AJNR. American journal of neuroradiology最新文献

Background and purpose: Robustness against input data perturbations is essential for deploying deep-learning models in clinical practice. Adversarial attacks involve subtle, voxel-level manipulations of scans to increase deep-learning models' prediction errors. Testing deep-learning model performance on examples of adversarial images provides a measure of robustness, and including adversarial images in the training set can improve the model's robustness. In this study, we examined adversarial training and input modifications to improve the robustness of deep-learning models in predicting hematoma expansion (HE) from admission head CTs of patients with acute intracerebral hemorrhage (ICH).

Materials and methods: We used a multicenter cohort of n=890 patients for cross-validation/training, and a cohort of n=684 consecutive ICH patients from two stroke centers for independent validation. Fast Gradient Sign Method (FGSM) and Projected Gradient Descent (PGD) adversarial attacks were applied for training and testing. We developed and tested four different models to predict ≥3mL, ≥6mL, ≥9mL, and ≥12mL HE in independent validation cohort applying Receiver Operating Characteristics (ROC) Area Under the Curve (AUC). We examined varying mixtures of adversarial and non-perturbed (clean) scans for training as well as including additional input from the hyperparameter-free Otsu multi-threshold segmentation for model.

Results: When deep-learning models trained solely on clean scans were tested with PGD and FGSM adversarial images, the average HE prediction AUC dropped from 0.8 to 0.67 and 0.71, respectively. Overall, the best performing strategy to improve model robustness was training with 5-to-3 mix of clean and PGD adversarial scans and addition of Otsu multi-threshold segmentation to model input, increasing the average AUC to 0.77 against both PGD and FGSM adversarial attacks. Adversarial training with FGSM improved robustness against similar type attack but offered limited cross-attack robustness against PGD-type images.

Conclusions: Adversarial training and inclusion of threshold-based segmentation as an additional input can improve deep-learning model robustness in prediction of HE from admission head CTs in acute ICH.

Abbreviations: ATACH-2= Antihypertensive Treatment of Acute Cerebral Hemorrhage; AUC= Area Under the Curve; Dice=Dice coefficient; CNN= Convolutional Neural Network; FGSM= Fast Gradient Sign Method; ICH= Intracerebral hemorrhage; HD= Hausdorff distance; HE= Hematoma expansion; PGD= Projected Gradient Descent; ROC= Receiver Operating Characteristics; VS= Volume similarity.

Background and purpose: Frontal paraventricular cystic changes have a varied etiology that includes connatal cysts, subependymal pseudocysts, necrosis, and enlarged perivascular spaces. These may be difficult to distinguish by neuroimaging and have a variety of associated prognoses. We aim to refine the neuroimaging definition of frontal horn cysts and correlate it with adverse clinical conditions.

Materials and methods: In this cross-sectional study, the pre-and postnatal neuroimaging database at a quaternary referral children's hospital was searched for all reports containing "frontal horn cysts", "periventricular cysts", or "connatal cysts" after IRB exemption. Frontal paraventricular abnormalities were categorized as either cysts, necroses, enlarged perivascular spaces, caudothalamic groove subependymal pseudocysts, frontal horn asymmetries, intraventricular septations, or ependymal vessels based on location and appearance. Cyst number, size, location, morphology, and signal/density/echotexture were documented, as were additional brain abnormalities. Clinical outcomes were recorded when available. Fisher's exact and Chi-squared tests were used to evaluate categorical data associations, and Kruskall-Wallis tests were employed to compare the medians among groups.

Results: 205 brain imaging exams (148 MRI; 55 US; 2 CT) from 110 distinct subjects (5 fetal: median 29.3, mean 27.5, and range 22.4 to 32.8 gestational weeks; 105 postnatal: mean 2.5 years, median 15 days, range 0 days to 19 years) were included. Seventy-one exams (35%) were initially diagnosed as connatal cysts but, instead, represented necrosis (n=23), enlarged perivascular spaces (n=20), caudothalamic groove germinolytic cysts (n=11), septations/adhesions (n=10), ventricular asymmetries (n=6), and a blood vessel (n=1). These entities differed in size, shape, location, and orientation (p<0.001). Congenital heart disease (p<0.04) and gastrointestinal (p<0.04) disorders were more common in subjects with frontal cysts and necrosis than in subjects with enlarged perivascular spaces; however, the frontal cyst and necrosis groups showed no differences in outcome (p>0.05).

