This composite diagnostic image presents immunohistochemical staining of murine coronal brain sections used to evaluate gliosis following repetitive mild traumatic brain injury (rmTBI). Panels A-C focus on microglial activation in the optic tract (OT) using Iba1 staining. Compared to the Sham group (A), the rmTBI group (B) displays a significant increase in Iba1 immunoreactivity, characterized by a higher density of Iba1-positive microglia with amoeboid morphology (red arrowheads in insets). Panels D-I illustrate astrogliosis using Glial Fibrillary Acidic Protein (GFAP) staining in the optic tract (D-E) and corpus callosum (G-H). The rmTBI group shows increased GFAP intensity and astrocyte hypertrophy (blue arrowheads) in both white matter tracts compared to Sham controls. Accompanying bar graphs (C, F, I) provide relative quantification of the signals, demonstrating statistically significant increases in inflammatory markers (p<0.0001 for OT Iba1 and GFAP; p=0.0320 for CC GFAP). Scale bars indicate 1 mm for whole brain views and 100 m for magnified insets. These findings highlight the localized neuroinflammatory response and microstructural disruption characteristic of repetitive head injuries.

This diagnostic image is an axial Fluid-Attenuated Inversion Recovery (FLAIR) Magnetic Resonance Imaging (MRI) scan of the human head at the level of the superior cerebral hemispheres. The scan displays a cross-sectional view of the brain tissue, clearly showing the convoluted surface anatomy of the gyri and sulci. The cerebral cortex and white matter appear generally homogenous; however, the image highlights focal pathological changes. Two white arrows point to small, hyperintense (bright) punctate spots located in the subcortical white matter of the left frontal lobe. These findings represent nonspecific gliosis spots, which are areas of reactive glial cell changes resulting from previous neural injury. In a clinical context, such bihemispheric white matter lesions can be associated with various inflammatory or infectious conditions, including neuroborreliosis (Lyme disease). The image serves as an educational example of how systemic infections can manifest with subtle, multifocal white matter abnormalities on neuroimaging.

This medical comparison image displays diagnostic neuroimaging of a traumatic brain injury across two modalities and time points. Panel A presents a non-contrast axial head CT scan acquired on the day of injury. It demonstrates multiple hemorrhagic brain contusions, characterized by a mixed-density 'salt and pepper' appearance, primarily involving the right frontal and temporal lobes and the left frontal lobe. A hyperdense, crescentic collection along the right cerebral hemisphere (indicated by black arrowheads) signifies an acute subdural hematoma, associated with a mild midline shift. Panel B displays follow-up axial MRI using Fluid-Attenuated Inversion Recovery (FLAIR) sequences 23 days post-injury. The MRI reveals persistent hyperintense signals in the previously noted contusion sites within the frontal and temporal lobes. Additionally, diffuse high-intensity signals are visible in the surrounding white matter, representing perilesional vasogenic edema and gliosis. The comparison illustrates the evolution of traumatic lesions from acute hemorrhage and density changes on CT to late-stage edema and parenchymal signal alterations on MRI, essential for monitoring post-traumatic neuro-regeneration and complications.

This diagnostic image is a coronal Fluid-Attenuated Inversion Recovery (FLAIR) MRI of the human head, demonstrating chronic neuroanatomical changes following a migrainous infarction. The primary findings are localized in the left parietal subcortical region. Visible pathology includes hyperintense signals indicative of gliosis and leukoaraiosis (white matter changes) surrounding well-defined hypointense cystic cavities, representing encephalomalacia. The image illustrates the long-term sequelae of ischemic injury in the context of migraine with aura, highlighting the evolution from an acute infarct to permanent parenchymal loss and surrounding glial scarring. These features are clinically significant for neuroradiological follow-up of stroke and the assessment of cerebral tissue viability. The modality effectively suppresses cerebrospinal fluid (CSF) signal to enhance the visibility of perilesional hyperintensities against the brain parenchyma.

