My both kidneys are normal in size pelvicalyceal system and ureters not dilated ..but it says that my - corticomedullary differentiation preserved ... what does it mean ?

Translation= normal

That your kidney tissue is anatomically normal

This is the description of a normal kidney. In many reports normal findings are stated to convey that the person reading the image paid attention to all elements of the tissue/organ. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV vaccine.