Understanding Permeability Changes in Vestibular Schwannomas as Part of the Dynamic Response to Radiosurgery Using Golden-Angle Radial Sparse Parallel Imaging: A Retrospective Study.

Background And Objectives: Vestibular schwannomas demonstrate different responses after stereotactic radiosurgery (SRS), commonly including a transient loss of internal enhancement on postcontrast T1-weighted MRI thought to be due to an early reduction in tumor vascularity. We used dynamic contrast-enhanced based golden-angle radial sparse parallel (GRASP) MRI to characterize the vascular permeability changes underlying this phenomenon, with correlations to long-term tumor regression.

Methods: Consecutive patients with vestibular schwannoma who underwent SRS between 2017 and 2019, had a transient loss of enhancement after SRS, and had long-term longitudinal GRASP studies (6, 18, and 30 months) were included in this retrospective cohort analysis (n = 19).

Increased TRPV4 Channel Expression Enhances and Impairs Blood Vessel Function in Hypertension.

Background: Endothelial cell TRPV4 (transient receptor potential vanilloid 4) channels provide a control point that is pivotal in regulating blood vessel diameter by mediating the Ca-dependent release of endothelial-derived vasoactive factors. In hypertension, TRPV4-mediated control of vascular function is disrupted, but the underlying mechanisms and precise physiological consequences remain controversial.

Methods: Here, using a comprehensive array of methodologies, endothelial TRPV4 channel function was examined in intact mesenteric resistance arteries from normotensive Wistar-Kyoto and spontaneously hypertensive rats.

T2-FLAIR Mismatch Sign Predicts DNA Methylation Subclass and CDKN2A/B Status in IDH-Mutant Astrocytomas.

Purpose: DNA methylation profiling stratifies isocitrate dehydrogenase (IDH)-mutant astrocytomas into methylation low- and high-grade groups. We investigated the utility of the T2-fluid-attenuated inversion recovery (T2-FLAIR) mismatch sign for predicting DNA methylation grade and cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B) homozygous deletion, a molecular biomarker for grade 4 IDH-mutant astrocytomas, according to the 2021 World Health Organization classification.

Experimental Design: Preoperative MRI scans of IDH-mutant astrocytomas subclassified by DNA methylation profiling (n = 71) were independently evaluated by two radiologists for the T2-FLAIR mismatch sign.

Two-Stage Training Framework Using Multicontrast MRI Radiomics for Mutation Status Prediction in Glioma.

Purpose To develop a radiomics framework for preoperative MRI-based prediction of isocitrate dehydrogenase () mutation status, a crucial glioma prognostic indicator. Materials and Methods Radiomics features (shape, first-order statistics, and texture) were extracted from the whole tumor or the combination of nonenhancing, necrosis, and edema regions. Segmentation masks were obtained via the federated tumor segmentation tool or the original data source.

Synthesizing 3D Multi-Contrast Brain Tumor MRIs Using Tumor Mask Conditioning.

Data scarcity and data imbalance are two major challenges in training deep learning models on medical images, such as brain tumor MRI data. The recent advancements in generative artificial intelligence have opened new possibilities for synthetically generating MRI data, including brain tumor MRI scans. This approach can be a potential solution to mitigate the data scarcity problem and enhance training data availability.

Signalling switches maintain intercellular communication in the vascular endothelium.

Background And Purpose: The single layer of cells lining all blood vessels, the endothelium, is a sophisticated signal co-ordination centre that controls a wide range of vascular functions including the regulation of blood pressure and blood flow. To co-ordinate activities, communication among cells is required for tissue level responses to emerge. While a significant form of communication occurs by the propagation of signals between cells, the mechanism of propagation in the intact endothelium is unresolved.

MRI-Based Deep Learning Method for Classification of IDH Mutation Status.

