Dilated thoracic aorta or aneurysm, and does the name matter?

So confused! About 10 years ago at age 67 my spiral CT for ex-smokers reported a 4cm TAA (no decimal point then or since) . Cardiologist at the time said just monitor annually using that CT scan technique. Nothing has reportedly changed but a couple of years ago the radiologist stopped noting it. I thought that was odd and cardiologist said the aneurysm size criteria changed and it had to be 4.5 to be reported as TAA. I did find out that the aorta has no bulge to it, just uniform dilation over an undisclosed distance and location. BTW need to find new cardiologist since I moved.