Imaging of Suspected Stroke in Children, From the AJR Special Series on Emergency Radiology.

Pediatric stroke encompasses different causes, clinical presentations, and associated conditions across ages. Although it is relatively uncommon, pediatric stroke presents with poor short- and long-term outcomes in many cases. Because of a wide range of overlapping presenting symptoms between pediatric stroke and other more common conditions, such as migraine and seizures, stroke diagnosis can be challenging or delayed in children. When combined with a comprehensive medical history and physical examination, neuroimaging plays a crucial role in diagnosing stroke and differentiating stroke mimics. This review highlights the current neuroimaging workup for diagnosing pediatric stroke in the emergency department, describes advantages and disadvantages of different imaging modalities, highlights disorders that predispose children to infarct or hemorrhage, and presents an overview of stroke mimics. Key differences in the initial approach to suspected stroke between children and adults are also discussed.

Arterial spin-labeled (ASL) perfusion in children with Sturge-Weber syndrome: a retrospective cross-sectional study.

PURPOSE: Sturge-Weber syndrome (SWS) is a developmental disorder with venous hypertension and associated tissue responses including pial angiomatosis, cortical calcifications, and cerebral atrophy. Arterial spin-labeled (ASL) perfusion is an advanced MR sequence which can assess perfusion, without the need for contrast. We systematically evaluated the potential benefits of using ASL in Sturge-Weber syndrome, to determine the extent of intracranial perfusion abnormality and stage of disease, relevant for prognostication and surgical planning. METHODS: Two pediatric neuroradiologists retrospectively evaluated ASL perfusion imaging of 31 children with confirmed SWS and recorded the presence of hyper-perfusion, hypo-perfusion, or normal perfusion. The presence and distribution of ASL abnormality were compared against the presence and side of atrophy/calcification and pial angiomatosis on standard MR sequences. RESULTS: Thirty-one children (52% female, median age 16.7 months) with SWS had ASL imaging. Seven (23%) had hyper-perfusion, 15 (48%) had hypo-perfusion, and 9 (29%) had no perfusion abnormalities. ASL perfusion abnormality matched the location of SWS findings on conventional imaging in 86% (19/22). ASL demonstrated statistically significant increased perfusion in the early stage of the disease and decreased perfusion when there was atrophy. The parietal lobe was involved in 86% of cases. CONCLUSION: ASL perfusion imaging is an advanced technique which may contribute to earlier diagnosis and more accurate prognostication of Sturge-Weber syndrome, helping guide management and potential surgical planning.

A Novel Phenotype of Calvarial Thickening and Increased Rates of Premature Calvarial Suture Closure in Children With Chronic Lung Disease.

PURPOSE: The purpose of this study was to characterize a novel type of calvarial thickening and provide objective measurements of skull thickness and calvarial suture morphology in patients with bronchopulmonary dysplasia. METHODS: Infants with severe bronchopulmonary dysplasia who also had undergone computed tomography (CT) scans were identified from the neonatal chronic lung disease program database. Thickness analysis was performed using Materialise Mimics. RESULTS: The chronic lung disease team treated 319 patients during the study interval of which, 58 patients (18.2%) had head CT available. Twenty-eight (48.3%) were found to have calvarial thickening. The rate of premature suture closure in the study population was 36.2% (21 of 58 patients), with 50.0% of affected cohort having evidence of premature suture closure on the first CT scan. Multivariate logistic regression identified 2 risk factors, requiring invasive ventilation at 6 months of age and fraction of inspired oxygen requirement at 6 months of age. Increased head circumference at birth protected against the development of calvarial thickening. CONCLUSIONS: We have described a novel subset of patients with chronic lung disease of prematurity who have calvarial thickening with remarkably high rates of premature closure of cranial sutures. The exact etiology of the association is unknown. In this patient population with radiographic evidence of premature suture closure, operative decision should be made after considering unequivocal evidence of elevated intracranial pressure or dysmorphology and balanced against the risk of the procedure.

