“A mild degree of” = mild;

“is noted” should be omitted;

“within” = in;

“arch of the aorta” = aortic arch;

rewritten version: “Mildly calcified aortic arch.”

Since arch calcification is an Aunt Minnie would could skip the description jump right to the diagnosis, which is atherosclerosis. “Mild aortic atherosclerosis.”