This will vary depending on the experience and requirements of different doctors and the requirements of different hospitals. Generally speaking, the results of major examinations are now mutually accepted nationwide, but there are also some doctors or hospitals that do not accept the results of other hospitals, so they need to be treated differently. The general principle is that if there is no significant change in the condition, there is no need for repeated MRI or CT examinations, unless the quality of the pictures from the original examination is poor.