B. It gives the physician metabolic information.
A PET scan measures important body functions, such as blood flow, oxygen use, and sugar (glucose) metabolism, to help doctors evaluate how well organs and tissues are functioning. MRI, on the other hand, gives very detailed pictures of soft tissues like the brain. MRI can be used to detect brain tumours, traumatic brain injury, developmental anomalies, multiple sclerosis, stroke, dementia, infection, and the causes of headache.