[quote=@onenote]
<Snipped quote by Konami>

O-O welp Eliza's getting studied and she didn't even know it. 

XD
[/quote]

In a way, yes. But really just about everyone in town has been a patient of Dr Pierce for one reason or another. It's not unbelievable that she might have access to Eliza's x-rays. In fact she ordered them herself to check on how Eliza's wings are doing. Being able to draw an Angel's skeletal structure is just a bonus.