Diffusion-weighted EPI- and HASTE-MRI and 18F-FDG-PET-CT early during chemoradiotherapy in advanced head and neck cancer.

Main Problem: Diffusion-weighted MRI (DW-MRI) has potential to predict chemoradiotherapy (CRT) response in head and neck squamous cell carcinoma (HNSCC) and is generally performed using echo-planar imaging (EPI). However, EPI-DWI is susceptible to geometric distortions. Half-fourier acquisition single-shot turbo spin-echo (HASTE)-DWI may be an alternative. This prospective pilot study evaluates the potential predictive value of EPI- and HASTE-DWI and 18F-fluorodeoxyglucose PET-CT (18F-FDG-PET-CT) early during CRT for locoregional outcome in HNSCC.

Methods: Eight patients with advanced HNSCC (7 primary tumors and 25 nodal metastases) scheduled for CRT, underwent DW-MRI (using both EPI- and HASTE-DWI) and 18F-FDG-PET(-CT) pretreatment, early during treatment and three months after treatment. Median follow-up time was 38 months.

Results: No local recurrences were detected during follow-up. Median Apparent Diffusion Coefficient (ADC)EPI-values in primary tumors increased from 77×10(-5) mm(2)/s pretreatment, to 113×10(-5) mm(2)/s during treatment (P=0.02), whereas ADCHASTE did not increase (74 and 74 mm(2)/s, respectively). Two regional recurrences were diagnosed. During treatment, ADCEPI tended to be higher for patients with regional control [(117.3±12.1)×10(-5) mm(2)/s] than for patients with a recurrence [(98.0±4.2)×10(-5) mm(2)/s]. This difference was not seen with ADCHASTE. No correlations between ΔADCEPI and ΔSUV (Standardized Uptake Value) were found in the primary tumor or nodal metastases.

Conclusions: HASTE-DWI seems to be inadequate in early CRT response prediction, compared to EPI-DWI which has potential to predict locoregional outcome. EPI-DWI and 18F-FDG-PET-CT potentially provide independent information in the early response to treatment, since no correlations were found between ΔADCEPI and ΔSUV.