Differentiation of recurrent tumor and posttreatment changes in head and neck squamous cell carcinoma: application of high b-value diffusion-weighted imaging.

Abstract

BACKGROUNDANDPURPOSE: High b-valueDWIhas been expected to have an additional diagnostic role and demonstrated some promising results in head and neck cancer. The aim of this study was to evaluate the diagnostic performance of DWI at a high b-value (b2000 s/mm2) compared with a standard b-value (b1000 s/mm2) and the ratio of ADC values of high and standard b-values for their ability to differentiate between recurrent tumor and posttreatment changes after the treatment of head and neck squamous cell carcinoma. MATERIALS AND METHODS: A total of 33 patients diagnosed with head and neck squamous cell carcinoma were enrolled in the present study; all had contrast-enhancing lesions on follow-up MR imaging. All patients underwent single-shot echo-planar DWI at b1000 s/mm2 and b2000 s/mm2, and corresponding ADC maps were generated (ADC1000 and ADC2000, respectively). The mean ADC1000, ADC2000, and ADCratio (ADCratio ADC2000/ADC1000 100) values were evaluated within a manually placed ROI with contrast-enhanced T1-weighted images as references. For the statistical analysis, we performed a Student t test and multivariate logistic regression. RESULTS: The mean ADC1000 in recurrent tumor was significantly lower than that in posttreatment changes (P.001), whereas the mean ADC2000 resulted in no significant difference (P .365). The mean ADCratio was significantly higher in recurrent tumor than that in posttreatment changes (73.5 7.2% vs 56.9 8.8%, respectively; P .001). Multivariate logistic regression analysis revealed that the ADCratio was the only independently differentiating variable (P .024). The sensitivity, specificity, and accuracy of ADCratio were 95.0%, 69.2%, and 84.8%, respectively, by use of the optimal cutoff value of 62.6%. CONCLUSIONS: We suggest that the ADCratio calculated from the ADC1000 and ADC2000 is a promising value for the differentiation of recurrent tumor and posttreatment changes in head and neck squamous cell carcinoma. ABBREVIATIONS: ADC1000ADC value calculated at b0 and 1000 s/mm2; ADC2000ADC value calculated at b0 and 2000 s/mm2; ADCratioratio of ADC2000 over ADC1000; HNSCC head and neck squamous cell carcinoma