CT texture analysis in colorectal liver metastases and the surrounding liver parenchyma and its potential as an imaging biomarker of disease aggressiveness, response and survival.

OBJECTIVES: To study the ratio between the CT texture of colorectal liver metastases (CRLM) and the surrounding liver parenchyma and assess the potential of various texture measures and ratios as predictive/prognostic imaging markers. MATERIALS: Seventy patients with colorectal cancer and synchronous CRLM were included. All visible metastases, as well as the whole-volume of the surrounding liver, were separately delineated on the portal venous phase primary staging CT. Texture features entropy (E) and uniformity (U) were extracted and ratios between the texture features (T) of the metastases and background liver (Tmetastases/Tliver) calculated. Texture features were compared with clinical outcome parameters: [1] extent of disease (i.e. number of metastases), [2] response to chemotherapy (in 56/70 patients who underwent chemotherapy and CT for response evaluation), and [3] overall survival. RESULTS: The Emetastases/Eliver ratio was lower in patients with limited disease (P = 0.02) and associated with overall survival, albeit not statistically significant when tested in multivariable analyses (HR 1.90; P = 0.07); Umetastases/Uliver was higher in patients with limited disease (P = 0.02). Emetastases showed a trend towards a higher value in patients that responded well to chemotherapy (P = 0.08). CONCLUSION: The ratio between the texture of liver metastases and the surrounding liver appears to reflect relevant changes in tissue microarchitecture and may be of value to assess the extent of disease and help predict overall survival.

Whole-volume vs. segmental CT texture analysis of the liver to assess metachronous colorectal liver metastases.

PURPOSE: It is unclear whether changes in liver texture in patients with colorectal cancer are caused by diffuse (e.g., perfusional) changes throughout the liver or rather based on focal changes (e.g., presence of occult metastases). The aim of this study is to compare a whole-liver approach to a segmental (Couinaud) approach for measuring the CT texture at the time of primary staging in patients who later develop metachronous metastases and evaluate whether assessing CT texture on a segmental level is of added benefit. METHODS: 46 Patients were included: 27 patients without metastases (follow-up >2 years) and 19 patients who developed metachronous metastases within 24 months after diagnosis. Volumes of interest covering the whole liver were drawn on primary staging portal-phase CT. In addition, each liver segment was delineated separately. Mean gray-level intensity, entropy (E), and uniformity (U) were derived with different filters (σ0.5-2.5). Patients/segments without metastases and patients/segments that later developed metachronous metastases were compared using independent samples t tests. RESULTS: Absolute differences in entropy and uniformity between the group without metastases and the group with metachronous metastases group were consistently smaller for the segmental approach compared to the whole-liver approach. No statistically significant differences were found in the texture measurements between both groups. CONCLUSIONS: In this small patient cohort, we could not demonstrate a clear predictive value to identify patients at risk of developing metachronous metastases within 2 years. Segmental CT texture analysis of the liver probably has no additional benefit over whole-liver texture analysis.