Dynamic contrast‐enhanced magnetic resonance imaging of abdominal solid organ and major vessel: Comparison of enhancement effect between Gd‐EOB‐DTPA and Gd‐DTPA

Purpose

To evaluate the differences in enhancement of the abdominal solid organ and the major vessel on dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) obtained with gadolinium ethoxybenzyldiethylenetriamine pentaacetic acid (Gd‐EOB‐DTPA: EOB) and gadolinium diethylenetriamine pentaacetic acid (Gd‐DTPA) in the same patients.

Materials and Methods

A total of 13 healthy volunteers underwent repeat assessments of abdominal MR examinations with DCE‐MRI using either Gd‐DTPA at a dose of 0.1 mmol/kg body weight or EOB at a dose of 0.025 mmol/kg body weight. DCE images were obtained at precontrast injection and in the arterial phase (AP: 25 seconds), portal phase (PP: 70 seconds), and equilibrium phase (EP: 3 minutes). The signal intensities (SIs) of liver at AP, PP, and EP; the SIs of spleen, renal cortex, renal medulla, pancreas, adrenal gland, aorta at AP; and the SIs of portal vein and inferior vena cava (IVC) at PP were defined using region‐of‐interest measurements, and were used for calculation of signal intensity ratio (SIR).

Results

The mean SIRs of liver (0.195 ± 0.140), spleen (1.35 ± 0.353), renal cortex (1.58 ± 0.517), renal medulla (0.548 ± 0.259), pancreas (0.540 ± 0.183), adrenal gland (1.04 ± 0.405), and aorta (2.44 ± 0.648) at AP as well as the mean SIRs of portal vein (1.85 ± 0.477) and IVC (1.16 ± 0.187) at PP in the EOB images were significantly lower than those (0.337 ± 0.200, 1.99 ± 0.443, 2.01 ± 0.474, 0.742 ± 0.336, 0.771 ± 0.227, 1.26 ± 0.442, 3.22 ± 1.20, 2.73 ± 0.429, and 1.68 ± 0.366, respectively) in the Gd‐DTPA images (P < 0.05 each). There was no significant difference in mean SIR of liver at PP between EOB (0.529 ± 0.124) and Gd‐DTPA (0.564 ± 0.139). Conversely, the mean SIR of liver at EP was significantly higher with EOB (0.576 ± 0.167) than with Gd‐DTPA (0.396 ± 0.093) (P < 0.001).

Conclusion

Lower arterial vascular and parenchymal enhancement with Gd‐EOB, as compared with Gd‐DTPA, may require reassessment of its dose, despite the higher late venous phase liver parenchymal enhancement. J. Magn. Reson. Imaging 2009;29:636–640. © 2009 Wiley‐Liss, Inc.     

Evaluating the severity of nonalcoholic steatohepatitis with superparamagnetic iron oxide‐enhanced magnetic resonance imaging

Purpose

To evaluate the utility of noninvasive assessment of human nonalcoholic fatty liver disease (NAFLD) patients using superparamagnetic iron oxide (SPIO)‐enhanced MRI.

Materials and Methods

Nineteen NAFLD patients underwent SPIO‐enhanced MRI. The values of τ, a time constant for an exponential approximation, were calculated using gradient‐echo echo‐planar imaging, and the values of %T2, a marker of the T2 relaxation effect of SPIO, were calculated using T2‐weighted fast spin‐echo images. Correlations between these values and the histological NAFLD activity scores were evaluated. The study protocol was approved by our Institutional Review Board and all patients gave informed consent.

Results

There was a statistically significant relationship between the NAFLD activity scores and the τ values (r = 0.66, P = 0.002). The %T2 values were also significantly correlated with the NAFLD activity score (r = ?0.58, P = 0.009). A cutoff τ value of 42.8 predicted “definitive NASH” (NAFLD activity score ≥5) with a specificity of 66.7% and a sensitivity of 99.9%, whereas a cutoff %T2 value of 32.5 predicted “definitive NASH” with a specificity of 72.7% and a sensitivity of 87.5%.

Conclusion

Noninvasive SPIO‐enhanced MRI may be helpful for identifying NASH patients among patients suspected of having NAFLD. J. Magn. Reson. Imaging 2008;28:1444–1450. © 2008 Wiley‐Liss, Inc.

