ADC for Differentiation between Posttreatment Changes and Recurrence in Head and Neck Cancer: A Systematic Review and Meta-analysis

BACKGROUND: Previous studies reported that the ADC values of recurrent head and neck cancer lesions are lower than those of posttreatment changes, however, the utility of ADC to differentiate them has not been definitively summarized and established. PURPOSE: Our aim was to evaluate the diagnostic benefit of ADC calculated from diffusion-weighted imaging in differentiating recurrent lesions from posttreatment changes in head and neck cancer. DATA SOURCES: MEDLINE, Scopus, and EMBASE data bases were searched for studies. STUDY SELECTION: The review identified 6 prospective studies with a total of 365 patients (402 lesions) who were eligible for the meta-analysis. DATA ANALYSIS: Forest plots were used to assess the mean difference in ADC values. Heterogeneity among the studies was evaluated using the Cochrane Q test and the I-2 statistic. DATA SYNTHESIS: Among included studies, the overall mean of ADC values of recurrent lesions was 1.03 ? 10(?3)mm(2)/s and that of the posttreatment changes was 1.51 ? 10(?3)mm(2)/s. The ADC value of recurrence was significantly less than that of posttreatment changes in head and neck cancer (pooled mean difference: ?0.45; 95% CI, ?0.59?0.32, P?<?.0001) with heterogeneity among studies. The threshold of ADC values between recurrent lesions and posttreatment changes was suggested to be 1.10 ? 10(?3)mm(2)/s. LIMITATIONS: Given the heterogeneity of the data of the study, the conclusions should be interpreted with caution. CONCLUSIONS: The ADC values in recurrent head and neck cancers are lower than those of posttreatment changes, and the threshold of ADC values between them was suggested.