Duy Le, MD

Edjlali M, Gentric JC, Régent-Rodriguez C, Trystram D, Ben Hassen W, Lion S, et al. Does Aneurysmal Wall Enhancement on Vessel Wall-MRI Help to Distinguish Stable From Unstable Intracranial Aneurysms? Stroke. 2014

As exciting as acute treatment is in the stroke world, just as much energy should be focused on prevention. As with any disease, if we can appropriately risk stratify in order to prevent catastrophic events from ever happening, then the battle will have been won. Although much work has been done to risk stratify cerebral aneurysms based on size (International Study of Unruptured Intracranial Aneurysms), Edjlali et al attempt to quantify another parameter of measuring aneurysm rupture risk: circumferential aneurysmal wall enhancement (CAWE). 

It has been known that arterial wall enhancement indicates evidence of inflammatory disease. This study evaluated 87 patients harboring 108 intracranial aneurysms. These patients were followed out for 6 months. Prospectively within 6 months, aneurysms were determined as unstable if it ruptured, became symptomatic or had undergone morphologic changes.

Patients underwent Vessel Wall MRI’s which consisted of a 3T MRI with gadolinium administration. The MRI’s were reviewed by 2 radiologist with excellent inter-reader and intra-reader agreement for CAWE (k=0.85 and k=0.90 respectively). CAWE was significantly more frequently seen in unstable aneurysms (27/31; 87%), as compared to stable aneurysms (22/77; 28.5%). Multivariate logistic regression including CAWE, size, location, multiplicity of aneruysms and daily aspirin intake revealed that CAWE was the only independent factor associated with unstable aneurysm (OR, 9.20; 95% CI; p=0.0002)

While it does appear that CAWE is seen more often in unstable aneurysms, it is also seen in about 30% in stable aneurysms. There is good sensitivity, but evidence of CAWE is not necessarily specific for an unstable aneurysm. Weaknesses of the study includes that patients were only followed patients out for 6 months; it would be important track these patients out over a number of years as well. Additionally, there may be a referral bias.

Taken together, from this limited data, it would be difficult to determine management of aneurysms solely based on CAWE. Stratifying aneurysmal rupture risk according to size is quite ingrained in our common practice. On the bright side however, evaluation for CAWE does not require any post imaging processing and appears easy to identify. This risk stratifying method is promising, but more work remains to be done. With a strong, positive, longitudinal cohort study evaluating CAWE, this method may prove useful in identifying those who are at high risk of bleeding; thus being able to classify and manage a patient as a high risk bleed without having to suffer the sequela of an actual bleed.