Molecular imaging in management of colorectal metastases by the interventional oncologist.

Interventional oncologists provide several effective treatment options for patients with metastatic colorectal cancer (mCRC), including embolization and ablation-based techniques. Molecular imaging methods such as positron emission tomography (PET) can play an important role in managing mCRC patients. In this review, we aim to highlight the role of molecular imaging in mCRC management by interventional oncologists including: initial staging and pretreatment planning; predicting molecular subtypes, prognosis, and treatment outcomes; intraprocedural guidance; and assessing treatment response and post-procedural monitoring.

The role of apparent diffusion coefficient histogram metrics for differentiating pediatric medulloblastoma histological variants and molecular groups.

BACKGROUND: Medulloblastoma, a high-grade embryonal tumor, is the most common primary brain malignancy in the pediatric population. Molecular medulloblastoma groups have documented clinically and biologically relevant characteristics. Several authors have attempted to differentiate medulloblastoma molecular groups and histology variants using diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps. However, literature on the use of ADC histogram analysis in medulloblastomas is still scarce. OBJECTIVE: This study presents data from a sizable group of pediatric patients with medulloblastoma from a single institution to determine the performance of ADC histogram metrics for differentiating medulloblastoma variants and groups based on both histological and molecular features. MATERIALS AND METHODS: In this retrospective study, we evaluated the distribution of absolute and normalized ADC values of medulloblastomas. Tumors were manually segmented and diffusivity metrics calculated on a pixel-by-pixel basis. We calculated a variety of first-order histogram metrics from the ADC maps, including entropy, minimum, 10th percentile, 90th percentile, maximum, mean, median, skewness and kurtosis, to differentiate molecular and histological variants. ADC values of the tumors were also normalized to the bilateral cerebellar cortex and thalami. We used the Kruskal-Wallis and Mann-Whitney U tests to evaluate differences between the groups. We carried out receiver operating characteristic (ROC) curve analysis to evaluate the areas under the curves and to determine the cut-off values for differentiating tumor groups. RESULTS: We found 65 children with confirmed histopathological diagnosis of medulloblastoma. Mean age was 8.3 ± 5.8 years, and 60% (n = 39) were male. One child was excluded because histopathological variant could not be determined. In terms of medulloblastoma variants, tumors were classified as classic (n = 47), desmoplastic/nodular (n = 9), large/cell anaplastic (n = 6) or as having extensive nodularity (n = 2). Seven other children were excluded from the study because of incomplete imaging or equivocal molecular diagnosis. Regarding medulloblastoma molecular groups, there were: wingless (WNT) group (n = 7), sonic hedgehog (SHH) group (n = 14) and non-WNT/non-SHH (n = 36). Our results showed significant differences among the molecular groups in terms of the median (P = 0.002), mean (P = 0.003) and 90th percentile (P = 0.002) ADC histogram metrics. No significant differences among the various medulloblastoma histological variants were found. CONCLUSION: ADC histogram analysis can be implemented as a complementary tool in the preoperative evaluation of medulloblastoma in children. This technique can provide valuable information for differentiating among medulloblastoma molecular groups. ADC histogram metrics can help predict medulloblastoma molecular classification preoperatively.

Validation of Sonographic Fronto-Occipital Ratio Based on Anatomical Landmarks Compared to MR/CT-Derived Indexes in Children with Chiari II and Ventriculomegaly.

