Multidetector computed tomography follow-up of hypoattenuating small liver lesions in patients with rectal cancer

Objective: To study the behavior of hypoattenuating liver lesions, deemed too small to characterize at baseline scanning with multidetector computed tomography (CT), in patients with rectal cancer. Methods: Retrospective review of locally advanced rectal cancer patients from a radiation oncology therapy database was conducted. Patients who presented before neoadjuvant chemoradiation without metastases at baseline CT and with follow-up scans for at least 1 year after therapy were evaluated. CT studies were reviewed for the presence and change in size of hypoattenuating liver lesions (<15 mm) at baseline and follow-up. Results: A total of 616 consecutive patients from the radiotherapy database were reviewed. Of these, 70 patients with a total of 163 hepatic lesions met the selection criteria. The mean patient age was 62.4 years (range, 26-85 years). All patients subsequently underwent surgery and adjuvant chemotherapy. The mean time of radiographic imaging from baseline CT to most recent surveillance CT was 3.3 years (range, 1.1-7.4 years). Two radiologists independently reviewed the CTs. The lesions were stable in 56 of 70 (80.0%, 95% confidence interval: 69%, 89%) patients. Of 163 lesions, 148 (90.8%) were stable, 8 (4.9%) regressed, and 7 (4.3%) progressed in size. No significant difference in results was found for patients stratified according to T-stage (P = 0.41) and N-stage (P > 0.99). Conclusion: In patients with rectal cancer, majority of small hypoattenuating liver lesions remain stable and are treated as benign lesions, at multidetector CT follow-up of more than a year. Nevertheless, hepatic lesion stability during systemic therapy should still be interpreted with caution and closely followed for at least 1 year after completion of therapy.