1. A computer-implemented method of visualization, comprising: (i) receiving at least one pre-operative image and at least one intra-operative image of an anatomical structure; (ii) straightening the pre-operative image to generate a straightened pre-operative image; (iii) identifying a region of interest in the intra-operative image; (iv) identifying a symmetric region in the straightened pre-operative image based on the intra-operative image, wherein the symmetric region is substantially symmetrical to a target region in the straightened pre-operative image, wherein the target region corresponds to the region of interest in the intra-operative image; (v) extracting the symmetric region from the pre-operative image and reflecting the extracted symmetric region to generate a reference image; (vi) rigidly registering the intra-operative image with the reference image to generate a registered intra-operative image; and (vii) overlaying the registered intra-operative image on the target region in the straightened pre-operative image to generate a first fused image.