Early CT Findings of Ischemia
The following findings indicate established or evolving infarct and may affect tPA/thrombectomy eligibility:
- Loss of gray-white differentiation — blurring of the cortical ribbon or deep gray nuclei
- Insular ribbon sign — loss of the normal gray-white interface at the insula
- Dense MCA sign — hyperdense MCA on non-contrast CT indicating thrombus
- Sulcal effacement — loss of CSF spaces from cerebral edema
- Hypodense parenchyma — low-density change in the expected vascular territory
Treatment Windows
| Window | Intervention | Key Criteria |
|---|---|---|
| 0–4.5h | IV tPA | NIHSS ≥4, no hemorrhage, no large established infarct (>1/3 MCA territory) |
| 0–24h | Thrombectomy | Large vessel occlusion; DAWN/DEFUSE-3 criteria if 6–24h |
| Any window | Thrombectomy eligibility | Core infarct <70 mL; tissue at risk >15 mL (CT perfusion) |
ASPECTS (Alberta Stroke Programme Early CT Score)
10-point scoring system for MCA territory ischemia. Subtract 1 point for each involved region.
Regions scored (10 total):
| Type | Regions |
|---|---|
| Deep (subcortical) | Caudate (C), Lentiform (L), Insula (I), Internal capsule (IC) |
| Cortical MCA territory | M1, M2, M3 (at basal ganglia level); M4, M5, M6 (supraganglionic level) |
Score interpretation: Score ≤6 is associated with poor functional outcome and is used as a threshold in many thrombectomy protocols. Score 7–10 indicates minimal established ischemia.
ASPECTS applies specifically to MCA territory strokes. It is not used for posterior circulation or ACA territory infarcts. Score all 10 regions on non-contrast CT before any intervention decision.
CT Perfusion — Thrombectomy Thresholds
| Parameter | Threshold | Represents |
|---|---|---|
| CBF <30% | Core infarct | Irreversibly infarcted tissue |
| Tmax >6s | Penumbra | Hypoperfused but salvageable tissue |
| Mismatch | Penumbra − Core | >15 mL AND >1.8 ratio = favorable for thrombectomy |
DAWN (2018) and DEFUSE-3 (2018) extended the thrombectomy window to 24h using perfusion mismatch criteria:
- DAWN: mismatch volume >10 mL
- DEFUSE-3: mismatch volume >15 mL with ratio >1.8
- Both require core infarct <70 mL
Heidelberg Bleeding Classification
Classifies hemorrhagic transformation after ischemic stroke. Types 1–2 are within the infarct; Type 3 is remote from the infarct.
| Type | Subtype | Description |
|---|---|---|
| 1 — Hemorrhagic Infarction (HI) | HI1 | Scattered petechiae along infarct margins; no space-occupying effect |
| HI2 | Confluent petechiae within infarcted area; no space-occupying effect | |
| 2 — Parenchymal Hematoma (PH) | PH1 | Hematoma ≤30% of infarcted area; mild space-occupying effect |
| PH2 | Hematoma >30% of infarcted area; significant space-occupying effect | |
| 3 — Remote Hemorrhage | 3a | Parenchymal hematoma remote but contiguous with infarct |
| 3b | Parenchymal hematoma remote and non-contiguous with infarct | |
| 3c | Subarachnoid hemorrhage | |
| 3d | Intraventricular hemorrhage | |
| 3e | Subdural hematoma |
Reporting Checklist — Acute Ischemic Stroke
- ASPECTS score (if MCA territory; score /10 — specify affected regions)
- Vessel occlusion site: ICA / M1 / M2 / M3 / ACA / PCA / basilar (hyperdense vessel sign)
- Affected vascular territory
- Collateral grade: good / poor / absent (on CTA source images)
- Early ischemic changes: gray-white differentiation loss / sulcal effacement / dense MCA sign
- CT perfusion (if performed): core volume (mL), penumbra volume (mL), mismatch ratio
- Hemorrhagic transformation: absent / HI1 / HI2 / PH1 / PH2
- Prior infarcts: location, chronicity
Reference
von Kummer R, Broderick JP, Campbell BC, et al. The Heidelberg Bleeding Classification: Classification of Bleeding Events After Ischemic Stroke and Reperfusion Therapy. Stroke. 2015;46(10):2981–2986.