## 5 Conclusions  
In early follow-up of naso-oropharyngeal carcinoma, ADC\({}_{\text{post}}\) values > 1.33 \(\times\) 10\({}^{-3}\) mm\({}^{2}\)/s, ADC\({}_{\text{post-pre}}\) > 65.5%, and ADC\({}_{\text{post-pre}}\) values > 0.72 \(\times\) 10\({}^{-3}\) mm\({}^{2}\)/s identified post-CRT changes with excellent specificity. Although mean AUC\({}_{\text{post/pre/muscle}}\) and K(trans)\({}_{\text{post/pre/muscle}}\) were similar in post-CRT changes (1.10 \(\pm\) 0.58; 1.08 \(\pm\) 0.91) and tumor persistence/recurrence (1.09 \(\pm\) 0.11; 1.03 \(\pm\) 0.12), in our sample K(trans)\({}_{\text{post/pre/muscle}}\) values less than 0.85 suggested post-CRT fibrosis, whereas K(trans)\({}_{\text{post/pre/muscle}}\) values more than 1.20 indicated inflammatory edema. Figure 5: Post-treatment magnetic resonance imaging (MRI) of a 47-year-old female patient with human-papillomavirus-negative carcinoma of the left palatine tonsil with ipsilateral lymph node metastasis (T4 aN1) and buccal space and mandibular invasion, recently treated (4 months before) with chemoradiotherapy (CRT). Early post-treatment MRI showed tumor progression with wide extension to the extrinsic muscles of the contralateral tongue (maximum tumor thickness 45 mm). Post-CRT tumor residual/relapse disease (white striped arrows) showed moderately high (intermediate) T2-weighted signal intensity (**A,B**), high signal on diffusion-weighted b800 imaging (**C**), low apparent diffusion coefficient value (0.79 \(\times\) 10\({}^{-3}\) mm\({}^{2}\)/s, (**D**), and moderate enhancement after gadolinium contrast injection (**E**). K(trans) value of the tumor (56.24 \(\times\) 10\({}^{-3}\) min) decreased on dynamic contrast enhancement-perfusion weighted imaging (**F**), compared to pre-treatment MRI (117.63 \(\times\) 10\({}^{-3}\) min). However, the ratio between K(trans) values of the primitive tumor and residual tissue after CRT, standardized with respect to K(trans) value of the ipsilateral trapezius (K(trans)\({}_{\text{post/pre/muscle}}\)), was 1.14. These findings suggested little or no reduction in tumor neoangiogenesis after CRT. **Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app13052799/s1](https://www.mdpi.com/article/10.3390/app13052799/s1)]([https://www.mdpi.com/article/10.3390/app13052799/s1](https://www.mdpi.com/article/10.3390/app13052799/s1)), Materials and Methods. Table S1: Patients' data retrieved in the study. M: male; F: female; O: oropharynx; N: nasopharynx; P: positive; N: negative; U: unknown; RT: post-chemoradiotherapy changes; PR: tumor persistence/recurrence. *The eighth edition of the American Joint Commission on Cancer TNM staging; Table S2. Magnetic resonance acquisition protocol performed for the study of naso-oropharyngeal carcinoma staging and 4-month follow-up from ending chemoradiotherapyotherapy. Unehn enhanced scans included sagittal fat-saturated T1- and T2- weighted sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) sequences with axial, coronal, and sagittal multiplanar reconstructions; axial T2-weighted turbo spin echo; axial fat-saturated echo-planar DWI spectral attenuated inversion recovery (SPAIR) with two b-values (b50-800 s/mm\({}^{2}\)) and ADC maps; two axial T1-weighted volumetric interpolated breath-hold examination (VIBE) DCE-PWI with application of flip angles (FAs) 5\({}^{\circ}\) and 15\({}^{\circ}\), respectively. Enhanced scans performed after intravenous gadolinium chelates contrast agent injection (gadobutrol, 1 mL/10 kg, flow 3 mL/s, followed by 20 mL saline flush) consisted of an axial VIBE DCE-PWI with application of FA 30\({}^{\circ}\) and peripheral K space sampling with time to center 2.2 s, an axial T1-weighted turbo spin echo, and an axial VIBE Dixon. Results. Table S3. Pre-treatment patients' data.