Pulmonary metastases from colorectal cancer: imaging findings and growth rates at follow-up CT

A 65-year-old female with a pulmonary metastasis 30 months after an operation for descending colon cancer (well-differentiated adenocarcinoma, T2N0M0). (A) An initial CT scan shows a nodule just at the lateral aspect of the heart in the right middle lobe. The estimated tumor volume was 705 mm³. Metastasectomy was delayed due to the patient's refusal. (B) The nodule had increased in size on the follow-up chest CT after 434 days from the initial CT. The estimated tumor volume was 1540 mm³. With these volumetric data and time interval, the tumor volume doubling time was calculated as 385 days.

A 61-year-old female with a pulmonary metastasis 23 months after an operation for sigmoid colon cancer (moderately differentiated adenocarcinoma, T3N1bM0). (A) An initial CT scan shows a small ovoid nodule (arrow) that is located along the bronchovascular bundle in the right lower lobe. The estimated tumor volume was 640 mm³. On the prospective interpretation, this nodule was missed. (B) The mass (arrow) increased in size on the follow-up chest CT (210 days from the initial CT). The estimated tumor volume was 1795 mm³. With these volumetric data and time interval, the tumor volume doubling time was calculated as 141 days.

A 53-year-old female with a pulmonary metastasis 19 months after an operation for rectal cancer (well-differentiated adenocarcinoma, T3N2bM0). (A) An initial CT scan shows a small nodule (the longest diameter is 7 mm) in the right lower lobe. The estimated tumor volume was 215 mm³. The nodule was detected at that time, yet follow-up was recommended because of the small size of the nodule. (B) The nodule increased in size on the follow-up chest CT (182 days from the initial CT). The estimated tumor volume was 435 mm³. With these volumetric data and time interval, the tumor volume doubling time was calculated as 179 days.