Diagnostic Value Of Different Magnetic Resonance Diffusion Models For Small Hepatocellular Carcinoma And Cirrhotic Nodules

Background and purposeHepatocellular carcinoma is one of the most common malignant tumors.About80%of HCCs occur in patients with a background of cirrhosis.The prognosis of HCC patients mainly depends on the stage of detection,early detection and treatment（including liver transplantation,surgical resection or radiofrequency treatment,etc.）can significantly improve the survival rate and the long-term prognosis of patients.Therefore,early detection of small hepatocellular carcinoma with cirrhosis and differentiation from cirrhotic nodules are essential.In clinical practice,only few cases are confirmed by pathology,and it is difficult to obtain complete pathological information for puncture.Therefore,non-invasive imaging evaluation and diagnosis of nodular lesions with cirrhosis are particularly important.In addition to its advantages of high resolution,and multi-parameter imaging,magnetic resonance imaging can provide qualitative and quantitative information for the evaluation of liver lesions by diffusion-weighted imaging,which is a non-invasive method to characterize the diffusion of water molecules in living tissues.It can reflect the structure and function of tissues and may provide auxiliary information for the identification of nodular lesions in the context of cirrhosis.More accurate imaging techniques of different diffusion models have gained widespread attention.Intra-voxel incoherent motion imaging reflects tissue diffusion characteristics while also providing information on microcirculatory perfusion.Diffusion kurtosis imaging energetically diffuses the non-Gaussian distribution of water molecules in the tissue,reflecting the complexity of the microstructure of the tissue and obtaining more quantitative indicators.The previous researches on the application of IVIM and DKI in hepatic lesions mainly focused on the assessment of benign and malignant lesions.There were few reports about small hepatocellular carcinoma and cirrhotic nodules.The purpose of this study was to investigate the diagnostic value of DWI,intra-voxel incoherent motion imaging,diffusion kurtosis imaging for small hepatocellular carcinoma and cirrhosis nodules,and to compare the diagnostic efficacy of the above three diffusion models.Materials and methodsFifty-seven patients with a total of 70 lesions were included eventually in this study,divided into small hepatocellular carcinoma group of 31 patients（39 lesions）,of which 3 appeared as nodule-in-nodule,liver cirrhosis nodule group of 26 cases（31lesions,including degenerative and dysplastic nodules of cirrhosis）.All patients included showed a background of varying degrees of cirrhosis on MRI.The above two groups were non-overlapping patients and all cases were confirmed by pathology or clinical diagnosis and were followed up for more than 6 months to confirm.All patients underwent MRI on a 3.0 T MR system（Prisma,Siemens Healthcare,Erlangen,Germany）using a 18-channel phased-array coil.The contrast agent used for the enhanced scan was gadopentetate dimeglumine injection（Gd-DTPA）or disodium acid disodium injection（Gd-EOB-DTPA）.Before examination,all patients were told fasting food and water more than 6h,and trained breath-holding.The patients took a supine position with an advanced head,and the body coil was placed on the upper abdomen.The scan range included the whole liver.All patients underwent routine liver MRI scans with coronal breath holding T2WI,axial T2WI,T1WI,and DWI（b=50,800s/mm²）and IVIM-DWI（b=0,20,l00,150,200,300,400,500,600,800,1000,1200s/mm²）,DKI（b=0,1000,2000s/mm²）,and axial TWIST-VIBE dynamic enhanced sequences and delayed phase coronal T1WI fat suppression sequences.All MR images were read by a chief physician of the abdomen’s magnetic resonance diagnostic direction,and then a resident of a magnetic resonance diagnosis research direction selected the region of interest on the corresponding parameter image based on the results of the reading to measure and record the data.For patients with multiple（≥3）cirrhotic nodules,one or two of the more significant lesions were selected for inclusion.DWI analysis and measurement:the mean ADC values of the lesion’s ROI were measured and obtained.IVIM dates were processed to obtain the mean D values,mean D*values,mean f values.DKI data were processed on DKE software to obtain the mean D values,D*values,f values and MD values,MK values,FA values were measured and recorded.The above values were measured and analyzed by Mann-Whitney U Test or two independent samples t test and P<0.05indicated statistically significant.ResultsIn small hepatocellular carcinoma,mostly showed low signals on T1WI,all lesions on T2WI showed hyperintensity,and most showed diffusion restricted on DWI.All lesions in the arterial phase were intensified in different degrees,and the signals in the portal vein phase and delayed phase were mostly decreased.In the liver cirrhosis nodules group,hyperintense signals were generally found on T1WI,equal or hypointensity on T2WI,and all showed no diffusion restricted on DWI,and one lesion showed arterial phase enhancement,portal phase and delay phase equal signal,other lesions showed no obvious enhancement.Mean ADC value,D value,D*value,and MD value of small hepatocellular carcinoma were（1.00±0.25）×10^-3 mm²/s,（0.89±0.21）×10^-3 mm²/s, （45.15±41.40）×10^-3 mm²/s,（1.22±0.34）×10^-33 mm²/s,and the above parameters of cirrhosis nodules were（1.23±0.17）×10^-3 mm²/s,（1.15±0.17）×10^-3 mm²/s,（82.56±41.85）×10^-3mm²/s,（1.51±0.38）×10^-3mm²/s,the above parameters in the small hepatocellular carcinoma were significantly lower than those in the cirrhotic nodule.Mean MK values of small hepatocellular carcinoma and cirrhotic nodules were0.83±0.24 and 0.68±0.16,respectively,the former was significantly higher than the latter.The mean f value and FA value were not significantly different between the two groups.ADC value,D value,D*value,MD value,MK value had differential diagnostic value for the two groups of lesions.The area under the ROC curve was 0.840,0.856,0.774,0.710,0.696,respectively;the best critical value for differential diagnosis were1.09×10^-3mm²/s,0.94×10^-3mm²/s,67.16×10^-3mm²/s,1.46×10^-3mm²/s,and 0.65, respectively.The corresponding sensitivities were 93.5%,93.5%,71%,54.8%,and76.9%respectively and specificity were 79.5%,66.7%,74.4%,79.5%,54.8%, respectively.The combined diagnostic value of ADC,D,D*,MD and MK was the highest,the area under the ROC curve was 0.942,and the sensitivity and specificity were 96.8%and 82.1%,respectively.ConclusionADC values,D values,f values,MD values and MK values are valuable for identifying small hepatocellular carcinoma and cirrhotic nodules.D value has the higher diagnostic efficiency,and combined diagnosis of three diffusion models is superior to single diffusion model.