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Hepatic steatosis can be observed in chronic liver diseases of different etiologies. The main predisposing factors for hepatic steatosis include chronic viral hepatitis， cholestatic liver disease， alcoholic liver disease， and nonalcoholic fatty liver disease. Simple fatty liver disease is the initial manifestation of hepatic steatosis， followed by steatohepatitis， liver fibrosis， liver cirrhosis， and even hepatocellular carcinoma. With the development of medical imaging technology， magnetic resonance imaging-proton density fat fraction （MRI-PDFF） has been widely used in the diagnosis of fatty liver disease （FLD） in clinical practice. MRI-PDFF is gradually becoming the gold standard for the noninvasive diagnosis of FLD due to its high accuracy and good repeatability. This article reviews the clinical application of MRI-PDFF in liver fat quantification and related research advances.
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A geomagnetic storms is a global disturbance in Earth's magnetic field usually occurred due to abnormal conditions in the interplanetary magnetic field (IMF) & solar wind plasma emissions caused by various solar phenomenon. 138 solar wind streams in solar cycle 22 & 173 solar wind streams in solar cycle 23, have been found, which are associated with proton density, observed during 1986 to 2010. We have analyzed & studied them statistically. We have found that yearly occurrences of geomagnetic streams are strongly correlated with proton density in 11-years sunspot cycle, but no significant correlation between the maximum & minimum phase of solar cycle 22 & 23 have observed
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Objective:To explore the value of proton density fat fraction(PDFF) based on histogram analysis for quantification hepatic steatosis and fibrosis in rabbit model and the interference of hepatic fibrosis to the evaluation of hepatic steatosis with PDFF.Methods:From March to November 2020, 135 New Zealand white rabbits were randomly divided into control group ( n=30) and experimental group ( n=105) using a random number table. The volume ratio of CCl 4 and olive oil was 1∶1 to prepare 50% CCl 4 oil solution, and experimental rabbits were subcutaneously injected with the oil solution. An equal dose of normal saline was subcutaneously injected for control group rabbits. At the end of the 4 th, 8 th, and 12 th week, 35 in the experimental group and 10 rabbits in the control group were randomly selected to conduct the mDixon-Quant scanning, and histogram analysis of PDFF was analyzed including volume, mean, median, standard deviation, 25 th, 50 th, 75 th, 90 th quantile, skewness, kurtosis, entropy and inhomogeneity. After the examination, the rabbits were sacrificed and the liver percentage of steatosis (PSH) and fibrosis (POF) were recorded by semi-quantitative analysis. Spearman correlation analysis was used to correlate PDFF with PSH and POF. Multiple linear regression analysis was used to determine independent PDFF histogram parameters for evaluating PSH and POF. A receiver operator characteristic (ROC) curve was used to assess the diagnostic accuracy of PDFF for discriminating mild from moderate-severe hepatic steatosis and mild from moderate-severe hepatic fibrosis with median of PSH or POF for dichotomy, and DeLong test was used to compare the area under the curve (AUC). With the correction of hepatic fibrosis, correlation coefficient and AUC were compared of PDFF for discrimination mild from moderate-severe hepatic steatosis. Results:The PDFF mean, median, standard deviation, 75 th, 90 th showed correlation with PSH ( r=0.558, 0.522, 0.319, 0.723, 0.646, -0.589, all P<0.05). The entropy and 75 th were independent parameters for evaluating PSH (β=2.347, -5.960, P=0.018, 0.001). The PDFF 75 th was the optimal parameter for discriminating mild from moderate-severe hepatic steatosis with AUC=0.915 ( P=0.001). The PDFF volume, mean, median, standard deviation, 75 th, 90 th, entropy showed correlation with POF ( r=0.355, 0.393, 0.376, 0.298, 0.485, 0.426, -0.681, all P<0.05). The entropy, standard deviation and volume (β=-11.041, 1.356, 0.190, P=0.001, 0.026, 0.016) were independent parameters for evaluation of hepatic fibrosis, and the entropy was the optimal parameter for hepatic fibrosis (AUC=0.771, P=0.001). The correlation between PSH and PDFF 75 th was less pronounced when fibrosis was present ( r=0.512, P=0.001) than when fibrosis was absent ( r=0.751, P=0.002). The PDFF 75 th showed a significant difference in discriminating mild hepatic steatosis from moderate-severe hepatic steatosis after correction of POF (AUC=0.895, 0.950, Z=2.970, P=0.025). Conclusions:PDFF based on histogram analysis provided a noninvasive, accurate estimation of quantification for hepatic steatosis and fibrosis. Hepatic fibrosis reduced the correlation between hepatic steatosis and PDFF and the presence of hepatic fibrosis can confound the quantification of hepatic steatosis with PDFF.
