Chemokine receptor CXCR4 was expressed in MM and lymphoma cells and CXCR4-targeting molecular imaging- 68Ga-Pentixafor PET/CT could be a promising technique to evaluate the extent of MM and lymphoma with higher accuracy. This prospective study is going to investigate whether metabolic characterization by 68Ga-Pentixafor PET/CT may be superior for diagnosis, risk stratification, and prognostic evaluation of MM and lymphoma.

Multiple myeloma:

Multiple myeloma (MM) is characterized by the neoplastic proliferation of plasma cells producing a monoclonal immunoglobulin. The Durie and Salmon and ISS clinical staging system have been well-accepted as a practical way to evaluate MM tumor burden nowadays. But it is difficult to assess the accurate tumor involvement because of the significant heterogeneity characterizing this disease at multiple levels such as clinical presentation, biologic characteristics, treatment response, and clinical outcome. New imaging modalities such as 18F-FDG PET/CT has been used to improve the efficacy of this system in assessing the extent and severity of MM, but the diagnostic accuracy of 18F-FDG PET/CT decreased in lower proliferative MM cells and inflammation. Recent studies showed Chemokine receptor CXCR4 was expressed in MM cells and CXCR4-targeting molecular imaging- 68Ga-Pentixafor PET/CT could be a promising technique to evaluate the extent of MM with higher accuracy. This prospective study is going to investigate whether metabolic characterization by 68Ga-Pentixafor PET/CT may be superior for diagnosis, risk stratification, and prognostic evaluation of MM.

Lymphoma:

Lymphoma is a frequent cancer with high CXCR4 expression. According to the previous studies, 68Ga-pentixafor-PET seems to be a highly selective and specific method for the in vivo quantification of CXCR4 expression. Thus our study is going to investigate the value of 68Ga-pentixafor-PET/CT for the diagnosis，differentiation and pretherapeutic evaluation of CXCR4 expression in lymphoma.

Inclusion criteria：

• suspected or confirmed untreated MM or lymphoma patients
• 18F-FDG PET/CT within two weeks
• signed written consent.

Exclusion criteria:

• pregnancy
• breastfeeding
• known allergy against Pentixafor
• any medical condition that in the opinion of the investigator,may significantly interfere with study compliance.