Diagnostic performance of the FDG-PET/CT in patients with resected mucinous colorectal liver metastases

Abstract Background and purpose: FDG-PET/CT has gained acceptance for tumours staging. Few and conflicting data exist on the sensitivity of FDG-PET/CT in identifying colorectal mucinous liver metastases (mucCRLM). The aim of this study was to evaluate the diagnostic performance of the FDG-PET/CT in patients with mucCRLM who underwent liver surgery. Methods All patients affected by mucCRLM scheduled for liver resection who had undergone preoperative FDG-PET/CT between 2005 and 2018 were analyzed. Diagnostic performance of FDG-PET/CT was assessed in organ and lesion-based analysis. Results 58 patients out of 131 (44.2%) affected by mucCRLM fulfilled the inclusion criteria. 118 mucCRLM were detected. FDG-PET/CT confirmed 71 (60.2%) CRLM in 51 patients. The sensitivity and specificity of FDG-PET/CT were 89.4% and 100% in the organ-based analysis and 60.7% and 100% in lesion-based analysis. Absence of micro-vascular invasion (100% vs. 23%, p  25% was associated with low risk of false negative (AUC 0.848; p = 0.006). Conclusions FDG-PET/CT had a significant rate of false negative results in patients with mucinous colorectal liver metastases. Negative FDG-PET/CT in patients with low percentage of viable tumour cells after chemotherapy should be considered with caution.