pulmonary embolism is best diagnosed by ?

Angiography : Angiography is a diagnostic test used by ophthalmologists to photograph structures in the back of the eye and is especially useful in finding damage to the blood vessels, which nourish the retina. There are two types of angiography: fluorescein and indocyanine green (ICG). Fluorescein angiography is used primarily to study blood circulation in and just beneath the surface of the retina, while ICG angiography is better for photographing the deeper choroidal vessels ref : david sutton 9th ed