1. A method for imaging a tissue specimen excised during surgery, the method comprising, by a combined positron emission tomography (PET) and micro computed tomography (micro CT) scanner: scanning the specimen with a computed tomography (CT) imaging system of the combined PET and micro CT scanner, scanning the specimen with a positron emission tomography (PET) imaging system of the combined PET and micro CT scanner; constructing a PET image based on data acquired by the PET imaging system; and constructing a micro CT image based on data acquired by the micro CT imaging system, wherein the micro CT image includes at least one visualization of a lesion marker.