The effect of fatty infiltration on the liver tissue enhancement during portal phase computed tomography

RATIONALE AND OBJECTIVES: To correlate the presence of fatty liver and the enhancement value of liver tissue during portal phase computed tomography. MATERIALS AND METHODS: Liver tissue enhancements during portal phase computed tomography were measured in 16 fatty liver and 35 control patients. All patients intravenously received 100 mL of non-ionic contrast material (320 mg iodine/ mL) at a rate of 3 mL/second, and the image acquisition started at 70 seconds. Attenuation values were measured on the 80-second portal phase images and the corresponding unenhanced images, and the contrast enhancement value (HU) of the liver tissue was calculated. Adjusted enhancement values were also calculated with the following equation: adjusted enhancement value = enhancement value (HU)/[dose (grams of iodine)/body weight (kg)]. RESULTS: The contrast enhancement value was significantly reduced in the fatty liver patients compared with the normal controls (37.0 +/- 7.2 vs 49.8 +/- 12.0 HU; P < .0001). This difference was still significant in adjusted enhancement value (80.1 +/- 13.7 vs 93.6 +/- 23.0 HU kg g(-1); P = .01). CONCLUSION: The liver tissue with fatty infiltration was less enhanced than controls, probably because of decreased portal perfusion.     

T(1) independent, T(2) (*) corrected chemical shift based fat-water separation with multi-peak fat spectral modeling is an accurate and precise measure of hepatic steatosis

Purpose:

To determine the precision and accuracy of hepatic fat‐fraction measured with a chemical shift‐based MRI fat‐water separation method, using single‐voxel MR spectroscopy (MRS) as a reference standard.

Materials and Methods:

In 42 patients, two repeated measurements were made using a T₁‐independent, T‐corrected chemical shift‐based fat‐water separation method with multi‐peak spectral modeling of fat, and T₂‐corrected single voxel MR spectroscopy. Precision was assessed through calculation of Bland‐Altman plots and concordance correlation intervals. Accuracy was assessed through linear regression between MRI and MRS. Sensitivity and specificity of MRI fat‐fractions for diagnosis of steatosis using MRS as a reference standard were also calculated.

Results:

Statistical analysis demonstrated excellent precision of MRI and MRS fat‐fractions, indicated by 95% confidence intervals (units of absolute percent) of [?2.66%,2.64%] for single MRI ROI measurements, [?0.81%,0.80%] for averaged MRI ROI, and [?2.70%,2.87%] for single‐voxel MRS. Linear regression between MRI and MRS indicated that the MRI method is highly accurate. Sensitivity and specificity for detection of steatosis using averaged MRI ROI were 100% and 94%, respectively. The relationship between hepatic fat‐fraction and body mass index was examined.

Conclusion:

Fat‐fraction measured with T₁‐independent T‐corrected MRI and multi‐peak spectral modeling of fat is a highly precise and accurate method of quantifying hepatic steatosis. J. Magn. Reson. Imaging 2011;33:873–881. © 2011 Wiley‐Liss, Inc.

     

多回波Dixon技术在非酒精性脂肪肝中脂肪定量及铁沉积的应用进展

非酒精性脂肪性肝病(NAFLD)病人的肝脏脂肪含量和铁过载与其病情的进展密切相关。基于MRI的水脂分离技术即Dixon技术不仅可以测量肝脏脂肪分数,还可得出R2*弛豫图来反映铁沉积情况,其具有无创性、可重复性等优点,在NAFLD的早期诊断、病情评估及疗效评价中具有重要的临床价值。就多回波Dixon技术在肝脏脂肪定量及铁沉积中的研究进展予以综述。     

Comparison of R2* correction methods for accurate fat quantification in fatty liver

Purpose:

To compare the performance of fat fraction quantification using single‐R₂* and dual‐R₂* correction methods in patients with fatty liver, using MR spectroscopy (MRS) as the reference standard.

Materials and Methods:

From a group of 97 patients, 32 patients with hepatic fat fraction greater than 5%, as measured by MRS, were identified. In these patients, chemical shift encoded fat‐water imaging was performed, covering the entire liver in a single breathhold. Fat fraction was measured from the imaging data by postprocessing using 6 different models: single‐ and dual‐R₂* correction, each performed with complex fitting, magnitude fitting, and mixed magnitude/complex fitting to compare the effects of phase error correction. Fat fraction measurements were compared with co‐registered spectroscopy measurements using linear regression.