INTRODUCTION: Ultrasound (US)-based indexes such as fronto-occipital ratio (FOR) can be used to obtain an acceptable estimation of ventricular volume. Patients with colpocephaly present a unique challenge due to the shape of their ventricles. In the present study, we aimed to evaluate the validity and reproducibility of the modified US-FOR index in children with Chiari II-related ventriculomegaly. METHODS: In this retrospective study, we evaluated Chiari II patients younger than 1 year who underwent head US and MR or CT scans for ventriculomegaly evaluation. MR/CT-based FOR was measured in the axial plane by identifying the widest diameter of frontal horns, occipital horns, and the interparietal diameter (IPD). US-based FOR (US-FOR) was measured using the largest diameter based on the following landmarks: frontal horn and IPD in the coronal plane at the level of the foramen of Monro, IPD just superior to the Sylvian fissures, and occipital horn posterior to the thalami and inferior to the superior margins of the thalami. Intraclass correlation coefficients (ICCs) were used to evaluate inter-rater reliability, and Pearson correlation coefficients and Bland-Altman plots were applied to assess agreement between US and other two modalities. RESULTS: Sixty-three paired US and MR/CT exams were assessed for agreement between US-FOR and MR/CT-FOR measurements. ICC showed an excellent inter-rater reliability for US-FOR (ICC = 0.99, p < 0.001) and MR/CT-FOR (ICC = 0.99, p < 0.001) measurements. The mean (range) values based on US-FOR showed a slight overestimation in comparison with MR/CT-FOR (0.51 [0.36-0.68] vs. 0.46 [0.34-0.64]). The Pearson correlation coefficient showed high cross-modality agreement for the FOR index (r = 0.83, p < 0.001). The Bland-Altman plot showed excellent concordance between US-FOR and MR/CT-FOR with a bias of 0.05 (95% CI: -0.03 to 0.13). CONCLUSION: US-FOR in the coronal plane is a comparable tool for evaluating ventriculomegaly in Chiari II patients when compared with MR/CT-FOR, even in the context of colpocephaly.

Benign longitudinal T2-hyperintense signal in the lateral cord in infancy: a cross-sectional study of spinal cord white matter maturation on magnetic resonance imaging.

BACKGROUND: Longitudinal T2-hyperintense signal is commonly seen in the spinal cord of infants and likely reflects normal unmyelinated white matter tracts, but it can be mistaken for pathology. Autopsy studies have described incomplete myelination of spinal cord in early childhood; however, the maturation timeline of the spinal cord has not been described on imaging. OBJECTIVE: The purpose of this study was to retrospectively evaluate the maturation timeline of the spinal cord on MRI to provide a baseline for image interpretation. MATERIALS AND METHODS: We retrospectively reviewed axial T2-W images of the spinal cord acquired on 1.5-tesla (T) and 3.0-T MRI in children ages 0-2 years for presence of longitudinal T2-hyperintense signal, and we subjectively graded this signal as 0 (absent) to 3 (pronounced). Further, we reviewed a summary of medical records for confounding pathology in the brain or spine. Cord signal was interpreted as normal in the clinical report by subspecialized pediatric neuroradiologists for all included children. RESULTS: We reviewed 437 MRI exams from 409 children and included 189 studies in the analysis. Longitudinal T2-hyperintense signal in the lateral cord was seen in 95% (19/20) of subjects <1 month of age and was not seen in subjects ages 21-24 months (0/15). Grade 3 signal was seen in 22% (11/50) of infants ages 0-2 months and was not seen infants older than 5 months. CONCLUSION: Characteristic symmetrical longitudinal T2 hyperintensity in the lateral spinal cord is common in infants and should not be mistaken for pathology, and it was not seen in children older than 21 months.

Comparison of the effect of topical versus systemic L-arginine on wound healing in acute incisional diabetic rat model.

