An EM algorithm for dynamic SPECT

Presents two variants of the EM algorithm for dynamic SPECT imaging, A version based on compartmental modeling which fits a sum of exponentials and a more general approach allowing for arbitrary decaying activities. The underlying probabilistic models are discussed and the incomplete and complete data spares are shown to be physically meaningful. The authors indicate that the second method, leading to a convex program in the M step, is easier to treat numerically and the authors present a possible numerical approach. Some preliminary numerical tests indicating the feasibility of the method are included.