18F-FDG PET/CT versus Diagnostic Contrast-Enhanced CT for Follow-Up of Stage IV Melanoma Patients Treated by Immune Checkpoint Inhibitors: Frequency and Management of Discordances over a 3-Year Period in a University Hospital

Jean-Baptiste Le Goubey; Charline Lasnon; Ines Nakouri; Laure Césaire; Michel de Pontville; Catherine Nganoa; Diane Kottler; Nicolas Aide

doi:10.3390/diagnostics11071198

¹⁸F-FDG PET/CT versus Diagnostic Contrast-Enhanced CT for Follow-Up of Stage IV Melanoma Patients Treated by Immune Checkpoint Inhibitors: Frequency and Management of Discordances over a 3-Year Period in a University Hospital

Diagnostics (Basel). 2021 Jul 1;11(7):1198. doi: 10.3390/diagnostics11071198.

Authors

Jean-Baptiste Le Goubey¹, Charline Lasnon^{2

3}, Ines Nakouri¹, Laure Césaire¹, Michel de Pontville¹, Catherine Nganoa⁴, Diane Kottler¹, Nicolas Aide^{3

4

5}

Affiliations

¹ Dermatology Department, University Hospital, 14000 Caen, France.
² Nuclear Medicine Department, François Baclesse Cancer Centre, 14000 Caen, France.
³ INSERM ANTICIPE U 1086, Normandy University, 14000 Caen, France.
⁴ Nuclear Medicine Department, University Hospital, 14000 Caen, France.
⁵ Normandie University, 14000 Caen, France.

Abstract

Aim: To perform a comprehensive analysis of discordances between contrast-enhanced CT (ceCT) and ¹⁸F-FDG PET/CT in the evaluation of the extra-cerebral treatment monitoring in patients with stage IV melanoma.

Materials and methods: We conducted a retrospective monocentric observational study over a 3-year period in patients referred for ¹⁸F-FDG PET/CT and ceCT in the framework of therapy monitoring of immune checkpoint (ICIs) as of January 2017. Imaging reports were analyzed by two physicians in consensus. The anatomical site responsible for discordances, as well as induced changes in treatment were noted.

Results: Eighty patients were included and 195 pairs of scans analyzed. Overall, discordances occurred in 65 cases (33%). Eighty percent of the discordances (52/65) were due to ¹⁸F-FDG PET/CT scans upstaging the patient. Amongst these discordances, 17/52 (33%) led to change in patient's management, the most frequent being radiotherapy of a progressing site. ceCT represented 13/65 (20%) of discordances and induced changes in patients' management in 2/13 cases (15%). The most frequent anatomical site involved was subcutaneous for ¹⁸F-FDG PET/CT findings and lung or liver for ceCT.

Conclusions: Treatment monitoring with ¹⁸F-FDG PET/CT is more efficient than ceCT and has a greater impact in patient's management.

Keywords: 18F-FDG PET/CT; Immune checkpoint inhibitors; contrast-enhanced CT; follow-up; melanoma; metastases; therapy monitoring; tyrosine kinase inhibitors.