Perfusion CT predicts survival for colorectal cancer patients

Surgery may take care of initial disease for patients with colorectal cancer, but changes in blood flow in the liver can help predict whether residual disease will threaten the health of these patients later on - even if no metastases are visible.

Researchers at Brighton and Sussex Medical School in the U.K. performed CT liver perfusion imaging for 88 patients who had undergone surgery to remove primary colon cancer. Among those, 51 had overt metastases visible in the liver, and 37 had none.

The protocol included a 50 mL bolus of contrast, followed by a series of images acquired every three seconds. The researchers noted the enhancement periods for the aorta, spleen and liver and made calculations to focus on the arterial phase of liver enhancement rather than portal.

Among 36 patients with no visible metastases who completed the study period, 12 had normal perfusion and 24 had an abnormal perfusion index. Patients in the first group had a 92% probability of survival at three years postsurgery, while those with abnormal perfusion had a 72% chance of survival. Among patients with visible metastases, survival was only 13.6% at three years.

"The survival is excellent if there are no metastases and normal perfusion," said lead author Dr. Kenneth Miles.

The progression of patients roughly corresponds with that associated with survival for Dukes' classification. Not all patients who show abnormal liver perfusion go on to develop liver metastases, Miles said. Some develop distant lesions.

"The question is what to do with patients who show this early abnormal blood flow," he said. "We're starting a protocol now to give them better imaging surveillance."