**Imaging Modality:** Magnetic Resonance Imaging (MRI), T1-weighted axial sequence. **Anatomical Region:** Axial section of the neurocranium at the level of the sella turcica, midbrain (pons), and orbits. **Observed Pathology:** Pituitary Apoplexy. The image demonstrates a significantly enlarged pituitary gland within an expanded sella turcica. **Characteristic Visual Features:** - **Sellar Mass:** There is a well-circumscribed, hyperintense lesion occupying the sella turcica. - **Signal Intensity:** The T1-weighted hyperintensity is highly suggestive of acute to subacute hemorrhage or high protein content within a pituitary adenoma. - **Mass Effect:** The enlarged gland shows evidence of superior extension (suprasellar extension), potentially compromising the optic chiasm. - **Surrounding Structures:** The sphenoid sinus is visible anterior to the sella, and the cavernous sinuses border the lesion laterally. The brainstem and temporal lobes appear unremarkable at this level. **Clinical Context:** In a patient presenting with sudden-onset severe headache ("thunderclap" presentation), these radiologic findings are pathognomonic for pituitary apoplexy, resulting from hemorrhage or infarction of a preexisting pituitary macroadenoma. **Key Diagnostic Features:** T1-hyperintense sellar mass with expansion of the bony sella and suprasellar protrusion.

**Imaging Modality:** Magnetic Resonance Imaging (MRI), Apparent Diffusion Coefficient (ADC) map. **Anatomical Region:** Axial section of the brain at the level of the pons, cerebellum, and temporal lobes. **Observed Pathology:** The image demonstrates areas of altered signal intensity. In the context of the provided clinical history of a postpartum patient with a sudden onset "thunderclap" headache, these findings are highly suspicious for Reversible Posterior Leukoencephalopathy Syndrome (PRES) or Reversible Cerebral Vasoconstriction Syndrome (RCVS). **Characteristic Visual Features:** - The ADC map is used to differentiate between cytotoxic edema (low ADC/dark) and vasogenic edema (high ADC/bright). - There is evidence of hyperintensity in the posterior regions, suggesting vasogenic edema rather than acute infarction. - Symmetrical or asymmetrical involvement of the subcortical white matter may be present, though the resolution of this specific map primarily highlights the posterior fossa and temporal regions. **Key Diagnostic Features:** The absence of restricted diffusion (which would appear dark on ADC) helps exclude acute ischemic stroke, pointing instead toward a reversible encephalopathy or vasoconstriction syndrome often associated with the peripartum period.

**Imaging Modality:** Non-contrast Computed Tomography (NCCT) of the head. **Anatomical Region:** Axial section at the level of the suprasellar cistern, midbrain, and skull base. **Observed Pathology:** There is a hyperdense signal located within the suprasellar cistern, consistent with acute subarachnoid hemorrhage (SAH). The hyperdensity appears concentrated in the region of the circle of Willis, suggesting potential aneurysmal rupture. **Characteristic Visual Features:** * **Hyperdensity:** High-attenuation (bright) material is visible in the basal cisterns, specifically the suprasellar cistern and extending slightly into the ambient cisterns. * **Vascular Structures:** A focal hyperdense area is noted near the expected location of the anterior communicating artery or internal carotid artery terminus, often referred to as a "bright artery sign" or sentinel clot. * **Ventricular System:** The visible portions of the temporal horns of the lateral ventricles and the fourth ventricle do not show immediate evidence of gross hydrocephalus or intraventricular extension in this single slice. **Clinical Context:** Findings are highly indicative of acute nontraumatic subarachnoid hemorrhage, correlating with the clinical presentation of a sudden-onset "thunderclap" headache. **Key Diagnostic Features:** Presence of extravasated blood in the subarachnoid space (cisterns) on non-contrast CT.

