目的：探讨结、直肠癌术后肺孤立性转移瘤的影像表现，与原发肺癌的鉴别。材料与方法：３１年间１３例结、直肠癌术后肺孤立肿物，均经手术切除及病理证实。转移性腺癌１１例１３次，原发肺癌２例。结、直肠癌切除与肺转移瘤切除间隔时间为３～９６个月，中位３３个月。均有正侧位胸片，病灶体层和ＣＴ各６例。结果：肿物直径１．５～８．５ｃｍ（中位３．４ｃｍ），类圆形３例，椭圆形８例１０个，浅分叶１０例；边缘光整８例１０个，不光整３例，毛刺１例。平片密度均匀１１例次。６例ＣＴ中５例见肿物位于肺外周；发现瘤内弥漫性斑片状钙化１例，不均匀低密度区、毛刺、胸膜凹陷各３例。结论：（１）结、直肠癌术后孤立性肺转移以边缘光整的圆／椭圆形肿物为多；（２）少数可表现为与肺原发癌相似；肿物内可有弥漫钙化；（３）ＣＴ对于确定肿物部位、数目、密度、边缘形态明显优于平片。 Objective: To investigate the imaging features of isolated pulmonary metastases after operation for colorectal cancer, and to identify the primary lung cancer. Materials and Methods: Thirty-three cases of isolated lung masses after surgery and colorectal cancer in 31 years were confirmed by surgical resection and pathology. There were 11 cases of metastatic adenocarcinoma in 13 cases and 2 cases of primary lung cancer. The interval between resection of resection of rectal cancer and metastases of lung metastases was 3 to 96 months and the median time was 33 months. All had lateral chest radiographs, 6 lesions and CT. Results: The tumor diameter was 1.5-8.5cm (median 3.4cm), 3 cases were round, 10 cases were oval, 8 cases were shallow, 10 cases were shallow, and 10 cases of marginal skin were 10 cases. Example, burr in 1 case. Plain film density 11 times. In 5 cases of 6 cases of CT, the tumor was located on the periphery of the lung; 1 case of diffused plaque calcification in the tumor, 3 cases of uneven low density area, burrs, and pleural depression were found. Conclusions: (1) The isolated lung metastases of colorectal cancer and rectal cancer are mostly round/elliptical tumors with marginal margins; (2) a few may be similar to primary lung cancer; diffuse calcification may be present in tumors. (3) CT is significantly superior to plain film in determining the site, number, density, and edge morphology of the tumor.