DIFFUSION-WEIGHTED MAGNETIC RESONANCE IMAGING EARLY AFTER CHEMORADIOTHERAPY TO MONITOR TREATMENT RESPONSE IN HEAD-AND-NECK SQUAMOUS CELL CARCINOMA

Purpose: To evaluate diffusion-weighted imaging (DWI) for assessment of treatment response in head and neck squamous cell carcinoma (HNSCC) three weeks after the end of chemoradiotherapy (CRT). Methods and Materials: Twenty-nine patients with HNSCC underwent magnetic resonance imaging (MRI) prior to and 3 weeks after CRT, including T-2-weighted and pre- and postcontrast T-1-weighted sequences and an echoplanar DWI sequence with six b values (0 to 1,000 s/mm(2)), from which the apparent diffusion coefficient (ADC) was calculated. ADC changes 3 weeks posttreatment compared to baseline (Delta ADC) between responding and nonresponding primary lesions and adenopathies were correlated with 2 years locoregional control and compared with a Mann-Whitney test. In a blinded manner, the Delta ADC was compared to conventional MRI 3 weeks post-CRT and the routinely implemented CT, on average 3 months post-CRT, which used size-related and morphological criteria. Positive and negative predictive values (PPV and NPV, respectively) were compared between the Delta ADC and anatomical imaging. Results: The Delta ADC of lesions with later tumor recurrence was significantly lower than lesions with complete remission for both primary lesions (-2.3% +/- 0.3% vs. 80% +/- 41%; p < 0.0001) and adenopathies (19.9% +/- 32% vs. 63% +/- 36%; p = 0.003). The Delta ADC showed a PPV of 89% and an NPV of 100% for primary lesions and a PPV of 70% and an NPV of 96% for adenopathies per neck side. DWI improved PPV and NPV compared to anatomical imaging. Conclusion: DWI with the Delta ADC 3 weeks after concluding CRT for HNSCC allows for early assessment of treatment response. (C) 2012 Elsevier Inc.