PET/CT and diffusion weighted MRI correlation after radiotherapy of head and neck tumors

Purpose: Head and neck carcinoma may cause a decreased apparent diffusion coefficient (ADC) on diffusion-weighted magnetic resonance imaging (DW MRI) and an increased standardized uptake value (SUV) on fluorodeoxyglucose (FDG) positron emission tomography (PET/CT). We analysed the reproducibility and treatment-related changes of ADC and SUV measurements in head and neck carcinoma and evaluated whether these biomarkers are correlated or independent. Materials and Method: This retrospective analysis of DW MRI and FDG PET/CT data series included 36 head and neck carcinoma. Kruskal-Wallis one-way ANOVA and Mann-Whitney U method was used to detect any statistical correlation and prognostic significance of ADC and SUV values in responders and nonresponders to radiotherapy. Results: Mean ADCmin, ADCmean and ADCmin/mean in head and neck carcinoma were 0,68 ± 0.17 × 10−3 mm2/s; 0,82 ± 0.17 x 10−3 mm2/s and 0,83 ± 0.10 mm² /s, respectively. Mean SUVmean and SUVlbm were 14.65 ± 5.5 and 10.96 ± 5.1, respectively. Spearman's correlation analysis showed no significant correlation between ADC and SUV measurements. Although statistically not significant, a trend towards higher SUV and lower ADC was observed in head and neck tumors. Statistically not significant a trend towards higher SUV and higher ADC was observed in nonresponders to radiotherapy. Conclusion: Our data suggest that ADC and SUV values are reproducible and independent biomarkers in head and neck carcinomas.