Purpose: Aim of our study was to compare the diagnostic performance of (18)F-FDG PET/CT and MR imaging (MRI) in the detection of liver metastases in patients with adenocarcinomas of the gastrointestinal tract.
Methods: A total of 49 patients with adenocarcinomas of the gastrointestinal tract who had undergone (18)F-FDG PET/CT and MRI of the liver were included in this study. The MRI protocol included diffusion-weighted imaging and dynamic contrast-enhanced MR imaging after intravenous injection of Gd-DTPA. PET and MR images were analyzed by two experienced radiologists. Imaging results were correlated with histopathological findings or imaging follow-up as available. Sensitivities of both modalities were compared using McNemar Test. Receiver operating characteristic (ROC) curves were calculated to determine the diagnostic performance in correctly identifying liver metastases.
Results: A total of 151 metastases were confirmed. For lesion detection, MRI was significantly superior to (18)F-FDG PET/CT. Sensitivity of MRI in detecting metastases was 86.8% for Reader 1 (R1) and 87.4% for Reader 2 (R2), of PET/CT 66.2% for R1 and 68.2% for R2. Regarding only metastases with diameters of 10 mm or less, sensitivities of MRI were 66.7% for R1 and 75.0% for R2, and were significantly higher than those of PET/CT (17.9% for R1 and 20.5% for R2). ROC analysis showed superiority for lesion classification of MRI as compared to (18)F-FDG PET/CT.
Conclusion: MRI is significantly superior to (18)F-FDG PET/CT in the detection and classification of liver metastases in patients with adenocarcinomas of the gastrointestinal tract, especially in the detection of small metastases.