Raymond class

The Raymond–Roy occlusion classification (RROC) is an angiographic classification scheme for grading the occlusion of endovascularly treated intracranial aneurysms . It is also known as the Raymond class, 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. Though not truly equivalent these are often equated to aneurysmal obliteration of 100%, >90% and <90% respectively.

Mascitelli et al.  in 2015 proposed a modified Raymond–Roy classification or modified Montreal scale, 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.

A validation study by Stapleton et al. confirmed that the predictive capability of the RROC was improved by the MMRC, showing not only that IIIa occluded more often (53.6% vs 19.2%) but that IIIb lesions would also further recanalize more frequently (65.1% vs 27.4%) .