BACKGROUND: Diabetes is associated with endothelial dysfunction and impaired wound healing. The amino acid L-arginine is the only substrate for nitric oxide (NO) synthesis. The purpose of this study was to compare the topical versus systemic L-arginine treatment on total nitrite (NOx) and vascular endothelial growth factor (VEGF) concentrations in wound fluid and rate of wound healing in an acute incisional diabetic wound model. MATERIALS AND METHODS: A total of 56 Sprague-Dawley rats were used of which 32 were rendered diabetic. Animals underwent a dorsal skin incision. Dm-sys-arg group (N = 8, diabetic) and Norm-sys-arg group (N = 8, normoglycemic) were gavaged with L-arginine. Dm-sys-control group (N = 8, diabetic) and Norm-sys-control group (N = 8, normoglycemic) were gavaged with water. Dm-top-arg group (N = 8, diabetic) and norm-top-arg group (N = 8, normoglycemic) received topical L-arginine gel. Dm-top-control group (N = 8, diabetic) received gel vehicle. On the day 5 the amount of NOx in wound fluid was measured by Griess reaction. VEGF/total protein in wound fluids was also measured on day 5 using enzyme-linked immunosorbent assay. All wound tissue specimens were fixed and stained to be evaluated for rate of healing. Data were analyzed using SPSS software (version 18.0, Chicago, IL, USA) through One-way analysis of variance test and Tukey's post-hoc. RESULTS: In dm-sys-arg group, the level of NOx on day 5 was significantly more than dm-top-arg group (P < 0.05). VEGF content in L-arginine treated groups were significantly more than controls (P < 0.05). Rate of diabetic wound healing in dm-sys-arg group was significantly more than dm-top-arg group. CONCLUSION: Systemic L-arginine is more efficient than topical L-arginine in wound healing. This process is mediated at least in part, by increasing VEGF and NO in the wound fluid.

Reliability and Validity of the Persian HIT-6 Questionnaire in Migraine and Tension-type Headache.

OBJECTIVE: Headache Impact Test (HIT-6) measures the impact headaches in a 1-month period. We validated the Persian translation of HIT-6, compared the HIT-6 psychometric analysis between migraine and tension-type headache (TTH) patients, and evaluated the capability of HIT-6 to differentiate between TTH, chronic migraine, and episodic migraine. METHODS: Qualified participants, including 274 patients diagnosed with migraine or TTH, were required to complete HIT-6, SF-36v2, and a symptoms questionnaire on their first visit. At 3 and 8 weeks from first visit, participants completed HIT-6. Internal consistency (Cronbach's α) and test-retest reproducibility (Pearson's correlation coefficient) were used to assess reliability. Convergent validity was also assessed. RESULTS: Tension-type headache, episodic, and chronic migraines included 24.5%, 61.9%, and 13.6% of the participants, respectively. Internal consistency among all patients, TTH, and migraine in the first visit were 0.74, 0.77, and 0.73, respectively. Test-retest reliability for HIT-6 between visit 1 and 2 showed a moderate level of correlation (r = 0.50). Convergent validity and also item total correlation were acceptable. There was no significant difference in HIT-6 total score between TTH and migraine. CONCLUSION: Persian HIT-6 is a valid and reliable questionnaire for the evaluation of headache. However, it cannot differentiate between chronic migraine, episodic migraine, and TTH in Iranian population.

Investigation of chemokine receptor CCR2V64Il gene polymorphism and migraine without aura in the Iranian population.

BACKGROUND AND OBJECTIVES: Migraine is a multifactorial common neurovascular disease with a polygenic inheritance. Inflammation plays an important part in migraine pathophysiology. C-C chemokine receptor 2 (CCR2) is an important chemokine for monocyte aggregation and transendothelial monocyte migration. The aim of our study was to investigate the association of migraine with CCR2V64Il polymorphism in the Iranian population. METHODS: We assessed 103 patients with newly diagnosed migraine and 100 healthy subjects. Genomic DNA samples were extracted from peripheral blood and genotypes of CCR2V64Il gene polymorphism were determined. For measuring the severity of headache, every patient filled out the MIGSEV questionnaire. RESULTS: There were no significant differences in the distribution of both 64Il allele and heterozygote (GA) genotype of CCR2 gene polymorphism (P = 0.396; OR = 0.92, 95% CI = 0.50-1.67 and P = 0.388; OR = 0.91, 95% CI = 0.47-1.73, resp.) between case and control groups. There was no significant difference of alleles frequency between three grades of MIGSEV (P = 0.922). CONCLUSIONS: In conclusion our results revealed no association between CCR2V64Il polymorphism and susceptibility to migraine and also headache severity in the Iranian population.

