Intravoxel Incoherent Motion Diffusion-Weighted Imaging for Evaluation of the Cell Density and Angiogenesis of Cirrhosis-Related Nodules in an Experimental Rat Model: Comparison and Correlation With Dynamic Contrast-Enhanced MRI

Background: Intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and dynamic contrast-enhanced MRI (DCE-MRI) are sensitive imaging modalities for detecting liver lesions, but their value in evaluating cirrhosis-related nodules remains unclear. Purpose: To investigate whether IVIM-DWI and DCE-MRI can differentiate different types of cirrhosis-related nodules, and whether these modalities can monitor changes in cell density and angiogenesis during the malignant transformation of cirrhosis-related nodules in a rat model Study Type: Prospective. Animal Model: Thirty-five male Sprague-Dawley rats with 106 cirrhosis-related nodules (19 regenerative nodules [RNs], 47 dysplastic nodules [DNs], and 40 hepatocellular carcinomas [HCCs]). Field Strength/Sequence: IVIM-DWI and DCE sequence at 3.0T MRI. Assessment: IVIM-DWI parameters (D, D*, f, and apparent diffusion coefficient [ADC]) and DCE-MRI parameters (K-trans, K-ep, and V-e) were calculated by two radiologists using postprocessing software. The "cell density" and "unpaired arterial ratio" were analyzed with a microscope by two pathologists. Statistical Tests: MRI parameters were compared among the different types of nodules by one-way analysis of variance or the Kruskal-Wallis test. The Pearson correlation test was used to analyze the correlation of MRI parameters with the pathological types of nodules, cell density, and unpaired arterial ratio. Results: The K-trans, K-ep, and V-e values of HCCs were significantly higher than those of DNs and RNs. D and ADC values were significantly lower in HCCs than in DNs and RNs. There were moderate positive correlations of K-trans with the pathological types of nodules and the unpaired arterial ratio. Moderate negative correlations were observed among D, ADC, and the pathological types of nodules, between D and cell density, and between ADC and cell density. Data Conclusion: IVIM-DWI and DCE-MRI are valuable in differentiating different types of cirrhotic-related nodules. D and ADC are correlated with changes in cell density during the malignant transformation of cirrhosis-related nodules, while K-trans is correlated with increased angiogenesis.