0 | None | None | None | None | No coverage | Unorganized clot | Blood clot | None |
1 | Mild: scattered inflammatory cells, mostly at neck | Less than 50% of wall thickness | Less than 50% of perimeter | Less than 50% compaction | Less than 50% coverage | Fibrin | Device only | Less than 50% neck coverage |
2 | Moderate: inflammatory cells occupy 25–75% of neck and wall | 50–75% of wall thickness | 50–75% of perimeter | 50–75% compaction | 50–75% coverage | Fibrin with organized tissue | Device plus fibrous tissue | 50–75% neck coverage |
3 | Severe: inflammatory cells occupy greater than 75% of neck and wall | Greater than 75% of wall thickness | Greater than 75% of perimeter | Greater than 75% compaction | Greater than 75% coverage | Organized fibroblastic tissue | | Greater than 75% neck coverage |
4 | | Necrosis extends beyond aneurysm wall | | | Complete coverage | | | Complete neck coverage |