A Novel Scoring System for Rupture Risk Stratification of Intracranial Aneurysms: A Hemodynamic and Morphological Study

Abstract

Objective: The aim of the present study is to investigate the potential morphological and hemodynamic risk factors related to intracranial aneurysms (IAs) rupture and establish a system to stratify the risk of IAs rupture to help the clinical decision-making.Methods: Patients admitted to our hospital for single-IAs were selected from January 2012 and January 2018. A propensity score matching was conducted to match patients. The morphological parameters were obtained from high solution CTA images, and the hemodynamic parameters were obtained in accordance with the outcomes of computational fluid dynamics (CFDs) simulation. Differences in the morphologic and hemodynamic parameters were compared. The significant parameters were selected to establish a novel scoring system (Intracranial Aneurysm Rupture Score, IARS). The comparison was drawn between the discriminating accuracy of IARS and the Rupture Resemblance Score (RRS) system to verify the value of IARS. Then, a group of patients with unruptured IAs was stratified into the high risk and low risk groups by IARS and RRS system separately and was followed up for 18–27 months to verify the value of IARS. The outcome of different stratifications was compared.Results: The matching process yielded 167 patients in each group. Differences of statistical significance were found in aneurysm length (p = 0.001), perpendicular height (H) (p < 0.001), aspect ratio (AR) (p < 0.001), size ratio (SR) (p < 0.001), deviated angle (DA) (p < 0.001), normalized average wall shear stress (NWSSa) (p < 0.001), wall shear stress gradient (WSSG) (p < 0.001), low shear area ratio (LSAR) (p = 0.01), and oscillatory shear index (OSI) (p = 0.01). Logistic regression analysis further demonstrated that SR, DA, NWSSa, LSAR, and OSI were the independent risk factors of IAs rupture. SR, DA, LSAR, and OSI were finally selected to establish the IARS. Our present IARS showed a higher discriminating value (AUC 0.81 vs. 0.77) in comparison with the RRS (SR, NWSSa, and OSI). After follow-up, seven patients were subject to IAs rupture. 5/26 in high risk group stratified by IARS, yet 7/57 in high risk group stratified by RRS. The accuracy of IARS was further verified (19.2% vs. 12.3%, AUC for the IARS and the RRS was 0.723 and 0.673, respectively).Conclusion: SR, DA, NWSSa, LSAR, and OSI were considered the independent risk factors of IAs rupture. Our novel IARS showed higher accuracy in discriminating IA rupture in comparison with RRS.

Systematic review of hemodynamic discriminators for ruptured intracranial aneurysms

“…Among the reviewed articles, four counted the AUC of both geometrical and hemodynamic indexes (Table 4). Jiang and Fan show a similar profile, in which the AUC of the aspect ratio is approximately 0.85, whereas the AUC of the best hemodynamic index is in a similar range [46,55]. These studies indicate that the geometric and hemodynamic indexes are comparable.…”

“…The first set of exclusion criteria were as follows: (a) CFD-unrelated (n = 5), (b) rupture-point-known (n = 10), (c) discriminator-unrelated (n = 26), (d) small number of aneurysms (less than 30) (n = 28), and (e) WSS or OSI undisclosed (n = 11), yielding a total of 32 studies. The second set of exclusion criteria were as follows: (f) location-specific (n = 14), (g) locationundefined (n = 2), (h) size-restricted (n = 1), and (i) metaanalysis (n = 2), yielding a total of 13 studies [38,39,[45][46][47][48][49][50][51][52][53][54][55]. Setting a specific location and size was avoided since those factors are known to be related to the aneurysm rupture rate and may lead to a possible bias; however, casematching studies based on location and size were permitted.…”

“…From the 13 included studies [38,39,[45][46][47][48][49][50][51][52][53][54][55], the following data were extracted: (1) year of publication, (2) study design, (3) location of aneurysms, (4) number of aneurysms, (5) number of ruptured aneurysms, (6) aneurysmal size, (7) aneurysmal aspect ratio, (8) aneurysmal WSS, (9) aneurysmal normalized WSS (NWSS), (10) aneurysmal OSI, and (11) aneurysmal LSA%. The mean (or median), p value, and area under the curve (AUC) from a receiver operating characteristic (ROC) analysis of these geometric and hemodynamic indexes were extracted.…”

“…Finally, the coefficient of variation (CV = SD/Mean) was calculated, and its average between ruptured and unruptured aneurysms was used to quantify the variability between groups. Table 1 summarizes the univariate analyses of 13 studies (3,692 aneurysms) [38,39,[45][46][47][48][49][50][51][52][53][54][55]. The percentage of ruptured aneurysms ranged from 30% to 50%.…”

Impacts of Internal Carotid Artery Revascularization on Flow in Anterior Communicating Artery Aneurysm: A Preliminary Multiscale Numerical Investigation

“…Despite both aberrantly high (>7 Pa) [38][39][40][41] and low TAWSS (<1.5 Pa) [27,[34][35][36][37], they have been reported to contribute to the IA rupture via complex mechanobiological mechanisms [14,17]; associations between low TAWSS and the risk of rupture of large IAs (>5 mm) have been identified by some of the latest investigations [14,15,59]. Additionally, high OSI (>0.2), which reflects the elevated local flow instability, was also considered as an important factor in the rupture of IAs by upregulating inflammatory cell-mediated destructive remodeling [14,56,[60][61][62]. Moreover, this corresponds with the lower and stronger oscillatory WSS and the prolonged RRT has been linked with higher rupture risk as well [15].…”