The number of areas examined at one time is determined by the coil. If the patient is having a head and thoracic spine examination, separate coils are used, divided into head-specific coils and spine coils. If the head examination is completed, the patient needs to get out of bed first and the technologist can change the coils before the next examination can be performed. However, if the patient undergoes a head and cervical spine examination, due to the updated equipment, there exists a dedicated combined head and neck coil, and the patient only needs to cooperate once to complete both examinations. If the patient needs a head scan as well as a cranial vascular examination, both examinations can be completed in one visit. Therefore, how many parts of the MRI can be done at one time is determined by the coil. Multi-site exams need to be scheduled in advance, and the time varies from hospital to hospital. Because MRI is radiation-free, patients can have multiple exams in a day without fear of harm.