Benign versus malignant focal liver lesions: Diagnostic value of qualitative and quantitative diffusion weighted MR imaging

Diffusion-weighted imaging has an emerging role for assessment of focal and diffuse liver diseases. The aim of this study was to evaluate the diagnostic performance of DWI for characterization of focal liver lesions (FLLs). Patients and methods: This prospective study included 40 consecutive patients with 64 focal liver lesions, who underwent MRI of the liver. All patients had one or more hepatic focal lesion of diameter more than 1 cm. DWI was reviewed (b values of 0, 50 and 600 s/mm²) and the mean ADC was calculated. Results: Quantitative assessment using ADC map was more accurate (87.5%) than qualitative assessment using DWI (75%) in characterization of FLLs. Mean ADC values of malignant lesions (0.94 + 0.32 multiplication sign 10^-3 mm²/s) were significantly lower than those of benign lesions (2.64 + 0.46 multiplication sign 10^-3 mm²/s), (ρ< 0.001). Using an ADC value above 1.6 multiplication sign 10^-3 mm²/s offered the best accuracy in differentiation of malignant from benign lesions (86%). Conclusion: DWI is a useful tool for FLLs characterization. Because of its known pitfalls and limitations, mainly the considerable overlap of ADCs values between solid benign and malignant lesions, it should be interpreted in combination with clinical data and conventional MRI sequence