     

High‐risk nodules detected in the hepatobiliary phase of Gd‐EOB‐DTPA‐enhanced mr imaging in cirrhosis or chronic hepatitis: Incidence and predictive factors for hypervascular transformation,preliminary results

Purpose:

To evaluate the incidence and predictive factors of hypervascular transformation during follow‐up of “high‐risk nodules” detected in the hepatobiliary phase of initial Gd‐EOB‐DTPA‐enhanced MRI in chronic liver disease patients.

Materials and Methods:

A total of 109 patients with chronic liver disease who underwent Gd‐EOB‐DTPA‐enhanced MRI several times were investigated. Of these, 43 patients had 76 high‐risk nodules with both hypointensity in the hepatobiliary phase and hypovascularity in the arterial phase of initial MRI. These nodules were observed until hypervascularity was detected. MRI and clinical findings were compared to assess the incidence and potential predictive factors for hypervascular transformation between the group showing hypervascular transformation and the group not showing hypervascularization.

Results:

The median observation period was 242.5 ± 203.2 days (range, 47–802 days). Overall, 24 of 76 high‐risk nodules (31.6%) showed hypervascular transformation during follow‐up (median observation period, 186.0 ± 190.3 days). The growth rate of the nodules (P < 0.001), the presence of fat within nodules (P = 0.037), and hyperintensity on T1‐weighted images (P = 0.018) were significantly correlated with hypervascularization.

Conclusion:

Subsets of high‐risk nodules tended to show hypervascular transformation during follow‐up, with an increased growth rate, the presence of fat, and hyperintensity on T1‐weighted images as predictive factors. J. Magn. Reson. Imaging 2013;37:1377–1383. © 2013 Wiley Periodicals, Inc.     

Assessing liver function using dynamic Gd‐EOB‐DTPA‐enhanced MRI with a standard 5‐phase imaging protocol

Purpose:

To evaluate liver function obtained by tracer‐kinetic modeling of dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) data acquired with a routine gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd‐EOB‐DTPA)‐enhanced protocol.

Materials and Methods:

Data were acquired from 25 cases of nonchronic liver disease and 94 cases of cirrhosis. DCE‐MRI was performed with a dose of 0.025 mmol/kg Gd‐EOB‐DTPA injected at 2 mL/sec. A 3D breath‐hold sequence acquired 5 volumes of 72 slices each: precontrast, double arterial phase, portal phase, and 4‐minute postcontrast. Regions of interest (ROIs) were selected semiautomatically in the aorta, portal vein, and whole liver on a middle slice. A constrained dual‐inlet two‐compartment uptake model was fitted to the ROI curves, producing three parameters: intracellular uptake rate (UR), extracellular volume (Ve), and arterial flow fraction (AFF).

Results:

Median UR dropped from 4.46 10^?2 min^?1 in the noncirrhosis to 3.20 in Child–Pugh A (P = 0.001), and again to 1.92 in Child–Pugh B (P < 0.0001). Median Ve dropped from 6.64 mL 100 mL^?1 in the noncirrhosis to 5.80 in Child–Pugh A (P = 0.01). Other combinations of Ve and AFF changes were not significant for any group.

Conclusion:

UR obtained from tracer kinetic analysis of a routine DCE‐MRI has the potential to become a novel index of liver function. J. Magn. Reson. Imaging 2013;37:1109–1114. © 2012 Wiley Periodicals, Inc.

     

Gd‐EOB‐DTPA‐enhanced MR imaging: Prediction of hepatic fibrosis stages using liver contrast enhancement index and liver‐to‐spleen volumetric ratio

Purpose:

To develop and evaluate a quantitative parameter for staging hepatic fibrosis by contrast enhancement signal intensity and morphological measurements from gadoxetic acid (Gd‐EOB‐DTPA)‐enhanced MR imaging.

Materials and Methods:

MR images were obtained in 93 patients; 75 patients had histopathologically proven hepatic fibrosis and 18 patients who had healthy livers were evaluated. The liver‐to‐muscle signal intensity ratio (SI_post = SIliver/SImuscle), contrast enhancement index (CEI = SIpost/SIpre), and liver‐to‐spleen volumetric ratio (VR = Vliver/Vspleen) were evaluated for staging hepatic fibrosis.