Results:

Linear regression demonstrated higher agreement with MRS using single‐R₂* correction compared with dual‐R₂* correction. Among single‐R₂* models, all 3 fittings methods performed similarly well (slope = 1.0 ± 0.06, r² = 0.89–0.91).

Conclusion:

Single‐R₂* modeling is more accurate than dual‐R₂* modeling for hepatic fat quantification in patients, even in those with high hepatic fat concentrations. J. Magn. Reson. Imaging 2013;37:414–422. © 2012 Wiley Periodicals, Inc.     

Quantification of hepatic macrosteatosis in living,related liver donors using T1‐independent,T2*‐corrected chemical shift MRI

Purpose:

To evaluate the diagnostic implications of the iterative decomposition of water and fat using echo‐asymmetry and the least‐squares estimation (IDEAL) technique to detect hepatic steatosis (HS) in potential liver donors using histopathology as the reference standard.

Materials and Methods:

Forty‐nine potential liver donors (32 male, 17 female; mean age, 31.7 years) were included. All patients were imaged using the in‐ and out‐of‐phase (IOP) gradient‐echo (GRE) and IDEAL techniques on a 1.5 T MR scanner. To estimate the hepatic fat fraction (FF), two reviewers performed regions‐of‐interest measurement in 15 areas of the liver seen on the IOP images and on the IDEAL‐FF images. The magnetic resonance imaging (MRI) and pathology values of macrosteatosis were correlated using the Pearson correlation coefficient. We analyzed the diagnostic performance of IOP imaging and IDEAL for detecting HS.

Results:

The results of the hepatic‐FF estimated on IDEAL were well correlated with the histologic degree of macrosteatosis (γ = 0.902, P < 0.001). IDEAL showed 100% sensitivity and 91% specificity for detecting HS, and IOP imaging showed 87.5% sensitivity and 97% specificity, respectively.

Conclusion:

IDEAL is a useful tool for the preoperative diagnosis of HS in potential living liver donors; it can also help to avoid unnecessary biopsies in these patients. J. Magn. Reson. Imaging 2012;36:1124–1130. © 2012 Wiley Periodicals, Inc.     

血浆置换联合连续性静脉-静脉血液透析滤过治疗妊娠期急性脂肪肝伴急性肝肾功能衰竭

目的探讨血浆置换(PE)联合连续性静脉-静脉血液透析滤过(CVVHDF)治疗妊娠期急性脂肪肝(AFLP)伴急性肝肾功能衰竭的疗效。方法回顾性分析第四军医大学西京医院2012年1月至2015年1月收治的11例AFLP伴急性肝肾功能衰竭患者的临床资料。本组患者均接受PE联合CVVHDF治疗,观察治疗前后患者的症状、体征、肝肾功能、血氨、凝血系列、血常规等生化指标的变化。结果经对症支持以及PE联合CVVHDF治疗,11例患者存活9例,死亡2例。存活患者治疗前后总胆红素、直接胆红素、血氨均明显下降,凝血酶原时间缩短,纤维蛋白原含量升高,尿素氮、血肌酐等肾功能指标明显下降(P<0.05),肝性脑病缓解、病情好转、转普通病房康复。随访1年,7例患者接受随访,其中1例进展为慢性肾脏病,无患者进展至慢性肝衰竭。结论 PE联合CVVHDF治疗妊娠期急性脂肪肝伴急性肝肾功能衰竭,可取得良好临床效果。     

Gd-EOB-DTPA enhanced MRI of the liver: Correlation of relative hepatic enhancement,relative renal enhancement,and liver to kidneys enhancement ratio with serum hepatic enzyme levels and eGFR

Objectives

To assess the correlation of relative hepatic enhancement (RHE), relative renal enhancement (RRE) and liver to kidneys enhancement ratio (LKR) with serum hepatic enzyme levels and eGFR in Gd-EOB-DTPA enhanced MRI of the liver and to assess threshold levels for predicting enhancement of the liver parenchyma.

Methods

Data of 75 patients who underwent Gd-EOB-DTPA enhanced MRI of the liver were collected. Images were obtained before contrast injection, during the early arterial phase, late arterial phase, venous phase, delayed phase, and hepatobiliary phase which was 20 min after Gd-EOB-DTPA administration. Signal intensity of the liver and the kidneys in all phases was defined using region-of-interest measurements for relative enhancement calculation. Serum hepatic enzyme levels and eGFR were available in all patients. Spearman correlation test was used to test the correlation of RHE, RRE and LKR with serum hepatic enzyme levels and eGFR.

