MRI (magnetic resonance imaging) is a clinical tool to evaluate brain anatomy and to detect various CNS (Central nervous system) abnormalities like tumors, infections, degenerative diseases (such as Alzheimer's disease) etc. Perfusion refers to the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue. Perfusion MRI is important in assessment of above mentioned diseases and to provide required diagnosis to the patient on time. Potential applications include the evaluation of tissue at risk. This technique have great potential in becoming important clinical tools in the diagnosis and treatment of patients with cerebrovascular disease and other brain disorders.