Intravoxel incoherent motion MRI for predicting early response to induction chemotherapy and chemoradiotherapy in patients with nasopharyngeal carcinoma

BackgroundTo investigate the value of intravoxel incoherent motion (IVIM) diffusion‐weighted magnetic resonance imaging (DW‐MRI) in predicting the early response to induction chemotherapy (IC) and chemoradiotherapy (CRT) in nasopharyngeal carcinoma (NPC).MethodsFifty NPC patients who received IC and CRT underwent an IVIM DW‐MRI on a 1.5‐Tesla MRI scanner. The pretreatment and posttreatment (20 days after IC initiation) IVIM‐based parameters (ADC, D, D*, and f), and their percentage changes (△%), were compared between the effective (complete response or partial response) and ineffective (stable disease) groups based on RECIST 1.1, and between the residual and nonresidual groups.ResultsNone of the perfusion‐related parameter' values showed significant differences between the effective and ineffective groups (p values for pref, postf, △%f, preD*, postD*, and △%D* were 0.364, 0.129, 0.792, 0.804, 0.167, and 0.428, respectively), or between the residual and nonresidual groups (P values for pref, postf, △%f, preD*, postD*, and △%D* were 0.328, 0.776, 0.546, 0.558, 0.214, and 0.414, respectively). The ineffective group exhibited higher preADC, higher preD and lower △%D values than the effective group (all P <  0.001). The nonresidual group had lower preD, lower preADC and higher △%D values (all P <  0.05) than the residual group. △%D had the highest area under curve (0.859) in predicting the response to IC, whereas preD had the highest area under curve (0.841) in predicting tumor residue after CRT.ConclusionDiffusion‐related IVIM‐based parameters might be more helpful than perfusion‐related parameters in predicting the early effects of IC and CRT for NPC. J. Magn. Reson. Imaging 2016;43:1179–1190.