Texture in the monitoring of regorafenib therapy in patients with colorectal liver metastases

Background The morphological changes seen during treatment with regorafenib represent challenges when evaluating treatment response using RECIST. Computed tomography texture analysis (CTTA) has potential as a non-invasive functional imaging biomarker during treatment with anti-angiogenetic therapies. Purpose To explore changes in three-dimensional tumor CTTA in colorectal liver metastases (CRLM) in a cohort of patients with metastatic colorectal cancer during treatment with regorafenib. Material and Methods Twenty-seven patients with CRLM were treated with regorafenib and evaluated using CTTA. Texture analysis was applied in the standard contrast-enhanced CT performed in the portal-venous phase (PVP-CT) and in two selected scan series derived from a dynamic contrast-enhanced CT (DCE-CT). A total of 269 scan series were analyzed. Results In the unfiltered dataset of the PVP-CT, all texture parameters, except for kurtosis, changed significantly during treatment. In the filtered PVP-CT dataset, the CTTA parameters entropy, uniformity, and standard deviation were markedly associated with overall survival (OS) at spatial scaling factors (SSF) of 1.0- 2.0, but did not change significantly during treatment. Skewness increased significantly during treatment and was evaluated at SSF >= 1.0. In general, the same trends in texture parameter changes were seen when analyzing DCE-CT datasets. However, these changes did not reach the same level of significance. Conclusions In this exploratory study, we demonstrated substantial changes in the texture parameters during treatment with regorafenib, most evident in the unfiltered dataset of the PVP-CT. Some texture parameters showed prognostic association with OS. Texture may potentially help evaluate the treatment response in patients treated with regorafenib.