Weakly Supervised Multi-Task Learning for Cell Detection and Segmentation

Reliable attenuation and scatter compensation (ASC) is a pre-requisite for quantification tasks and beneficial for visual interpretation tasks in single-photon emission computed tomography (SPECT) imaging. For this purpose, we develop a SPECT reconstruction method that uses the entire SPECT emission data, i.e. data in both the photopeak and scattered windows, and acquired in list-mode format, to perform ASC. Further, the method uses the energy attribute of the detected photons while performing the reconstruction. We implemented a GPU-version of this method using an ordered subsets expectation maximization (OSEM) algorithm for faster convergence and quicker computation. The performance of the method was objectively evaluated using realistic simulation studies on the task of estimating activity uptake in the caudate, putamen, and globus pallidus regions of the brain in a dopamine transporter (DaT)-SPECT study. The method yielded improved performance in terms ob bias, variance, and mean square error compared to existing ASC techniques in quantifying activity in all three regions. Overall, the results provide promising evidence of the potential of the proposed technique for ASC in SPECT imaging.