AJNR. American journal of neuroradiology最新文献

Background: Radiologically Isolated Syndrome (RIS) entails incidental Multiple Sclerosis (MS)-like MRI lesions. Longitudinal fMRI could clarify brain-symptom links; however, no longitudinal resting-state fMRI studies in RIS existed until now.

Objectives: Compare 14-month clinical, neuropsychological, and resting-state functional connectivity (FC) trajectories in RIS, MS, and healthy controls (HC), and relate FC change to fatigue.

Methods: Nineteen RIS, 20 MS, and 22 HC completed baseline and 14-month assessments (fatigue, neuropsychology) and 3T MRI (rs-fMRI, 3D T1, FLAIR). FC within canonical networks and the ventral attention network (VAN) seed-to-voxel (CONN) connections were tested with a repeated-measures ANOVA (FWE-corrected). Regression analysis related to FC to fatigue; ROC curves evaluated discrimination.

Results: Fatigue rose in MS but was stable in RIS. VAN connectivity showed opposing trajectories (group × time, p < 0.001): RIS increased within-VAN (and within-DAN vs. HC), whereas MS decreased within-VAN. In MS, VAN connectivity increased with orbitofrontal and striatal regions and decreased with thalamus/caudate (FWE p<0.05). Greater increases in within-VAN and VAN-thalamus/caudate connectivity were predicted to lead to fatigue reduction. A composite VAN metric differentiated RIS from MS (AUC=0.919). Lesion volumes were unchanged.

Conclusions: RIS and MS exhibit divergent, VAN-centered FC trajectories paralleling fatigue evolution. VAN-based longitudinal FC metrics may provide sensitive, noninvasive biomarkers that complement lesion measures in early MS.

Background and purpose: The glymphatic system facilitates perivascular clearance, and its dysfunction has been implicated in neurodegenerative diseases. Diffusion Tensor Imaging Along the Perivascular Space (DTI-ALPS) has been proposed as an indirect approach to assess glymphatic function, but its reliability is debated. The choice of b-value is an aspect of possible improvement. While a b-value of 1000 s/mm² is commonly used, the optimal b-value for DTI-ALPS remains unknown. This study aims to determine the optimal b-value for DTI-ALPS.

Methods: Simulations were conducted to examine how the choice of maximum b-value influences bias, precision, and effect size of the ALPS index. DTI-ALPS was applied in a cohort of 194 participants divided into four groups: healthy controls (n=42), Parkinson's disease patients (n=119), Parkinson's disease dementia patients (n=16), and progressive supranuclear palsy patients (n=17). ALPS indices were calculated by manually placing regions of interest on projection and association fibers in each hemisphere. Group differences in ALPS indices across b-values were analyzed using mixed models.

Results: In vivo, ALPS indices were higher at a b-value of 500 and 250 s/mm² compared to a b-value of 1000 s/mm² in both hemispheres. Simulations indicated a bias-variance trade-off: very low b-values reduced sensitivity and compromised precision, while high b-values improved precision but reduced accuracy. The simulated effect size of the ALPS index peaked at intermediate b-values (≈700 s/mm²). In vivo, ALPS indices were lower in Parkinson's disease dementia and Progressive supranuclear palsy patients compared to healthy controls, though differences varied across b-values.

Conclusions: Both simulations and in vivo results suggest that the commonly used b-value of 1000 s/mm² is not optimal for assessing diffusion in the perivascular spaces. Intermediate b-values at approximately 700 s/mm² appear more suitable. However, further optimization of acquisition parameters is needed.

Background and purpose: Scrub typhus is an endemic zoonosis caused by Orientia tsutsugamushi, presenting with a range of neurological manifestations. Despite its high prevalence in endemic areas and clinical relevance, a systematic description of the neuroimaging patterns remains sparse. This study emphasizes the imaging spectrum with clinic-radiological correlations of neurological manifestations of scrub typhus across three tertiary care centers in South India.

Materials and methods: This retrospective multicenter study included 55 patients with neurological symptoms and serologically confirmed scrub typhus, who underwent MRI between January 2020 and March 2025. Two experienced neuroradiologists reviewed the imaging for patterns, along with available CT imaging. Detailed demographic, clinical, and laboratory data were studied from health records.

