Island Sign on Computed Tomography Is Associated With Cerebral Amyloid Angiopathy in Patients With Intracerebral...

Irregular hematoma border is a prominent yet understudied imaging feature of cerebral amyloid angiopathy (CAA)-related intracerebral hemorrhage (ICH). We investigated whether island sign and irregular shape could be an additional imaging marker of CAA-related ICH.

This cross-sectional analysis included a prospective cohort of consecutive patients with supratentorial ICH with both computed tomography and magnetic resonance imaging. Presence of island sign and irregular shape on computed tomography was assessed blinded to clinical and magnetic resonance imaging data. The primary outcome was probable CAA by Boston criteria v2.0. Multivariable logistic regression analysis was conducted to evaluate associations of island sign or irregular shape with probable CAA. Diagnostic accuracy of the simplified Edinburgh criteria before and after incorporating island sign or irregular shape was compared using area under the receiver operating characteristics curve and DeLong test.

Among 488 patients, 51 (10.5%) patients had CAA-ICH. Island sign (39.2% versus 4.1%, P<0.001) and irregular shape (54.9% versus 30.2%, P<0.001) were more frequent in CAA-ICH than non-CAA-ICH. In multivariable analysis, island sign was independently associated with probable CAA in the overall cohort (adjusted odds ratio [OR], 4.67 [95% CI, 1.63-13.38]) and in patients with lobar ICH (OR, 4.49 [95% CI, 1.14-17.61]). Irregular shape was not related to CAA-ICH. Among patients with lobar ICH, the simplified Edinburgh criteria incorporating island sign has improved diagnostic performance of probable CAA (area under the receiver operating characteristics curve 0.817 versus 0.754, P=0.033).

Island sign is associated with magnetic resonance imaging-based diagnosis of CAA and improves the diagnostic accuracy of the simplified Edinburgh criteria, aiding in accurate identification of CAA-related ICH.