Isocitrate dehydrogenase (IDH) mutation status has emerged as an important prognostic marker in gliomas. This study sought to develop deep learning networks for non-invasive IDH classification using T2w MR images while comparing their performance to a multi-contrast network. Methods: Multi-contrast brain tumor MRI and genomic data were obtained from The Cancer Imaging Archive (TCIA) and The Erasmus Glioma Database (EGD).

Association of partial T2-FLAIR mismatch sign and isocitrate dehydrogenase mutation in WHO grade 4 gliomas: results from the ReSPOND consortium.

Purpose: While the T2-FLAIR mismatch sign is highly specific for isocitrate dehydrogenase (IDH)-mutant, 1p/19q-noncodeleted astrocytomas among lower-grade gliomas, its utility in WHO grade 4 gliomas is not well-studied. We derived the partial T2-FLAIR mismatch sign as an imaging biomarker for IDH mutation in WHO grade 4 gliomas.

Methods: Preoperative MRI scans of adult WHO grade 4 glioma patients (n = 2165) from the multi-institutional ReSPOND (Radiomics Signatures for PrecisiON Diagnostics) consortium were analyzed.

Endothelial PAR2 activation evokes resistance artery relaxation.

Protease-activated receptor-1 & -2 (PAR1 and PAR2) are expressed widely in cardiovascular tissues including endothelial and smooth muscle cells. PAR1 and PAR2 may regulate blood pressure via changes in vascular contraction or relaxation mediated by endothelial Ca signaling, but the mechanisms are incompletely understood. By using single-cell Ca imaging across hundreds of endothelial cells in intact blood vessels, we explored PAR-mediated regulation of blood vessel function using PAR1 and PAR2 activators.

Mitochondrial ATP Production is Required for Endothelial Cell Control of Vascular Tone.

Arteries and veins are lined by nonproliferating endothelial cells that play a critical role in regulating blood flow. Endothelial cells also regulate tissue perfusion, metabolite exchange, and thrombosis. It is thought that endothelial cells rely on ATP generated via glycolysis, rather than mitochondrial oxidative phosphorylation, to fuel each of these energy-demanding processes.

Distinguishing Brain Metastasis Progression From Radiation Effects After Stereotactic Radiosurgery Using Longitudinal GRASP Dynamic Contrast-Enhanced MRI.

Background: Differentiating brain metastasis progression from radiation effects or radiation necrosis (RN) remains challenging. Golden-angle radial sparse parallel (GRASP) dynamic contrast-enhanced MRI provides high spatial and temporal resolution to analyze tissue enhancement, which may differ between tumor progression (TP) and RN.

Objective: To investigate the utility of longitudinal GRASP MRI in distinguishing TP from RN after gamma knife stereotactic radiosurgery (SRS).

Deep multi-task learning and random forest for series classification by pulse sequence type and orientation.

Purpose: Increasingly complex MRI studies and variable series naming conventions reveal limitations of rule-based image routing, especially in health systems with multiple scanners and sites. Accurate methods to identify series based on image content would aid post-processing and PACS viewing. Recent deep/machine learning efforts classify 5-8 basic brain MR sequences.

Small-world connectivity dictates collective endothelial cell signaling.

Every blood vessel is lined by a single layer of highly specialized, yet adaptable and multifunctional endothelial cells. These cells, the endothelium, control vascular contractility, hemostasis, and inflammation and regulate the exchange of oxygen, nutrients, and waste products between circulating blood and tissue. To control each function, the endothelium processes endlessly arriving requests from multiple sources using separate clusters of cells specialized to detect specific stimuli.

A No-Math Primer on the Principles of Machine Learning for Radiologists.

Machine learning is becoming increasingly important in both research and clinical applications in radiology due to recent technological developments, particularly in deep learning. As these technologies are translated toward clinical practice, there is a need for radiologists and radiology trainees to understand the basic principles behind them. This primer provides an accessible introduction to the vocabulary and concepts that are central to machine learning and relevant to the radiologist.