The psychometric properties of the persian migraine-specific quality of life questionnaire version 2.1 in episodic and chronic migraines.

BACKGROUND: Migraine-specific quality of life (MSQ) is a valid and reliable questionnaire. Linguistic validation of Persian MSQ questionnaire, analysis of psychometric properties between chronic and episodic migraine patients, and capability of MSQ to differentiate between chronic and episodic migraines were the aims of this study. METHOD: Participants were selected from four different neurology clinics that were diagnosed as chronic or episodic migraine patients. Baseline data included information from MSQ v. 2.1, MIGSEV, SF-36, and symptoms questionnaire. At the third week from the baseline, participants filled out MSQ and MIGSEV. Internal consistency (Cronbach alpha) and test-retest reproducibility (intraclass correlation coefficients) were used to assess reliability. Convergent and discriminant validities were also assessed. RESULTS: A total of 106 participants were enrolled. Internal consistencies of MSQ among all patients, chronic and episodic migraines, were 0.92, 0.91, and 0.92, respectively. Test-retest correlation of MSQ dimensions between visits 1 and 2 varied from 0.41 to 0.50. Convergent, item discriminant, and discriminant validities were approved. In all visits MSQ scores were lower in chronic migraine than episodic migraine; however, the difference was not statistically significant. CONCLUSION: Persian translation of MSQ is consistent with original version of MSQ in terms of psychometric properties in both chronic and episodic migraine patients.

Statistical plots in oncologic imaging, a primer for neuroradiologists.

The simplest approach to convey the results of scientific analysis, which can include complex comparisons, is typically through the use of visual items, including figures and plots. These statistical plots play a critical role in scientific studies, making data more accessible, engaging, and informative. A growing number of visual representations have been utilized recently to graphically display the results of oncologic imaging, including radiomic and radiogenomic studies. Here, we review the applications, distinct properties, benefits, and drawbacks of various statistical plots. Furthermore, we provide neuroradiologists with a comprehensive understanding of how to use these plots to effectively communicate analytical results based on imaging data.

Application of the Intracranial Arterial Pulsatility Index for Determination of Prognosis after Lacunar Infarct.

Background: We aimed to investigate the usefulness of intracranial arterial pulsatility index to assess the prognosis of lacunar infarcts. Materials and Methods: Forty-nine patients with confirmed acute lacunar infarct were enrolled in the study. A transcranial color-coded sonography was performed to assess the pulsatility index of bilateral middle cerebral, posterior cerebral, vertebral, and proximal internal carotid arteries. Patients' clinical status was assessed using a modified Rankin scale. Spearman correlation was used for reporting the relation between quantitative data. Statistical significance was defined as a two-tail p-value of less than 0.05. Results: The mean age ± standard deviation was 64.1 ± 9.07 years old, and 57.1% of the patients were male. Upon discharge, only 8.2% of the patients were ranked as 0 on the modified Rankin scale; however, after a 6-month follow-up period, this number increased to 49%. There were no significant differences between the left and right pulsatility index measurements in any of the assessed arteries. Patients with vertebral artery pulsatility indexes >1 on their primary assessment had significantly worse outcomes during the first, third, and sixth months follow-up (all r > 0.3, p-values < 0.01). Pulsatility indexes from other arteries did not predict the prognosis. Conclusion: Sonography-assisted assessment of the vertebral artery blood flow during the early stage of lacunar infarct provides a reliable reference for prognosis estimation.

Clinical and Neuroimaging Characteristics of Ischemic Stroke in Rhino-Orbito-Cerebral Mucormycosis Associated with COVID-19.