Conclusions: Frontal paraventricular cystic changes represent a common interpretive dilemma. Enlarged perivascular spaces should be distinguished from other frontal cystic changes, which portend a more guarded prognosis, whether necrotic or otherwise.

Abbreviations: CMV= cytomegalovirus; CSPC= caudothalamic groove subependymal pseudocysts; FHCL= frontal horn cystic lesions; GA= gestational age; PVS= perivascular spaces.

Background and purpose: In this study, we aimed to develop and validate a novel nomogram model for predicting 90-day non-favorable clinical outcomes in patients with acute vertebrobasilar artery occlusion after endovascular treatment by integrating clinical and MRI features.

Materials and methods: This multicenter retrospective study analyzed data from 181 patients with vertebrobasilar artery occlusion eligible for endovascular treatment from two Chinese stroke centers. We developed a predictive model for non-favorable clinical outcomes (modified Rankin Scale score >3) using the data of 125 patients from Stroke Center A (2019-2023). The model was constructed using univariate and multivariate logistic regression analyses of clinical and MRI characteristics, with continuous variables dichotomized based on receiver operating characteristic curve analysis. Internal validation employed smooth bootstrapping, while external validation utilized 56 cases from Stroke Center B (2019-2023), ensuring model reliability and generalizability across diverse clinical settings.

Results: Age, NIHSS baseline score, recanalization, novel posterior circulation scores, and MRA-based posterior circulation collateral scores were independent predictors of 90-day prognosis, which were used to create a nomogram model. Internal validation demonstrated excellent discriminative performance of the model (mean area under the curve, 0.92 [95% CI: 0.91-0.93]), while external validation further confirmed its robust generalizability (area under the curve, 0.88). The patients were effectively stratified into the low-risk and high-risk groups using the nomogram model.

Conclusions: The posterior circulation collateral score was an independent predictor of prognosis. Our novel nomogram model, based on clinical and MRI characteristics, effectively predicts 90-day non-favorable clinical outcomes in patients with vertebrobasilar artery occlusion following endovascular treatment.

Abbreviations: AUC = area under the curve; ETO = estimated time of onset; EVT = endovascular treatment; FCO = favorable clinical outcome; mTICI = modified TICI; Novel-PCS = novel posterior circulation score; pc-ASPECTS = posterior circulation Acute Stroke Prognosis Early CT score; PC-CS = posterior circulation collateral score; ROC = receiver operating characteristic; VBAO = vertebrobasilar artery occlusion.

Background and purpose: In patients diagnosed with spontaneous intracranial hypotension (SIH), microspurs are considered the culprit lesion in most ventral dural leaks (type I). The imaging characteristics of discogenic spurs, and their prevalence in the general population has not been reported in the literature.

Materials and methods: This observational case-control study was conducted comparing the prevalence and characteristics of discogenic microspurs between SIH patients with a type I leak treated at a tertiary hospital between 2013 and 2023 and an age-and sex matched cohort of trauma patients.

Results: Each group consisted of 85 patients (mean age 51.6 years ± 11.9 years), 74% (58/85 patients) were female. The prevalence of discogenic microspurs in the control group and SIH group was 31.8% and 90.6%, respectively.The mean length of the culprit microspur responsible for a dural leak was larger compared to the mean length of all co-incidental microspurs from both the SIH and the control group not causing a dural leak (2.6mm versus 1.6mm, p<0.001).Our multivariate logistic regression revealed that an increasing length of a microspur (OR 1.942, CI 1.35-2.80, p<0.001) and a narrower diameter of the spinal canal (OR 0.85, CI 0.76-0.96, p=0.008) were predictive for a dural tear.

