Assessment of therapy response in patients with oropharyngeal carcinoma after primary radiochemotherapy using F-18 fluorodeoxyglucose positron emission tomography/Magnetic resonance imaging (F-18-FDG-PET/MRI)

Introduction Assessment of treatment response after primary radio-(chemo)-therapy (R(C)T) in patients with squamous cell carcinoma of the head and neck is of significant prognostic importance. This evaluation is currently performed using conventional cross-sectional imaging and histologic re-assessment after control biopsy. Innovative PET/MRI appears promising for the detection of residual vital tumor tissue.

Methods 6 patients with locally advanced oropharyngeal carcinoma (at least cT3) treated by primary R(C)T received pre- and post-therapeutic staging by F-18-FDG-PET/MRI. The response to therapy was analyzed post-therapeutically by nuclear medicine and radiology using FDG uptake, apparent-diffusion-coefficent (ADC), and capillary permeability (Ktrans). For further evaluation, control pharyngoscopy and sampling was performed in the former primary tumor region.

Results In 5 of 6 patients, PET/MRI showed no evidence of residual vital primary tumor at 12.5 ± 5.5 weeks after completed R(C)T. Histologic correlation likewise revealed no evidence of residual tumor in these patients. In one patient, the PET/MR-graphic suspicion of the presence of a vital residual tumor was also confirmed by control pharyngoscopy.

Conclusion PET/MRI could be performed in all patients without complications and appears suitable for early assessment of therapy response. With expansion of the study population, the combination of multiparametric MRI with FDG-PET may offer advantages over current follow-up imaging.

Publication History

Article published online:
12 May 2023