Diagnostic Utility of Diffusion-Weighted Magnetic Resonance Imaging in Differentiating Benign and Malignant Focal Liver Lesions

Abstract

Background: Accurate characterization of focal liver lesions (FLLs) is essential for appropriate staging in oncologic patients and to avoid unnecessary invasive procedures in benign conditions. Diffusion-weighted magnetic resonance imaging (DWI) provides functional information regarding tissue cellularity through apparent diffusion coefficient (ADC) measurements and may improve differentiation between benign and malignant lesions without the need for contrast administration.
Objective: To determine the diagnostic utility of diffusion-weighted magnetic resonance imaging in differentiating benign and malignant focal liver lesions and to establish an optimal ADC cut-off value for lesion characterization.
Methods: This cross-sectional study was conducted over one year at a tertiary care center. Twenty-eight patients with ultrasound-detected FLLs (≥1 cm) underwent MRI on a 1.5T system. Imaging protocol included conventional sequences and DWI with b - values of 0, 400, and 800 s/mm². Qualitative assessment was performed using signal intensity on DWI and ADC maps. Quantitative evaluation was done by calculating mean ADC values using region-of-interest (ROI) measurements. Histopathology and/or operative findings served as the reference standard where applicable.
Results: Thirty-four focal liver lesions were analyzed (13 benign, 21 malignant). Qualitative DWI at b - 800 showed an overall accuracy of 67.6%. ADC map analysis significantly improved diagnostic accuracy to 94.1% (p < 0.001). Mean ADC value for malignant lesions (0.90 ± 0.15 × 10-³ mm²/s) was significantly lower than that of benign lesions (2.19 ± 0.29 × 10-³ mm²/s) (p < 0.001). ADC cut-off ranged from 0.68 – 1.21 × 10-³ mm²/s for malignant lesions and 1.21 – 3.38 × 10-³ mm²/s for benign lesions. Overall accuracy of DWI compared with histopathology was 96.43%.
Conclusion: DWI is a valuable adjunct in liver MRI protocols for differentiating benign and malignant FLLs. Quantitative ADC measurement significantly enhances diagnostic performance over qualitative assessment alone. DWI should be interpreted in conjunction with conventional MRI sequences and clinical findings for optimal accuracy.