Fig 1.

Schematic of patient selection for our study. The decision of obtaining a CTA/CECT of the brain immediately following the initial NCCT was made by the neurologist in charge of the patient, on the basis of the degree of suggestion of an underlying origin for the intracranial hemorrhage (ICH). Seventy-six percent (190/250) turned out to have such an underlying cause (aneurysm, vascular malformation, vasculitis, venous infarction, Moyamoya disease, or brain tumor), whereas 24% (60/250) were finally diagnosed with primary ICH. Among the 60 patients with primary ICH, 56 underwent follow-up brain imaging. Among the 4 who did not, 2 died before follow-up imaging. AVM indicates arteriovenous malformation; NCT, noncontrast CT.