1. A method of processing a medical image, comprising: obtaining a first plurality of images of a subject, the first plurality of images collectively defining a first image volume; filtering the first plurality of images to create a second plurality of images, each image in the second plurality of images comprising an average of at least two images in the first plurality of images, wherein each image in the first plurality of images is a thin image, and each image in the second plurality of images is a thick image; selecting a first thin image from the first plurality of images; adding a lost noise image to a second thick image in the second plurality of images to create a noise restored image, the second thick image in the second plurality of images corresponding to the first thin image in the first plurality of images; determining a gradient image based on pixel values in the second plurality of images, the gradient image comprising a gradient value at each pixel location in the second thick image; and combining, based on the determined gradient image, the first thin image and the noise restored image to obtain a corrected image in which an appearance of a imaging artifact is reduced; and displaying the corrected image.