Baseline values of DCE-CT of liver in patients with colorectal cancer

Purpose: Assessment of baseline values in CT perfusion (CTp) studies is as much difficult as it plays a crucial role for an accurate computation of perfusion parameters. Besides that, the unenhanced stage of CTp provides repeated measures of baseline. This study aims at computing and analysing the voxel-based baseline values of normal liver in a set of patients with colorectal cancer. Methods and Materials: 40 patients with colorectal cancer, free from any hepatic diseases, underwent axial CTp examinations of liver at colorectal cancer diagnosis. A large region of interest (ROI) was drawn on one central section of the liver, avoiding large vessels. Baseline portion (BP) of each time concentration curve (TCC) of the ROI was determined through the use of an adaptive 3D filtering and the relative baseline value (HU) was computed as the mean of the TCC values over BP. Mean, median, and standard deviation values were computed for each patient as well as for the entire cohort. Results: For each patient, mean and median baseline values coincide, this suggesting quite symmetric distributions. The average and standard deviation (std) of baseline mean values of all patients are 61.7HU (range 32÷79HU), and 10.1, with 73% of values within one std interval (51÷71HU). Moreover, baseline colorimetric maps showed a high spatial correlation. Conclusion: Baseline values of normal liver of patients with colorectal cancer are compliant with values of normal liver in healthy subjects reported in the literature. The spatial coherence of maps hints at a local similarity of tissue features.