Early responses assessment of neoadjuvant chemotherapy in nasopharyngeal carcinoma by serial dynamic contrast-enhanced MR imaging.

PURPOSE

To evaluate the feasibility of utilizing serial dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) prospectively for early prediction of neoadjuvant chemotherapy (NAC) response in nasopharyngeal carcinoma (NPC) patients.

MATERIALS AND METHODS

Sixty-three advanced NPC patients were recruited and received three DCE-MRI exams before treatment (Pre-Tx), 3days (Day3-Tx) and 20days (Day20-Tx) after initiation of chemotherapy (one NAC cycle). Early response to NAC was determined based on the third MRI scan and classified partial response (PR) as responders and stable disease (SD) as non-responders. After intensity-modulated radiotherapy (IMRT), complete response (CR) patients were classified as responders. The kinetic parameters (K, K, v, and v) derived from extended Tofts' model analysis and their corresponding changes ΔMetrics (X=3 or 20days) were compared between the responders and non-responders using the Student's T-test or Mann-Whitney U test.

RESULTS

Compared to the SD group, the PR group after one NAC cycle presented significantly higher mean K values at baseline (P=0.011) and larger ΔK and ΔK values (P=0.003 and 0.031). For the above parameters, we gained acceptable sensitivity (range: 66.8-75.0%) and specificity (range: 60.0-66.7%) to distinguish the non-responders from the responders and their corresponding diagnosis efficacy (range: 0.703-0.767). The PR group patients after one NAC cycle showed persistent inhibition of tumor perfusion by NAC as explored by DCE-MRI parameters comparing to the SD group (P<0.05) and presented a higher cure ratio after IMRT than those who did not (83.3% vs. 73.8%).

CONCLUSIONS

This primarily DCE-MRI based study showed that the early changes of the kinetic parameters during therapy were potential imaging markers to predicting response right after one NAC cycle for NPC patients.