Raymond–Roy occlusion classification of intracranial aneurysms
The Raymond–Roy occlusion classification (RROC) is an angiographic classification scheme for grading the occlusion of endovascularly treated intracranial aneurysms 1. It is also known as the Raymond class, Montreal scale, modified Montreal scale or the Raymond Montreal scale.
- class I: complete obliteration
- class II: residual neck
- class III: residual aneurysm
The scheme was originally created to evaluate aneurysm occlusion class, and not predict aneurysmal recurrence.
Mascitelli et al. 1 in 2015 proposed a modified Raymond–Roy classification where class III is subdivided to reflect progression to occlusion:
- class IIIa: contrast opacification within the coil interstices of a residual aneurysm
- class IIIb: contrast opacification outside the coil interstices, along the residual aneurysm wall
Mascitelli et al.'s study found that class IIIa aneurysms progress to complete occlusion more than class IIIb aneurysms.