Here's some MRI images of prurient interest from an earlier study with the objective "To find out whether taking images of the male and female genitals during coitus is feasible and to find out whether former and current ideas about the anatomy during sexual intercourse and during female sexual arousal are based on assumptions or on facts."

http://bmj.com/cgi/content/full/319/7225/1596

pics:

http://bmj.com/cgi/content/full/319/7225/1596/F3

Can't say they do much for me...

The full text of the "Magnetic resonance imaging (MRI) of sexual intercourse: second experience in missionary position and initial experience in posterior position." is on sale from the Journal of Sex and Marital Therapy for the low, low price of $22. Less well heeled individuals wil have to content themselves with the abstract

From the first MRI image link: "Eight women had a complete sexual response during sexual stimulation (experiments 4-11) and these women described their orgasm as 'superficial.' "

A project like this won an Ig Nobel in 2001:
http://www.abc.net.au/rn/science/ss/stories/s250347.htm