radiologic sign radiologic sign a radiologic sign is an objective indication of some medical fact (that is, a medical sign) that is detected by a physician during radiologic examination with medical imaging (for example, via an x-ray, ct scan, mri scan, or sonographic scan). the dark areas on both sides of the intestines indicate that air is present in both sides. this is called "rigler's sign". examples double decidual sac sign face of the giant panda sign football sign golden s sign hampton's hump hilum overlay sign kerley lines mickey mouse sign omental cake peribronchial cuffing pneumatosis intestinalis rigler's sign westermark sign