Transmission from vaccinated individuals in a large SARS-CoV-2 Delta variant outbreak.

An outbreak of over 1,000 COVID-19 cases in Provincetown, Massachusetts (MA), in July 2021-the first large outbreak mostly in vaccinated individuals in the US-prompted a comprehensive public health response, motivating changes to national masking recommendations and raising questions about infection and transmission among vaccinated individuals. To address these questions, we combined viral genomic and epidemiological data from 467 individuals, including 40% of outbreak-associated cases. The Delta variant accounted for 99% of cases in this dataset; it was introduced from at least 40 sources, but 83% of cases derived from a single source, likely through transmission across multiple settings over a short time rather than a single event.

Evidence of transmission from fully vaccinated individuals in a large outbreak of the SARS-CoV-2 Delta variant in Provincetown, Massachusetts.

Multiple summer events, including large indoor gatherings, in Provincetown, Massachusetts (MA), in July 2021 contributed to an outbreak of over one thousand COVID-19 cases among residents and visitors. Most cases were fully vaccinated, many of whom were also symptomatic, prompting a comprehensive public health response, motivating changes to national masking recommendations, and raising questions about infection and transmission among vaccinated individuals. To characterize the outbreak and the viral population underlying it, we combined genomic and epidemiological data from 467 individuals, including 40% of known outbreak-associated cases.

Mitochondria regulate TRPV4-mediated release of ATP.

Background And Purpose: Ca influx via TRPV4 channels triggers Ca release from the IP -sensitive internal store to generate repetitive oscillations. Although mitochondria are acknowledged regulators of IP -mediated Ca release, how TRPV4-mediated Ca signals are regulated by mitochondria is unknown. We show that depolarised mitochondria switch TRPV4 signalling from relying on Ca -induced Ca release at IP receptors to being independent of Ca influx and instead mediated by ATP release via pannexins.

"The Pituitary within GRASP" - Golden-Angle Radial Sparse Parallel Dynamic MRI Technique and Applications to the Pituitary Gland.

MRI is the preferred radiologic modality for evaluating the pituitary gland. An important component of pituitary MRI examinations is dynamic contrast-enhanced MRI. Compared to conventional dynamic techniques, golden-angle radial sparse parallel (GRASP) imaging offers multiple advantages, including the ability to achieve higher spatial and temporal resolution.

COVID-19 as 'Game Changer' for the Physical Activity and Mental Well-Being of Augmented Reality Game Players During the Pandemic: Mixed Methods Survey Study.

Background: Location-based augmented reality (AR) games, such as Pokémon GO and Harry Potter: Wizards Unite, have been shown to have a beneficial impact on the physical activity, social connectedness, and mental health of their players. In March 2020, global social distancing measures related to the COVID-19 pandemic prompted the AR games developer Niantic Inc to implement several changes to ensure continued player engagement with Pokémon GO and Harry Potter: Wizards Unite. We sought to examine how the physical and mental well-being of players of these games were affected during the unprecedented COVID-19 restriction period as well as how their video game engagement was affected.

Disrupted endothelial cell heterogeneity and network organization impair vascular function in prediabetic obesity.

Background: Obesity is a major risk factor for diabetes and cardiovascular diseases such as hypertension, heart failure, and stroke. Impaired endothelial function occurs in the earliest stages of obesity and underlies vascular alterations that give rise to cardiovascular disease. However, the mechanisms that link weight gain to endothelial dysfunction are ill-defined.

Bilateral Retrocerebellar Arachnoid Cysts Presenting as Peripheral Vertigo: Case Report and Literature Review.

Bilateral retrocerebellar arachnoid cysts are exceedingly rare. We report a case of a 38-year-old woman, who presented with progressive vertigo and was found to have bilateral retrocerebellar arachnoid cysts. The patient's clinical presentation was most consistent with benign positional peripheral vertigo, while the cysts were thought to be incidental findings.