Results:

VR was most strongly correlated with fibrosis stage (7.21; r = ?0.83; P < 0.001). Sensitivity, specificity, and area under the ROC curve demonstrated by linear regression formula generated by VR and CEI in predicting fibrous scores were 100%, 73%, and 0.91, respectively, for the detection of hepatic fibrosis F1 or greater (≥ F1),100%, 87%, and 0.96 for ≥ F2, 74%, 98%, and 0.93 for ≥ F3 and 91%, 100%, and 0.97 for F4.

Conclusion:

The liver‐to‐spleen volumetric ratio and contrast enhancement index were reliable biomarkers for the staging of hepatic fibrosis on Gd‐EOB‐DTPA‐enhanced MR imaging. J. Magn. Reson. Imaging 2012;36:1148–1153. © 2012 Wiley Periodicals, Inc.

     

Novel liver macromolecular MR contrast agent with a polypropylenimine diaminobutyl dendrimer core: comparison to the vascular MR contrast agent with the polyamidoamine dendrimer core.

As MRI contrast agents, more hydrophobic molecules reportedly accumulate in the liver and thus are potentially useful as liver MRI contrast agents. In this study, a generation-4 polypropylenimine diaminobutane dendrimer (DAB-Am64), which is expected to be more hydrophobic than the generation-4 polyamidoamine dendrimer (PAMAM-G4D), was used to synthesize a conjugate with 2-(p-isothiocyanatobenzyl)-6-methyl-diethylenetriaminepentaacetic acid (1B4M) [DAB-Am64-(1B4M-Gd)(64)] for complexing Gd(III) ions. This DAB conjugate quickly accumulated in the liver and its characteristics were studied and compared with those of a PAMAM conjugate [PAMAM-G4D-(1B4M-Gd)(64)], which is known to be a useful vascular MRI contrast agent, in regard to its availability as a liver MRI contrast agent. DAB-Am64-(1B4M-Gd)(64) accumulated significantly more in the liver and less in blood than PAMAM-G4D-(1B4M-Gd)(64) (P < 0.001). Contrast-enhanced MRI with DAB-Am64-(1B4M-Gd)(64) was able to homogeneously enhance liver parenchyma and visualize both portal and hepatic veins of 0.5 mm diameter in mice. In conclusion, DAB-Am64-(1B4M-Gd)(64) is a good candidate for a liver MRI contrast agent.     

Phantom and animal studies of a new hepatobiliary agent for MR imaging: comparison of Gd-DTPA-DeA with Gd-EOB-DTPA

PURPOSE: To investigate the characteristics of Gd-DTPA-DeA as a hepatobiliary contrast agent for MR imaging in comparison with those of Gd-EOB-DTPA. MATERIALS AND METHODS: We undertook phantom experiments to assess T1 relaxivity for Gd-DTPA-DeA, Gd-EOB-DTPA, and Gd-DTPA in human plasma. For Gd-DTPA-DeA and Gd-EOB-DTPA, we evaluated the contrast effect in rats using an SPGR sequence. The contrast ratios of liver and abdominal aorta were measured up to 21 minutes after intravenous administration of the agents. Visualization of the bile duct and renal pelvis was also assessed. RESULTS: In human plasma, T1 relaxivity was similar for Gd-DTPA-DeA and Gd-EOB-DTPA, and higher than those for Gd-DTPA. Whereas the contrast ratio of liver peaked about five minutes after the injection of Gd-EOB-DTPA and was followed by a subsequent decline, a continuous rise was shown for Gd-DTPA-DeA, resulting in a larger maximal contrast effect. Contrast ratios of the abdominal aorta were larger for Gd-DTPA-DeA. Biliary excretion was observed for both agents but occurred earlier with Gd-EOB-DTPA. While renal excretion was shown for all rats three minutes after the injection of Gd-EOB-DTPA, it was not observed for Gd-DTPA-DeA. CONCLUSION: Gd-DTPA-DeA may be used as a hepatobiliary contrast agent and shows different pharmacokinetics from Gd-EOB-DTPA.     

