ring around thyroid on ct?

i am having severe problem with my neck,larger on the left, tightness hard to swallow drink breathe, and now i have developed some thyroid type symptoms - flushing with racing heart beat that just hits me all of a sudden weakness etc. the ct scan is supposedly normal but i got a copy and on two images only there is a bright white ring type thing that goes only halfway around my thyroid in the back of it, is that normal? i saw some images online where it is present with thyroid cancer goiters etc, and could not find it on a normal neck ct image...also thyroid blood levels are normal when tested twice this year...