FDG-PET Demonstrates Different Metabolic Activities among Lymphoma Subtypes.

Lymphomas may often present with more than one pathologic type in the same individual. This study assesses the variability of FDG uptake values as determined by SUV’s in various lymphoma subtypes to serve as a platform for differentiating and confirming the pathologic diagnosis in all disease sites.

Methods: We retrospectively evaluated the PET-CT studies of 184 lymphoma patients at initial staging or at relapse prior to therapy. Lymphoma subtypes were classified according to the WHO classification. SUV’s were obtained in a total of 1120 nodal or extranodal disease sites in 11 lymphoma subtypes. Mean SUV’s were calculated for each lymphoma subtype by dividing the total maximum SUV’s by the number of disease sites in all patients. Consequently, mean SUV +/− SD and SUV range were determined and correlated with histologic diagnosis as shown in the Table.

Results: Results are summarized in Table 1. The highest mean SUV’s were obtained in aggressive non-Hodgkin’s lymphomas (NHL) followed by Hodgkin’s disease (HD) and indolent NHL. Starting from the subtype with the highest mean SUV of the means and in a rank of decreasing order, the subtypes of lymphoma are as follows; Burkitts, DLCL, T cell rich B cell, natural killer T cell, HD, Anaplastic T-cell, mantle cell, marginal zone, follicular, T cell peripheral and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL).

Conclusions: While SUV’s may be quite variable, a general pattern does exist for each lymphoma subtype. A major discrepancy between the SUV’s and histologic diagnosis should be assessed by repeat biopsy.