In Associated Particle Imaging (API), a neutron and alpha particle are created in a DT fusion reaction. Due to conversation of momentum in the center-of-mass frame, the two particles are moving in opposite directions. API utilizes this by measuring the position of the alpha particle in a detector. From this measurement one can infer the direction the neutron is traveling in (assuming no scattering event took place). The neutron can then interact through inelastic neutron scattering (INS) in a target material and the resulting gamma ray can be detected in a gamma detector. The energy of the gamma ray identifies the target isotope and by measuring the time between the alpha detection and the gamma detection events one can calculate the depth at which the scattering event took place. Measuring many of these INS events results in a complete 3D reconstruction of the density distribution for different isotopes. Resolution of several centimeters have been achieved in our lab.