Oesophageal squamous cell carcinoma. Histogram-derived ADC parameters are not predictive of tumour response to chemoradiotherapy

To evaluate correlations between tumour response to definitive chemoradiotherapy (CRT) in oesophageal squamous cell carcinoma (SCC) and histogram-derived apparent diffusion coefficient (ADC) parameters on diffusion-weighted MR images. Forty patients with clinical T3-4 oesophageal SCC underwent concurrent CRT. MR examination at 3 T was performed 1-3 days prior to CRT. Readout-segmented echo-planar diffusion imaging was used to acquire ADC maps. Pre- and post-treatment CT examinations were performed. Histogram parameters (mean, 10th, 25th, 50th, 75th, 90th percentiles, skewness and kurtosis) of the ADC values were compared with post-treatment disease status based on RECIST and the tumour regression ratio. None of the ADC parameters showed significant correlation with post-treatment status (range of Spearman's ρ values - 0.19 to 0.14, range of p values 0.22-0.47) or tumour regression ratio (range of Spearman's ρ values - 0.045 to 0.18, range of p values 0.26-0.96). Neither progression-free survival (PFS) (p = 0.17) nor overall survival (OS) (p = 0.15) was significantly different between the two groups corresponding to the lower (< median) and upper arms (≥ median) of the mean ADC values. Histogram-derived pretreatment ADC parameters were not predictive imaging biomarkers for tumour response to CRT in patients with oesophageal SCC. (orig.)