Anatomical diagram and flowchart presenting a lateral view of the human brain cortex, specifically mapped for intraoperative cognitive tasks used during neurosurgical mapping. The illustration identifies five major regions: Frontal lobe, Parietal lobe, Occipital lobe, Anterior temporal lobe, and Posterior temporal lobe. Each region is annotated with recommended clinical tasks to preserve functional integrity during lesion resection. Key tasks listed include: 1) Frontal lobe: sensori-motor, counting, picture naming, semantic association, and writing; 2) Parietal lobe: sensori-motor, picture naming, calculation, and visuospatial tasks; 3) Occipital lobe: visual field, picture naming, and reading; 4) Temporal regions: counting, picture naming, and semantic association, with the posterior temporal lobe specifically adding reading and visual field assessments. This diagram serves as a clinical guide for selecting direct electrical stimulation (DES) tasks based on tumor location to protect eloquent cortical areas involved in language, motor, and cognitive processing.

Anatomical diagram presenting four renderings of a standard human cortical surface used to map simulated focal brain lesions. The brain is shown in lateral and medial views across two rows. The cortical surface is rendered in blue, with regions of interest (ROIs) belonging to the default mode network (DMN) highlighted in light red; these include the precuneus, posterior cingulate, medial prefrontal cortex, and lateral parietal cortex. Superimposed on the cortex are various colored outlines representing 22 distinct lesion locations (labeled L323 through L636). Each lesion encompasses 50 ROIs, approximately 5% of the cortical surface. The diagram illustrates lesion distribution across major functional zones, including the frontal lobe, temporo-parietal junction, and cortical midline. A color-coded legend at the bottom of each row correlates specific colors with lesion identifiers, serving as a reference for neuroanatomical location and clinical significance in studies of functional connectivity and network disruption (diaschisis).

Educational diagram illustrating Lesion Network Mapping (LNM) in the context of Post-Traumatic Stress Disorder (PTSD) pathophysiology. (A) Representative axial brain slices (T1-weighted MRI template) show localized focal brain lesions highlighted in green across three different subjects, demonstrating anatomical heterogeneity. (B) Functional connectivity maps (normative connectomes) for these subjects, with orange-red areas indicating high connectivity to the respective lesion sites. (C) Clinical categorization of subjects based on symptoms: 'Meets criteria for PTSD', 'Subthreshold PTSD symptoms', and 'No PTSD symptoms'. (D) A group-level statistical brain map (medial and lateral views) showing the 'PTSD circuit.' Regions in yellow-orange represent areas where high lesion connectivity is associated with a lower probability of developing PTSD. These regions prominently include the medial prefrontal cortex (mPFC), amygdala, and medial temporal lobe. The infographic explains how lesion locations and their functional networks can influence psychiatric clinical outcomes and potentially inform future neuromodulation (TMS) targets.

This diagnostic image is a non-contrast computed tomography (CT) scan of the head in an axial section at the level of the midbrain and suprasellar region. The primary finding is the presence of linear, hyperdense (bright white) signals within the subarachnoid spaces, specifically involving the suprasellar and ambient cisterns. These findings are highly characteristic of acute subarachnoid hemorrhage (SAH). The brain parenchyma shows relatively preserved gray-white matter differentiation at this level, though there is a subtle mass effect on the basal cisterns. Bony structures of the skull vault and the sphenoid bone demonstrate normal high attenuation. The orbits and paranasal sinuses are partially visualized in the anterior field. This image serves as a clinical demonstration of the sensitivity of non-contrast CT in detecting acute intracranial bleeding within the CSF-filled spaces of the basal cisterns, a critical step in the emergency diagnostic pathway for patients presenting with sudden-onset severe headache.

