Sharing can be difficult for twins...

This is an amazing video recently shared in the internet. The images were obtained with magnetic resonance imaging (MRI) in Imperial College London. The technique is not a conventional one, since images need to be acquired very fast. This video is a series of planar images put together. Why were the twins imaged? A relatively common complication in which the blood supplies of twins sharing the same placenta become connected (twin-to-twin transfusion) was studied. This complication can be fatal to both twins. Fortunately, an operation that involves blocking the shared blood vessels usually saves the twins, but its impact on brain development is relatively unknown.

Interesting Links:
Interview with Dr. Taylor-Clarke - http://www.newscientist.com/article/dn21888-unborn-twins-caught-on-video-mri-for-the-first-time.html
Fetal MRI - http://link.springer.com/article/10.1007%2Fs00247-004-1246-0?LI=true