Utility of intravoxel incoherent motion diffusion-weighted imaging in predicting early response to concurrent chemoradiotherapy in oesophageal squamous cell carcinoma

Aim: To investigate the utility of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in predicting the early response to concurrent chemoradiotherapy (CRT) in oesophageal squamous cell carcinoma (OSCC).

Materials and methods: Thirty-three patients with OSCC who received CRT underwent IVIM-DWI at three time points (before CRT, at the end of radiotherapy 20 Gy, and immediately after CRT). After CRT, the patients were divided into the responders (complete response or partial response) and the non-responders (stable disease) based on RECIST 1.1. The IVIM-DWI parameters (apparent diffusion coefficient [ADC], true diffusion coefficient [D], the pseudo-diffusion coefficient [D*], and the perfusion fraction [f]) values and their percentage changes (Δvalue) at different time points were compared between the responders and the non-responders. Receiver-operating characteristic (ROC) curve analysis was used to determine the efficacy of IVIM-DWI parameters in identifying the response to CRT.

Results: The tumour regression ratio showed negative correlations with ADC_pre (r=-0.610, p=0.000), ADC_{20 Gy} (r=-0.518, p=0.002), D_pre (r=-0.584, p=0.000), and D_{20 Gy} (r=-0.454, p=0.008), and positive correlation with ΔD_{20 Gy} (r=0.361, p=0.039) and ΔD_post (r=0.626, p=0.000). Compared to the non-responders, the responders exhibited lower ADC_pre, D_pre, ADC_{20 Gy}, and D_{20 Gy}, as well as higher ΔADC_{20 Gy}, ΔD_{20 Gy}, and ΔD_post (all p<0.05). D_pre had the highest sensitivity (92.9%) and value of area under the ROC curve (0.865) in differentiating the responders from the non-responders.

Conclusion: Diffusion-related IVIM-DWI parameters (ADC and D) are potentially helpful in predicting the early treatment effect of CRT in OSCC.