Assessment of tumor heterogeneity by CT texture analysis : Can the largest cross-sectional area be used as an alternative to whole tumor analysis?

To determine if there is a difference between contrast enhanced CT texture features from the largest cross-sectional area versus the whole tumor, and its effect on clinical outcome prediction. Methods: Entropy (E) and uniformity (U) were derived for different filter values (1.0–2.5: fine to coarse textures) for the largest primary tumor cross-sectional area and the whole tumor of the staging contrast enhanced CT in 55 patients with primary colorectal cancer. Parameters were compared using nonparametric Wilcoxon test. Kaplan–Meier analysis was performed to determine the relationship between CT texture and 5-year overall survival. Results: E was higher and U lower for the whole tumor indicating greater heterogeneity at all filter levels (1.0–2.5): median (range) for E and U for whole tumor versus largest cross-sectional area of 7.89 (7.43–8.31) versus 7.62 (6.94–8.08) and 0.005 (0.004–0.01) versus 0.006 (0.005–0.01) for filter 1.0; 7.88 (7.22–8.48) versus 7.54 (6.86–8.1) and 0.005 (0.003–0.01) versus 0.007 (0.004–0.01) for filter 1.5; 7.88 (7.17–8.54) versus 7.48 (5.84–8.25) and 0.005 (0.003–0.01) versus 0.007 (0.004–0.02) for filter 2.0; and 7.83 (7.03–8.57) versus 7.42 (5.19–8.26) and 0.005 (0.003–0.01) versus 0.006 (0.004–0.03) for filter 2.5 respectively (p ≤ 0.001). Kaplan–Meier analysis demonstrated better separation of E and U for whole tumor analysis for 5-year overall survival.