Conclusions: A discogenic microspur is a common incidental finding and may be found in almost one third of the general population. The length of the culprit microspur and the diameter of the spinal canal are distinct morphological characteristics for type I associated CSF leaks.

Abbreviations: CI = Confidence interval; CSF = Cerebrospinal fluid; CT = Computed tomography; ED = Emergency department; MRI = Magnetic resonance imaging; OR = Odds ratio; SD = Standard deviation; SIH = Spontaneous intracranial hypotension.

Background and purpose: Flat panel conebeam CT (CBCT) is essential for detecting hemorrhagic complications during neuroendovascular treatments. Despite its superior image quality and trajectory over conventional CBCT (circular scan), the dual-axis butterfly scan has a slightly higher radiation dose relative to conventional CBCT. This study evaluates the image quality in dose-reduction mode to uncover the appropriate radiation dose for the butterfly scan.

Materials and methods: We prospectively included patients who were scheduled for neuroendovascular treatment and underwent conventional CBCT and the dose-reduction mode of the butterfly scan. Two reduced radiation dose modes were used for the butterfly scan: medium-dose butterfly scan (70% of the original dose, 45 mGy) or low-dose butterfly scan (50% of the original dose, 30 mGy). The enrolled patients were assigned alternately to undergo either the medium- or low-dose butterfly scan. We evaluated and compared artifacts, contrast, and discrimination of the corticomedullary junction between conventional CBCT and one of the dose-reduction modes of the butterfly scan, with a 5-point scale scoring system.

Results: Twenty patients were enrolled in each of the medium- and low-dose groups, totaling 40 patients. Compared with conventional CBCT, the medium-dose butterfly group exhibited reduced artifacts, enhanced contrast, and corticomedullary junction discrimination (except in the occipital lobe). While the low-dose butterfly group exhibited markedly reduced artifacts and improved contrast (except in the occipital lobe), a significant improvement in corticomedullary junction discrimination was not observed.

Conclusions: Even with dose reduction, the specialized trajectory of the butterfly scan enables artifact reduction, contrast improvement, and enhanced corticomedullary junction discrimination. However, the impact of the reduced dose was more noticeable, particularly in the occipital region where susceptibility to bone interference resulted in decreased contrast and compromised corticomedullary junction discrimination.

Glucose transporter type 1 deficiency syndrome (GLUT1-DS) is an uncommon condition represented by an infantile-onset disorder, frequently arising from heterozygous mutations in the SLC2A1 gene. Individuals with GLUT1-DS may present with early-onset seizures (typically manifesting before 4 years of age), developmental delay, and complex movement disorders. In fewer cases, stroke-like events or hemiplegic migraine-like symptoms are also reported, defined by unilateral paresis affecting 1 side of the body and/or one-half of the face, occasionally accompanied by speech impairment. Currently, the pathomechanism underlying these acute transient clinical manifestations is poorly understood. MR imaging studies performed in the absence of acute manifestations frequently reveal nonspecific imaging signs associated with this syndrome. We present findings obtained using the arterial spin-labeling technique for perfusion imaging and MRA during the acute onset of stroke-like episodes in a series of 4 pediatric patients with GLUT1-DS. We observed reversible hypoperfusion in the left hemisphere and associated reversible attenuation of distal MCA branches on MRA. A notable association between unilateral cerebral hypoperfusion and transient crossed cerebellar diaschisis was evident on perfusion maps as well.

Background and purpose: This study investigates the practicality and utility of the "outline sign," which refers to the thin curvilinear hyperenhancing line that may be seen along the margin of a meningioma on a spin-echo postcontrast T1-weighted image. For cases in which the differential diagnosis may include other tumors, visualization of the outline sign may help to increase the diagnostic confidence for a meningioma. Therefore, in the temporal bone region such as the cerebellopontine angle or jugular foramen, where differential considerations may include a schwannoma or paraganglioma, we additionally investigated whether the outline sign may be observed in these nonmeningioma lesions.

