 3. Patients with a diffuse or localized thick subarachnoid clot on baseline CT scan. Measurements defining clot thickness and extension are as follows: Diffuse: Clot with long axis 20 mm, or any clot if present in both hemispheres Localized: Clot with long axis 20 mm Thick: Clot with short axis 4 mm Thin: Clot with short axis 4 mm 