Results: MRI abnormalities were found in 46 of the 55 patients (83.6%). Leptomeningeal enhancement was the most common observation (49.1%), primarily affecting the parieto-occipital and cerebellar sulci, and was best appreciated on post-contrast FLAIR. Encephalitic changes were seen in 16.4% with heterogeneous patterns including cortical, basal ganglia, thalamic, hippocampal, ADEM-like, and ANE-like involvement. 12.7% had cerebellitis, 9.1% had multifocal restricted diffusion, 7.3% had white matter hyperintensities, 7.3% had rhombencephalitis, and 5.5% had myelitis. Lacunar/cerebellar infarcts (5.5%), cerebral venous thrombosis (3.6%), and micro haemorrhages (9.1%) were among the vascular manifestations. Cranial nerves were involved in 5.5%. 20/28 patients (71.4%) had CT abnormalities, with diffuse cerebral edema being the most prevalent. Leptomeningeal enhancement frequently occurred with encephalitis and cerebellitis, while myelitis occurred with rhombencephalitis. ASL was performed in 6 patients, demonstrating hyperperfusion in cases of encephalitis and cerebellitis. Follow-up imaging in 7 patients revealed complete resolution of leptomeningeal and cerebellar enhancement, with variable evolution of encephalopathic changes, ranging from complete resolution to gliosis and volume loss.

Conclusions: Scrub typhus neuroinfection demonstrates a broad imaging spectrum, most frequently leptomeningeal enhancement with characteristic parieto-occipital and cerebellar predilection. MRI remains the modality of choice, though CT retains diagnostic value in acute or resource-limited settings. Recognition of these patterns in febrile patients from endemic regions can expedite diagnosis and treatment, preventing neurological sequelae.

Structured reporting in radiology is universally endorsed by the radiology societies, including American Society of Neuroradiology/American Society of Spine Radiology (ASNR/ASSR), Structured reporting offers many advantages including: standardization of reports and simplifying reports for referring providers and researchers to extract meaningful and important information. Furthermore, templates can guide radiologists by providing a "checklist" on necessary items to include in the report which can facilitate patient care and optimize patient management.Despite the known benefits of structured reporting, currently structured reporting of spinal metastasis continues to lack. This is explained by many factors including complexity of spinal metastasis, variability of its appearance based on primaries, multiplicity of lesions/variable extent of disease, and technical differences among MRI acquisition protocols between institutions.In this white paper from the American Society of Spine Radiology Education and Standards, we aim to provide a recommended structured reporting of spinal metastasis highlighting pertinent observations that are needed in reporting metastasis, reflecting relevance of radiology report to recent advances in treatment modalities, discussing advanced and emerging imaging modalities, and finally touching briefly on follow up recommendations and challenges.

Background and purpose: Accurate detection of pituitary microadenomas is critical for the diagnosis and treatment of Cushing's disease (CD). However, conventional MRI often has limited resolution and thick slices, leading to missed lesions and suboptimal surgical planning. This study investigates the diagnostic utility of artificial intelligence-assisted compressed sensing (ACS) applied to conventional anatomical MRI, combined with DCE-MRI using united Compressed Sensing with Radial Acquisition (uCSR), aiming to improve spatial resolution and lesion detection without prolonging scan time, while uCSR enhances temporal resolution and motion robustness in dynamic contrast imaging.

Materials and methods: This prospective study included 61 patients with surgically confirmed Cushing's disease who underwent both conventional and ACS-accelerated MRI sequences, including T2WI, contrast-enhanced T1-weighted imaging (T1WI-C), and delayed FLAIR, along with DCE-MRI using uCSR technique. Image quality assessments and lesion detection rates were compared. Pharmacokinetic parameters (Ktrans, Kep, Ve) derived from DCE were evaluated across lesion types.

Results: A total of 61 patients (median age, 42 years old; 56% female) were included, with 71 lesions identified, including 9 patients with multiple lesions and 2 patients with ectopic lesions. ACS-T1WI-C achieved higher image clarity scores compared with conventional T1WI-C (4.7 ± 0.3 vs 4.1 ± 0.6; P < 0.001) and higher signal-to-noise ratio (SNR, 30.1 ± 3.4 vs 22.3 ± 2.4; P < 0.001). Similarly, ACS-T2WI showed higher contrast-to-noise ratio (CNR, 12.4 ± 3.1 vs 8.5 ± 2.3; P < 0.001). Across all sequences, the combination of ACS-T1WI-C and delayed FLAIR detected all 71 lesions, corresponding to a sensitivity of 94.9% and specificity of 93.5%, significantly higher than conventional sequences (P < 0.001). Interobserver agreement for lesion detection was excellent (κ = 0.91) for ACS sequences. Multiple lesions (14.7%) showed significant pharmacokinetic differences; adrenocorticotropic hormone (ACTH)-secreting adenomas demonstrated significantly lower Ktrans and Kep compared with Rathke's cysts and non-functional adenomas (P < 0.01).

Conclusion: ACS significantly improves image quality and lesion detection in CD, providing high-resolution imaging without extending acquisition time. uCSR-based DCE-MRI further aids lesion-type differentiation, contributing to more accurate preoperative localization and diagnosis.

