Implementation and clinical utility of ultra-low-field portable magnetic resonance imaging for postprocedural neurological evaluation in ambulatory neurosurgery: illustrative cases
Jul 2026· Journal of Neurosurgery: Case Lessons· Vol 12· 0 citations· 17 references
Medicine
Abstract
BACKGROUND Elective endovascular neurosurgical procedures are increasingly performed in ambulatory neurosurgery centers, enabled by advances in catheter technology, safety of conscious sedation, and refined patient selection. Although complication rates are low, rapid evaluation of postprocedural neurological deficits remains critical. Conventional MRI is often impractical in outpatient or procedural settings, whereas ultra-low-field portable MRI (ULF-pMRI) systems (such as Swoop) allow bedside imaging with favorable diagnostic performance. OBSERVATIONS Two women in their 60s developed acute neurological deficits at an ambulatory neurosurgery center (ANSC) after diagnostic cerebral angiography in one case and elective internal carotid artery flow diversion in the other. In both cases, repeat angiography showed patent vessels. Bedside ULF-pMRI with diffusion-weighted and fluid-attenuated inversion recovery sequences demonstrated no acute infarction or hemorrhage. Symptoms fully resolved with supportive management. The availability of rapid portable MRI helped both patients avoid hospital admission, allowing same-day discharge without recurrent neurological symptoms. LESSONS In these 2 cases, ULF-pMRI demonstrated timely, informative neuroimaging in an ANSC setting. When paired with clinical improvement, bedside MRI safely guided disposition decisions, helped avoid unnecessary transfers, and supported patient safety as outpatient neurointervention expands. https://thejns.org/doi/10.3171/CASE26245
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
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
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
Background: Flow diverters (FDs) are widely used to treat intracranial aneurysms. Although effective, FD-related thrombosis or progressive stenosis may lead to acute or delayed cerebral hypoperfusion with significant neurological morbidity. Management options are limited when medical or endovascular rescue strategies fail. This study aims to evaluate the role of extracranial–intracranial bypass (EC-IC bypass) as a rescue strategy across the spectrum of FD-related cerebral hypoperfusion. Methods: We retrospectively reviewed all patients who underwent EC-IC bypass for FD-related cerebral hypoperfusion over a 10-year period in our institution. Both acute and chronic presentations were included. Clinical status was assessed using the modified Rankin Scale (mRS). Imaging evaluation included digital subtraction angiography (DSA), computed tomography angiography (CTA), magnetic resonance angiography (MRA) and quantitative magnetic resonance imaging for bypass flow assessment. Surgical technique, antiplatelet therapy, timing of intervention and clinical outcomes were analysed. Results: Five patients with FD-related cerebral hypoperfusion who underwent superficial temporal artery–middle cerebral artery bypass (STA-MCA bypass) were identified. Two distinct patterns emerged. Three patients developed early hypoperfusion within the first month of FD placement, presenting with acute neurological deficits and treated by emergent or urgent bypass under dual antiplatelet therapy. Two patients developed late hypoperfusion years after the procedure, presenting with progressive haemodynamic symptoms and treated by elective flow-augmentation bypass under aspirin monotherapy. At discharge, only one patient had an mRS ≥ 3. At one-year follow-up, a favourable outcome (mRS ≤ 2) was observed in all patients with available data. Follow-up data were missing for one patient. Conclusions: EC-IC bypass represents a feasible rescue strategy for FD-related cerebral hypoperfusion when medical or endovascular treatments fail. In our experience, though limited, STA-MCA bypass can provide sufficient cerebral reperfusion, even in urgent settings and under dual antiplatelet therapy, leading to favourable neurological outcomes.
Alessandro Tozzi, V. Caldiera, G. Ganci et al.· Neurology International· 0 citations
Background
Spontaneous intracranial hypotension (SIH) is a rare disorder characterized by cerebrospinal fluid loss and associated neurological effects, including coma. An epidural blood patch (EBP) is an established treatment, but procedural assessment often relies on patient feedback. In patients with impaired consciousness, an objective surrogate is needed.
Case
A 40-year-old man with a newly identified intracranial lesion developed progressive cognitive decline with subsequent imaging demonstrating SIH. Despite medical and neurosurgical interventions, his neurological status continued to deteriorate. An EBP was performed based on clinical and radiographic findings. Given his comatose state and inability to provide verbal feedback, electromyography (EMG) with fluoroscopic guidance was used to assess procedural safety and efficacy. Following EMG-assisted EBP, the patient demonstrated progressive neurological improvement.
Conclusions
This case highlights the utility of electromyography as an innovative adjunct in performing epidural blood patch in patients with compromised consciousness, offering an effective approach for managing severe spontaneous intracranial hypotension.
Antonio Pereira, Elizabeth Kasparov, Dominique Williams et al.· Anesthesia and Pain Medicine· 0 citations
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.
A. Conte, Fabrizio Alfieri, Angelo Localzo et al.· BMC Emergency Medicine· 0 citations
