Characterization of Focal Hepatic Lesions Using Diffusion-Weighted Magnetic Resonance Imaging and Its Correlation with Contrast-Enhanced Computed Tomography

Abstract

Background: Focal hepatic lesions include benign, malignant, and inflammatory entities with overlapping appearances on conventional imaging. Diffusion-weighted magnetic resonance imaging (DWI) and apparent diffusion coefficient (ADC) mapping provide functional information that may improve lesion characterization. Objective: To evaluate the role of diffusion-weighted magnetic resonance imaging (DWI) and quantitative apparent diffusion coefficient (ADC) measurements in the characterization of focal hepatic lesions, with correlation to contrast-enhanced computed tomography (CECT) and final diagnosis. Materials and Methods: This cross-sectional comparative study included 50 consecutively enrolled patients with focal hepatic lesions examined between April 2023 and November 2024. Magnetic resonance imaging (MRI) was performed on a 1.5-tesla system using conventional sequences, diffusion-weighted imaging (DWI; b values 50, 400, and 800 s/mm²), and apparent diffusion coefficient (ADC) maps. The study-derived ADC threshold of 1.2 × 10⁻³ mm²/s was evaluated using sensitivity, specificity, predictive values, accuracy, and receiver operating characteristic (ROC) analysis. Results: Twenty-eight lesions (56%) were benign/non-malignant and 22 (44%) were malignant. Mean central ADC was significantly higher in benign/non-malignant lesions than in malignant lesions (1.63 ± 0.65 vs 0.84 ± 0.46 × 10⁻³ mm²/s; p<0.001); corresponding peripheral ADC values were 1.61 ± 0.57 and 0.81 ± 0.28 × 10⁻³ mm²/s (p<0.001). Peripheral ADC demonstrated 75% sensitivity, 95.45% specificity, 84% accuracy, and an area under the ROC curve (AUC) of 0.975. Conclusion: Diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping is a useful adjunct for focal hepatic lesion characterization. ADC values should be interpreted with lesion morphology and enhancement because abscesses and cystic/necrotic malignancies may overlap.

Keywords: apparent diffusion coefficient, CECT, diffusion-weighted MRI, focal hepatic lesions, liver MRI