The diagnostic yield of CTP for cerebral venous thrombosis (CVT) is uncertain. We aimed to estimate the sensitivity, specificity, predictive values and area under the curve (AUC) of CTP for CVT diagnosis, hypothesizing that CTP review would increase CVT diagnosis accuracy. Retrospective analysis of patients with stroke-like symptoms undergoing brain NCCT, CTA and CTP at a single centre. Patients with a final diagnosis of CVT (8) were analyzed together with a control group (40, 5:1 ratio) by three neurologists blinded to diagnosis. Brain NCCT+/-CTA showed poor sensitivity (37.5%) with high specificity (100%) for CVT diagnosis, which increased to 50% and 100% respectively after additional review of all the CTP maps. The discrimination of brain NCCT+/-CTA for CVT was moderate, AUC of 68.8 (95% CI: 50.8-86.7), increasing to AUC of 75 (95% CI: 56.5-93.5) after adding all the CTP maps reviews.

Background and purpose: Recent studies have demonstrated bias in various medical imaging artificial intelligence (AI) models, yet the factors underpinning these biases remain relatively unclear. This study evaluated potential sociodemographic biases in AI-based glioblastoma MRI segmentation models trained on datasets varying in size and demographic composition. We evaluated four nnUNet models with different training datasets: (1) the Federated Tumor Segmentation postoperative (FeTS2) model trained on a large (>10k exams) multi-national, multi-institution dataset, (2) the Brain Tumor Segmentation (BraTS) 2024 postoperative glioma model trained on a moderate size (>2k exams) multi-institution, North American dataset, (3) a model trained on a small (>200 exams), private, demographically homogenous, single-institution dataset, and (4) a model trained on an equally small (>200 exams), but demographically heterogenous dataset.

Materials and methods: Models were evaluated for bias using an independent, manually corrected dataset of 480 patients (mean age 52 ± 14) that was prospectively collected from a single high-volume academic brain tumor center. Automated FLAIR and enhancing tumor segmentations from the AI models were evaluated using Dice scores. Sociodemographic factors were collected and analyzed using beta regression to assess their influence on model performance.

Results: The model trained exclusively on White, non-Hispanic males had the lowest overall Dice scores (0.943 for FLAIR, 0.909 for Enhancement) and exhibited biases in age and smoking status. The BraTS model demonstrated the highest Dice scores (0.996 for FLAIR, 0.999 for Enhancement) and had the least bias overall.

Conclusions: Demographic bias was relatively low in glioblastoma MRI segmentation models. The model trained on the smallest and most homogenous dataset exhibited the most bias. Greater demographic heterogeneity even without increasing training dataset size was associated with reduced bias. The BraTS model, trained on a moderate-sized cohort that included more diverse tumor types, performed better and demonstrated less bias than the FeTS2 model, despite the FeTS2 being trained on the largest dataset.

Background and purpose: The safety and efficacy of intravenous tenecteplase in acute ischemic stroke patients with primary medium and distal vessel occlusions (MDVO) selected for mechanical thrombectomy remain an area of active investigation. This observational study aimed to compare tenecteplase and alteplase in MDVO patients treated with mechanical thrombectomy (MT).

Methods: A retrospective, propensity score-weighted analysis of two cohorts: patients with patients with primary MDVO who received bridging intravenous thrombolysis prior to MT, from the multicenter TETRIS registry treated with tenecteplase, and patients from a tertiary center cohort treated with alteplase. The primary outcome was a modified Rankin Scale (mRS) score of 0-2 at 90 days. Secondary outcomes included mortality, symptomatic intracranial hemorrhage (sICH), and early and final successful reperfusion rates, assessed using the extended Thrombolysis in Cerebral Infarction (eTICI) 2b-3 scale.

Results: We included 110 patients, 65 receiving tenecteplase and 45 receiving alteplase. mRS 0-2 at 90 days was achieved in 53.8% of tenecteplase-treated patients versus 48.9% of alteplase-treated patients (p = 0.41). Mortality and sICH rates were similar between groups (12.3% vs. 13.3%, p=0.68; 3.1% vs. 0%, p = 0.51, respectively). There was no significant difference in early reperfusion between tenecteplase and alteplase (40.2% vs. 31.1%; p = 0.53). Final successful reperfusion did not significantly differ (80.4% vs. 88.9%; p = 0.28).

Discussion and conclusion: In MDVO, tenecteplase yielded comparable safety and functional outcomes to alteplase, without statistically significant differences in early or final reperfusion. In light of recent trials questioning the benefit of MT in MDVO, these data suggest comparable safety and functional outcomes between tenecteplase and alteplase as bridging thrombolysis prior to mechanical thrombectomy, within the limits of this observational study.

