Contrast enhanced (ce) CT in staging and end-of-treatment evaluation in lymphoma in the FDG PET/CT era: A need or a habit?

Objectives: To evaluate if PET/low dose CT (ldCT) could obviate the need of a ceCT in staging and residual disease assessment in patients (pts) affected by lymphoma. Methods: We prospectively enrolled 58 pts, 35 Hodgkin Lymphoma (HL) and 23 Non Hodgkin Lymphoma (NHL), (27 women and 31 men; mean age 45.5 ± 18.5 yrs) referred to PET/ldCT and PET/ceCT for staging and 81 pts, 59 HL and 22 NHL, (33 women and 48 men; mean age 42.8 ± 17.9 yrs) referred to examinations for re-staging after treatment. In staging the diagnostic performances of PET/ldCT and of PET/ceCT were compared. In re-staging the accuracy of both examinations in residual disease detection was compared to clinical response. Results: In staging, on a site based analysis, PET/ld-CT and PET/ce-CT were discordant in 9/2088 (0,4%): 7 PET/ldCT negative and PET/ceCT positive and 2 vice versa. PET/ceCT could change the clinical stage in one single pt due to the detection of positive spleen lesion (stage III) resulted negative at PET/ldCT negative (stage II). In re-staging after treatment, sensitivity, specificity, positive and negative predictive values in detecting residual disease were 100%, 94%, 75% and 100%, respectively for both studies. Conclusions: In lymphoma patients ceCT does not add significant value to PET/ldCT both in staging and, particularly, in re-staging after treatment. While ceCT could be avoided in re-staging phase, in staging, ce-CT could be suggested for the accurate detection of abdomininal involvement.