超顺磁性氧化铁MR成像评估大鼠非酒精性脂肪肝炎枯否细胞功能的初步研究

目的 初步探讨超顺磁性氧化铁(SPIO)作为MRI对比剂评估大鼠非酒精性脂肪肝炎(NASH)枯否细胞(KC)功能的可行性.方法 20只雄性SD大鼠按完全随机法分为实验组和对照组,每组10只,实验组喂养高脂饲料,对照组喂养普通饲料.8周后对所有大鼠行肝脏MRI及SPIO增强扫描,计算肝脏组织平均信号强度下降百分比(PSIL)和SPIO增强前后肝脾对比信号强度比值(RSIR),测定血清总胆固醇(TC)和甘油三酯(TG)值,并取肝脏标本行HE和普鲁士蓝染色分析病理表现.采用两组独立样本均数t检验比较2组不同序列SPIO增强后PSIL和RSIR值的差异.结果 实验组1只大鼠因麻醉过深死亡,其余9只血清TC及TG值分别为(6.58±1.25)和(1.53±0.23)mmoL/L,较对照组[分别为(1.64±0.22)和(0.55±0.14)mmol/L]均明显升高(t值分别为11.716和11.588,P值均＜0.01).SPIO增强扫描后两组肝实质信号强度在各序列明显下降,在PDWI及T_1WI上实验组PSIL分别为(34.78±4.51)%和(60.38±3.49)%,较实验组[分别为(64.96±2.42)%和(81.08±1.66)%]小,差异有统计学意义(t值分别为-18.451和-16.240,P值均＜0.01).PDWI、T_2WI、T_2~*WI和T_1WI序列实验组RSIR分别为1.002±0.141、5.000±0.516、20.004±1.490和2.601±0.077,均较对照组(0.400±0.102、1.500±0.115、0.503±0.105和-0.300±0.058)大(t值分别为10.745、19.800、39.168和92.785,P值均＜0.01).实验组肝脏组织中普鲁士蓝染色阳性颗粒积分(2.33±0.50)分较对照组(4分)明显减少(t=-10.000,P＜0.01).结论 高脂饮食诱导的SD大鼠NASH模型接近人类发病情况且容易建立,临床应用型1.5 T MR通过SPIO增强肝脏扫描可评估KC的功能,提示NASH的发病机制与KC功能的下降有关.     

大鼠CCL4模型诱发的脂肪肝Mn-DPDP磁共振研究

目的 :评价Mn DPDP磁共振检查对大鼠脂肪肝的诊断价值。方法 :选取 70只体重为 2 0 0～ 2 5 0gSD健康大鼠 ,随机分为两组 :对照组 10只 ,给以正常饲料和饮用水喂养 ;处理组 60只 ,制成CCL4脂肪肝纤维化模型。从处理组中每周随机抽取第 1～ 13周末各 4～ 5只 ,每只大鼠经尾静脉注射 2 5 μmol/kgMn DPDP ,对肝脏进行FMPSPGR和SET1WI序列扫描 ,扫描延迟时间为 15min、3 0min、1、2、3和 4h。MRI检查后取肝脏大体标本HE染色后进行病理学对照。结果 :大鼠脂肪肝在FMPSPGR序列增强前平扫信号比正常对照组低 ,两组差异有显著性意义 (P <0 .0 5 ) ,不同程度脂肪肝之间差异无显著性意义 (P >0 .0 5 ) ;增强后信号绝对值较对照组低 ,差异有极显著性意义 (P <0 .0 0 1) ,但相互之间差异无显著性意义 (P >0 .0 5 )。大鼠脂肪肝在SET1WI序列增强前平扫信号较对照组高 ,中度和重度脂肪变比对照组和轻度脂肪变信号绝对值高 ,差异有显著性意义 (P <0 .0 5 ) ,二者之间差异无显著性意义 (P >0 .0 5 )。增强后轻度脂肪变信号绝对值较相同时间点对照组低 ;中度脂肪变在增强后 15min信号绝对值较对照组稍低 ,随后各时间点较对照组升高 ;重度脂肪变在增强后各时间点信号绝对值较对照组升高。结论 :大鼠脂肪肝注射Mn DPDP后采