1. A system for determining neurovascular information for a patient, the system comprising: at least one computer system configured to: receive patient-specific data regarding a geometry of an anatomical structure of the patient, the anatomical structure including at least a portion of a plurality of cerebral arteries and at least a portion of brain tissue connected to the cerebral arteries; create a three-dimensional model representing the anatomical structure based on the patient-specific data; divide at least a portion of the three-dimensional model representing the brain tissue into segments; and determine perfusion information associated with at least one of the brain tissue segments based on the three-dimensional model and a physics-based model relating to the anatomical structure.