Ascending aorta size:01/17echo 3.8cm;05/17 CT (calcium scoring 0)4.0cm;11/17 MRI/MRA 3.3 x3.5 cm. Which of the above 3 measurements is most accurate?

Mri/mra. would go by mri/mra finding. if there was no significant aortic insuficiency or aortic valvular heart disease on the echo. would just repeat the echo in 1-2 years to see if ascending aorta increases in size.