Comparative Analysis Of Quantitative Assessment Of Nonalcoholic Fatty Liver Disease: By IDEAL-IQ And MRS

Background and PurposeFatty liver, also known as hepatic steatosis, refers to fat mainly meaning triglyceride in the liver cells abnormal and excessive deposition. According to etiology, fatty liver can be classified into alcoholic liver disease(alcoholic liver disease, AFLD) and nonalcoholic liver disease(nonalcoholic liver disease, NAFLD), this is the most common type of classification. The incidence of fatty liver was higher, it is increasingly frequent among adults and children. Its prevalence reaches 20-30% in the general population and 75-100% in obese and diabetes populations. Fatty liver incidence and mortality due to geographical differences and different, the economic of Europe is developed, the incidence of fatty liver is slightly higher than the average. In a developing country, such as china, the incidence of fatty liver is relatively lower, but in recent years, with the enhancement of the standard of living and quality, the incidence of fatty liver increased year by year, the type is also more diversified, and seriously affect people,s lives, so it is vital to early diagnosis of fatty liver. The most common method to diagnosis fatty liver is ultrasound, it can be used for screening and follow-up, but the results is dependent on the operator highly. Then CT, by measuring the hepatic parenchyma to diagnosis fatty liver quickly, but the existence of ionizing and other precipitates affects the results, and the radiation is vulnerable by people, so its application is limited. In recent years, MR imaging techniques develop rapidly, advantages that show soft tissue much clearer than two means combined with excellent soft tissue contrast, noninvasive functional imaging and non-ionizing radiation. On previous literature, researchers discuss the relevance of magnetic resonance spectroscopy(MRS) and pathological, also reported the comparative study of the MRI and ultrasound, CT to diagnosis fatty liver, respectively, but they did not related to quantitative research. Our study is to explore the effectiveness of MR quantitative diagnosis fatty liver, and introduct the new quantitative method IDEAL-IQ, and explore its performance to quantitative diagnosis fatty liver. Therefore, the object of this study is:1、make the grading standard of hepatic steatosis by IDEAL-IQ and MRS; 2 、 explore the relevance of IDEAL-IQ and MRS quantifying liver fat content. Materials and MethodsCase of GE Discovery750 3.0T MR scanner, 8-channel phased-array body coil, 87 patients with fatty liver prospective study, another 20 cases were randomly selected healthy people. Conventional scan sequence using coronal breath single shot fast spin-echo(T2WI / TSE) and axial fat-suppressed respiratory triggered; fast spoiled gradient echo sequence pairs(FSPGR-dual echo).DWI(diffusion-weighted imaging, DWI): Traditional DWI sequence selected b = 0,800 s / mm2; MRS use point resolved selective spectroscopy, and IDEAL-IQ(iterative decomposition of water and fat with Echo asymmetry and the Least Squares Estimation Quantification sequence) is also used.All data use SPSS17.0 software package for processing. Results1.Among 107 subjects, IDEAL-IQ scan winner accounted for 98.5%(105/107);MRS accounted for 71.0%(76/107),fatty liver 60,normal people 16;scanning time, IDEAL-IQ and MRS was(21±1)s,(253.8±21.6)s, respectively, and the average value was 21 s, 253.8s,respectively.2.With CT as the gold standard, divided into fatty liver group and normal group, drawing ROC curve, the optimal threshold of RLC and FF to diagnosis fatty liver was 7.24%, 8.50%,respectively;the sensitivity of RLC and FF was 90.0%, 90.0%,and the specificity was 87.5%, 93.7%.3.With CT as the gold standard, the fatty liver was divided into mild, moderate and severe group, and drawing IDEAL-IQ,MRS diagnosis the mild to moderate and moderate to severe ROC curve, the optimal threshold of IDEAL-IQ was 15.27%, 27.00%;the optimal threshold of MRS was 17.58%, 26.04%;then the sensitivity of IDEAL-IQ and MRS identified the mild to moderate was 97.0%, 69.7%,the specificity was 94.4%, 61.1%; the sensitivity of IDEAL-IQ and MRS identified the moderate to severe was 100%, 66.7%,the specificity was 72.7%, 81.8%.4.The result of RLC and FF was 21.04±9.07, 19.72±8.73,value of the difference was not statistically significant(P=0.344).The scatter plot showed that there was a linear relationship between the two, Pearson correlation analysis obtained RLC and FF was positively correlated(r=0.784). Conclusions1. IDEAL-IQ, MRS can be quantitatively accurate diagnosis of fatty liver.2. The correlation coefficient of IDEAL-IQ and MRS was 0.784;the threshold values were 8.50%, 7.24%;the threshold values of diagnosis of mild to moderate,moderate to severe were 15.27%, 27.00% and 17.58%, 26.04%.3. On scanning success rate, scanning time, IDEAL-IQ are better than MRS, it can replace the cumbersome step of MRS, and can become an independent standards to diagnosis fatty liver.