(Class I: complete obliteration; Class II: residual neck; Class III: residual aneurysm), but not all Class III aneurysms behave the same over time.
Raymond Roy occlusion classification
Angiographic outcomes of conventional aneurysm coiling are generally reported using the three-point scale of Roy and Raymond, where aneurysms are designated as complete occlusion, residual aneurysm, or residual neck 1).
Unfortunately, this scale is inadequate for describing aneurysms treated with flow diverting stents. Residual or complete filling of the aneurysm is very common immediately after technically successful flow diversion but is not common after technically successful en- dosaccular treatment. A small neck remnant at follow-up is often accepted as adequate treatment after aneurysm coiling, whereas slight filling of an aneurysm treated with a flow diverting stent may be enough to perpetuate continued mass effect, progressive aneurysm growth and in some cases spontaneous rupture. Finally, a simple assessment of the degree of filling does not take into account the dynamic nature of the contrast stasis and its potential role in predicting aneurysm closure over time. To address these issues, we propose a novel grading scale for the assessment of aneurysms treated with flow diversion. This simple scale accounts for both the amount of aneurysm filling and the degree of contrast stasis seen. We hope this scale will standardize the communication of clinical results with flow diversion. We further anticipate that the simultaneous grading of both filling and stasis will facilitate future research and analysis of flow diverting interventions 2).