AJNR. American journal of neuroradiology最新文献

Background and purpose: Freezing of gait (FOG) presents a significant challenge in the management of Parkinson's disease (PD). Our study explored the potential to predict PD-FOG using an unbiased machine learning (ML) approach that leverages conventional T1-weighted MRI and clinical measures.

Materials and methods: Thirty-seven participants (16 PD-FOG, 21 PD-nFOG) underwent standard isotropic 1mm³ T1-weighted MRI. Brain morphometric measures, including subcortical volume, cortical volume, mean curvature, area, local gyrification index, and thickness, were extracted using FreeSurfer7. Participants were divided into discovery (13 PD-FOG, 17 PD-nFOG) and independent testing (3 PD-FOG, 4 PD-nFOG) datasets. We tested the predictive ability of each FreeSurfer-derived measure, each clinical measure, and every combination of those measures using three ML models: Random Forest (RF), Support Vector Machine (SVM)-Linear, and SVM-Non-Linear. Feature reduction was performed using the least absolute shrinkage and selection operator before model development.

Results: The SVM-linear model outperformed SVM-Non-Linear and RF models when tested on the independent dataset (area under the curve [AUC]: 0.71, precision: 75%, sensitivity: 75%, specificity: 66.67%). FreeSurfer-derived cortical area from twenty-seven regions predicted PD-FOG, involving several cortical and subcortical regions. None of the other measures, either in combination or isolation, predicted PD-FOG. The identified features were significantly correlated with clinical and physical therapy measures of PD-FOG using univariate and multivariate statistics, bolstering confidence in the selected feature set.

Conclusions: Our results demonstrate that FreeSurfer-derived cortical area measures from 27 key regions across the frontal, temporal, parietal, and occipital lobes can moderately predict FOG in PD (AUC = 0.71) using a linear SVM model. While preliminary, our work outlines an MRI-based analytical approach that may inform future external validation efforts and contribute to understanding the potential role of cortical morphology in PD-FOG risk. However, given the limited sample size and constrained independent testing cohort, these findings should be interpreted as exploratory and warrant replication in larger, multi-center studies.

Background and purpose: Patients with suspected brain tumors typically undergo MRI with an IV contrast agent to detect regions of disrupted BBB caused by the tumor. Gadolinium-based contrast agents are standard for enhancing lesion visualization but may be contraindicated in patients with renal insufficiency. Ferumoxytol is an iron oxide nanoparticle approved for the treatment of iron deficiency anemia, and unlike gadolinium-based contrast agents, is not contraindicated in patients with renal impairment. Our study aimed to evaluate whether ferumoxytol-enhanced MRI is superior to pre-contrast imaging for structural delineation of intra-axial malignant brain lesions.

Materials and methods: This was a prospective, blinded re-read study of MRI images from patients with known or suspected intra-axial primary malignant or metastatic brain tumors, enrolled in an Institutional Review Board-approved research study, to support an FDA New Drug Application. Following FDA guidance, 3 independent neuroradiologist readers, blinded to contrast agent information, evaluated brain lesions of randomly ordered ferumoxytol-enhanced, gadolinium-enhanced, or pre-contrast images in separate reading sessions organized by an independent contract research organization. The 3 primary endpoints were the degree of contrast enhancement, border delineation, and the internal morphology of lesions, assessed using a 4-point visualization scale (1=none/poor; 4=excellent).

Results: In total, 153 patients were enrolled in the study (median age, 54 years; 57% male; 92% white). All 3 readers scored ferumoxytol-enhanced MRI images significantly higher than the pre-contrast images for visualizing lesions (p<0.001 for each primary endpoint). Average mean scores across readers for ferumoxytol-enhanced images were 2.8 for contrast enhancement, 3.0 for border delineation, and 2.6 for internal morphology, compared to 1.0, 2.1, and 1.7, respectively, for the pre-contrast images (p<0.001 for all). Safety data indicated that ferumoxytol administration was well-tolerated with adverse events consistent with its profile as an iron replacement therapy.

Conclusions: This study provides robust evidence that ferumoxytol-enhanced MRI improves lesion visualization compared to pre-contrast imaging. Ferumoxytol as an MRI contrast agent in brain tumor imaging may provide a valuable clinical alternative to gadolinium-based contrast agents in appropriate patient groups.

Periventricular nodular heterotopia (PNH) is a neuronal migrational anomaly frequently associated with filamin-A (FLNA) gene variants. However, in the absence of a pathogenic FLNA gene or in the context of other genetic mutations, PNH may demonstrate a distinct pattern of distribution, often accompanied by a variety of brain abnormalities. PNH associated with cerebellar hypodysgenesis (CHD) and malformation of cortical development (MCD) involving the mesial temporal lobes, without detectable FLNA variants, is a known, but under-reported, association. PNH in this context demonstrates a phenotypically distinct distribution (i.e., along the infrasylvian lateral ventricles). In this review, we report the prenatal MRI finding of this unusual association and provide key insights into this abnormality.

