Value of PET/MRI for assessing tumor resectability in NSCLC-intra-individual comparison with PET/CT.

Objective: The purpose of this study was to compare the diagnostic accuracy of positron emission tomography (PET)/MRI with PET/CT for determining tumor resectability of non-small cell lung cancer (NSCLC).

Methods: Sequential trimodality PET/CT/MRI was performed in 36 patients referred with the clinical question of resectability assessment in NSCLC. PET/CT and PET/MR images including weighted sequence (-Dixon) and respiration gated weighted sequence (-Propeller) were evaluated for resectability-defining factors; longest diameter of the tumor, minimal tumor distance to the carina, mediastinal invasion, invasion of the carina, pleural infiltration, pericardial infiltration, diaphragm infiltration, presence of additional nodules.

Results: There was no significant difference of maximal axial diameter measurements of the primary lung tumors and narrow limits of agreement in Bland-Altman analysis ranging from -11.1  mm to + 11.8  mm for -Propeller and from -14.3  mm to + 13.8  mm for -Dixon sequence. A high agreement of PET/MR with PET/CT for the different resectability-defining factors was observed ( from 0.769 to 1.000). There was an excellent agreement of -Propeller sequence and CT for additional pulmonary nodule detection ( of 0.829 and 0.833), but only a moderate and good agreement using -Dixon sequence ( of 0.484 and 0.722).

Conclusion: In NSCLC the use of PET/MRI, including a dedicated pulmonary MR imaging protocol, provides a comparable diagnostic value for determination of tumor resectability compared to PET/CT.

Advances In Knowledge: Our findings suggest that whole body PET/MRI can safely be used for the local staging of NSCLC patients. Further studies are warranted to determine whether it is feasible to integrate an imaging sequence in a whole body PET/MRI setting with the potential advantage of detection of liver or brain metastases.