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

Abstract

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); AUC(post/muscle post):AUC(pre/muscle pre) (AUC(post/pre/muscle)); K(trans)(post/muscle post):K(trans)(pre/muscle pre) (K(trans)(post/pre/muscle)) were assessed. In detecting post-CRT changes, ADC(post) > 1.33 x 10(-3) mm(2)/s and an increase >0.72 x 10(-3) mm(2)/s and/or >65.5% between ADC(post) and ADC(pre) values (ADC(post-pre); ADC(post-pre%)) had 100% specificity, whereas hypointense signal intensity on DWIb800 images showed specificity 80%. Although mean AUC(post/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 ADC(post) > 1.33 x 10(-3) mm(2)/s, ADC(post-pre%) > 65.5%, and ADC(post-pre) > 0.72 x 10(-3) mm(2)/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.