Effects of the time dependence of a bioluminescent source on the tomographic reconstruction.

There are two goals in this simulation study: (1) to show that the time variation of the bioluminescence source can cause artifacts in the tomographic images such that quantification and localization becomes impossible; and (2) to show that the a priori knowledge of the light kinetics can be used to eliminate these artifacts. These goals are motivated by the fact that the half-life of luciferase has been reported as 30 min to 2 h in vivo. We perform two-dimensional simulations. We consider a 40 mm diameter circular region with an inclusion of 6 mm diameter located 10 mm away from the center. The measurement data is simulated using a finite-element-based forward solver. We model the noncontact measurements such that four-wavelength data is collected from four 90 degrees apart views. The results show that the ratio of the total imaging time to the half-life of the exponentially decaying bioluminescent source is the deciding factor in the reconstruction of the source. It is also demonstrated that a priori knowledge of the source kinetics is required to perform tomographic bioluminescence imaging of short half-life bioluminescent sources and the use of spatial a priori information alone is not adequate.