Reply: Staging, Restaging, and Treatment Response Assessment in Lymphomas: What We Should Know
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* Roberto Delgado-Bolton
* Giuseppe Esposito
* Patrick M. Colletti
* Hossein Jadvar

**REPLY:** We appreciate the letter to the editor written by Kanoun et al. from France. They address 2 important issues related to 18F-FDG PET/CT in lymphoma, one is initial staging and the other is interim 18F-FDG PET/CT for early evaluation of response to therapy. Regarding the first point, our review was solely focused on the utility of 18F-FDG PET/CT in restaging and treatment response assessment (1). For initial staging, 18F-FDG PET/CT has demonstrated high efficacy in many cancers including lymphoma (2). However, this will be a topic for another appropriate use criteria document. Kanoun et al. summarize some of the diagnostic value that 18F-FDG PET/CT can offer in initial staging of lymphomas.

With regards to the role of 18F-FDG PET/CT in the interim evaluation of response to therapy before completion of therapy, we did not include it in our analysis, as there is still no consensus based on the relatively limited available evidence (3–7), even if some groups have incorporated interim 18F-FDG PET/CT in their clinical practice. However, we do agree that there is increasing literature on this specific topic (8–15). We feel that at this point the use of interim 18F-FDG PET/CT for the early assessment of response to therapy in lymphoma should probably remain limited to clinical trials and not as routine clinical procedure; the only exception could be for those expert groups with experience in this setting within controlled environments (e.g., standardized protocols, homogeneous population, and double-blind reading) (16).

## Footnotes

*   Published online Feb. 1, 2018.

*   © 2018 by the Society of Nuclear Medicine and Molecular Imaging.

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