Colonic PolypsPolypsIntestinal PolypsColonography, Computed TomographicAdenomatous PolypsColonoscopyColonic NeoplasmsAdenomatous Polyposis ColiColonDiverticulosis, ColonicAdenomaNasal PolypsRectal DiseasesSigmoid DiseasesGenes, APCMyelitis, TransverseRadiographic Image Interpretation, Computer-AssistedIntestinal MucosaColon, TransverseColonic DiseasesColorectal NeoplasmsTransverse SinusesSensitivity and SpecificityRetrospective Studies