Change pixels per unit for an imported asseet, but only on x axis

Instead of changing the transform scale values of my imported asset, I thought it would be a better idea to change the pixels per unit and keep the scale to 1 on all axis. The problem is that my preferred scale of the asset is 0.45 on the x-axis and 0.34 on the y-axis. Is there any way to resize the image on the x-axis in unity without changing the scale property in the transform?

I have tried to just stretch the picture in pixlr.com (simple image editor) and while that worked fine, it made the image more blurry so is there any way for me to accomplish the same thing without quality loss?

If this is about an UI image, then just uncheck the preserve aspect button and set the width (from the rect transform of the image) to any value that you want and the image will sttech/shrink in function of the values provided.