AJNR. American journal of neuroradiology最新文献

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.

Background and purpose: Different types of software to analyze CTP data in patients with ischemic stroke are available. Assessing their comparability and interchangeability in clinical practice represents an only partly addressed question. Here we present a comparison between 2 distinct commercially available CTP types of software, analyzing their performance in estimating ischemic core volumes and evaluating the possible impact on patient stratification strategies to endovascular treatment (EVT).

Materials and methods: In this single-center retrospective monocentric observational study, 109 patients with stroke (mean age = 72.4 ± 12.4 years, M/F = 41/68) were included from January 2023 to June 2024. To evaluate the possible clinical relevance of the use of different types of software, DAWN and DEFUSE-3 criteria were applied to stratify the population. The software was compared (Viz.ai and syngo.via), and for both programs, different relative CBF thresholds were used to define the ischemic core.

Results: The 2 software programs showed significant differences in core volume identification, independently from the used threshold (all comparisons with P < .001). When the DAWN criteria for EVT were applied, the use of one software compared with another led to a significant (P = .005) increase in subjects excluded from EVT. The use of a more conservative threshold significantly reduced (P = .68) this discrepancy.

Conclusions: Within-subject analysis of CTP data with different software and thresholds might lead to significantly different core estimation and treatment stratification in patients with stroke. Though this effect can be mitigated by using specific thresholds, the physician should be aware of these differences when evaluating CTP data in clinical practice, given the possible direct implications in their decision-making process.

Background and purpose: Advancements in CT myelography (CTM) have improved visualization of CSF-venous fistulas (CVFs), a frequent cause of spontaneous intracranial hypotension (SIH). However, the relative impact of the timing of image acquisition and the contrast density in the subarachnoid space remain unclear. This study compared the effects of timing and contrast density in the ipsilateral subarachnoid space and assessed the impact of other technical factors on CVF conspicuity using a validated instrument to stratify diagnostic confidence.

Materials and methods: A retrospective review of International Classification of Headache Disorders, 3rd edition-confirmed patients with SIH with CVFs was performed. Only fistulas classified as definite by the Duke CSF-Venous Fistula Confidence Score (DCCS) were included. All available CTMs covering each index fistula site were reviewed, excluding examinations occurring after surgery or embolization for a definite CVF. We assigned a DCCS to each acquisition and recorded contrast density in the subarachnoid space ipsilateral to the known CVF and image acquisition time. Patient positioning and scanner type were also collected as potential confounders. Ordinal logistic regression was used to assess associations with CVF conspicuity.

Results: One hundred forty-four patients with 149 definite CVFs comprised the final cohort, from which 222 CTMs and 697 acquisitions were assessed. Both increased contrast density and reduced acquisition time were associated with increased CVF conspicuity in univariate analyses (P < .001). When adjusting for sex, scanner type, and patient positioning in the multivariate model, contrast density and time remained significant predictors of conspicuity (P < .001). Density had a 4-fold greater impact on conspicuity than time, with a 14.3% increase in likelihood of CVF detection per 100 Hounsfield unit (HU) increase in attenuation and an optimal target threshold at 836 HU.

Conclusions: Both contrast density and time influence conspicuity of CVFs on CTM; however, the greater relative impact of density suggests that myelogram technique should prioritize maximization of contrast density for optimal visualization of CVFs. Positioning strategies to increase local contrast pooling may improve CVF detection more effectively than timing adjustments alone.

CSF-venous fistulas are a common and increasingly recognized cause of spontaneous intracranial hypotension. Most CSF-venous fistulas occur in the thoracic spine and usually arise from nerve root sleeve diverticula. Myelography in the lateral decubitus position is necessary to detect and localize these fistulas, because this technique maximizes contrast density within diverticula, thereby permitting visualization of draining veins. Many modifications to decubitus myelography have been employed in an attempt to improve the conspicuity of CSF-venous fistulas. In theory, maximizing the subarachnoid-venous pressure gradient during imaging should increase contrast flow through CSF-venous fistulas, improving detection of these sometimes-subtle leaks. Augmentation of intrathecal pressure through saline injection before myelography is a simple technique to achieve this and is common in many practices. However, only one prior case report has demonstrated the impact of pressurization on the visualization of a CSF-venous fistula. In this multi-institutional, retrospective case series, we report on a larger cohort of patients in whom CSF-venous fistulas were either occult or nondefinite on myelography without saline pressurization and subsequently definitely seen on myelography with saline pressurization. While our study design precludes determining the incremental yield of saline infusion, it nonetheless provides further support for the value of saline pressurization during myelography in patients with suspected CSF-venous fistulas.

