Objective: The full diagnostic value of diffusion-weighted (DW) MRI in the evaluation of liver metastases remains uncertain. The aim of the present study was to assess the diagnostic accuracy of DW-MRI and contrast-enhanced MRI (CE-MRI) using extracellular gadolinium chelates, with the reference standard established by consensus interpretation of confirmatory imaging and histopathologic data.
Methods: MR examinations of 51 patients with extrahepatic malignancies were retrospectively reviewed by two independent observers who assessed DW-MRI and CE-MRI for detection of liver metastases.
Results: By reference standard, 93 liver lesions (49 metastases and 44 benign lesions) were identified in 27 patients, 11 patients had no liver lesions, and 13 patients had innumerable metastatic and/or benign lesions. There was no difference in diagnostic performance between the two methods for either observer for the diagnosis of metastatic lesions per patient. For per-lesion analysis, sensitivity of DW-MRI was equivalent to CE-MRI for observer 1 (67.3% vs. 63.3%, p = 0.67), but lower for observer 2 (65.3% vs. 83.7%, p = 0.007). By pooling data from both observers, the sensitivity of DW-MRI was 66.3% (65/98) and 73.5% (72/98) for CE-MRI, with no significant difference (p = 0.171).
Conclusion: DW-MRI is a reasonable alternative to CE-MRI for the detection of liver metastases.