The Brain Tumor Segmentation - Metastases (BraTS-METS) Challenge 2023: Brain Metastasis Segmentation on Pre-treatment MRI.

The translation of AI-generated brain metastases (BM) segmentation into clinical practice relies heavily on diverse, high-quality annotated medical imaging datasets. The BraTS-METS 2023 challenge has gained momentum for testing and benchmarking algorithms using rigorously annotated internationally compiled real-world datasets. This study presents the results of the segmentation challenge and characterizes the challenging cases that impacted the performance of the winning algorithms.

Differentiation of intracranial Rosai-Dorfman histiocytosis from meningioma using MR perfusion.

Intracranial Rosai-Dorfman disease may be indistinguishable from meningioma. This distinction is essential, as they are treated very differently. We present two cases where perfusion imaging helped make this distinction, allowing one to be treated successfully without craniotomy.

Differential Diagnosis and Radiographic Imaging of Pituitary Lesions: An Integrated Approach.

The sellar and parasellar region of the skull base is an area that can harbor a broad range of pathologic conditions. Formulating a differential diagnosis of a lesion in this region relies heavily on neuroimaging in addition to clinical and laboratory data. In this article, the authors briefly discuss some of the common pathologic conditions and their associated radiographic and clinical features.

Orbital cellulitis, sinusitis and intracranial abnormalities in two adolescents with COVID-19.

We review two cases of adolescents with orbital cellulitis, sinusitis and SARS- CoV-2 infection presenting to emergency departments within a 24 hour period. SARS-CoV-2 samples obtained within 24 hours were positive, supporting prior infection despite relatively limited early symptoms of COVID-19. Unusual clinical and radiographic characteristics included hemorrhagic abscess with blood of varying age in the first, intracranial epidural abscess in the second, radiographic signal consistent with hemorrhagic or thrombotic phenomena, retro-maxillary antral fat changes, and meningeal enhancement or extension in both cases.

Predominant enhancement of glucose uptake in astrocytes versus neurons during activation of the somatosensory cortex.

Glucose is the primary energetic substrate of the brain, and measurements of its metabolism are the basis of major functional cerebral imaging methods. Contrary to the general view that neurons are fueled solely by glucose in proportion to their energetic needs, recent in vitro and ex vivo analyses suggest that glucose preferentially feeds astrocytes. However, the cellular fate of glucose in the intact brain has not yet been directly observed.

A claim in search of evidence: reply to Manger's thermogenesis hypothesis of cetacean brain structure.

In a recent publication in Biological Reviews, Manger (2006) made the controversial claim that the large brains of cetaceans evolved to generate heat during oceanic cooling in the Oligocene epoch and not, as is the currently accepted view, as a basis for an increase in cognitive or information-processing capabilities in response to ecological or social pressures. Manger further argued that dolphins and other cetaceans are considerably less intelligent than generally thought. In this review we challenge Manger's arguments and provide abundant evidence that modern cetacean brains are large in order to support complex cognitive abilities driven by social and ecological forces.

Cetaceans have complex brains for complex cognition.

A group of eminent cetacean researchers respond to headlines charging that dolphins might be "flippin' idiots". They examine behavioural, anatomical and evolutionary data to conclude that the large brain of cetaceans evolved to support complex cognitive abilities.

High-resolution in vivo imaging of the neurovascular unit during spreading depression.

Spreading depression (SD) is a propagating wave of neuronal depolarization and ionic shifts, seen in stroke and migraine. In vitro, SD is associated with astrocytic [Ca2+] waves, but it is unclear what role they play and whether they influence cerebral blood flow, which is altered in SD. Here we show that SD in vivo is associated with [Ca2+] waves in astrocytes and neurons and with constriction of intracortical arterioles severe enough to result in arrest of capillary perfusion.

The number of glutamate receptors opened by synaptic stimulation in single hippocampal spines.

The number of receptors opening after glutamate release is critical for understanding the sources of noise and the dynamic range of synaptic transmission. We imaged [Ca2+] transients mediated by synaptically activated NMDA receptors (NMDA-Rs) in individual spines in rat brain slices. We show that Ca2+ influx through single NMDA-Rs can be reliably detected, allowing us to estimate the number of receptors opening after synaptic transmission.

Imaging calcium concentration dynamics in small neuronal compartments.

Calcium and its regulation play central roles diverse physiologic processes. Quantification of calcium concentrations ([Ca2+]) in small neuronal compartments is crucial to understanding Ca2+-dependent signaling. Here, we describe techniques that are optimized for 2-photon imaging of [Ca2+] dynamics in small compartments such as dendrites and dendritic spines.

Facilitation at single synapses probed with optical quantal analysis.

Many synapses can change their strength rapidly in a use-dependent manner, but the mechanisms of such short-term plasticity remain unknown. To understand these mechanisms, measurements of neurotransmitter release at single synapses are required. We probed transmitter release by imaging transient increases in [Ca(2+)] mediated by synaptic N-methyl-D-aspartate receptors (NMDARs) in individual dendritic spines of CA1 pyramidal neurons in rat brain slices, enabling quantal analysis at single synapses.

An image analysis algorithm for dendritic spines.

The structure of neuronal dendrites and their spines underlie the connectivity of neural networks. Dendrites, spines, and their dynamics are shaped by genetic programs as well as sensory experience. Dendritic structures and dynamics may therefore be important predictors of the function of neural networks.

Structure and function of dendritic spines.

Spines are neuronal protrusions, each of which receives input typically from one excitatory synapse. They contain neurotransmitter receptors, organelles, and signaling systems essential for synaptic function and plasticity. Numerous brain disorders are associated with abnormal dendritic spines.