PURPOSE: The aim of this study was to compare clinical, neuroimaging, and laboratory features of rhino-orbito-cerebral mucormycosis (ROCM) in COVID-19 patients with and without ischemic stroke complications. METHODS: This observational study was conducted between August and December 2021 and 48 patients who had confirmed ROCM due to COVID-19, according to neuroimaging and histopathology/mycology evidence were included. Brain, orbit and paranasal sinus imaging was performed in all included patients. Data pertaining to clinical, neuroimaging, and laboratory characteristics and risk factors were collected and compared between patients with and without ischemic stroke complications. RESULTS: Of the patients 17 were diagnosed with ischemic stroke. Watershed infarction was the most common pattern (N = 13, 76.4%). Prevalence of conventional risk factors of stroke showed no significant differences between groups (patients with stroke vs. without stroke). Cavernous sinus (p = 0.001, odds ratio, OR = 12.8, 95% confidence interval, CI: 2.3-72) and ICA (p < 0.001, OR = 16.31, 95%CI: 2.91-91.14) involvement was more common in patients with stroke. Internal carotid artery (ICA) size (on the affected side) in patients with ischemic stroke was significantly smaller than in patients without stroke (median = 2.4 mm, interquartile range, IQR: 1.3-4 vs. 3.8 mm, IQR: 3.2-4.3, p = 0.004). Superior ophthalmic vein (SOV) size (on the affected side) in patients with stroke was significantly larger than patients without stroke (2.2 mm, IQR: 1.5-2.5 vs. 1.45 mm IQR: 1.1-1.8, p = 0.019). Involvement of the ethmoid and frontal sinuses were higher in patients with stroke (p = 0.007, OR = 1.85, 95% CI: 1.37-2.49 and p = 0.011, OR = 5, 95% CI: 1.4-18.2, respectively). Patients with stroke had higher D­dimer levels, WBC counts, neutrophil/lymphocyte ratios, and BUN/Cr ratio (all p < 0.05). CONCLUSION: Stroke-related ROCM was not associated with conventional ischemic stroke risk factors. Neuroimaging investigations including qualitative and quantitative parameters of cavernous sinus, ICA and SOV are useful to better understand the mechanism of stroke-related ROCM in COVID-19 patients.

Distribution of IntraThalamic Injury According to Nuclei and Vascular Territories in Children With Term Hypoxic-Ischemic Injury.

BACKGROUND: Term hypoxic-ischemic injury (HII) on magnetic resonance imaging (MRI) is described as the basal ganglia thalamus [BGT], watershed [WS], or combined [BGT/WS] groups. We aimed to determine differences between HII groups in intrathalamic distribution. METHODS: Delayed MRIs of children with HII and thalamic injury were reviewed. Custom tools were placed over T2-weighted and/or fluid-attenuated inversion recovery axial images to determine distribution of intrathalamic injury: (1) six subjective (whole/near-whole, central, anterior, posterior, lateral, medial); (2) four nuclear (anterior [AN], ventrolateral [VLN], medial [MN], and pulvinar [PN]); and (3) three arterial (thalamoperforating arteries [TPA], thalamogeniculate arteries [TGA], and posterior choroidal arteries [PCA]) locations. We compared the frequency of injury of the aforementioned intrathalamic locations between HII groups. RESULTS: The 128 children (mean age at MRI 7.35 ± 3.6 years) comprised 41% (n = 53) BGT, 26% (n = 33) WS, and 33% (n = 42) BGT/WS. The VLN was the most frequent injured nuclear region (66%, n = 85), and the TGA (93%, n = 128) was the most frequent arterial region involved. VLN injury occurred more frequently in the BGT group (P < 0.001), PN in the WS group (P < 0.001), and AN (P < 0.001), MN (P < 0.001), PN (P = 0.001), and all nuclei together (P < 0.001) in the BGT/WS group. The combination of all vascular territories was significantly associated with BGT/WS (P < 0.001). CONCLUSIONS: There are significant differences in intrathalamic nuclear and arterial injuries between the different types of HII.

