"The exact aetiology is not known, but it is thought that infection may be a common causative association. Chronic rhinosinusitis is present in ~25% of patients 7, but a causal relationship has not been firmly established."
"T1: intermediate to low signal"
"T1 C+ (Gd): peripheral enhancement is seen on post-contrast images"
"Similar, less common polyps can arise in the sphenoid sinus and extend into the nasopharynx; these are termed sphenochoanal polyps. Likewise, there are nasochoanal, frontochoanal, and ethmochoanal polyps 9."