Proton Density and T2-Weighted Volume Registration

We first consider the problem of registering PD images to transformed T2 as a means of testing the registration algorithm. Each T2-weighted scan was rotated by $90^\circ$ and translated 5 cm and then registered with the corresponding PD scan. Since these T2 and PD images were acquired at the same time and are originally in the same coordinate system, by perturbing one scan by a known amount, we have accurate ground-truth upon which to validate the registration process. All 36 test cases registered with sub-voxel, and in most cases with sub-millimeter accuracy. Note that the method has a large region of convergence and thus does not require the starting pose to be very near the correct solution.