This diagnostic image is an axial non-contrast computed tomography (CT) scan of the brain at the level of the basal cisterns. The primary finding is an acute subarachnoid hemorrhage (SAH), characterized by high-attenuation (hyperdense) material filling the normally hypodense cerebrospinal fluid (CSF) spaces. The hyperdensity is diffusely distributed throughout the suprasellar cistern, interpeduncular cistern, and the ambient cisterns. The distribution is notably prominent on the right side, extending into the right sylvian fissure and outlining the contours of the midbrain. This visual evidence of 'blood in the cisterns' creates a characteristic pentagonal or star-shaped appearance in the center of the scan. The presence of these findings in a 42-year-old patient with sudden severe headache is consistent with an aneurysmal rupture, specifically a blood blister-like aneurysm of the internal carotid artery as suggested by the clinical context. The image serves as a critical educational example of intracranial hemorrhage recognition and anatomical localization for neuroradiology and emergency medicine training.

This unenhanced axial computerized tomography (CT) scan of the head demonstrates the superior cerebral hemispheres. The primary finding is the presence of focal hyperdensity within the cortical sulci bilaterally, specifically localized to the precentral sulci as indicated by blue arrows. These hyperdense signals are consistent with acute subarachnoid hemorrhage (SAH) confined to the sulcal spaces, often referred to as convexal subarachnoid hemorrhage (cSAH). The surrounding brain parenchyma shows preserved gray-white matter differentiation without evidence of large-scale edema, mass effect, or midline shift. The skull remains intact with normal bony density and no signs of fracture. The extracerebral space (subarachnoid space) elsewhere appears typically hypodense. This diagnostic image is clinically significant for identifying non-aneurysmal or focal SAH in patients presenting with sudden severe headache (thunderclap headache) or focal neurological deficits, serving as a critical teaching tool for neuroradiology and emergency medicine.

This diagnostic image is an axial Fluid-Attenuated Inversion Recovery (FLAIR) MRI of the human brain, focusing on the supratentorial region. The image demonstrates multiple focal and confluent T2-hyperintense lesions located within the deep and periventricular white matter. These hyperintensities are most prominent in the parieto-occipital areas, characterized by patchy signal changes adjacent to the lateral ventricles. The ventricular system maintains a relatively normal morphology and size, though the surrounding white matter disturbances suggest focal gliosis or leukoencephalopathy. The cortical ribbon appears intact with darker signal intensity compared to the underlying white matter pathology. This radiological finding is clinically significant for evaluating demyelinating diseases, chronic small vessel ischemic changes, or metabolic white matter disturbances in neurology and neuroradiology education.

Diagnostic axial MRI of the brain using T2-Fluid Attenuated Inversion Recovery (FLAIR) sequences, shown in three representative slices at different neuroanatomical levels. The images demonstrate extensive, confluent periventricular white matter hyperintensities (WMH) involving the frontal and occipital horns of the lateral ventricles, characteristic of chronic small vessel ischemic disease. In the leftmost slice, a focal area of encephalomalacia and gliosis is visible in the left anterior region, appearing as a central hypointense signal surrounded by a hyperintense rim, consistent with sequelae of a prior left anterior choroidal artery territory stroke. The ventricular system appears mildly dilated, likely representing ex-vacuo changes secondary to global brain volume loss. These findings are clinically relevant for assessing chronic cerebrovascular burden and correlating imaging with neurological symptoms such as cognitive decline, motor fluctuations, or previous ischemic events in elderly patients.

This diagnostic image consists of two axial T2-weighted fluid-attenuated inversion recovery (FLAIR) MRI scans of the human brain at the level of the temporal lobes and midbrain. The primary findings are small, punctate, hyperintense foci located within the deep white matter of both the left and right temporal lobes, indicated by white arrows. These hyperintensities represent gliotic changes or white matter hyperintensities (WMHs). The cortical gray matter, sulcal patterns, and ventricular systems appear otherwise unremarkable for the age-matched clinical context. These images are used to demonstrate neuroanatomical correlates in chronic pain conditions, such as burning mouth syndrome, emphasizing the presence of small vessel ischemic changes or gliosis in brain regions associated with mood and pain modulation. The target audience includes neurology and radiology students or clinicians studying white matter disease progression and its clinical associations.