Background and purpose: Idiopathic intracranial hypertension (IIH) is a condition marked by elevated intracranial pressure, often leading to vision loss if untreated. While cerebrospinal fluid (CSF) opening pressure is a primary diagnostic criterion, it lacks sensitivity in normotensive cases. This study aimed to develop a non-invasive, imaging-based diagnostic model integrating a novel MRI-Rigidity Index (MRI-RI) and a conventional MRI-derived IIH-MR Score to assess intracranial rigidity and improve diagnostic accuracy across the IIH spectrum.

Materials and methods: Sixty-one participants were prospectively analyzed and divided into three groups: confirmed IIH (n=23), normotensive with IIH-compatible imaging (n=18), and healthy controls (n=20). The male-to-female distribution was 7/16 in Group 1, 5/13 in Group 2, and 8/12 in Group 3. All subjects underwent 1.5T MRI, including structural sequences and phase-contrast (PC) CSF flow imaging. The MRI-RI was calculated as Vmax² × |NFV|/Vmean, where Vmax reflects peak CSF flow velocity, Vmean represents mean flow velocity, and |NFV| denotes the net cerebrospinal fluid displacement per cardiac cycle, calculated as a magnitude-based volumetric measure independent of flow direction. A six-parameter IIH-MR Score (range: 0-10) quantified perioptic CSF distension, Meckel's cave size, sella morphology, optic disc protrusion, optic nerve tortuosity, and posterior scleral flattening. Interobserver agreement, intergroup comparisons, ROC analysis, and correlation with CSF pressure were performed.

Results: MRI-RI and IIH-MR Scores differed significantly across groups (p<0.001), with the highest values in confirmed IIH and the lowest in controls. A total MRI score ≥6 yielded 100% sensitivity and 92% specificity for detecting elevated CSF pressure; ≥7 provided 100% specificity. MRI-RI was notably elevated in normotensive patients with IIH-compatible features. Strong correlations were found between total MRI score and CSF pressure (r=0.85), and MRI-RI (r=0.66). Interobserver agreement was excellent (ICC=0.88-0.96; kappa=0.76-0.91).

Conclusion: The combined use of MRI-RI and IIH-MR Score allows comprehensive, non-invasive evaluation of intracranial rigidity in IIH. MRI-RI may detect early mechanical alterations even in normotensive patients, while IIH-MR Score offers structurally grounded diagnostic support. These tools may enhance early diagnosis and reduce the need for lumbar puncture in selected cases.

Background and purpose: Moyamoya disease (MMD) is characterized by chronic progressive stenosis of intracranial vessels and subsequent formation of abnormal collateral vessel networks. Indirect revascularization techniques, such as encephalo-duro-arterio-synangiosis (EDAS), promote angiogenesis to restore perfusion but have variable success rates. This study aimed to identify clinical and radiographic predictors of successful collateral vessel ingrowth after EDAS, emphasizing the role of contralateral interhemispheric collaterals.

Materials and methods: We conducted a single-center retrospective analysis of cerebral hemispheres from adult MMD patients who underwent EDAS. We assessed demographic characteristics, clinical presentation, procedural details, clinical and radiographic outcomes. Angiographic outcomes were assessed using the Orbital Grading System. Univariate analysis was performed to identify factors associated with favorable postoperative collateral development. Consequently, preoperative contralateral interhemispheric collateralization was quantitatively evaluated through pixel density analysis on digital subtraction angiography (DSA), comparing the moyamoya-affected hemisphere to the contralateral hemisphere.

Results: 61 MMD hemispheres of 43 adult patients were included in the study. Median times to last clinical and angiographic follow up were 29.9 months and 13.6 months, respectively. Higher Suzuki-stages (V and VI; p=<0.01), occlusions of the anterior cerebral artery (ACA; p=0.03) and internal carotid artery (ICA; p=0.048) were associated with superior postoperative collateralization. The presence of robust contralateral collaterals on preoperative angiography significantly predicted poor postoperative neovascularization (p=0.01). Pixel density analysis showed that increased pixel density ratios of moyamoya-affected hemisphere to contralateral hemisphere significantly correlated with reduced postoperative collateral vessel formation (Orbital Grading System, OR=130.94, p=0.008; Matsushima grading system, OR=52.09, p=0.018).

Conclusion: Higher Suzuki-stages, ACA and ICA occlusion predict successful neovascularization after EDAS. The presence of robust preoperative contralateral interhemispheric collaterals is an important predictor of poor collateral vessel ingrowth following EDAS. This finding suggests that such collateralization might reduce the local ischemic stimulus required for effective indirect revascularization. These findings could refine surgical decision-making by identifying patients who may be less likely to benefit from EDAS.