Disappearing or residual tiny (≤5mm) colorectal liver metastases after chemotherapy on gadoxetic acid-enhanced liver MRI and diffusion-weighted imaging: Is local treatment required?

Abstract

OBJECTIVES: To evaluate the clinical course of disappearing colorectal liver metastases (DLM) or residual tiny (≤5mm) colorectal liver metastases (RTCLM) on gadoxetic acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) in patients who had colorectal liver metastases (CLM) and received chemotherapy. METHODS: Among 137 patients who received chemotherapy for CLM and underwent gadoxetic acid-enhanced MRI and DWI between 2010 and 2012, 43 patients with 168 DLMs and 48 RTCLMs were included. The cumulative in situ recurrence rate of DLM and progression rate of RTCLM and their predictive factors were evaluated. RESULTS: A total of 150 DLMs and 26 RTCLMs were followed up without additional treatment. At 1 and 2years, respectively, the cumulative in situ recurrence rates for DLM were 10.9% and 15.7% and the cumulative progression rates for RTCLM were 27.2% and 33.2%. The in situ recurrence rate at 2years was 4.9% for the DLM group that did not show reticular hypointensity of liver parenchyma on hepatobiliary phase. CONCLUSIONS: DLM on gadoxetic acid-enhanced liver MRI and DWI indicates a high possibility of clinical complete response, especially in patients without chemotherapy-induced sinusoidal obstruction syndrome. Thirty-three percent of RTCLMs showed progression at 2years. KEY POINTS: • DLMs on gadoxetic acid-enhanced MRI and DWI showed low recurrence rates. • If there is sinusoidal obstruction syndrome, evaluation of DLM needs special care. • The progression rate for residual tiny CLMs was 33.2% at 2years.