Abstract WMP29: Contrast Enhancement Measurement of Unruptured Intracranial Aneurysms: A 3T High-Resolution Vessel Wall Imaging Validation Study

Abstract

Background: High-resolution vessel wall imaging (HR-VWI) has emerged as a valuable tool in assessing unruptured intracranial aneurysms (UIAs). There is no standardized method to quantify contrast enhancement of the aneurysmal wall. Contrast enhancement is reflected as signal intensity (SI) at the time of objective quantification. This study compares all the existing methods to objectively quantify contrast enhancement of UIAs. Methods: 3T HR-VWI was used to prospectively image patients with UIAs. Three different methods were analyzed in T1 pre- and post-contrast sequences: (1) circumferential aneurysm wall enhancement (CAWE) = mean post-contrast SI; (2) aneurysm-to-pituitary enhancement ratio (CR stalk ) = ratio of CAWE over pituitary stalk enhancement; and (3) enhancement ratio (ER) = max post-contrast SI - max pre-contrast SI/max pre-contrast SI x 100%. Known risks factors of aneurysm instability such as size ≥7mm and location in the anterior communicating (ACOM) and basilar arteries (BA) were used for analysis. Results: Forty-seven patients with 53 UIAs were included in the study. Mean age was 63.5 years, and 35 (74.5%) were women. UIAs ≥ 7mm showed significantly higher SI measurements for CAWE (273.1 vs 206.9, P =.05), CR stalk (0.49 vs 0.38, P =.006), and ER (85.7% vs 52.5%, P =.002) compared to smaller UIAs. SI was higher in UIAs located in the ACOM and BA (279.6 vs 235.7; 0.45 vs 0.44; 75.1% vs 61.3%) for CAWE, CR stalk and ER, respectively. ROC curves demonstrated sensitivity/specificity values of 0.74/0.64 for CAWE ≥ 205, 0.74/0.60 for CR stalk ≥ 0.398, and 0.71/0.73 for ER ≥ 62.1%. We found a moderately strong correlation between CAWE and CR stalk (Spearman = 0.69), CAWE and ER (Spearman = 0.52) and CR stalk and ER (Spearman = 0.47), with P <.001 in all cases. Conclusion: Three different methods: CAWE, CR stalk and ER may be used reliably to quantify SI in the wall of UIAs. Figure: ROC curves for (A) CAWE, (B) CR stalk and (C) ER.