Joint dynamic imaging of morphogenesis and function in the developing heart.

In the developing heart, time-lapse imaging is particularly challenging. Changes in heart morphology due to tissue growth or long-term reorganization are difficult to follow because they are much subtler than the rapid shape changes induced by the heartbeat. Therefore, imaging heart development usually requires slowing or stopping the heart. This, however, leads to information loss about the unperturbed heart shape and the dynamics of heart function. To overcome this limitation, we have developed a non-invasive heart imaging technique to jointly document heart function (at fixed stages of development) as well as its morphogenesis (at any fixed phase in the heartbeat) that does not require stopping or slowing the heart. We review the challenges for imaging heart development and our methodology, which is based on computationally combining and analyzing multiple high-speed image sequences acquired throughout the course of development. We present results obtained in the developing zebrafish heart. Image analysis of the acquired data yielded blood flow velocity maps and made it possible to follow the relative movement of individual cells over several hours.