Magnetic Resonance with Diffusion and Dynamic Perfusion-Weighted Imaging in the Assessment of Early Chemoradiotherapy Response of Naso-Oropharyngeal Carcinoma

The purpose of this study was to differentiate post-chemoradiotherapy (CRT) changes from tumor persistence/recurrence in early follow-up of naso-oropharyngeal carcinoma on magnetic resonance (MRI) with diffusion (DWI) and dynamic contrast-enhanced perfusion-weighted imaging (DCE-PWI). A total of 37 patients were assessed with MRI both for tumor staging and 4-month follow-up from ending CRT. Mean apparent diffusion coefficient (ADC) values, area under the curve (AUC), and K(trans) values were calculated from DWI and DCE-PWI images, respectively. DWI and DCE-PWI values of primary tumor (ADC, AUC, K(trans)pre), post-CRT changes (ADC, AUC, K(trans)post), and trapezius muscle as a normative reference before and after CRT (ADC, AUC, K(trans)muscle pre and muscle post; AUCpost/muscle post:AUCpre/muscle pre (AUCpost/pre/muscle); K(trans)post/muscle post:K(trans)pre/muscle pre (K(trans)post/pre/muscle) were assessed. In detecting post-CRT changes, ADCpost > 1.33 × 10−3 mm2/s and an increase >0.72 × 10−3 mm2/s and/or >65.5% between ADCpost and ADCpre values (ADCpost-pre; ADCpost-pre%) had 100% specificity, whereas hypointense signal intensity on DWIb800 images showed specificity 80%. Although mean AUCpost/pre/muscle and K(trans)post/pre/muscle were similar both in post-CRT changes (1.10 ± 0.58; 1.08 ± 0.91) and tumor persistence/recurrence (1.09 ± 0.11; 1.03 ± 0.12), K(trans)post/pre/muscle values < 0.85 and >1.20 suggested post-CRT fibrosis and inflammatory edema, respectively. In early follow-up of naso-oropharyngeal carcinoma, our sample showed that ADCpost > 1.33 × 10−3 mm2/s, ADCpost-pre% > 65.5%, and ADCpost-pre > 0.72 × 10−3 mm2/s identified post-CRT changes with 100% specificity. K(trans)post/pre/muscle values less than 0.85 suggested post-CRT fibrosis, whereas K(trans)post/pre/muscle values more than 1.20 indicated inflammatory edema.