Neuroimaging Correlations

Neuroimaging Toolkit - Scan Spectrum

Vascular Events - Clots & Bleeds

• Ischemic Stroke (Clots):
  • NCCT: Early signs (hyperdense MCA, loss grey-white differentiation, insular ribbon sign). Later: hypodensity.
  • MRI: DWI (hyperintense), ADC (hypointense), MRA (occlusion).
  • Thrombolysis: tPA within 4.5 hrs.
• Hemorrhagic Stroke (Bleeds):
  • ICH: NCCT shows hyperdense lesion. Common: Hypertensive (basal ganglia, pons), Amyloid (lobar).
  • SAH: 📌 "Worst headache of life". NCCT: blood in cisterns/sulci. CTA for aneurysm.
  • SDH: Crescent-shaped, crosses sutures. Acute (hyperdense), chronic (hypodense).
  • EDH: Lens-shaped (biconvex), doesn't cross sutures. MMA tear. Lucid interval.

⭐ DWI is the most sensitive sequence for acute ischemic stroke, showing restriction within minutes.

Trauma & Tumors - Impact & Invaders

• Traumatic Brain Injury (TBI):

  Feature	Epidural Hematoma (EDH)	Subdural Hematoma (SDH)
  Vessel	Middle Meningeal Artery (MMA)	Bridging Veins
  CT Shape	Biconvex (lenticular) 📌 Lemon	Crescentic 📌 Banana
  Sutures	Does NOT cross	CAN cross
  Clinical	Lucid interval	Gradual (elderly, alcoholics)

  

  • Diffuse Axonal Injury (DAI):
    • Shearing forces. CT: Punctate hemorrhages (corpus callosum, brainstem). MRI (more sensitive): SWI shows microhemorrhages.

• Brain Tumors:

  • Adults (Supratentorial):
    • Glioblastoma (GBM): Most common primary adult. Aggressive. Necrosis, hemorrhage. Butterfly glioma (crosses corpus callosum).
    • Meningioma: 2nd most common primary adult. Dural based, homogenous enhancement, dural tail. Often benign.
  • Children (Infratentorial - Posterior Fossa):
    • Medulloblastoma: Most common malignant (child). Cerebellar vermis (midline), hydrocephalus. Homer Wright rosettes.
    • Pilocytic Astrocytoma: Most common benign (child). Posterior fossa. Cystic + mural nodule (enhances). Rosenthal fibers.
  • Metastases: Most common intracranial tumor overall. Multiple lesions, grey-white junction, vasogenic edema.

⭐ Epidural hematoma (EDH) is typically arterial and does not cross suture lines, while subdural hematoma (SDH) is usually venous and can cross suture lines.

Infections & Demyelination - Germs & Glitches

• Brain Abscess: MRI: Central DWI restriction, ring enhancement. MRS: ↑Lactate, amino acids.
• HSV Encephalitis: MRI: Temporal lobe T2/FLAIR hyperintensity, hemorrhage. DWI restriction.
• TBM: MRI: Basal exudates (enhancement), hydrocephalus, tuberculomas.
• Neurocysticercosis (NCC): MRI: Stages (Vesicular + scolex, Colloidal, Granular, Calcified). 📌 VesCo GraCa.
• Multiple Sclerosis (MS): MRI: Periventricular, corpus callosum T2/FLAIR lesions. Active: Gd enhancement.

  ⭐ Dawson's fingers, ovoid lesions perpendicular to the lateral ventricles, are characteristic of Multiple Sclerosis on MRI.

• ADEM: MRI: Large, fluffy, asymmetric white matter lesions; monophasic.
• PML (JC Virus): MRI: Asymmetric subcortical white matter lesions, no enhancement.

High‑Yield Points - ⚡ Biggest Takeaways

• CT excels for acute hemorrhage, bone detail, and initial trauma assessment.
• MRI offers superior soft tissue contrast for tumors, infarcts (DWI), and demyelinating diseases.
• T1-MRI: Fat bright, CSF dark; shows anatomy. Subacute hemorrhage also bright.
• T2-MRI: Water/edema bright, highlights pathology. FLAIR suppresses CSF, aiding periventricular lesion detection.
• DWI is crucial for acute stroke detection, showing restricted diffusion rapidly.
• Contrast reveals Blood-Brain Barrier (BBB) breakdown in tumors, infections, active inflammation.