Malignant lymphoma, because it occurs in lymph nodes or tissues and organs of the lymphatic system, is a type of malignant tumor that can invade parts all over the body. Therefore, for the follow-up examination of lymphoma, the most commonly used method is PET-CT, which is a very good method for follow-up examination. If the patient does not have the conditions to undergo PET-CT, a whole-body enhanced CT scan from head to toe can also be done, which is also relatively common. However, for some special lymphomas, such as patients with gastric mucosa-associated lymphoma, they need to undergo a gastroscopy for their follow-up. For patients with nasal cavity NK/T-cell lymphoma, they need to undergo enhanced MRI of the nasopharynx and neck area. Therefore, the most commonly used method for follow-up examinations of malignant lymphoma is still PET-CT.