Prospective Comparative Study Of Diffusion-Weighted Mri Versus Fdg-Pet For Detection Of Recurrence After (Chemo) Radiation For Head And Neck Squamous Cell Carcinoma

High-dose (chemo)radiation for head and neck squamous cell carcinoma (HNSCC) may result in late edema and necrosis, resembling recurrent disease. FDG-positron emission tomography/computed tomography (PET/CT) has a high negative predictive value for recurrent disease; however, it is limited by the positive predictive value. The diagnostic accuracy of conventional magnetic resonance imaging (MRI) with diffusion-weighted (DW) MRI to detect a local recurrence has been compared with the standard FDG-PET/CT. Seventy-four patients clinically suspected of local recurrence after (chemo)radiation for laryngeal, hypopharyngeal, or oropharyngeal cancers were prospectively included in this study and underwent an MRI including diffusion-weighted imaging (DW-MRI) and an FDG-PET/CT. Qualitative assessment of DW-MRI and FDG-PET/CT was performed by an experienced radiologist resp. nuclear physician blinded for the other modality. Reference standard was the absence of a biopsy-proven local recurrence within 6 months following imaging. Four patients were excluded due to contraindications or disruption of the MRI (eg, claustrophobia or patient stature). Seventy-three percent (51 of 70) of the FDG-PET/CTs were positive compared to only 46% (32 of 70) of the DW-MRI. FDG-PET/CT had a diagnostic accuracy of 72% compared to 73% for MR-DWI. The negative predictive value of FDG-PET/CT was 94% compared to 71% for MR-DWI. The positive predictive value of FDG-PET/CT was 64% compared to 75% for DW-MRI. See Table 1 for the complete results. In this study, DW-MRI showed superior positive predictive value but inferior negative predictive value compared to FDG-PET/CT. False negative results will cause delay in the detection of recurrence and therefore will potentially influence the chance of successful salvage surgery. Therefore, based on these results, we consider FDG-PET/CT to be superior to MR-DWI in the follow-up of HNSCC after (chemo)radiation therapy. Future improvements in DWI techniques which will decrease artefacts and enhance contrast, may enable DWI to resemble FDG-PET/CT negative predictive value without compromising the higher positive predictive value of DWI.Abstract 225; Table 1ImagingRecurrencecontrolDW-MRI positive24832DW-MRI negative12738353570FDG-PET/CT positive341953FDG-PET/CT negative11617353570 Open table in a new tab