Changes in breast tissue thickness and in implant projection 5years after augmentation with high- and extra-high-profile round implants were measured through MRI with a DICOM standard viewer. Twenty-four females with small-volume breast asymmetry without hypertrophy or ptosis underwent subfascial breast augmentation for cosmetic purposes, by using micro-textured soft cohesive silicone gel-filled round implants, from a single manufacturer. MRI measured the linear antero-posterior dimension of breast tissue thickness and projection of the implants. Statistical analysis of data was performed by Pearson correlation coefficient, line graph, and scatter diagram. The "r" of Pearson for right and left breasts indicated a significant correlation between the breast tissue thickness before and 5years after augmentation. Closeness of the lines displayed in the line graph indicated strong linear positive correlation between the breast tissue thicknesses. The "r" values for projection of right and left implants indicated a significant correlation between the projection standardized by the manufacturer and that encountered 5years after augmentation with high- and extra-high-profile round implants. A scatter diagram of data indicated a strong positive correlation between implant projection standardized by the manufacturer and that encountered 5 years after augmentation, on both breasts. Soft cohesive silicone gel-filled high- and extra-high-profile round implants supported breast tissue compressing without significant loss of the implant projection. Despite the consistency of the soft cohesive silicone gel, the implant softness and flexibility were preserved, resulting in low-pressure gradient over the mammary parenchyma without significant changes of the breast tissue thickness. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.