Fig. 3

Contrast axial T1-weighted MRI obtained in pre-treatment (A, C) and late-course of IMRT after IC (B, D). ROIs were delineated to indicate the Vpre (A, C, red) and LCV (B, D, red). Case 1: a 43-years of male with T3N2M0 NPC, showing a VRR < 75.1%, from Vpre = 30.2 cm³ (A) to LCV = 22.4 cm³ (B), suffered from local recurrence at the 28th month of follow-up. Case 2: a 40-years of male with T4N2M0 NPC, showing a VRR > 75.1%, from Vpre = 21.2 cm³ (C) to LCV = 1.7 cm³ (D), without local recurrence till the final follow-up (at the 81th month). IMRT intensity-modulated radiotherapy, IC induction chemotherapy, ROI tumor regions of interest, NPC nasopharyngeal carcinoma, Vpre tumor volume before treatment, LCV late-course volume, VRR volume regression rate