Cerebrovascular and aneurysm prediction tools
Models for intracranial aneurysm treatment: recanalization risk after endovascular coiling, occlusion after the WEB device, and functional outcome by microsurgical strategy for giant aneurysms.
Key terms
- Raymond-Roy classification
The Raymond-Roy classification grades how completely a coiled intracranial aneurysm is occluded on angiography: class 1 complete, class 2 residual neck, class 3 residual aneurysm.
- Aneurysm recanalization after coiling
Recanalization is the reappearance of blood flow into a coiled aneurysm over time, from coil compaction, aneurysm growth or thrombus resolution. Major recanalization often prompts retreatment.
- Coil packing density
Coil packing density is the volume of the coils placed in an aneurysm divided by the aneurysm's volume, expressed as a percentage. Denser packing is associated with lower recanalization.
- Stent-assisted coiling
Stent-assisted coiling places a stent across an aneurysm's neck to hold coils inside the sac, allowing endovascular treatment of wide-neck aneurysms. It requires antiplatelet therapy.
- Woven EndoBridge (WEB) device
The Woven EndoBridge (WEB) is an intrasaccular flow disruptor: a braided nitinol device placed inside a wide-neck bifurcation aneurysm to disrupt flow at the neck and promote thrombosis.
- Wide-neck aneurysm
An intracranial aneurysm is usually called wide-necked when its neck is 4 mm or wider, or its dome-to-neck ratio is under 2. Wide necks make simple coiling harder.
- Giant intracranial aneurysm
A giant intracranial aneurysm has a maximum diameter of 25 mm or more. They can present with hemorrhage or mass effect and often need bypass or parent artery occlusion.
- Cerebral revascularization (EC-IC bypass)
Cerebral bypass routes blood from an extracranial donor artery (or a graft) to an intracranial artery, so that a complex aneurysm and its parent vessel can be clipped, trapped or occluded safely.
- Modified Rankin Scale (mRS)
The modified Rankin Scale grades disability after stroke or neurosurgery from 0 (no symptoms) to 6 (death). Scores of 0 to 2 or 0 to 3 are commonly used as a good outcome.
- Survival analysis (time-to-event modeling)
Survival analysis models how long until an event happens, while correctly handling patients whose follow-up ends before the event (censoring).
- Concordance index (C-index)
The C-index measures how well a model ranks patients by risk: the chance that, of two patients, the one predicted at higher risk has the event first. 0.5 is chance, 1.0 is perfect.
- Calibration of a prediction model
A calibrated model's predicted risks match observed rates: of patients given a 20% risk, about 20% have the event. Calibration matters as much as discrimination for clinical use.
- SHAP (Shapley additive explanations)
SHAP explains an individual prediction by splitting it into contributions from each input feature, based on Shapley values from game theory.
Research and educational tools. Not for clinical decision-making.