Circumferential wall enhancement with contrast ratio measurement in unruptured intracranial aneurysm for aneurysm instability

Abstract

Background: Aneurysm wall enhancement on high-resolution vessel wall imaging (HR-VWI) may represent vessel wall inflammation for unruptured intracranial aneurysms (UIAs). Further evidence for the role of circumferential aneurysm wall enhancement (CAWE) in evaluating the instability of UIAs is required, especially in small aneurysms (<7 mm).

Methods: We analyzed patients with saccular UIAs who prospectively underwent HR-VWI on a 3.0 T MRI scanner in our center from September 2017 to August 2021. The presence of AWE was identified and quantitatively measured using the aneurysm-to-pituitary stalk contrast ratio (CRstalk) with maximal signal intensity value. The PHASES and ELAPSS scores were used to assess the risk of aneurysm rupture and growth. We evaluated the association of CAWE and CRstalk value with intracranial aneurysm instability.

Results: One hundred patients with 109 saccular UIAs were included in this study. Eighty-three UIAs (76.1%) had a size smaller than 7 mm. PHASES and ELAPSS scores were significantly higher in UIAs with CAWE than in UIAs without CAWE (p < .01). The association of CAWE with PHASES and ELAPSS scores remained in small UIAs (<7 mm). The optimal cutoff value of CRstalk for CAWE was 0.5. PHASES and ELAPSS scores were significantly higher in UIAs with CRstalk ≥0.5 than in UIAs with CRstalk <0.5 (p < .01).

Conclusions: CAWE on HR-VWI is a valuable imaging marker for aneurysm instability in UIAs. CRstalk value ≥0.5 may be associated with a higher risk of intracranial aneurysm rupture and growth.

Keywords: ELAPSS score; PHASES score; aneurysm wall enhancement; unruptured intracranial aneurysm; vessel wall imaging.

FIGURE 1

Circumferential aneurysm wall enhancement on high‐resolution vessel wall imaging (HR‐VWI) is shown in a middle cerebral artery aneurysm (a, three‐dimensional (3D) digital subtraction angiography; b, precontrast 3D HR‐VWI; c, postcontrast 3D HR‐VWI). Focal aneurysm wall enhancement on HR‐VWI is shown in an internal carotid artery aneurysm (d, 3D digital subtraction angiography; e, precontrast 3D HR‐VWI; f, postcontrast 3D HR‐VWI)

FIGURE 2

Example of aneurysm‐to‐pituitary stalk contrast ratio (CRstalk) measurement in an internal carotid artery (ICA) aneurysm. The maximal signal intensity value of aneurysm wall and pituitary stalk on postcontrast T1‐weighted images was used to calculate the CRstalk (CRstalk = SIwall/SIstalk). Postcontrast T1‐weighted images of left ICA aneurysm (a) and sagittal images of pituitary stalks (b) showing each maximal signal intensity (MAX). CRstalk of the aneurysm was calculated as 0.66. Receiver operating characteristic curve of CRstalk to differentiate circumferential aneurysm wall enhancement, the area under the curve was 0.953 (c)