The CT scan may detect how thick the questionable area of your bladder is, which can reveal many things. Also, they may be testing your kidneys during the CT scan. I have had kidney stones in the past which can produce blood in the urine AND, if not discharged from the bladder quickly enough, irritate the inside of the bladder. Crystallization (pre-stone) can causes similar problems without the pain of stones.
I can only comment on my personal experience. For me I was having discomfort and urgency during urination for several months. I took various medications which did not relive my symptoms. Finally my urologist did what I called a bladder scope. He injected water my bladder and looked inside the bladder. He did not see any evidence of cancer, but he sent what was washed out of my for testing. The results of the test showed high grade carcinoma. After that I did a CT scan to check for tumor or growth in my organs, none found. Next I had a surgical procedure called a TURBT. A TURBT checks bladder and kidneys to determine where the carcinoma cells are coming from among other areas. After this procedure I was referred to Stanford to determine the best form of treatment to follow. The treatment suggested was a BCG procedure which I started Friday. So I guess I am saying is there many steps to get to where I am right now. And the more professionals that look at the results the clearer the picture emerges. I hope so anyway.