The thickness and volume of the renal cortex measured by CT scans can show how well the kidneys are working. In a study of 36 patients with kidney problems, the thicker the cortex and the larger the volume, the better the kidney function. The researchers found that there were clear differences in cortex thickness and volume between patients with normal kidney function and those with mild or severe kidney problems. This suggests that CT scans can be a useful tool to help doctors assess how well the kidneys are functioning.