Diagnostic Accuracy and Sensitivity of Diffusion-Weighted and of Gadoxetic Acid-Enhanced 3-T MR Imaging Alone or in Combination in the Detection of Small Liver Metastasis (≤1.5 cm in Diameter)

Abstract

PURPOSE: To compare the diagnostic accuracy and sensitivity of combined gadoxetic acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) with each imaging approach alone for detecting small hepatic metastases (≤ 1.5 cm). MATERIALS AND METHODS: Institutional review board approved this retrospective study and waived informed patient consent. Eighty-six patients with 179 liver metastases underwent liver MRI including unenhanced and gadoxetic acid-enhanced imaging and DWI at 3.0 T. Three image sets including unenhanced images-gadoxetic acid set (early dynamic and hepatocyte phase), DWI set, and the combined set-were analyzed independently and in consensus by 2 observers for detecting liver metastases using receiver operating characteristic analysis. RESULTS: There was a tendency toward an increased diagnostic accuracy for the combined set (mean, 0.965) compared with that for each image set alone (mean, 0.911 for gadoxetic acid set; 0.926 for DWI set). The combined set showed better sensitivity (mean, 97.47%/95.0%: values on per-lesion/per-patient basis) than each imaging set alone (mean, 90.7%/83.7% for gadoxetic acid set; 91.6%/83.0% for DWI set) (P < 0.05) on both per-lesion basis and per-patient basis. All image sets showed similar positive predictive values. CONCLUSIONS: The combination of gadoxetic acid-enhanced MRI and DWI yielded better diagnostic accuracy and sensitivity in the detection of small liver metastasis than each magnetic resonance scan sequence alone.