Circumferential Thick Enhancement at Vessel Wall MRI Has High Specificity for Intracranial Aneurysm Instability

Abstract

Purpose To identify wall enhancement patterns on vessel wall MRI that discriminate between stable and unstable unruptured intracranial aneurysm (UIA). Materials and Methods Patients were included from November 2012 through January 2016. Vessel wall MR images were acquired at 3 T in patients with stable (incidental and nonchanging over 6 months) or unstable (symptomatic or changing over 6 months) UIA. Each aneurysm was evaluated by using a four-grade classification of enhancement: 0, none; 1, focal; 2, thin circumferential; and 3, thick (>1 mm) circumferential. Inter- and intrareader agreement for the presence and the grade of enhancement were assessed by using κ statistics and 95% confidence interval (CI). The sensitivity, specificity, and negative and positive predictive values of each enhancement grade for differentiating stable from unstable aneurysms was compared. Results The study included 263 patients with 333 aneurysms. Inter- and intrareader agreement was excellent for both the presence of enhancement (κ values, 0.82 [95% CI: 0.67, 0.99] and 0.87 [95% CI: 0.7, 1.0], respectively) and enhancement grade (κ = 0.92 [95% CI: 0.87, 0.95]). In unruptured aneurysms (n = 307), grade 3 enhancement exhibited the highest specificity (84.4%; 233 of 276; 95% CI: 80.1%, 88.7%; P = .02) and negative predictive value (94.3%; 233 of 247) for differentiating between stable and unstable lesions. There was a significant association between grade 3 enhancement and aneurysm instability (P < .0001). Conclusion In patients with intracranial aneurysm, a thick (>1 mm) circumferential pattern of wall enhancement demonstrated the highest specificity for differentiating between stable and unstable aneurysms. © RSNA, 2018.

Visualizing wall enhancement over time in unruptured intracranial aneurysms using 3D vessel wall imaging

“…The reason that stable aneurysms show wall enhancement might be explained by the dynamic change of inflammatory cell infiltration through the different stages of the aneurysm evolution . Another possible explanation for the difference in observed enhancement between our study and the study by Edjlali et al is that we graded enhancement by the percentage of enhancement present, whereas Edjlali et al required vessel wall enhancement to be completely circumferential. Besides, this difference may be due to variations in the VWI technique, as well as actual differences between patient cohorts…”

“…This result differs from previous reported studies. Edjlali et al reported circumferential aneurysm wall enhancement in 11/14 (79%) of unstable unruptured aneurysms and 22/27 (82.6%) of stable aneurysms. In the study of Nagahata et al, strong enhancement was seen in 4/83 (4.8%) and faint enhancement in 11/83 (13.3) aneurysms.…”

Quantitative Susceptibility Mapping and Vessel Wall Imaging as Screening Tools to Detect Microbleed in Sentinel Headache

“…AWE might be a novel biomarker of IA instability [18,19], since it is associated with inflammatory and/or atherosclerotic reaction along with thickening of the aneurysm walls [18,27]. Unstable unruptured IAs demonstrated AWE more frequently than stable ones [28][29][30]. Additionally, the pattern of AWE is significantly associated with the morphological changes observed in IAs, such as aneurysmal sac expansion or daughter sac formation [31].…”

Vessel wall imaging in intracranial aneurysms

“…Protected by copyright. 31 Finally, Wang et al analyzed HR-VWI findings of 89 UIAs (31 symptomatic and 58 asymptomatic). An enhancement ratio (ER) was calculated after several signal intensities were measured in the aneurysm neck, body, and dome using T1 pre-and post-gadolinium sequences.…”