Or, if you don't want to edit the image:
1. Select the image
2. Select "Object" > "Clipping path" > "Options"
3. Select "Type": Alpha Channel, and press OK. The new path is now selected.
4. Select "Object" > "Clipping path" > "Convert clipping path to frame". The original image gets selected (oddly enough), so
5. Select the path with the black arrow again.
6. Select "Object" > "Convert shape" > "Ellipse"
and you end up with a rather good elliptical fit.
North America
Europe, Middle East and Africa
Asia Pacific