Ischemic Stroke – CT Brain (Non-contrast) | Key Radiological Features
1. Hyperacute Phase (0–6 hours)
Often subtle / may be normal
- Dense artery sign (e.g., Dense MCA sign) → acute thrombus
- Loss of gray–white differentiation
- Insular ribbon sign
- Lentiform nucleus obscuration
- Sulcal effacement (early edema)
- No hemorrhage (key to thrombolysis decision)
2. Acute Phase (6–24 hours)
- Hypodense area in vascular territory (wedge-shaped)
- Cytotoxic edema → ↓ attenuation
- Progressive loss of gray-white differentiation
- Mass effect
- Sulcal effacement
- Ventricular compression
3. Subacute Phase (1–7 days)
- Well-defined hypodensity
- Peak mass effect (3–5 days)
- Fogging effect (transient normalization ~1–2 weeks)
- Gyriform (cortical) enhancement (if contrast)
- ± Hemorrhagic transformation
4. Chronic Phase (>2–3 weeks)
- Encephalomalacia (CSF density area)
- Volume loss → ex vacuo ventricular dilatation
- Gliosis
- No mass effect
High-Yield Signs (Rapid Recall)
- Dense MCA sign → thrombus
- Insular ribbon loss → earliest cortical sign
- Obscured lentiform nucleus → deep gray involvement
- Wedge-shaped hypodensity → territorial infarct
- Mass effect peaks at 3–5 days
- Fogging effect → pseudo-normal CT (pitfall)
ASPECTS (MCA Stroke) – Quick Note
- 10-point score (NCCT)
- 1 point deducted for each early ischemic change region
- ≤6 → poor prognosis / large infarct core