The comparison between true non-contrast (left column) and contrast-enhanced CT (right column) shows apparent CT number enhancement in soft-tissue, i.e. iodine uptake. The digits next to each circular region-of-interest (ROI) represent the measured mean CT numbers from the same ROI. Due to continuous bowel motion, we can only perform rigid alignment of relatively static major structure (e.g. ribs, spinal cord, and major abdominal muscle). However, those ROIs (range of diameter: ~24mm to ~30mm) were still placed in close proximity to the same tissues or organs. Display range: [-160, 240] HU.