F-FDG-PET/MRI in preoperative staging of oesophageal and gastroesophageal junctional cancer.

Aim: To evaluate integrated 2-[F]-fluoro-2-deoxy-d-glucose (F-FDG) positron-emission tomography (PET)/magnetic resonance imaging (MRI), in comparison with the standard technique, integrated F-FDG-PET/computed tomography (CT), in preoperative staging of oesophageal or gastroesophageal junctional cancer.

Materials And Methods: In the preoperative staging of 16 patients with oesophageal or gastroesophageal junctional cancer, F-FDG-PET/MRI was performed immediately following the clinically indicated F-FDG-PET/CT. MRI-sequences included T1-weighted fat-water separation (Dixon's technique), T2-weighted, diffusion-weighted imaging (DWI), and gadolinium contrast-enhanced T1-weighted three-dimensional (3D) imaging. PET was performed with F-FDG. Two separate teams of radiologists conducted structured blinded readings of F-FDG-PET/MRI or F-FDG-PET/CT, which were then compared regarding tumour measurements and characteristics as well as assessment of inter-rater agreement (Cohen's kappa) for the clinical tumour, nodal and metastatic (TNM) stage.

Results: There were no medical complications. Comparison of tumour measurements revealed high correlations without significant differences between modalities. The maximum standardised uptake value (SUV) values of the primary tumour with F-FDG-PET/MRI had excellent correlation to those of F-FDG-PET/CT (0.912, Spearman's rho). Inter-rater agreement between the techniques regarding T-stage was only fair (Cohen's kappa, 0.333), arguably owing to relative over-classification of the T-stage using F-FDG-PET/CT. Agreements in the assessment of N- and M-stage were substantial (Cohen's kappa, 0.849 and 0.871 respectively).

Conclusion: Preoperative staging with F-FDG-PET/MRI is safe and promising with the potential to enhance tissue resolution in the area of interest. F-FDG-PET/MRI and F-FDG-PET/CT correlated well for most of the measured values and discrepancies were seen mainly in the assessment of the T-stage. These results facilitate further studies investigating the role of F-FDG-PET/MRI in, e.g., predicting or determining the response to neoadjuvant therapy.