MR imaging of the lumbosacral plexus (LSP) is a critical tool for evaluating pelvic and lower extremity peripheral nerve disorders. The rarity of this examination type and the complexity of underlying anatomy can produce challenges for interpretation. This pictorial review outlines a structured approach for evaluating lumbosacral plexus MRI (LSP MRI), emphasizing key imaging anatomy, MRI protocols, and a spectrum of commonly encountered pathologies to aid radiologists in interpretating LSP MRI. Anatomic variants and age-related changes in nerve morphology can further complicate evaluation, necessitating a systematic approach. We discuss the appearance of neoplastic, traumatic, infectious/inflammatory, treatment-related, and compressive etiologies. A search pattern and reporting pearls are provided to facilitate efficient assessment of LSP MRI.

Background and purpose: MR-guided focused ultrasound (MRgFUS) is a promising and noninvasive treatment for medication-refractory essential tremor (ET). However, the mechanism of long-term postoperative brain structural remodeling remains unclear. This study aimed to investigate the changes in gray matter volume (GMV) before and after MRgFUS, as well as to explore the relationship between GMV changes and tremor control.

Materials and methods: Twenty-six patients with ET who underwent MRgFUS successfully were included in this study. They underwent structural MR imaging and clinical assessment before and one year after treatment. The Computational Anatomy Toolbox and spatially unbiased infratentorial template were used to estimate changes in GMV. Then, voxel- and region of interest-wise GMV analyses were conducted. Additionally, longitudinal changes were assessed by using one-way repeated measures ANOVA. Finally, the Pearson correlation was used to assess the relationship between GMV changes and tremor improvement.

Results: Patients with ET showed significantly decreased GMV in the left postcentral gyrus, left thalamus, and right superior temporal gyrus from baseline to one year postoperation (clusters 1 through 3, respectively, voxel-level P < .001, cluster-level P _{family-wise error (FWE)} < .05). Increased GMV was found in the left crus I, left crus II (cluster 4), and left lobule V (cluster 5) of the cerebellum (voxel-level P < .001, cluster-level P _FWE < .05). Region of interest-wise analysis revealed that GMV reduction mainly occurred in the left external and internal globus pallidus (P_{false discovery rate ( FDR)} = .04). Additionally, ROI-wise analysis using the Automatic Anatomic Labeling 3 (AAL3) Brain or Oxford Thalamic Connectivity Atlases identified significant GMV reductions in the lateral posterior or temporal region of the left thalamus (lateral posterior: P _FDR = .01; temporal region: P _FDR = .001). GMV changes in clusters 2 through 4 from baseline to 1 year postoperatively were significantly correlated with symptom improvement (P < .05).

Conclusions: Our findings suggest that MRgFUS may induce brain plasticity, affecting regions adjacent to the ablation lesion as well as remote brain areas. The reduction in GMV in the thalamic nuclei, which are located in nonablated regions, may reflect neuroplastic changes and functional deafferentation induced by the MRgFUS.

Aurora (https://aurora-report.com/) is an open-source Web application that introduces structured, standardized reporting for neuroimaging, currently focused on dementia and movement disorders. Developed by and for radiologists and neuroradiologists, Aurora provides a stepwise workflow to support evaluation and reporting. It includes validated atrophy scales such as medial temporal lobe atrophy, global cortical atrophy, entorhinal cortex atrophy, and Koedam posterior atrophy, as well as a systematic approach to describe small vessel disease based on Standards for Reporting Vascular Changes on Neuroimaging, version 2 criteria. Each section offers literature-based guidance and annotated examples for scoring. The platform features built-in calculators for atrophy and movement disorder metrics, including midbrain and pons measurements, midbrain-to-pons ratio, Magnetic Resonance Parkinsonism Index (MRPI), and MRPI version 2.0. Aurora generates structured reports in English (US) or Portuguese (PT). To our knowledge, it is the first freely available platform to unify standardized reporting and calculation for dementia and movement disorders.