Hi Motley,
By anulo aortic ectasia they are referring to dilation or bulging at the base of the aorta as it connects to the heart.
I can't interpret the discrepancy between the echo and MRI without seeing the study, although calling the MRI a poor study suggests the pictures may not be as clear as they should. Typically either modality provides a pretty clear image of the aorta. MRIs provide 3-dimensional information that is sometimes helpful but the aorta is appropriately followed by either an MRI or an echo.
Honestly the more important thing here is a rate of change between studies. They just need to pick one and repeat it over time following for changes.
Good luck.
You may be interested in the following web site, which provides information about diagnostic testing used to measure the aorta.
http://www.bicuspidfoundation.com
Best Wishes!