Materials and methods: A total of 39 clinical MRIs of meningiomas, schwannomas, and paragangliomas with confirmed histopathologic data were studied retrospectively. Two experienced head and neck radiologists independently assessed for the presence or absence of an outline sign and subsequently formed a consensus opinion while blinded to patient information and histopathologic data. Interreader reliability was assessed by Cohen κ statistics. Simple bivariate comparisons were performed on the consensus opinions to assess for statistical differences in presence of the sign in meningiomas versus schwannomas and paragangliomas. Sensitivity, specificity, and accuracy of the sign with respect to identifying an underlying meningioma were calculated.

Results: Both readers displayed identical opinions in assessment of the outline sign in 34 of the 39 cases (87%), including 13 of the 14 meningiomas (93%), with substantial agreement (Cohen κ of 0.74). The outline sign was present in 12 of 14 meningiomas (86%), which was significantly greater in frequency compared with schwannomas (3 of 22, 14%) and paragangliomas (1 of 3, 33%). The outline sign demonstrated high sensitivity (86%), specificity (84%), and accuracy (85%) in identifying an underlying meningioma.

Conclusions: The outline sign can serve as a useful tool for diagnosing meningiomas. It may help distinguish meningiomas from other enhancing tumors, for example schwannomas and paragangliomas in the temporal bone region.

Background and purpose: Leptomeningeal collaterals have been associated with better outcomes in large-vessel stroke, but little is known about how the Circle of Willis (CoW) collaterals affect stroke outcomes. We aimed to determine the relationship between three anatomically distinct CoW subtypes and 90-day outcomes in acute ischemic stroke patients after successful revascularization via endovascular thrombectomy (EVT).

Materials and methods: We performed a retrospective analysis of patients treated with successful EVT for large-vessel occlusion at a comprehensive stroke center between May 2016 and November 2023. The CoW anatomy was trichotomized using baseline computed tomography angiography as follows: (I) complete CoW (C-CoW), (II) non-isolating incomplete CoW (NI-CoW), and (III) isolating incomplete CoW (I-CoW). Chi-squared and logistic regression analyses were utilized to determine the association of the CoW subtype with two co-primary outcomes: the 90-day modified Rankin Scale and 90-day mortality.

Results: A total of 465 patients were included in the analysis. Multivariable logistic regression analysis demonstrated a significant association between I-CoW and 90-day mRS compared to NI-CoW [OR (95% CI), 1.83 (1.08-3.09); p=0.02]. Additionally, I-CoW anatomy was associated with a higher 90-day mortality than C-CoW [OR (95%CI), 2.58 (1.01-6.60); p=0.04] and NI-CoW [OR (95% CI), 1.89 (1.13-3.18); p=0.01].

Conclusions: CoW variants are associated with functional and mortality outcomes in patients treated with endovascular thrombectomy for anterior circulation large vessel occlusion. Further research is needed to determine how CoW vessel anatomy may impact clinical assessment, triage, and treatment in acute ischemic stroke.

Abbreviations: CoW = Circle of Willis; EVT = endovascular thrombectomy; C-CoW = complete Circle of Willis; NI-CoW = non-isolating incomplete Circle of Willis; I-CoW = isolating Circle of Willis; AIS = acute ischemic stroke; LVO = large vessel occlusion; ACom = anterior communicating artery; PCom = posterior communicating artery; Tan CS = Tan collateral scores; ACA = anterior cerebral artery; PCA = posterior cerebral artery.

The purpose of this video is to introduce digital subtraction myelography for CSF-venous fistula (CVF) detectection.^1-3 CVF is the most recently identified and likely the most prevalent type of spinal CSF leak that leads to spontaneous intracranial hypotension^4,5 CVFs are occult on conventional MRI and CT, necessitating the use of myelography for the diagnosis. This video highlights one such technique, which is important because an increasing number of centers are starting to diagnose CVF.