Wall Redness of Enlarged Unruptured Cerebral Aneurysm

The wall of enlarged unruptured cerebral aneurysm (EUCA) is thought to be reddish, thin, and fragile. This study aimed to evaluate the EUCA wall redness based on quantitative signal intensity method and to compare the clinical and radiological characteristics between EUCA and non-EUCA.

In this retrospective analysis, red (R), green (G), blue (B), and RGB signal intensities of aneurysm were quantitatively measured using an intraoperative digital picture in 150 cases. Color intensities were measured by two independent investigators. Aneurysm redness was defined as an R/RGB ratio since the brightness of the operative field differed by each surgery or angle of the microscope.

The median aneurysm size was 4.9 mm (IQR 3.9-5.9 mm). Median color intensity of R, G, B, RGB, and R/RGB ratio were 206 (185-215), 129 (107-150), 136 (115-157), 157 (140-174), and 1.26 (1.20-1.38), respectively. The intraclass correlation coefficient for R/RGB ratio was 0.73 (P<0.0001). The proportion of female sex was significantly higher for EUCA (p = 0.019). Median R/RGB ratio in GUCA was significantly larger than that of non-EUCA (OR 1.25, 95% CI 1.19-1.35) (p = 0.035). Even after adjustment of female sex, a R/RGB ratio ≧1.36 was related to EUCA (OR 3.02, 95% CI 1.30-7.02).

The present study showed that a R/RGB ratio could be calculated easily and a larger R/RGB ratio was related to EUCA. When EUCA is managed by surgical treatment, more careful manipulation should be needed compared to non-EUCA due to a "red" wall of EUCA.