Less invasive imaging methods such as x-rays or ultrasounds do not work because the vocal cords are surrounded by cartilage which distort image quality.
The erbium oxide nanoparticles that have been successfully made by employing ultrasound are erbium carboxioxide, hexagonal and spherical geometry erbium oxide.
If the results of the ultrasound and intracranial imaging are normal, renewed diagnostic efforts may be made, during which fluorescein angiography is an appropriate consideration.