To contrast or not to contrast? Evaluating the diagnostic accuracy of hepatobiliary contrast agents in liver FDG-PET/MR: a prospective study.

Abstract

The role of hepatobiliary contrast-enhanced imaging in the evaluation of liver malignancies in FDG-PET/MR remains underexplored. The aim of this study was to assess the diagnostic performance of stand-alone FDG-PET, non-contrast-enhanced (NCE) PET/MR, and contrast-enhanced (CE) PET/MR with and without hepatobiliary phase (HBP). This prospective, single-center diagnostic accuracy study enrolled 60 patients with histologically confirmed abdominal malignancies and malignant liver lesions. Each patient underwent whole-body FDG-PET/MR, including dedicated upper abdominal imaging with NCE, CE without HBP, and CE with HBP. Three blinded radiologists independently evaluated the images in consensus. The reference standard was histopathology or follow-up imaging. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were calculated. Fisher's exact test and Mann-Whitney U test were used for statistical comparisons. A total of 134 malignant liver lesions (38 primary tumors, 96 metastases) were identified. CE FDG-PET/MR with HBP achieved the highest diagnostic accuracy (97%), sensitivity (97.8%), and specificity (95.2%). NCE FDG-PET/MR had an accuracy of 67%, sensitivity of 78%, and specificity of 44%, while stand-alone FDG-PET had the lowest accuracy (52%). The addition of HBP significantly improved specificity (75.6-95.2%, p = 0.013) and enabled detection of smaller lesions (median size 7 mm vs. 19 mm, p = 0.00017). The inclusion of hepatobiliary contrast significantly enhances the diagnostic performance of FDG-PET/MR for liver malignancies, particularly in detecting small or poorly defined lesions. These findings support the integration of HBP into PET/MR workflows to optimize liver lesion detection and staging. Not applicable.