PET is also known as a pet-CT test, and the test recommends drinking plenty of water to promote the expulsion of contrast media from the body. However, there is no fixed specific value, you can drink as much as possible according to your own situation. Pet examination before doing this kind of examination, the examinee still need to perfect some basic examination, such as height, weight, blood sugar and other items, mainly to see whether the patient can tolerate this kind of examination, there is also a need to assess whether it can be better display. Then, the subject needs to be injected with a visualizing agent (referred to as 18F-FDG, fluorodeoxyglucose), which usually takes some time after injection to allow it to be distributed throughout the body to improve accuracy. The patient is then scanned on the machine. Before the scan, the bladder needs to be emptied and no metal jewelry, including metal dentures, should be worn. Once it is over you can wait for the report. It is recommended to drink plenty of water after the PET test, as the contrast agent in the body can be eliminated from the body with urine, and drinking plenty of water is beneficial for the elimination of the contrast agent.