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  Pneumocephalus — CT Brain (Key Radiological Features) 1. Density Very low attenuation (black) HU ≈ −1000 (air) 2. Typical Locations Subdural (most common) Epidural Intraventricular Intracerebral / intraparenchymal Subarachnoid / cisternal 3. Characteristic Signs Mount Fuji sign (tension pneumocephalus) → Separation + compression of frontal lobes by subdural air Air bubble / multiple loculi sign → Scattered small air pockets Air-fluid level → Suggests CSF leak or communication 4. Mass Effect (if tension) Sulcal effacement Ventricular compression Midline shift Frontal lobe compression 5. Distribution Pattern Clues Non-dependent air (rises anteriorly/superiorly) Often frontal region in supine CT May outline cisterns → “negative contrast effect” 6. Associated Findings Skull base fracture Postoperative changes (craniotomy) Sinus/mastoid air communication CSF leak One-line clinical correlation Simple pneumocephalus → incidental, small, no mass effect Tension pneumocephalus → neuro...

  Radiological features of hydrocephalus on CT brain (concise) 1) Ventricular dilatation (core feature) Enlargement of lateral ventricles (rounded frontal horns) Dilated 3rd ventricle ± Dilated 4th ventricle (helps localize obstruction) Temporal horns early dilatation (sensitive early sign) 2) Disproportionate ventriculomegaly Ventricles enlarged out of proportion to cortical sulci Helps differentiate from cerebral atrophy (where sulci also enlarged) 3) Periventricular lucency (transependymal CSF seepage) Hypodense rim around ventricles Indicates raised intraventricular pressure 4) Effacement of cortical sulci & cisterns Sulcal effacement (compressed brain parenchyma) Basal cisterns may be compressed 5) Ballooning of ventricular horns Frontal and occipital horns become rounded/bulbous Loss of normal concavity 6) Signs suggesting type (useful clinically) Obstructive (non-communicating): Dilatation proximal to block e.g., enlarged lateral + 3rd ventricle, normal 4th → aquedu...

  Midline Shift on CT Brain — Key Radiological Features (Concise) 1. Septum Pellucidum Displacement (Most sensitive marker) Shift from midline (measured at level of foramen of Monro ) Quantified in mm (clinically significant ≥5 mm) 2. Third Ventricle Shift Deviated from midline Often compressed or slit-like 3. Pineal Gland Displacement Normally midline → shift indicates deep central displacement Useful when calcified (acts as a marker) 4. Lateral Ventricle Asymmetry Ipsilateral ventricle: compressed Contralateral ventricle: dilated (± obstructive hydrocephalus) 5. Effacement of Sulci Loss of cortical sulci on affected side due to mass effect 6. Subfalcine Herniation (Cingulate Shift) Cingulate gyrus displaced under falx cerebri Often accompanies significant MLS 7. Basal Cistern Compression Indicates raised ICP and possible transtentorial progression Measurement (Standard) Distance between: Ideal midline (line through falx) Actual septum pellucidum position Clinical Correlation Thr...

  Depressed Skull Fracture — CT Brain (Non-contrast) Key radiological features: 1. Bony Abnormality Inward displacement of skull fragment(s) below adjacent inner table Step defect in calvarium Often comminuted fragments Best seen in bone window 2. Depth Criteria (Clinical relevance) Depression > thickness of adjacent skull → significant Associated with higher risk of dural tear & brain injury 3. Intracranial Complications Underlying contusion / intracerebral hemorrhage Extradural hematoma (EDH) Subdural hematoma (SDH) Subarachnoid hemorrhage (SAH) Pneumocephalus (air entry) 4. Soft Tissue Findings Scalp swelling / hematoma Possible foreign body (in compound fractures) 5. Dural / Brain Involvement Dural breach (suggested by pneumocephalus or deep fragment) Brain laceration in severe cases 6. Special Situations Open (compound) fracture → air, contamination Over venous sinus → risk of sinus injury/thrombosis Frontal sinus involvement → CSF leak risk One-line summary: ...

Skull Fracture (Non-depressed) — CT Brain Features  1. Linear (most common) Thin radiolucent line in bone window Sharp, non-sclerotic margins Often crosses vascular grooves (vs grooves: branching, sclerotic margins) May cross sutures (vs sutures: serrated, symmetric) No displacement or depression 2. Diastatic fracture Widening of cranial sutures beyond normal Common in children Typically along coronal, sagittal, lambdoid sutures 3. Comminuted (non-depressed) Multiple intersecting fracture lines Bone fragmented but no inward displacement 4. Basilar skull fracture Often indirect signs predominate : Pneumocephalus Air-fluid levels in paranasal sinuses Opacification of mastoid air cells Fracture line may be subtle (bone window essential) Common sites: temporal bone, sphenoid, occipital base General CT Clues (All Types) Best seen in bone window Look for overlying scalp swelling/hematoma Assess for associated intracranial injury (EDH, SDH, contusion) Use multiplanar reconstructions ...

  Intracerebral Hemorrhage (ICH) — CT Brain (Non-contrast) Key radiological features (concise): 1. Hyperdense Intraparenchymal Lesion Acute blood = hyperdense (bright) (≈60–80 HU) Common sites: basal ganglia (putamen), thalamus, lobar, cerebellum, brainstem 2. Surrounding Edema Hypodense rim around hematoma (perihematomal edema) Develops within hours → increases over days 3. Mass Effect Effacement of sulci, ventricles Midline shift (quantify if needed) Compression of adjacent structures 4. Intraventricular Extension Hyperdense blood in ventricles May show fluid–fluid level / layering Risk of acute hydrocephalus 5. Shape & Margins Typically irregular or round/oval May have heterogeneous density (active bleed, clot retraction) “Swirl sign” → hypodense areas within clot (ongoing bleeding) 6. Location Clues (Etiology hint) Deep (putamen/thalamus) → hypertensive Lobar → amyloid angiopathy, tumor, AVM Multiple → metastasis, coagulopathy 7. Evolution (brief) Hyperacute (0–6 h):...