 As mentioned above, delayed complications can develop after tissue transfer flaps are used in reconstructive surgery, which include fat necrosis and flap atrophy. These late complications are thought to be caused by a relative vascular insufficiency supplying the flaps. It is proposed that the increased venous congestion and increased rates of fat necrosis with the use of DIEP flaps when compared to TRAM flaps in breast reconstruction is due to a relative venous insufficiency that is not diminished enough to cause flap loss, but is on occasion great enough to result in the development of fat necrosis 7. The late development of flap atrophy may also be due to a relative arterial or venous insufficiency that occurs at the time of surgical reconstruction, and results in a relative global tissue flap ischemia leading to the development of flap atrophy. One of the goals of this experiment is to determine if any characteristic of the optical properties in a tissue transfer flap in the near post-operative setting can predict the development of either fat necrosis or flap atrophy. 