Edinburgh CT Criteria (CAA-Associated Lobar ICH)
The Edinburgh CT criteria (Rodrigues and colleagues 2018) estimate the probability that cerebral amyloid angiopathy caused a lobar intracerebral hemorrhage already seen on non-contrast CT.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Subarachnoid extension of the lobar hemorrhage on CT
- Yes
- Finger-like projections from the hematoma on CT
- No
- APOE e4 status
- Positive
Result: High probability
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Scope
- For a LOBAR intracerebral hemorrhage already seen on non-contrast CT. Estimates whether cerebral amyloid angiopathy caused it.
- Original
- Low = neither subarachnoid extension nor APOE e4. High = subarachnoid extension AND at least one other predictor. Medium = everything else.
- Simplified
- CT only. Low = no subarachnoid extension. Medium = subarachnoid extension. High = subarachnoid extension AND finger-like projections.
- Direction
- THE SIMPLIFIED VERSION CAN ONLY READ LOWER, NEVER HIGHER. Three of eight combinations differ and the original is higher in all three.
- Why
- The whole gap is APOE e4. With APOE negative the two versions always agree.
- Not a count
- A common restatement calls the original a count of any two of three findings. IT IS NOT. Subarachnoid extension is a GATE.
- Projections
- Finger-like projections NEVER count on their own in either version. They raise the category only once subarachnoid extension is present.
- Rule out
- Neither subarachnoid extension nor APOE e4: 100% sensitivity for moderate or severe CAA in the derivation study.
- Rule in
- Subarachnoid extension AND either APOE e4 or finger-like projections: 96% specificity in the derivation study.
- APOE unknown
- The genotype is almost never back when the CT is read. The original is then NOT computed rather than guessed.
- Limits
- Does not diagnose the hemorrhage, does not apply to deep or infratentorial hemorrhage, does not establish CAA, does not replace the MRI-based Boston criteria, and does not decide anticoagulation.
What you enter
- Subarachnoid extension of the lobar hemorrhage on CT.
- Finger-like projections from the hematoma on CT.
- APOE e4 status.
Full field descriptions
- Subarachnoid extension of the lobar hemorrhage on CT. THE GATE: without it neither version can reach high probability.
- Finger-like projections from the hematoma on CT. Never counts on its own - it raises the category only once subarachnoid extension is present.
- APOE e4 status. Use "unknown" if the genotype is not back - that is the usual state when the CT is read, and it is why the simplified version exists. With "unknown" the original criteria are not computed.
How this is calculated
Rodrigues MA, Samarasekera N, Lerpiniere C, et al. The Edinburgh CT and genetic diagnostic criteria for lobar intracerebral haemorrhage associated with cerebral amyloid angiopathy: model development and diagnostic test accuracy study. Lancet Neurol. 2018;17(3):232-240. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.