Introduction Globally, the incidence of intracranial aneurysms is estimated to range between 3 and 5%. Despite the low rupture rate of approximately 3-50/100000, mortality and morbidity among patients with ruptured IA remain as high as 50%. The PHASES score was established to quantify IA rupture risk. MR-Vessel Wall Imaging (VWI) has gained popularity in assessing neurovascular diseases, such as IAs. Aneurysm wall enhancement (AWE) is utilized as a marker of wall instability. We evaluate two distinct quantified measures of post-contrast T1-SPACE AWE in conjunction with the PHASES score as a sign of wall instability.

Methods We conducted an IRB approved study of patients with multiple IAs scanned using VWI protocol between January 2018 to June 2022. AWE was evaluated qualitatively and quantitatively on T1-SPACE sequences. DSA or CTA studies were utilized to evaluate the IA Wall Morphology (IAWM). Quantified AWE values were obtained using 3-point ROIs on the IA wall and normalized with white matter signal intensity obtained using 10 mm circular ROIs. Percentage change in normalized AWE from pre to post contrast imaging was calculated. Furthermore, a ratio of post-contrast quantified AWE to post-contrast pituitary infindibulum (PI) signal intensity (AWPI ratio) was also obtained. Pearson correlation test, and unpaired t-tests were used to assess statistical correlations in SPSS v28.

Results We evaluated 126 IAs in 56 patients (Age: 63.37 +/- 13.11, 27-88, 42 female). The mean size of IAs was 5.15mm +/- 4.34 mm, 2-30 and the mean PHASES score was 4.51 +- 2.99, 0-16. Qualitatively, AWE was seen in 62 (49.2%) IAs and irregular IAWM in 44 (52.3%). PHASES score showed a moderately strong correlation to AWPI ratio, r = 0.452, and to percentage increase in AWE, r = 0.364. IAs in PHASES ≤6 (n=101), PHASES ≥7 (n=25) showed mean AWPI ratios of 0.60 and 0.81 (p<0.001), and percentage increase in AWE of 31.23% and 75.80% (p<0.001). The mean PHASES scores for IAs with and without AWE were 3.41 and 5.66 respectively, (p<0.001). The AWPI ratios of IAs with and without irregular IAWM were 0.755 and 0.584, (p<0.001). The difference in percentage change in AWE between the two groups was measured at 66.53% and 33.35% (p<0.001).

Conclusions Our findings demonstrates a correlation between increased AWPI, Percentage Increase and higher PHASES score, suggesting possible use of both approaches for patient management and IA rupture risk stratification.

Disclosures A. Patel: None. A. Malik: None. S. Hasib Akhter Faruqui: None. R. Abdalla: None. C. Zhou: None. J. Moore: None. A. Shaibani: None. V. Rayz: None. M. Markl: None. T. Carroll: None. D. Cantrell: None. S. Ansari: None.