| Objective It has been one of the clinical difficult problem for diagnosis of liver fibrosis and its staging. Therefore, it is uergently needed to be the development of noninvasive, high repeatability and accuracy of the assessment of liver fibrosis instead of percutaneous liver biopsy. With the rapid development of magnetic resonance (MR) hardware and software, IVIM-DWI can evaluate the water molecules diffuse and microcirculation perfusion before the morphological changes in the tissue of liver fibrosis, which provides a new method for noninvasive evaluation of liver fibrosis. The monoexponential model of IVIM-DWI can adopt multiple b values for assessment of water molecules diffuse within the tissue of liver fibrosis. This study was designed to determine the application value of the monoexponential model of IVIM-DWI in liver fibrosis.Methods IVIM examinations were performed on a GE3.0T MR scanner in25patients with liver fibrosis and25healthy volunteers as the control group.25cases of patients with liver fibrosis were punctured the posterior lobe of liver by ultrasound. Liver fibrosis was confirmed by pathology and staged on a scale of FO-4(the Knodell scoring system:F0、F1、F2、F3、F4). IVIM raw data were reprocessed off-line on GE AW4.5Functool software, which would automatically generate standard ADC values of monoexponential model of pseudo color maps. Two experienced radiologists manully put the same size of ROIs (Region of Interest, ROI) in three liver regions (right posterior hepatic lobe, right anterior hepatic lobe, medial segment of the left lobe) per person, respectively, which were avoided peripheral vascular artifacts and surrounding lesions. ROIs were selected150mm2. When taking all the b values (0,50,100,100,200,600,800s/mm2), it would get the standard ADC values of monoexponential model,which was namely ADCtotal. When taking4b values (0,400,600,800s/mm2), it would get the standard ADC values of monoexponential model, which was namely ADC0-400-600-800-The mean ADCtotal、ADC0-400-600-800values from the study group and the control group were compared among the right posterior hepatic lobe, right anterior hepatic lobe and medial segment of the left lobe. Receiver Operating Characteristic (ROC) curves and independent-samples t-tests were used to calculate the mean ADCtotal ADC0-400-600-800values from the study group and the control group. Spearman rho correlation analysis was used for the stage of liver fibrosis. The mean values (ADCtotal、ADC0-400-600-800) of the liver fibrosis stages between the subgroups FO-1and F2-4, the subgroups FO-2and F3-4were compared.Results There were no significant difference in the mean ADCtotal、ADCo-400-600-800values obtained from the right posterior hepatic lobe, right anterior hepatic lobe and medial segment of the left lobe of the liver fibrosis and the control groups (P>0.05) Using ROC analysis, the Area Under the Curve (AUC) values of ADCtotal、 ADCo-400-600-800were all between0.8and1. When taking cutoff values for diagnosis, the sensitivity, specificity, false positive and false negative of ADCtotal、ADC0-400-600-800were relatively higher. The mean ADCtotal、ADCo-400-600-800values of the liver in the study group were significantly lower than the values in the control group (P<0.05). As the stage of the fibrosis increased, the mean values (ADCtotal、ADCo-400-600-800) decreased by Spearman rho correlation analysis. The mean values (ADCtotal、 ADCo-400-600-800) of liver fibrosis stages between the subgroups FO-1and F2-4, the subgroups FO-2and F3-4showed significant differences (P<0.05).Conclusions The monoexponential model of IVIM-DWI adopted multiple b values for quantitative analysis of the water molecules diffuse in the organization, which had the ability of objective evaluation of liver fibrosis. Therefore, the monoexponential model of IVIM-DWI could be used as a noninvasive and valuable method for assessment of liver fbrosis, which provided more diagnostic information for the clinical. Objective The early detection of hepatic fibrosis has important clinical implications. So, a kind of noninvasive diagnosis of liver fibrosis is urgently needed. Intravoxel incoherent motion (IVIM) is a new technique which can be used to investigate both diffusion and perfusion changes in tissues. This study was designed to determine the value of IVIM, which including monoexponential and biexponential models, in the diagnosis of liver fibrosis and its stages.Methods IVIM examinations were performed on a GE3.0T MR scanner in25patients with liver fibrosis and25healthy volunteers as the control group.25cases of liver fibrosis patients were punctured by ultrasound in the posterior lobe of liver. Patients with liver fibrosis diagnosis were confirmed by pathology and staged on a scale of FO-4(the Knodell scoring system:F0、F1、F2、F3、F4). IVIM raw data will automatically generate the pseudo color maps of monoexponential model (standard ADC)and biexponential model (slow ADC (Dslow), fast ADC (Dfast) and fraction of fast ADC (FF)) by the post-processing of GE AW Functool4.5software. Two experienced radiologists will put the same sive of ROIs (150mm2) manually on DWI figures in the posterior lobe, right anterior lobe of liver and left lobe, respectively. Cares were taken to avoid peripheral vascular artifacts and surrounding lesions. The standard ADC values of monoexponential model and the values of biexponential model (slow ADC (Dslow), fast ADC (Dfast) and fraction of fast ADC (FF)) were all measured in three liver regions per person. The mean values (standard ADC values, Dslow values, Dfast values and FF values) from the study group and the control group were compared among the right posterior hepatic lobe, right anterior hepatic lobe and medial segment of the left lobe. Receiver Operating Characteristic (ROC) curves and independent-samples t-tests were used to calculate the mean standard ADC values, Dslow values, Dfast values and FF values from the study group and the control group. Spearman rho correlation analysis was used for the stage of liver fibrosis. The mean values (standard ADC, Dslow, Dfast, and FF) of the liver fibrosis stages between the subgroups FO-1and F2-4, the subgroups FO-2and F3-4were compared.Results Among the normal liver and liver fibrosis, there were no significant difference in the mean standard ADC values, Dslow values, Dfast values, and FF values obtained from the right posterior hepatic lobe, right anterior hepatic lobe and medial segment of the left lobe (P>0.05). Using ROC analysis, the Area Under the Curve (AUC) values of standard ADC, Dslow, Dfast, FF were all between0.7and0.9. When taking cutoff values for diagnosis, the sensitivity of standard ADC and Dslow were relatively higher, while the specificity of Dslow was relatively lower. The mean standard ADC values, Dslow values, Dfast values and FF values of the liver in the study group were significantly lower than the values in the control group (P<0.05). As the stage of the fibrosis increased, the mean values (standard ADC、Dslow、Dfast and FF) decreased by Spearman rho correlation analysis. The mean valuel (Standard ADC, Dslow, Dfast, and FF) of liver fibrosis stages between the subgroups FO-1and F2-4, the subgroups FO-2and F3-4showed significant differences (P<0.05).Conclusions The monoexponential model of IVIM-DWI can only reflect the condition of diffusion in liver fibrosis by quantitative analysis. But biexponential model can be used to investigate both diffusion and perfusion changes in tissues by quantitative analysis. Therefore, the biexponential model can be more comprehensive than monoexponential model to the evaluation of liver fibrosis, and liver fibrosis progression, and curative effect of dynamic monitoring on the patients. Consequently, the biexponential can be provided more and more comprehensive for clinical diagnostic information. |
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