Magnetic Resonance Imaging-Based Distribution and Reversibility of Lesions in Pediatric Vigabatrin-Related Brain Toxicity.

BACKGROUND: We aimed to systematically characterize the magnetic resonance imaging (MRI) findings in vigabatrin-related neurotoxicity in children and determine the reversibility of lesions based on follow-up images. METHODS: We evaluated children with a history of refractory seizures who had a brain MRI while on vigabatrin therapy. We included available brain MRI studies before vigabatrin therapy initiation, during vigabatrin treatment, and after vigabatrin was discontinued. A pediatric neuroradiologist systematically assessed images on T2/fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted imaging /apparent diffusion coefficient sequences to identify hyperintense lesions and/or restricted diffusion. The frequency of abnormal signal at each location was determined, as well as the reversibility of these after vigabatrin discontinuation. RESULTS: MRIs of 43 patients were reviewed: 13 before vigabatrin initiation, 18 during treatment, and 12 after vigabatrin discontinuation. In the MRIs acquired during vigabatrin treatment, most lesions on T2/FLAIR occurred in the globus pallidi, thalami, and midbrain. Correspondingly, the most common locations for restricted diffusion were the globus pallidi, thalami, and subthalamic nuclei. On MRI after vigabatrin discontinuation, complete resolution of lesions on T2/FLAIR in all patients was seen in the midbrain, dentate nuclei, subthalamic nuclei, and hypothalami. Complete resolution of restricted diffusion was observed in the globus pallidi, midbrain, dentate nuclei, hippocampi, anterior commissure, and hypothalami. CONCLUSION: Globus pallidi and thalami are the most commonly affected structures in vigabatrin-related toxicity, and most vigabatrin-related neuroimaging findings are reversible.

Watershed infarction in COVID-19: The necessity of neuroimaging in patients with subtle neurological symptoms.

Background: Cerebrovascular diseases comprise a significant portion of neurological disorders related to coronavirus disease 2019 (COVID-19). We evaluated the clinical and imaging characteristics of a cohort of COVID-19 patients with stroke and also identified patients with watershed infarcts. Methods: In this cross-sectional study, seventy-three COVID-19 patients with ischemic stroke were included between October 2020 and January 2021. Patients were evaluated based on the following clinical and imaging features: severity of COVID-19 (critical/ non-critical), stroke type, presence/absence of clinical suspicion of stroke, medical risk factors, Fazekas scale, atherothrombosis, small vessel disease, cardiac pathology, other causes, and dissection (ASCOD) criteria classification, and presence or absence of watershed infarction. Clinical outcomes were assessed based on Modified Rankin Scale (MRS) and mortality. Results: Most cases of ischemic stroke were due to undetermined etiology (52.1%) and cardioembolism (32.9%). In terms of imaging pattern, 17 (23.0%) patients had watershed infarction. Watershed infarction was associated with the clinically non-suspicious category [odds ratio (OR) = 4.67, P = 0.007] and death after discharge (OR = 7.1, P = 0.003). Patients with watershed infarction had a higher odds of having high Fazekas score (OR = 5.17, P = 0.007) which was also shown by the logistic regression model (adjusted OR = 6.87, P = 0.030). Thirty-one (42%) patients were clinically non-suspected for ischemic stroke. Critical COVID-19 was more common among patients with watershed infarct and clinically non-suspicious patients (P = 0.020 and P = 0.005, respectively). Patients with chronic kidney disease (CKD) were more prone to having stroke with watershed pattern (P = 0.020). Conclusion: Watershed infarct is one of the most common patterns of ischemic stroke in patients with COVID-19, for which clinicians should maintain a high index of suspicion in patients with critical COVID-19 without obvious clinical symptoms of stroke.

