Diagnostic Accuracy of Portable Low- and Ultra-Low-Field MRI for Acute Ischemic Stroke: A Systematic Review and Meta-Analysis.

Low-Field and Portable MRI for Acute Ischemic Stroke: A Systematic Review

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.

Abbreviated versus full diagnostic protocol MRI for breast cancer detection: a diagnostic test accuracy systematic review and meta-analysis.

BACKGROUND To systematically compare the diagnostic accuracy of abbreviated breast MRI (AB-MRI) and full diagnostic protocol MRI (FDP-MRI) for breast cancer detection. METHODS Ovid-MEDLINE, Embase, Cochrane Library, and Web of Science were searched up to December 1, 2025. Risk of bias was assessed using the modified Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. RESULTS Forty studies (14,266 patients) were included. In screening settings, the first postcontrast subtracted (FAST) protocol achieved sensitivity comparable to FDP‑MRI but significantly lower specificity; adding T2‑weighted (T2W) imaging raised specificity to a level not statistically different from FDP‑MRI. In enriched‑screening settings, FAST with or without T2W performed comparably. In diagnostic settings, FAST combined with ultrafast (UF) and T2W demonstrated significantly higher specificity than FDP‑MRI (ratio 1.61, p < 0.001), while FAST and rapid abridged multiphase (RAMP) with or without T2W or diffusion‑weighted imaging (DWI) were comparable to FDP‑MRI. T2W + DWI alone showed significantly reduced sensitivity in diagnostic settings. CONCLUSION The diagnostic performance of AB‑MRI protocols relative to FDP‑MRI varies by protocol and clinical setting; findings apply only to the specific regimens evaluated. FAST maintains high sensitivity, with T2W offsetting specificity limitations in screening, while FAST + UF + T2W offers superior specificity in diagnostic settings. However, most subgroup analyses included only 3-4 studies, and others fewer than three; all results therefore require cautious interpretation and validation in larger, prospective studies before clinical adoption.

Perfusion imaging-guided risk stratification and endovascular decision-making in low-NIHSS large-vessel occlusion stroke: a systematic review and exploratory meta-analysis

Efficacy and safety of magnetic resonance imaging- vs. computed tomography-guided reperfusion in acute ischemic stroke: a systematic review and meta-analysis

Objective Acute ischemic stroke (AIS) is a leading cause of death and disability. Timely reperfusion improves outcomes, but optimal patient selection depends on neuroimaging; CT is fast and widely available, whereas MRI offers greater precision in identifying salvageable brain tissue. This systematic review (SR) and meta-analysis evaluates the comparative effectiveness of MRI-guided reperfusion (MRI-R) vs. CT-guided reperfusion (CT-R) in adult AIS. Methods We conducted a PRISMA-compliant SR and searched PubMed, Embase, Cochrane Library, Web of Science, CINAHL and Google Scholar for English or Spanish studies comparing MRI-R vs. CT-R in adult AIS. Randomized trials, cohort, and case-control designs were included. Primary outcome was mortality; secondary outcomes were 90-day functional independence modified Rankin Scale (mRS) 0–2) and symptomatic intracranial hemorrhage (sICH). Data were pooled with a random-effects model; risk of bias was assessed using Cochrane RoB 2.0 and ROBINS-I tools. Results From 11,578 records, 13 studies (27,313 patients) met inclusion criteria. Meta-analysis of 11 studies (27, 197 patients) showed MRI-R was associated with increased 90-day mRS ≤2 (RR 1.28, 95 % CI 1.06–1.55; p = 0.01; I2 = 82.6 %), reduced mortality (RR 0.72, 95 % CI 0.62–0.84; p = 0.002; I2 = 0 %) and lowered sICH (RR 0.59, 95 % CI 0.45–0.78; p = 0.002; I2 = 7.6 %) compared with CT-R. Subgroup analyses by CT comparator type (NCCT-only or multimodal CT) and reperfusion strategy (IVT, MT, or both) for successful reperfusion and 90-day functional independence showed no statistically significant differences between groups. Conclusion MRI-R was associated with improved functional outcomes, reduced mortality and lower sICH rates than CT-guided strategies. However, these findings should not be interpreted as definitive superiority given the high heterogeneity in functional outcomes, baseline patient characteristic differences between imaging groups, and detected publication bias. CT remains essential for rapid hyperacute assessment, while in well-equipped centers, MRI can improve patient selection through detailed tissue characterization, provided this does not delay reperfusion and patients have no contraindications. Further, prospective, randomized studies are needed to confirm these findings. Systemic review registration https://www.crd.york.ac.uk/PROSPERO/view/CRD420251165578, CRD420251165578

Prospective blinded interim evaluation of a portable radiofrequency device TES HT to support triage in emergency department patients with mild head trauma or acute neurological symptoms.

BACKGROUND Emergency Department (ED) evaluation of patients presenting with mild head trauma or acute neurological symptoms is common and often requires rapid exclusion of intracranial pathology. Although computed tomography (CT) is the diagnostic reference standard, its widespread use raises concerns regarding radiation exposure, cost, and ED workflow efficiency. TES HT100 is a portable, non-invasive radiofrequency-based device intended to assist early triage decisions. We report the prespecified interim analysis of a prospective validation study conducted in an ED population. METHODS Between December 2024 and January 2026, adult patients were enrolled at the Emergency Department of Pineta Grande Hospital, Castel Volturno, Italy. In this single-center, blinded diagnostic accuracy study, participants were included in two predefined cohorts: mild head trauma and non-traumatic acute neurological symptoms. TES HT100 provides a binary output and was compared with radiologist-interpreted head CT as the reference standard. Sensitivity, specificity, predictive values, likelihood ratios, accuracy, and balanced accuracy were calculated with 95% confidence intervals. Additional exploratory analyses stratified CT findings into acute clinically relevant abnormalities and chronic/incidental intracranial abnormalities without changing the prespecified primary endpoint. Robustness analyses assessed the impact of excluded or non-evaluable cases. TRIAL REGISTRATION ClinicalTrials.gov Identifier NCT07490418, registered on 23 March 2026. RESULTS The interim analysis included 301 patients (151 trauma; 150 neurological symptoms). CT-positive prevalence was 52.2%, consistent with the CT-imaged Emergency Department population and the protocol-defined broad intracranial abnormality endpoint. Overall sensitivity was 96.2% (95% CI 91.9-98.2), specificity 82.6% (75.6-88.0), PPV 85.8%, NPV 95.2%, and accuracy 89.7%. The positive likelihood ratio was 5.54 and the negative likelihood ratio 0.05. Exploratory category-specific analyses showed sensitivity and NPV of 96.6% and 98.4%, respectively, for acute clinically relevant abnormalities, and 96.0% and 96.0%, respectively, for chronic/incidental abnormalities. Specificity was lower in the acute-target analysis (50.6%), supporting interpretation of TES HT100 as a structural-abnormality triage signal rather than a lesion-specific acute-pathology classifier. CONCLUSIONS In this interim evaluation, TES HT100 demonstrated high sensitivity and a low negative likelihood ratio compared with CT in ED patients with head trauma or acute neurological symptoms. These findings support further evaluation of TES HT100 as a triage-support adjunct in CT-imaged ED populations. Exploratory acute/chronic analyses provide additional clinical context but should not be interpreted as evidence of lesion-specific performance for acute abnormalities or as justification for replacing CT.

Role of Low-Field Portable MRI in Small Vessel Disease Identification.

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.