Hello, I read your message carefully and understood your medical problem. Immunotherapies are of two types. Some of them mark the cancer cells to make them easier for the immune system to find these cells and destroy them. The other type strengthens the immune system to function better against cancer. Side effects of immunotherapy include flu-like symptoms, heart palpitations, diarrhea, and edemas. When these side effects are expected to happen your doctor takes preventive decisions by keeping you in a certain regime of medication that prevents the complications. MRI works through a magnetic field that is based on the movement of the hydrogen atoms in the presence of the magnetic field. There is no real radiation in this case so an MRI can be considered a safe examination. CT scans use X-rays which can be harmful if frequently done. In your case, I do not think that this test will cause a damage to your health. PET scan uses a radioactive dye that is injected into the vein to make specific structures visible. In this case, the radiation is considered minimal even though the tracers are present and it is an invasive procedure. These tracers mostly are just glucose being attached with a radioactive component. Immunosuppression can be dangerous as it predisposes you for other health complication such as infections. As about the radiological examinations as I discussed above they do not do as much harm as it is generally thought. Furthermore, it is very important for you to do these tests. The favorite place for the eye melanoma to spread is liver and gives hematological symptoms in this case. It can metastasize to brain, lungs, bones and kidney too. It is very important to run all the tests necessary and to prevent the complications of this disease. Hope this is useful for you. Thank you.