Re-Evaluating Risk Factors, Incidence, and Outcome of Aneurysmal and Non-Aneurysmal Subarachnoid Hemorrhage.

OBJECTIVE: Subarachnoid hemorrhage (SAH) is one of the world's most life-threatening types of stroke. SAH can be classified into two main categories, aneurysmal (aSAH) and non-aneurysmal SAH (naSAH). In the present study, we aimed to prospectively evaluate SAH and its subcategories incidences, risk factors, complications, and outcomes in central Iran. METHODS: All SAH patients diagnosed between 2016 and 2020 were included in Isfahan SAH Registry. Demographic, clinical characteristics, incidence rates (based on age categories), and laboratory/imaging findings were collected and compared between aSAH and naSAH subgroups. Complications during hospital stay and outcomes were also analyzed. Binary logistic regression analysis was performed to investigate the predictors of aSAH versus naSAH. Kaplan-Meier curves and Cox regression were used to evaluate the survival probability. RESULTS: A total of 461 SAH patients were included through Isfahan SAH Registry. The SAH annual incidence rate was 3.11 per 100,000 person-years. aSAH had higher incidence rate than naSAH (2.08/100,000 vs. 0.9/100,000 person-years, respectively). In-hospital mortality was 18.2%. Hypertension (P = 0.003) and smoking (P = 0.03) were significantly associated with aSAH, whereas diabetes mellitus (P < 0.001) was more associated with naSAH. After Cox regression analysis, there were higher hazard ratios for reduced in-hospital survival in conditions including altered mental status, Glasgow Coma Scale ≤13, rebleeding, and seizures. CONCLUSIONS: This study provided an updated estimation of SAH and its subgroups incidences in central Iran. Risk factors for aSAH are comparable to the ones reported in the literature. It is noteworthy that diabetes mellitus was associated with a higher incidence of naSAH in our cohort.

Role of Fluorodeoxyglucose-PET in Interventional Radiology.

Fluorodeoxyglucose (FDG)-PET has expanding applications in the field of interventional radiology. FDG-PET provides both qualitative and quantitative assessments of malignancy, infection, and inflammation. These assessments can assist interventional radiologists in selecting the most appropriate treatment options for their oncology patients. FDG-PET is also useful for evaluating the response to interventional treatments and in predicting the prognosis of oncology patients. Finally, FDG-PET can assist the interventional radiologist in diagnosing and monitoring response to treatment of infection and inflammation. Nevertheless, there is a need for additional prospective studies to further establish the role of FDG-PET in these applications.

Neuroimaging Findings in Parechovirus Encephalitis: A Case Series of Pediatric Patients.

BACKGROUND: Human parechovirus infection can cause parechovirus encephalitis in neonates and should be considered as a differential diagnosis in the emergency department. Neuroimaging features of parechovirus encephalitis have been described in neonates and young infants, but there is a paucity of literature regarding magnetic resonance imaging brain injury patterns in older children. We aim to present three cases of parechovirus encephalitis, showing distinctive magnetic resonance imaging brain patterns of injury in two newborns and, for the first time, in an adolescent. METHODS: We conducted a retrospective review of parechovirus encephalitis cases in our pediatric hospital. Clinical information and neuroimaging findings are described in detail. RESULTS: Classical neuroimaging findings in neonatal parechovirus encephalitis include restricted diffusion of the subcortical and periventricular white matter with frontoparietal predominance, in association with corpus callosum signal abnormality and bilateral swollen thalami. Parechovirus encephalitis in the adolescent appeared with an additional pattern of white matter signal abnormality in the corona radiata in continuity with the corticospinal tracts. CONCLUSIONS: Parechovirus encephalitis should be considered in the differential diagnosis when magnetic resonance imagingdemonstrates white matter injury with typical (sunburst type) distribution in the deep and periventricular white matter in both neonates and adolescents, especially in those with comorbidities or therapy that lead to an immunosuppressive status.