Results

In the hepatobiliary phase all serum hepatic enzymes were significantly correlated with RHE; total bilirubin (TBIL) and cholin esterase (CHE) showed strongest correlations. TBIL and CHE were significantly correlated with RRE in the arterial phases. TBIL and CHE were significantly correlated with LKR in the arterial phase and hepatobiliary phase. eGFR showed no correlation.

Conclusions

In Gd-EOB-DTPA enhanced MRI, TBIL and CHE levels may predict RHE, RRE and LKR.     

Hepatic fat quantification using chemical shift MR imaging and MR spectroscopy in the presence of hepatic iron deposition: validation in phantoms and in patients with chronic liver disease

Purpose:

To compare the accuracy of four chemical shift magnetic resonance imaging (MRI) (CS‐MRI) analysis methods and MR spectroscopy (MRS) with and without T2‐correction in fat quantification in the presence of excess iron.

Materials and Methods:

CS‐MRI with six opposed‐ and in‐phase acquisitions and MRS with five‐echo acquisitions (TEs of 20, 30, 40, 50, 60 msec) were performed at 1.5 T on phantoms containing various fat fractions (FFs), on phantoms containing various iron concentrations, and in 18 patients with chronic liver disease. For CS‐MRI, FFs were estimated with the dual‐echo method, with two T2*‐correction methods (triple‐ and multiecho), and with multiinterference methods that corrected for both T2* and spectral interference effects. For MRS, FF was estimated without T2‐correction (single‐echo MRS) and with T2‐correction (multiecho MRS).

Results:

In the phantoms, T2*‐ or T2‐correction methods for CS‐MRI and MRS provided unbiased estimations of FFs (mean bias, ?1.1% to 0.5%) regardless of iron concentration, whereas the dual‐echo method (?5.5% to ?8.4%) and single‐echo MRS (12.1% to 37.3%) resulted in large biases in FFs. In patients, the FFs estimated with triple‐echo (R = 0.98), multiecho (R = 0.99), and multiinterference (R = 0.99) methods had stronger correlations with multiecho MRS FFs than with the dual‐echo method (R = 0.86; P ≤ 0.011). The FFs estimated with multiinterference method showed the closest agreement with multiecho MRS FFs (the 95% limit‐of‐agreement, ?0.2 ± 1.1).

Conclusion:

T2*‐ or T2‐correction methods are effective in correcting the confounding effects of iron, enabling an accurate fat quantification throughout a wide range of iron concentrations. Spectral modeling of fat may further improve the accuracy of CS‐MRI in fat quantification. J. Magn. Reson. Imaging 2011;33:1390–1398. © 2011 Wiley‐Liss, Inc.

     

Enhanced tumor detection in the presence of fatty liver disease: Cell-specific contrast agents

It is assumed that hepatobiliary, cell-specific contrast agents will be adversely affected by the presence of diffuse liver disease. The diagnostic efficacy for tumor detection in the presence of fatty liver disease was experimentally studied at contrast-enhanced magnetic resonance (MR) imaging with manganese-DPDP (N,N′-dipyridoxylethylenediamine-N,N′-diacetate 5,5′-bis[phosphate]) and gadobenate dimeglumine (Gd-BOPTA/dimeg) and compared with conventional and chemical shift imaging. Carcinosarcoma was implanted into the liver of rats, and fatty liver was induced with L-ethionine. Without contrast agents, the tumor-fatty liver contrast-to-noise ratio (C/N) was increased on T1-weighted and decreased on T2-weighted MR images relative to tumor-bearing control rats without fatty liver. Chemical shift imaging (phase-contrast method) increased the tumor—fatty liver C/N from 2.3 ± 1.0 to 6.1 ± 1.7 (P <.001). Mn-DPDP and Gd-BOPTA/dimeg increased the tumor—fatty liver C/N from -5.4 ± 1.6 to -11.0 ± 1.9 and ?9.8 ± 3.4, respectively (P <.001). The hepatobiliary, cell-specific contrast agents were equally effective in both fatty and nonfatty liver and outperformed both chemical shift and conventional MR imaging in detecting liver tumors.     

环状RNA在非酒精性脂肪肝中作用机制的研究进展

随着肥胖、糖尿病、高血压、高脂血症在全球的流行,非酒精性脂肪肝已经成为全球第一大慢性肝病,其作用机制复杂,至今仍未达成共识。但近年来研究发现,基因调控在其发生发展过程中起着重要作用。环状RNA具有稳定性、广泛性、保守性及组织特异性等性质,在基因表达调控中发挥重要作用。因此,研究非酒精性脂肪肝发生发展过程中环状RNA的调控作用有助于了解其发病机制并推动其临床治疗的进展。     

Doppler waveforms of the hepatic veins in children with diffuse fatty infiltration of the liver

Objective

The aim of this study was to investigate the effect of fatty infiltration of the liver (FIL) on the Doppler waveform pattern in the hepatic veins of obese children.

