Differentiating malignant from benign hyperintense nodules on unenhanced T1-weighted images in patients with chronic liver disease: using gadoxetic acid-enhanced and diffusion-weighted MR imaging

Purpose: To evaluate value of gadoxetic acid-enhanced and diffusion-weighted (DW) MRI for distinguishing malignant from benign hyperintense nodules on unenhanced T1-weighted images (T1WIs) in patients with chronic liver disease. Materials and methods: Forty-two patients with 37 malignant and 41 benign hyperintense nodules on unenhanced T1WIs who underwent gadoxetic acid-enhanced and DW MRI, followed by histopathological examination, were included. Qualitative and quantitative analyses were conducted. Significant findings on univariate and multivariate analyses were identified and their diagnostic performances were analyzed for predicting hyperintense hepatocellular carcinomas (HCCs). Results: In univariate analysis, hyperintensity on T2WI, arterial enhancement, washout, hypointensity on hepatobiliary phase, and diffusion restriction were more frequently observed (P < 0.05) in hyperintense HCCs. Tumor-to-liver SI ratio on hepatobiliary phase and minimum apparent diffusion coefficient (ADC _min ) were significantly lower in hyperintense HCCs (P < 0.05). In multivariate analysis, hyperintensity on T2WI (OR, 13.58; P = 0.02), arterial enhancement (OR, 8.21; P = 0.002), and ADC _min ≤ 0.83 × 10 ⁻³  mm ² /s (OR, 6.88; P = 0.008) were independently significant factors for predicting hyperintense HCCs. When two of three criteria were combined, 75.7% (28/37) of hyperintense HCCs were identified with a specificity of 92.7%, and when all three criteria were satisfied, the specificity was 97.6%. Conclusion: Gadoxetic acid-enhanced and DW MRI may be helpful for differentiating malignant from benign hyperintense nodules on unenhanced T1WI.