Background and purpose: Surgical shunt placement is a common treatment for idiopathic intracranial hypertension (IIH) but is hampered by high revision rates. Prior predictive models for shunt revision in IIH have overlooked disease-specific neuroimaging markers. We developed an explainable machine learning model to identify the strongest predictors of shunt revision across neuroimaging markers, clinical severity variables, and shunt-specific factors. The primary objective was to assess the contribution of IIH-related neuroimaging markers within this multimodal predictive framework.

Materials and methods: In this single-center retrospective cohort study of IIH patients treated from 2001 to 2022, we analyzed 23 variables, including validated neuroradiologic biomarkers, clinical characteristics, and shunt-specific factors. We developed ten machine learning classifiers, which were trained and tuned on 75% of the data using stratified 5-fold cross-validation. Final model performance was validated on an independent, held-out test set comprising the remaining 25% of patients. We then employed SHapley Additive exPlanations for model interpretability and Kaplan-Meier analysis to evaluate time-dependent risk of shunt revision.

Results: Among 128 patients (78 with shunt revision, 50 without), a stacked ensemble model (random forest + XGBoost) achieved the best performance on the independent held-out test set (25% of the cohort), with an accuracy of 78.2% (95% confidence interval, 63.1%-90.2%) and an area under the curve of 82.7% (95% confidence interval, 71.5%-92.0%). Model interpretability showed that optic nerve sheath diameter (MRI-derived), papilledema and visual field deficits (ophthalmic clinical and neuro-ophthalmic measures), together with shunt characteristics (nonprogrammable valves, lumboperitoneal shunting, higher initial valve pressure), were the highest contributors to predicted revision risk. Kaplan-Meier analysis showed longer shunt survival with programmable valves and in patients without preoperative visual field deficits, papilledema, or obesity.

Conclusions: In this cohort, MRI-derived optic nerve sheath diameter, papilledema, visual field deficits, and shunt characteristics were consistently among the most influential contributors to predicted risk of shunt revision. These findings highlight the added value of MRI-derived markers within a multimodal preoperative assessment, although prospective external validation is required before clinical adoption.

Abbreviations: SHAP = SHapley Additive exPlanations; ICP = Intracranial Pressure; IIH = Idiopathic Intracranial Hypertension; ML = Machine Learning; ONSD = Optic Nerve Sheath Diameter; LPS = Lumboperitoneal Shunt; XGBoost = Extreme Gradient Boosting.

Background and purpose: Middle meningeal artery embolization (MMAE) is an effective treatment for non-acute subdural hematoma (NASDH) patients, and it is increasingly being adopted into routine clinical practice as standard of care. This study aims to determine whether additional surgery is necessary to prevent treatment failure for NASDH patients treated with MMAE.

Materials and methods: We conducted a retrospective cohort study using the 2016-2022 Nationwide Readmissions Database. NASDH patients were stratified into standalone MMAE vs. combined MMAE+surgery groups. Propensity score matching (PSM) accounted for presenting symptoms and discharge functional status. The Elixhauser Comorbidity Index (ECI) quantified comorbidity burden. The primary outcome was treatment failure, defined as NASDH-related death, readmission, or surgical evacuation within 180 days post-discharge.

Results: Among 3,213 NASDH patients (1,669 MMAE-only; 1,544 MMAE+surgery), 1,108 patients per group remained after PSM. Overall, surgery was not associated with lower treatment failure (5.3% vs 7.5%; HR 0.67 [95% CI, 0.37-1.21]; p=0.19). A significant interaction between surgery and ECI was observed (p-interaction=0.002). Surgery reduced treatment failure in patients with low comorbidity burden (ECI<5; HR 0.29 [95% CI, 0.11-0.78]; p=0.01). For patients with medium (ECI 5-14, n=996) or high (ECI≥15, n=589) comorbidity burden, surgery was not associated with different outcomes (p=0.56 and 0.43, respectively).

Conclusions: For neurologically stable NASDH patients who underwent MMAE, baseline comorbidity burden significantly blunted the marginal benefit of surgery. Additional surgical evacuation was not associated with different rates of treatment failure for the majority of NASDH patients with medium to high comorbidity burdens.

Abbreviations: MMAE = Middle Meningeal Artery Embolization; NASDH = Non-Acute Subdural Hematoma; ECI = Elixhauser Comorbidity Index; PSM = Propensity Score Matching; HFRS = Hospital Frailty Risk Score; NRD = Nationwide Readmissions Database.

