The purpose of this study is to present a method of boundary enhancement algorithms for magnetic resonance images using a V-filter and clinical applications. By iterated V-filtering, the signal-to-noise ratio can be increased with preservation of edge sharpness. This is due to the relationship of the signal-to-noise ratio to the mean-to-variance ratio. These techniques were applied to clinical cases using MRI in the evaluation of the brain tumor. The boundaries of the brain tumor and the edematous region were precisely extracted.