Diffusion-weighted MRI: Role in diagnosing hepatic focal lesions

Abstract

Objective The objective of this study was to highlight the role of quantitative and qualitative diffusion-weighted MRI (DW-MRI) in differentiating benign and malignant hepatic focal lesions, thus increasing the efficacy of conventional hepatic MRI, in addition to evaluating the effect of using different b-values. Patients and methods This study was carried out from January to November 2016. We prospectively scanned patients with suspected liver focal lesion referred from Hepatology Unit by high-field 1.5 T MRI. The data were tabulated and manipulated using SPSS, version 14, with the level of significance set at less than 0.05. Results The study revealed that benign lesions such as simple hepatic cysts and hemangiomata showed facilitated diffusion [high signal intensity (SI) on diffusion-weighted imaging and also high SI on apparent diffusion coefficient (ADC) map], whereas malignant solid tumors such as hepatocellular carcinoma (HCC) and metastases demonstrated restricted diffusion (high SI on diffusion-weighted imaging and low SI on ADC map). Regarding the quantitative results, the mean ADC of non-neoplastic liver parenchyma, simple liver cyst, hepatic hemangioma, liver metastases, and HCC measured 1.08 ± 0.22, 2.83 ± 0.19, 2.11 ± 0.18, 1.34 ± 0.27, and 1.07 ± 0.21 × 10-3 mm2/s, respectively. There was a highly statistically significant difference in mean ADC between benign focal hepatic lesions such as hemangioma and malignant lesions such as metastases or HCC (P = 0.001). Conclusion DW-MRI is a very useful additive to conventional MRI sequences in categorizing focal hepatic lesions, thus increasing the confidence of differentiating benign and malignant lesions, particularly if there is a contraindication for contrast injection or for better detection of minute lesions adjacent to vessels.