ISCHEMIC STROKE / ACUTE THERAPY
Angiographic grading of cerebral revascularization
Created 03/03/2022, last revision 04/05/2023
- revascularization is a broader term and includes:
- recanalization (clot removal from the target vessel)
- anterograde reperfusion of the peripheral circulation
- recanalization does not automatically mean reperfusion (if peripheral embolization persists, recanalization will have little or no clinical effect)
- reperfusion is a better marker of revascularization because it considers the state of the tissue and is, therefore, more closely related to the clinical outcome
- on the other hand, the quantification of recanalization is an essential parameter of the direct effect of the intervention
- at the end of each endovascular intervention, both recanalization (AOL scale) and reperfusion (mTICI scale) should be assessed and reported
- criteria of successful intervention: mTICI 2b-3 and AOL 2-3
- other scales have been presented but are rarely used
- The Qureshi scale
- The Recanalization in Brain Ischemia (RBI) scale
- the Mori scale

Revascularization | ||
Recanalization
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restoration of flow in the occluded arterial segment (primary arterial occlusive lesion) |
AOL |
Reperfusion
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restoration of flow in the territory of an occluded vessel (distal vascular bed) |
mTICI
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Reperfusion assessment
Modified Treatment In Cerebral Infarction (mTICI)
- modified Treatment In Cerebral Infarction (mTICI) score specifies the extent of tissue perfusion; it was derived from the original TICI classification (Thrombolysis In Cerebral Infarction)
- the original name was changed to reflect the current endovascular practice
- TICI 2 was divided – reperfusion in < 1/2 of the target vascular territory (mTICI 2a) and > 1/2 of it (mTICI 2b) [Zaidat, 2013]
- it has good interrater reliability and strongly predicts clinical outcome
- the mTICI has better reproducibility and predictive value than the original TICI [Yoo, 2013]
- the original name was changed to reflect the current endovascular practice
Recanalization assessment
- recanalization scales evaluate the direct effect of therapeutic intervention on the Target Arterial Lesion (TAL)
- they do not directly assess downstream perfusion but may still provide additional prognostic information (residual stenosis increases the risk of reocclusion or distal embolization)
Arterial Occlusive Lesion (AOL) scale
- the Arterial Occlusive Lesion (AOL) scale is the grading scale intended to measure the degree of recanalization at the TAL
- it is preferred for its ease of use and accurate assessment of device effectiveness at the site of occlusion
- AOL describes arterial patency at the site of occlusion based on the degree of luminal opening (none, partial, or complete) with further qualification based simply on the presence (grades 2 or 3) or absence (grades 0 or 1) of downstream flow
- there is good agreement between AOL and mTICI and an excellent ability to predict the outcome
- target arterial lesion (TAL) assessment may be problematic (see below)
- for example, in a tandem lesion of ICA+M1 – recanalization of the siphon with persistent M1 occlusion may result in conflicting assessment – AOL 3 / mTICI 0
- it would be better to evaluate the whole thrombus (⇒ problem with determining its distal end)
- differentiating partial recanalization with residual intraluminal thrombus from underlying intracranial atherosclerotic stenosis is another challenge
The Arterial Occlusive Lesion (AOL) scale
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0 | Complete occlusion of the target artery |
1 | Incomplete occlusion or partial local recanalization at the target artery with no distal flow |
2 | Incomplete occlusion or partial local recanalization at the target artery with any distal flow |
3 | Complete recanalization and restoration of the target artery with any distal flow |
- TAL = most proximal part of the intracranial occlusion
- except for isolated extracranial artery occlusion (e.g., ICA occlusion with distal hypoperfusion)
- for combined occlusion of the cervical segment of ICA+ M1, the target artery is the MCA
ICA | MCA |
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