Background and purpose: Cerebral Metabolic Rate of Oxygen (CMRO2) provides a direct measure of brain tissue metabolism and function, making it valuable in understanding physiological changes in infarct tissue in ischemic stroke patients. However, changes in cerebral metabolism and their significance in infarct tissue post-reperfusion remain underexplored. In this study, we examined the longitudinal changes in CMRO2 in infarct tissue in successfully reperfused ischemic stroke patients.

Materials and methods: Fifty-one ischemic stroke patients with anterior circulation large vessel occlusion who underwent successful endovascular thrombectomy (EVT) were screened from a prospective longitudinal multicentre perspective study. MRI scans obtained at three post-EVT time points generated CBF and Oxygen Extraction Fraction (OEF) maps, from which CMRO₂ maps were calculated. Mean CMRO₂ values of manually delineated infarct ROIs and contralateral homologs were extracted and relative CMRO₂ values (ratio of infarct and contralateral CMRO₂ values) were analysed. The 3-month mRS scores were binarized into disabled (mRS > 1) and non-disabled (mRS ≤ 1), and relative CMRO₂ was compared between the groups cross-sectionally and longitudinally.

Results: Relative CMRO₂ values decreased significantly from 24-72 hours to 3 months (p < 0.001). Relative CMRO₂ was significantly higher in the non-disabled patients than in the disabled patients at all time points, except at 24-72 hours. Longitudinal analysis in both non-disabled and disabled patients revealed a significant decrease in the relative CMRO₂ values from 24-72 hours to 3 months (p < 0.001 for both). However, after 3 months, a visual but non-significant difference in CMRO₂ trajectory was observed between the two groups.

Conclusions: Post successful thrombectomy, relative cerebral metabolism in the infarct is elevated in the acute stage, before stabilizing over time. Patients with better functional outcomes consistently show better cerebral metabolism than patients with poor functional outcomes.

Abbreviations: mTICI＝ modified TICI; OEF＝ Oxygen Extraction Fraction; CMRO2 = Cerebral Metabolic Rate of Oxygen; EVT = Endovascular Thrombectomy; PRAISE = Post-Reperfusion pathophysiology in Acute Ischemic StrokE; FSL = Functional MRI of the Brain Software Library; SD = Standard Deviation; IQR = Interquartile Range; ns = not statistically significant.

Background and purpose: Double inversion recovery (DIR) is an MRI technique in which two types of tissue are suppressed, usually cerebrospinal fluid (CSF) and white matter (WM). The suppression is achieved with two inversion pulses prior to the acquisition of the imaging data. In the presence of strong inhomogeneities in the static magnetic field B₀ and/or the radiofrequency (RF) field, inversion may be inadequate, resulting in bright signal in tissues that should have been suppressed. The purpose of this work was to develop a DIR scan with inversion pulses that are robust against inhomogeneities in the B₀ and RF field.

Materials and methods: In this prospective study, the DIR sequence was equipped with inversion pulses designed with optimal control. Robustness against field inhomogeneities was incorporated into the cost functional for pulse optimization. DIR and controlled DIR (C-DIR) MRI images were acquired at 3T in 14 participants (9 male, age=36.1±11.5 years) enrolled between October 2024 to August 2025 from a single academic medical center: nine healthy; two with relapsing-remitting multiple sclerosis; one with persistent concussion symptoms; two with asymptomatic white matter hyperintensities. Suppression of CSF, presence of artifacts, and visibility of multiple sclerosis lesions and white matter hyperintensities were independently assessed visually by a radiologist. In eight healthy volunteers, means and SDs were computed for signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), with significance evaluated using a Student's t-test.

Results: C-DIR exhibits improved inversion in the presence of inhomogeneities in the B₀ and the radiofrequency field, resulting in the removal of artifactual signal. CNR increases ranged from 27% between gray matter and CSF (p<.001) to 102% between the brainstem and adjacent CSF (p<0.001). SNR in the cortical gray matter was 10.74±1.48 in DIR and 11.68±2.21 in C-DIR (p=.07).

Conclusions: Inversion with a robust RF pulse improves the quality of DIR, demonstrating artifact reduction and improved CNR.

Background and purpose: Spinal CSF leaks cause spontaneous intracranial hypotension (SIH), characterized by orthostatic headaches, but the detection of these leaks may require specialized and invasive spinal imaging. We have noted the presence of small lateral dural CSF collections of unclear significance on digital subtraction myelography (DSM) in some of these patients suspected of having SIH. The purpose of the present study was to compare radiographic and anatomic intraoperative findings in patients with such small lateral dural CSF collections who underwent surgical exploration.

