Functional imaging of head and neck squamous cell carcinoma with diffusion-weighted MRI and FDG PET/CT: quantitative analysis of ADC and SUV

Purpose Head and neck squamous cell carcinoma (HNSCC) 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 of ADC and SUV measurements in HNSCC and evaluated whether these biomarkers are correlated or independent. Methods This retrospective analysis of DW MRI and FDG PET/CT data series included 34 HNSCC in 33 consecutive patients. Two experienced readers measured tumour ADC and SUV values independently. Statistical comparison and correlation with histopathology was done. Intra- and inter-observer agreement for ADC and SUV measurements was assessed. Results Intraclass correlation coefficient (ICC) analysis showed almost perfect reproducibility (>0.90) for ADC(mean), ADC(min), SUVmax and SUVmean values for intra-observer and inter-observer agreement. Mean ADC(mean) and ADC(min) in HNSCC were 1.05 +/- 0.34 x 10(-3) mm(2)/s and 0.65 +/- 0.29 x 10(-3) mm(2)/s, respectively. Mean SUVmean and mean SUVmax were 7.61 +/- 3.87 and 12.8 +/- 5.0, respectively. Although statistically not significant, a trend towards higher SUV and lower ADC was observed with increasing tumour dedifferentiation. Pearson's correlation analysis showed no significant correlation between ADC and SUV measurements (r -0.103, -0.051; p 0.552, 0.777). Conclusion Our data suggest that ADC and SUV values are reproducible and independent biomarkers in HNSCC.