Thoracic staging with F-FDG PET/MR in non-small cell lung cancer - does it change therapeutic decisions in comparison to F-FDG PET/CT?

Objective: To investigate whether differences in thoracic tumour staging between F-FDG PET/CT and PET/MR imaging lead to different therapeutic decisions in Non-Small Cell Lung Cancer (NSCLC).

Material And Methods: Seventy-seven NSCLC patients that underwent whole-body F-FDG PET/CT from the base of skull to the upper thighs and thoracic PET/MR were enrolled in this retrospective study. Thoracic PET/CT and PET/MR images were staged according to the 7th edition of the AJCC staging manual. Staging results of both modalities were discussed separately in a simulated interdisciplinary tumour board and therapeutic decisions based on both imaging modalities were recorded. Descriptive statistics were used to compare the results and reasons for changes in the therapeutic decision were investigated.

Results: Staging results differed in 35 % of patients (27 patients) between thoracic PET/CT and PET/MR. Differences were detected when assessing the T-stage in 18 % (n = 14), the N-stage in 23 % (n = 18), and the M-stage in 1 % (n = 1). However, patient therapy management was changed in only six patients (8 %).

Conclusion: Despite the variability of thoracic F-FDG PET/CT and PET/MR in TNM-staging, both modalities lead to comparable therapeutic decisions in patients suffering from NSCLC. Hence, F-FDG PET/MR can be considered an possible alternative to F-FDG PET/CT for clinical NSCLC staging.

Key Points: • PET/CT and PET/MR provide comparable results in early stages in NSCLC • Clinical impact of different staging results has not been investigated • PET/CT and PET/MR lead to comparable therapeutic decisions • PET/MR can be considered an alternative to PET/CT for NSCLC staging.