Quantitative Imaging in the Time Domain Featuring Gradient Based Minimization and Broyden Updating

In this letter, we present numerical and experimental results on gradient-based ultra-wide band minimization, utilizing central difference technique and Broyden´s updating strategy. The feasibility and accuracy of this new inverse scattering algorithm is compared with the adjoint method with forward and reverse time-stepping algorithm. Simulation experiments from MRI derived numerical data show that images produced by the proposed scheme are comparable to the adjoint method. However, the former is more accurate in detecting smaller target in experimental setup. As expected, the Broyden´s strategy takes longer time to converge averaging at 26 minutes per iteration compared to 28 seconds for the adjoint method. These results suggest that the proposed method is more robust when reconstructing smaller and noisy target even though the computational complexity is increased.