Abstract
Cerebral small vessel disease (SVD) is the most common age-related brain pathology. Magnetic resonance imaging (MRI) is the reference standard for identifying SVD biomarkers, including white matter hyperintensity, recent small subcortical infarcts, lacunes, perivascular spaces, cerebral microbleeds, and cortical superficial siderosis. However, SVD is usually detected only when patients undergo conventional high-field MRI, limiting early identification, longitudinal monitoring, and equitable access to brain health evaluation. 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. We review the emerging evidence for portable MRI-based detection of SVD features, with an emphasis on white matter hyperintensity. Future portable MRI work on SVD should prioritize longitudinal validation, standardized reporting, and integration into pragmatic vascular prevention trials.
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
BACKGROUND: White matter hyperintensities (WMH) are widely used to assess cerebral small vessel disease but reflect late-stage injury. Diffusion magnetic resonance imaging (MRI) biomarkers have been proposed to capture earlier small vessel disease-related microstructural damage but their temporal progression relative to WMH and risk factors associated with progression remain unexplored. METHODS: We identified 2077 participants from the population-based cohort study of the Mayo Clinic Study of Aging in Olmsted County, Minnesota (aged 50–101 years) collected between 05/2005 and 09/2024 with longitudinal neuroimaging. Using multioutput nonlinear mixed-effects models in those with at least 2 fluid-attenuated inversion recovery-MRI and diffusion MRI scans, we characterized the temporal progression of WMH and 4 diffusion MRI biomarkers: fractional anisotropy of the genu of the corpus callosum, peak width of skeletonized mean diffusivity, free water, and Arteriolosclerosis-score, which were automatically estimated. Models incorporated participant-specific time shifts, correlations between biomarkers, and effects of risk factors (sex, education, APOE ε4 status, cardiometabolic conditions). RESULTS: The study population had a mean age of 78 years, 47% were women, 28% were APOE ε4 allele carriers, and 80% were cognitively unimpaired, with an average follow-up of 5.2 years (SD, 4.3 years) for fluid-attenuated inversion recovery-MRI and 4.3 years (SD, 3.9 years) for diffusion MRI. Arteriolosclerosis-score, fractional anisotropy of the genu of the corpus callosum, free water, and peak width of skeletonized mean diffusivity became abnormal in 50% of the study population 16, 12, 10, and 7 years before WMH become abnormal (half-width of CI <1 year), respectively. Global markers (Arteriolosclerosis-score, free water, peak width of skeletonized mean diffusivity, and WMH) were correlated, indicating shared substrates of widespread white matter injury. Fractional anisotropy of the genu of the corpus callosum, a vascular risk microstructural injury biomarker, was weakly coupled with WMH and had an earlier but more linear worsening across adulthood. Cardiometabolic conditions predicted earlier worsening of all biomarkers. Female participants showed earlier WMH, fractional anisotropy of the genu of the corpus callosum, and Arteriolosclerosis-score abnormalities, whereas male participants exhibited earlier peak width of skeletonized mean diffusivity and free water abnormalities. CONCLUSIONS: Diffusion MRI biomarkers were abnormal at least a decade before WMH become abnormal in the population, revealing a prolonged phase of early small vessel disease and highlighting their potential for small vessel disease prevention.
P. Vemuri, Mingzhao Hu, Emily S. Lundt et al.· Stroke· 0 citations
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
Inroduction Cerebral small vessel disease contributes substantially to cognitive decline in older adults, but conventional structural magnetic resonance imaging markers mainly reflect accumulated lesion burden and do not directly characterize diffusion-derived alterations in brain fluid homeostasis. We investigated whether combining diffusion imaging along the perivascular space and white matter free-water imaging improves identification of Montreal Cognitive Assessment (MoCA)-defined cognitive impairment in elderly patients with cerebral small vessel disease. Methods This prospective study included 100 patients with cerebral small vessel disease and 50 healthy controls. According to MoCA scores, patients were classified as cognitively normal (n = 42) or cognitively impaired (n = 58). All participants underwent 3.0-T magnetic resonance imaging, including conventional structural imaging and diffusion tensor imaging. Conventional structural magnetic resonance imaging markers were evaluated on anatomical imaging, whereas diffusion-derived metrics were used to assess perivascular diffusion and free-water burden. Group comparisons, correlation analyses, multivariate logistic regression, and receiver operating characteristic analyses were performed. Results Analysis along the perivascular space decreased progressively from healthy controls to cognitively normal patients and cognitively impaired patients, whereas white matter free water increased in the opposite direction (all p < 0.001). Lower ALPS-Index values and higher white matter free-water values were both associated with lower MoCA scores. The clinical information model showed moderate discrimination for MoCA-defined cognitive impairment (area under the curve = 0.764, 95% confidence interval: 0.669–0.859). After incorporating age, sex, education, hypertension, and diabetes as covariates, the traditional cerebral small vessel disease marker model achieved an area under the curve of 0.819 (95% confidence interval: 0.731–0.908), whereas the glymphatic-edema signature combining ALPS-Index and white matter free water achieved better discriminative performance (area under the curve = 0.928, 95% confidence interval: 0.875–0.981). The combined imaging model incorporating conventional structural markers, ALPS-Index, and white matter free water achieved the highest discriminative performance (area under the curve = 0.950, 95% confidence interval: 0.906–0.993). Discussion Perivascular diffusion imaging and white matter free water capture complementary aspects of altered perivascular diffusion and extracellular free-water accumulation in cerebral small vessel disease and improve identification of MoCA-defined cognitive impairment beyond conventional structural magnetic resonance imaging markers.
Chunhong Yang, Sunmei Cai, Bingbing Wang et al.· Frontiers in Neurology· 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
Vascular cognitive impairment and dementia (VCID) is a leading modifiable contributor to dementia, accounting for an estimated 27-33% of attributable dementia cases. Neuroimaging is central to detection, phenotyping, and longitudinal monitoring. This neuroradiology-focused review integrates the STRIVE-2 imaging lexicon with the VasCog-2 clinical framework and reviews the advanced MRI techniques most pertinent to VCID, spanning clinically established to emerging research approaches: arterial spin labelling, diffusion tensor imaging including peak width of skeletonised mean diffusivity (PSMD), quantitative susceptibility mapping, vessel architecture imaging, and resting-state functional MRI. Unlike previous reviews, we consolidate operational quantitative thresholds already informing decisions (the Staals total small-vessel-disease score, longitudinal white matter hyperintensity progression linked to dementia risk, microbleed and cortical superficial siderosis (cSS) criteria for anti-amyloid therapy eligibility, and validated PSMD reference ranges) and we critically address gaps between research-grade acquisitions and routine clinical workflows. Automated segmentation and structured reporting are transitioning into deployment, expanding the radiologist's role to combine pattern recognition with quantitative characterisation. We outline current limitations of standardisation, reproducibility, and external validation that remain prerequisites before quantitative VCID imaging achieves formal regulatory biomarker qualification.
Jose Federico Ojeda-Esparza, D. Botta, A. Fitsiori et al.· British Journal of Radiology· 0 citations