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Objective To investigate the value of magnetic resonance imaging-proton density fat fraction (MRI-PDFF) and FibroScan in the quantitative evaluation of liver fat content in patients with chronic hepatitis B (CHB). Methods A total of 96 patients with CHB who were hospitalized in Department of Hepatology, The Second Clinical Medical College of Guangzhou University of Chinese Medicine, from February 2017 to July 2020 were enrolled, and all patients were diagnosed based on liver pathological examination. MRI-PDFF and FibroScan were performed before surgery. According to the results of liver biopsy, the patients were divided into non-fatty liver disease group with 44 patients, mild fatty liver disease group with 33 patients, and moderate-to-severe fatty liver disease group with 19 patients. A one-way analysis of variance was used for comparison of normally distributed continuous data between multiple groups, and the least significant difference t -test was used for further comparison between two groups; the Kruskal-Wallis H test was used for comparison of non-normally distributed continuous data between multiple groups, and the Mann-Whitney U test was used for further comparison between two groups; Bonferroni correction was also performed. The receiver operating characteristic (ROC) curve was plotted to analyze the area under the ROC curve (AUC) of hepatic fat fraction (HFF) and controllable attenuation parameters (CAP) in the diagnosis of fatty liver disease and obtain their sensitivities, specificities, and optimal cut-off values. The intraclass correlation coefficient was used to investigate the consistency of MRI-PDFF data. Results The moderate-to-severe fatty liver disease group had a significant increase in MRI-PDFF HFF compared with the non-fatty liver disease group and the mild fatty liver disease group (all P < 0.05), and the mild fatty liver disease group had a significant increase in MRI-PDFF HFF compared with the non-fatty liver disease group( P < 0.05). The moderate-to-severe fatty liver disease group had a significant increase in FibroScan CAP compared with the non-fatty liver disease group and the mild fatty liver disease group (all P < 0.05), and the mild fatty liver disease group had a significant increase in FibroScan CAP compared with the non-fatty liver disease group ( P < 0.05). In the diagnosis of mild fatty liver disease, MRI-PDFF HFF had an AUC of 0.901 ( P < 0.001), a sensitivity of 90.9%, and a specificity of 82.7% at the optimal cut-off value of 5.1%, and in the diagnosis of moderate-to-severe fatty liver disease, MRI-PDFF HFF had an AUC of 0.972 ( P < 0.001), a sensitivity of 96.1%, and a specificity of 89.5% at the optimal cut-off value of 9.7%. In the diagnosis of mild fatty liver disease, FibroScan CAP had an AUC of 0.829 ( P < 0.001), a sensitivity of 77.3%, and a specificity of 78.8% at the optimal cut-off value of 258.5 dB/m, and in the diagnosis of moderate-to-severe fatty liver disease, FibroScan CAP had an AUC of 0.830 ( P < 0.001), a sensitivity of 76.6%, and a specificity of 78.9% at the optimal cut-off value of 285.5 dB/m. Conclusion Both MRI-PDFF and FibroScan can objectively evaluate the degree of fatty liver disease in patients with CHB. MRI-PDFF HFF and FibroScan CAP can be used as noninvasive markers for the quantitative analysis of CHB with hepatic steatosis, and MRI-PDFF HFF tends to have higher diagnostic efficiency.
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Magnetic resonance imaging-proton density fat fraction (MRI-PDFF) is an imaging method that uses magnetic resonance technology to perform objective, quantitative, and noninvasive assessment of fat in the whole liver. This article mainly analyzes the correlation between MRI-PDFF value and the “gold index” nonalcoholic steatohepatitis (NASH) liver histological evaluation and explores its advantages and disadvantages as a noninvasive evaluation index for NASH clinical trials. Current studies have shown that MRI-PDFF, as an emerging noninvasive technique, is suitable for quantifying liver fat content and evaluating the degree of hepatic steatosis, but it cannot replace liver biopsy as a tool for the diagnosis of NASH. Meanwhile, the relative reduction in MRI-PDFF after drug intervention is not only highly correlated with the improvement of fat deposition, but also correlated with the improvement of inflammation and ballooning degeneration, and MRI-PDFF can predict the overall improvement of liver histology to a certain extent. Therefore, MRI-PDFF is considered a potential surrogate endpoint for NASH clinical trials.
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PURPOSE: By using the micro-imaging unit modified from NMR spectrometer, the high resolution MRI protocols of finer than 100 micron in 5 minutes, is sought for mouse, which plays a central role in animal studies MATERIALS AND METHODS: C57BL/6 mouse, lighter than 50 gram, is used for the experiments. The superconducting magnet is vertical type with 89 mm inner diameter at 4.9 Tesla. The diameter of rf-coil is 30 mm. Mostly used techniques are the fast spin echo and the gradient echo pulse sequence. RESULTS: For 2D images, proton density and T2 weighted images are obtained and their optimum experimental variables were sought. Minute structure of mouse brain can be recognized and 3D brain image is also obtained additionally. 3D image will be useful particularly for the dynamic contrast study using various contrast agents. CONCLUSION: Like the case of human and other small animals, the high resolution of mouse brain is enough to recognize the minute structure of it. Recently, similar studies are reported domestically, but it seems only a beginning stage. Due to easiness of breeding /control, mouse MRI study will soon play a vital part in brain study.