Hi, I don't think a comma is needed here.
I would say
"The study investigates the structure using.... "
not
"The study investigates the structure, using.... "
A logic can help me determine that it's not "structure uses" but "the study uses" here, otherwise, a comma may be used to avoid confusion, as LeonTheOutsider mentioned.
This study investigates the structure of the implied volatility smile, using prices of equity options traded at LIFFE.
Am I the only one who has a problem making any sense of the sentence?