This study intends to evaluate the application value of Positron Emission Tomography/Magnetic Resonance (PET/MR) in the staging and efficacy evaluation of NK/T cell lymphoma, aiming to explore a more accurate system for predicting the prognosis of patients and guiding the treatment.

Nature Killer/T-cell Lymphoma (NKTCL) is a highly heterogeneous, aggressive lymphoma subtype with poor prognosis. Ninty percent of patients have lesions involving the nasal region, other extranodal organs include adrenal glands, gastrointestinal tract, skin and so on. Local tumor infiltration (bone, skin, paranasal sinus, etc) is a poor prognostic factor. Therefore, NK/T-cell lymphomas have high demands on the resolution of fine anatomical structures. PET/CT and nasopharyngeal contrast-enhanced MR are routine examination methods for diagnostic staging and efficacy evaluation, but the images cannot be fused, and the divided examinations bring inconvenience to patients.

Inclusion Criteria:

• Pathologically diagnosed NK/T-cell lymphoma based on the WHO classification 2016
• Age from 14 to 70 years-old
• ECOG 0-2 score
• Patients with a life expectancy of at least 6 months
• Patient has not been treated before for NK/T cell lymphoma
• Commit to abide by the research procedures and cooperate with the implementation of the whole process of research
• Written informed consent

Exclusion Criteria:

- Subjects who meet any of the following criteria are not eligible for study entry

• Diagnosed aggressive NK cell leukemia

• Pregnant or lactating women

• Liver and kidney insufficiency

• Other PET/MR contraindications:

  1. Those with implanted functional electronic devices such as cardiac pacemakers
  2. Carotid aneurysm clipping and other implants are ferromagnetic materials
  3. Implanted perfusion devices such as insulin perfusion pumps
  4. Those who do not cooperate in examinations such as coma, mental illness, and critically ill patients
  5. Those who are claustrophobic

• Other concurrent and uncontrolled medical conditions that the investigator believes will affect the patient's participation in the study