Role of gadoxetic acid-enhanced MRI in the differential diagnosis of chemotherapy-induced focal nodular hyperplasia-like lesions and liver metastases in patients with colorectal cancer.

Purpose: To describe the gadoxetic acid-enhanced magnetic resonance imaging (MRI) features and follow-up changes of hepatic focal nodular hyperplasia (FNH)-like lesions induced by chemotherapy in patients with colorectal cancer (CRC) and the differential diagnosis of FNH-like lesions and liver metastases.

Methods: We retrospectively analyzed the data of patients with CRC who received chemotherapy and gadoxetic-enhanced MRI at our hospital. Based on imaging features and pathological findings, the patients were classified into two groups: FNH-like lesions and liver metastases. Two abdominal radiologists reviewed and compared the signal intensities of all images in each phase for both groups. The characteristics of the FNH-like lesions in the hepatobiliary phase were evaluated, and changes in size of lesions were monitored.

Results: Thirty patients with 82 FNH-like lesions and 30 with 49 liver metastases following chemotherapy were included in the study. All MRI findings were statistically significantly different between the two groups (p < 0.05). In FNH-like lesions, three enhancement patterns were observed in the hepatobiliary phase: hyperintense/isointense (18.3%), heterogeneous hyperintense (8.5%), and ring-like enhancement (73.2%). The median time from completion of chemotherapy to development of FNH-like lesions was 31 months. During 4-87 months of follow-up, 27 patients with 73 lesions showed the following outcomes: 41 lesions (56.16%) showed stability, 21 lesions (28.77%) growth, and 11 lesions (15.07%) reduction or disappearance.

Conclusion: Gadoxetic acid-enhanced MRI can distinguish between chemotherapy-induced FNH-like lesions and liver metastases in patients with CRC. The FNH-like lesions exhibited three enhancement patterns in the hepatobiliary phase, and the changes varied during follow-up.