Pretreatment Dynamic Contrast-Enhanced MRI Improves Prediction of Early Distant Metastases in Patients with Nasopharyngeal Carcinoma

The identification of early distant metastases (DM) in patients with newly diagnosed, previously untreated nasopharyngeal carcinoma (NPC) plays an important role in selecting the most appropriate treatment approach. Here, we sought to investigate the predictive value of distinct MRI parameters for the detection of early DM. Between November 2010 and June 2011, a total of 51 newly diagnosed NPC patients were included. All of the study participants were followed until December 2014 at a single institution after completion of therapy. DM was defined as early when they were detected on pretreatment FDG-PET scans or within 6 months after initial diagnosis. The following parameters were tested for their ability to predict early DM: pretreatment FDG-PET standardized uptake value (SUV), MRI-derived AJCC tumor staging, tumor volume, and dynamic contrast-enhanced (DCE) values. The DCE-derived v e was defined as the volume fraction of the extravascular, extracellular space. Compared with patients without early DM, patients with early DM had higher SUV, tumor volume, DCE mean (median) v e, v e skewness, v e kurtosis, and the largest mean v e selected among sequential slices (P<0.05). No differences were identified when early DM were defined only according to the results of pretreatment FDG-PET. Among different quantitative DCE parameters, the mean v e had the highest area under curve (AUC, 0.765). However, the AUCs of SUV, tumor volume, mean v e, v e skewness, v e kurtosis, or the largest mean v e selected among the sequential slices did not differ significantly from one another (P=0.82). Taken together, our results suggest that DCE-derived v e may be a useful parameter in combination with SUV and tumor volume for predicting early DM. Dynamic contrast-enhanced MRI may be complementary to FDG-PET for selecting the most appropriate treatment approach in NPC patients.