Methods

In this prospective study, 59 patients with diffuse FIL and 45 normal healthy children who served as control group underwent hepatic vein B-mod and duplex Doppler sonography. The Doppler sonography spectrum of the right hepatic vein was classified into three groups: triphasic waveform, biphasic waveform, and monophasic or flat waveform.

Results

There was a statistically significant difference in the phasicity of hepatic venous flow between patients and control subjects (p < 0.001). The Doppler flow pattern in the right hepatic vein was triphasic in 28 (47.5%), biphasic in 28 (47.5%), and monophasic in 3 (5%) children with fatty liver, while it was triphasic in 43 (95.6%) and biphasic in 2 (4.4%) control subjects. There was an inverse correlation between the sonographic grade of fatty infiltration of the liver and the phasicity of hepatic venous flow (r = −0.479, p < 0.001).

Conclusions

Abnormal right hepatic vein Doppler waveform, biphasic as well as monophasic, can be seen in healthy obese children with diffuse FIL.     

姜黄素对大鼠非酒精性脂肪性肝病的治疗作用及其对肝脏瘦素表达的影响

目的 研究姜黄素对大鼠非酒精性脂肪性肝病(NAFLD)的治疗作用以及对肝脏瘦素表达的影响.方法 采用高脂诱导大鼠NAFLD模型,设立正常对照组、NAFLD模型组及3种不同浓度的姜黄素治疗组.称量各组大鼠体重/肝湿重,计算肝指数;检测各组大鼠血清甘油三酯(TG)和总胆固醇(TC)含量;采用HE染色对各组大鼠肝组织进行病理学检测;采用免疫组织化学法对各组大鼠肝组织瘦素蛋白进行检测;采用PCR法对各组大鼠肝组织瘦素mRNA进行检测.结果 与NAFLD模型组相比,治疗组大鼠肝指数及血清中TG、TC含量均降低,肝组织脂肪变性程度明显减轻.与正常组比较,模型组大鼠肝组织瘦素mRNA及蛋白的表达水平明显升高(P＜0.05).与模型组比较,治疗组大鼠肝组织瘦素mRNA及蛋白的表达含量明显减少(P＜0.05),瘦素mRNA及蛋白的表达水平以高浓度治疗组降低更加明显(P＜0.01).结论 姜黄素可减轻高脂诱导的NAFLD大鼠肝组织的脂肪变性,其机制可能与姜黄素抑制肝组织瘦素的表达有关.     

硫化氢在非酒精性脂肪性肝病大鼠血浆中的浓度变化

目的观察非酒精性脂肪性肝病（NAFLD）大鼠血浆硫化氢（H2s）浓度变化。方法 SPF级雄性sD大鼠按随机数字法分为重度NAFLD模型组（重度组）、轻度NAFLD模型组（轻度组）、空白对照组（对照组）。重度组给予高脂饲料约20g／d;轻度组高脂饲料量为重度组的50％,总重量与重度组相同;对照组给予重度组相同重量的普通饲料。12W后每周处死1只重度组大鼠,观察脂肪肝程度;至16W时,重度组达到重度脂肪肝,终止实验。腹主动脉采集血液,离心取血浆,检测甘油三酯（TG）、胆固醇（TC）、H2S及肝组织匀浆TG浓度。结果 （1）Tc、TG：实验结束时,重度组Tc、TG分别为（8．45±1．19）、（2．43±0．38）mmol／L,轻度组分别为（5．89±1．24）、（1．825±0．41）mmol／L,对照组分别为（1．98±O．14）、（0．84±0．22）mmol／L,3组间均有非常显著差异（P〈0．01）。（2）肝组织TG：重度组（0.82±0．13）mmol／L,轻度组（0．62±0．14）mmol／L,对照组（0．42±O．10）mmol／L,3组间也均有非常显著差异（P〈0．01）。（3）血浆H2S浓度：与对照组比较,重度组和轻度组H2s明显下降（P〈0．01）,重度组比轻度组下降更显著（P〈0．05）。结论NAFLD大鼠血浆H2s浓度下降,与脂肪肝程度相关;H2S下降是由于消耗过多。