The Application Of IVIM-DWI Based On IShim Sequence In The Identification Of Focal Liver Lesions

PART Ⅰ IVIM-DWI reproducibility study of normal liver based on iShimObjective:To study the repeatability of normal liver IVIM-DWI based on iShim.Methods:The normal liver of 30 healthy volunteers was scanned by Siemens 3.0 T MR scanner,two sequences of IVIM-DWI and iShim IVIM-DWI were used respectively,and 9 b values of 0,20,40,80,120,400,800,1000 s/mm2 were used to obtain the ADC D*f values of IVIM-DWI and iShim IVIM-DWI respectively.In the region without large intrahepatic vessels and obvious artifacts,there were 3 ROIs at the same level in the left and right hepatic lobes.The mean values were measured for 3 times with the same thickness interval.A total of 15 ROIs were selected for the left and right hepatic lobes at 5 levels.Independent sample T test was used,and P<0.05 was considered statistically significant.Bland-Altman method was used to evaluate the repeatability of two sequences of ADC D D*f.Results:The ADC D and f values of the left lobe of the liver of the two sequences were significantly higher than that of the right lobe of the liver,and the difference of ADC D values between the left and right lobe of the liver of the IVIM-DWI sequence was statistically significant,while the difference of ADC D values between the left and right lobe of the liver of the iShim IVIM-DWI sequence was not statistically significant.The bias degree of ADC D value in the left lobe of the liver in IVIM-DWI sequence was 35.4%and 33.8%,respectively,and 31.2%and 31.7%,respectively,in the right lobe of the liver.The degree of bias of ADC D value in the left lobe of the liver was 28.3%,27.3%,and 24.4%,22.5%,respectively,in the right lobe of the liver.The D*value of the two sequences showed the greatest degree of bias.The iShim IVIM-DWI sequence has a small degree of parameter bias.Conclusion:The ADC D and f values of the left lobe of the liver in the two sequences of IVIM-DWI and iShim IVIM-DWI were significantly higher than those in the right lobe of the liver.In the ADC D D*and f,the measurement consistency of D*was the worst.PART Ⅱ The Application of IVIM-DWI Based on iShim Sequence in the Identification of Focal Liver LesionsObjective:To explore the value of intra-voxel incoherent motion diffusion weighted imaging(IVIM-DWI)based on iShim in the diagnosis of benign and malignant focal lesions of the liver.Methods:A total of 56 patients with liver focal lesions admitted for examination from July 2016 to January 2018 were collected.All the patients were treated with liver MR routine sequence iShim IVIM-DWI(b=0,20,40,80,120,200,400,800,1000s/mm2),and the apparent diffusion coefficient(ADC),slow apparent diffusion coefficient(D*),and fast apparent diffusion coefficient(D*)perfusion score(f)were obtained through the single and dual index model.H test was used to compare the differences among the parameters,and ROC was used to calculate the diagnostic efficacy of the parameters.Results:ADC values in all focal lesions were slightly higher than D values.Except for the regenerated nodules,the d-value ADC value of all benign liver lesions was greater than that of malignant liver lesions,but the ADC and d-value of regenerated nodules were lower than that of malignant liver lesions,which included hepatocellular carcinoma and intrahepatic cholangiocarcinoma,indicating that the ADC and d-value of hepatocellular carcinoma were lower than that of intrahepatic cholangiocarcinoma.The diagnostic threshold of each parameter for benign and malignant liver lesions is ADC(1.174×10-3 mm2/s),D(1.068×10-3 mm2/s),f(16.7%),D*(33.1×10-3 mm2/s).Conclusion:Except for D*,ADC D f has statistical significance in the differential diagnosis of liver focal lesions.In the comparison of benign and malignant liver lesions,the value of ADC D for malignant liver lesions is lower than that for benign liver lesions,but benign liver lesions contain regenerative nodules,and the value of ADC D is lower than that for malignant liver lesions.The parameters of IVIM-DWI based on iShim alone cannot accurately identify focal liver lesions.