Materials and methods: This retrospective cohort study included a consecutive group of patients suspected of having SIH who 1) did not have a spinal longitudinal extradural collection or CSF-venous fistula on spinal imaging; 2) underwent DSM under general anesthesia in the lateral decubitus position; and 3) underwent surgery for the finding of small lateral dural CSF collections of uncertain significance.

Results: The study group consisted of 27 patients (22 women and 5 men; mean age, 44.6 years; range, 16-72 years). DSM demonstrated a total of 31 small lateral dural CSF collections measuring 0.6-2.4 mm in diameter (mean, 1.3 mm) and 1.3-12.3 mm (mean, 3.5 mm) caudal to the origin of the neve root sleeve. Intraoperative exploration found evidence of a CSF leak in all 27 patients. One or more CSF-venous fistulas were found in 23 patients, and a pedicular type lateral CSF leak, in 4 patients. Radiographic differentiation between these 2 types of spinal CSF leaks could not be made with confidence.

Conclusions: Some patients suspected of having SIH have small lateral dural CSF collections on DSM caudal to the origin of the nerve root sleeve. We have found evidence of a CSF leak in all these patients on surgical exploration. This observation expands their treatment options.

Background and purpose: Cerebral malaria (CM) is a leading cause of childhood mortality and neurologic morbidity in sub-Saharan Africa and South Asia and a strong association between diffuse brain swelling and mortality has been well-established. Our goal was to characterize patterns of cortical edema on brain MRI in children with CM and determine their association with patient outcomes.

Materials and methods: We retrospectively reviewed admission brain MR images obtained from Malawian children with clinical CM admitted at a single center from 2013-2019. Two neuroradiologists assessed the pattern of cortical edema on T1-, T2-, and DWI by using a consensus approach. The overall degree of brain volume (brain volume score [BVS]) and other brain imaging findings were also assessed, including focal signal changes in the basal ganglia, white matter, and posterior fossa. We evaluated the frequency and associations of these imaging findings with clinical outcomes at hospital discharge (deceased, alive with neurologic sequelae, or alive without neurologic sequelae).

Results: We included admission brain MRI scans from 190 children with clinical CM. Cortical edema was identified in 163 MRIs. The predominant pattern of cortical edema was diffuse cortical involvement with relative sparing of the occipital and peri-Rolandic areas: 103 (63.2%) had this pattern, whereas 37 (22.7%) had sparing of the occipital cortex only, and 23 (14.1%) had generalized cortical edema without focal sparing. The presence of occipital and peri-Rolandic sparing inversely correlated with BVS (β = -0.26, P < .001) and outcomes (OR: 0.3; 95% CI: 0.1-0.6; P = .002).

Conclusions: Pediatric CM is associated with a typical pattern of cortical edema that relatively spares the occipital and peri-Rolandic areas, which become progressively involved with more severe disease.

Background and purpose: The ARCADIA-MRI study, an ancillary study to the randomized Atrial Cardiopathy and Antithrombotic Drugs in Prevention After Cryptogenic Stroke (ARCADIA) trial, reported that the risk of incident nonlacunar covert infarcts was lower in the apixaban group than in the aspirin group. This article presents the additional, prespecified, exploratory outcomes beyond the primary article, specifically examining the effect of apixaban on hemorrhagic lesions on MRI.

Materials and methods: The ARCADIA-MRI study was conducted in conjunction with ARCADIA trial visits, with follow-up durations ranging from 4 months to 5.3 years (median, 27 months). It included randomized patients who were eligible for cognitive testing and lacked MRI contraindications. Two experienced raters, blinded to treatment assignments, independently evaluated the baseline and follow-up MRI scans. The radiologic end points of this analysis were incident intracranial hemorrhage (>10 mm), microbleeds (≤10 mm), and superficial siderosis.

Results: MRI outcomes were compared between the 79 patients in the apixaban group and 95 in the aspirin group with both baseline and follow-up MRIs available. The treatment groups had similar baseline MRI findings. On the follow-up MRIs, the findings of incident bleeding events were similar between the treatment groups (all, P > .05): Intracranial hemorrhage occurred in 5.1% of patients in the apixaban group compared with 6.4% of patients in the aspirin group; microbleeds, 7.8% in the apixaban group and 10.8% in the aspirin group; and cortical superficial siderosis, in 7.7% of apixaban group and 12.9% in the aspirin group.

Conclusions: In an exploratory analysis of the ARCADIA-MRI substudy, MRI findings of incident bleeding events were similar in patients randomized to receive apixaban and aspirin.