1. A method for correcting attenuation of positron emission tomography (PET) image data of an area under examination, comprising: (a) segmenting magnetic resonance (MR) images of the area under examination utilizing a patch-based segmentation technique, wherein the area under examination is a part of a subject's body; (b) creating pseudo-computed tomography (CT) images from the segmented MR images; (c) generating attenuation correction maps for the PET image data from the pseudo-CT images, and (d) characterizing the attenuation correction maps generated from the pseudo-CT images relative to attenuation correction maps generated from CT images by comparing the attenuation correction maps generated from the pseudo-CT images to attenuation correction maps generated from CT images of a reference area under examination.