This is a clinical classification, not radiological. The classification needs to be determined by ED/Trauma doctor, not Radiologist. The role of Radiologist is to accurately measure the size and number of the lesions.
If there are multiple lesions, the largest lesion will determine BIG classification, immaterial of the type of bleed.
The classification is only for acute bleeds.
* pertains to non-aneurysmal SAH. If history of trauma is unclear or if concerned for aneurysmal bleed, exit pathway.