Dynamic Contrast-Enhanced Magnetic Resonance Imaging with Gd-EOB-DTPA for the Evaluation of Liver Fibrosis Induced by Carbon Tetrachloride in Rats

Effects of changes in SHP2 expression on liver fibrosis by influencing the apoptosis of hepatic stellate cells

Accumulating research has revealed that src-homology domain 2-containing protein tyrosine phosphatase-2 (SHP2), an oncogenic protein tyrosine phosphatase, is associated with liver fibrosis. Currently, it is still unclear whether SHP2 affects liver fibrosis by influencing the apoptosis of hepatic stellate cells (HSC). In present study, we investigate effects of SHP2 expression changes on liver fibrosis, with special emphasis on the apoptosis of HSC. Using adenovirus vector, wild-type SHP2 gene and short hairpin RNA targeting SHP2 were introduced into rats with liver fibrosis and LX-2 cells in vitro. The expressions of type I and III collagen, pathological and functional changes, collagen deposition in rat liver and apoptosis of LX-2 cells were detected by immunohistochemical and HE staining, automated biochemical analyzer, Masson trichrome staining, and TUNEL. This study showed that overexpression of SHP2 exacerbated dysfunction, inflammatory damage, collagen deposition and increased expression of type I and III collagen in rat liver reduced apoptosis of LX-2 cells. On the contrary, low expression of SHP2 alleviated the aforementioned detection indicators of rats and promoted apoptosis of LX-2 cells. In conclusion, the downregulation of SHP2 expression alleviates liver fibrosis by inducing the apoptosis of HSC, while overexpressed SHP2 exacerbates liver fibrosis by inhibiting the apoptosis of HSC.

Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced MRI improves diagnosis and efficacy evaluation of early-stage hepatocellular carcinoma

OBJECTIVE

To investigate the use of hepatocyte-specific contrast agent Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (EOB-MRI) in the diagnosis and efficacy evaluation of patients with early-stage hepatocellular carcinoma.

METHODS

A retrospective clinical study was conducted on 157 patients diagnosed with stage Ia-Ib liver cancer. Of these, 100 patients underwent preoperative EOB-MRI, while 57 patients underwent contrast-enhanced computerized tomography (CECT). The study compared the accuracy, sensitivity, and specificity of these two imaging modalities in diagnosing early-stage hepatocellular carcinoma. In the EOB-MRI group, 100 patients underwent radiofrequency ablation or interventional procedures, and imaging data were collected post-scan. The following arterial and hepatobiliary phase enhancement features were analyzed: length-diameter difference (LDD), signal intensity ratio of metastases to liver parenchyma (RatioM/L), relative signal intensity difference (RSID), normalized relative enhancement (NRE), contrast-to-noise ratio (CNR), and apparent diffusion coefficient (ADC) values. Based on treatment outcomes, patients were categorized into high and low response rate groups, and the imaging parameters between these two groups were compared. Univariate and multivariate analyses were performed to evaluate the significance of these parameters in predicting patient outcomes.

RESULTS

The accuracy of lesion detection by EOB-MRI was 97.4%, significantly higher than that of CECT (80.0%) (P < 0.05). The area under the curve (AUC) for the EOB-MRI group was 0.923 (95% CI: 0.784-1.000), with a sensitivity of 97.4% and a specificity of 83.3%. In comparison, the AUC for the CECT group was 0.712 (95% CI: 0.582-0.843), with a sensitivity of 77.2% and a specificity of 65.2%. The median response rate of patients with early-stage hepatocellular carcinoma to systemic therapy was 60% (range: 36%-81%). Using 60% as the cut-off value, patients were divided into a high response rate group (n = 53) and a low response rate group (n = 47). Univariate and multivariate logistic regression analyses of the EOB-MRI parameters in both groups identified ADC and NRE as independent predictors for assessing the treatment efficacy of early-stage hepatocellular carcinoma.

CONCLUSION

EOB-MRI is effective for both the diagnosis and evaluation of treatment efficacy in early-stage hepatocellular carcinoma.

Lobe-Based Hepatic Uptake Index of Gd-EOB-DTPA on Contrast-Enhanced MRI to Quantitatively Discriminate between Compensated and Decompensated Hepatitis B-Related Cirrhosis

Purpose

To use hepatic uptake index (HUI) of liver lobes on gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) to discriminate between patients with hepatitis B-related cirrhosis in compensated and decompensated statuses.

Methods

Forty-four consecutive patients with hepatitis B-related cirrhosis who underwent Gd-EOB-DTPA-enhanced MRI were divided into compensated and decompensated statuses based on clinical evaluation. Volume and signal intensity of individual lobes were retrospectively measured to calculate HUI of the right liver lobe (RHUI), medial (MHUI) and lateral (LHUI) left liver lobes, and caudate lobe (CHUI). Spearman's rank correlation analyses were performed to evaluate relationships of lobe-based HUI with Child-Pugh and model for end-stage liver disease (MELD) scoring system scores in compensated and decompensated statuses. The Mann-Whitney U-test was used to compare the lobe-based HUI between compensated and decompensated statuses. The performance of lobe-based HUI in distinguishing cirrhosis was evaluated using receiver operating characteristic (ROC) analysis, and the area under the ROC curve (AUC) was calculated as a measure of accuracy. Delong's method was used for statistical analysis to elucidate which HUI is optimal.

Results

Compensated and decompensated liver cirrhosis were confirmed in 25 (56.82%) and 19 (43.18%) patients, respectively. According to Spearman's rank correlation analysis, RHUI, MHUI, LHUI, and CHUI were all significantly associated with Child-Pugh and MELD scores (all P values <0.05). Receiver operating characteristic analysis demonstrated that among all lobe-based HUI parameters, RHUI could best perform the previous discrimination with a cut-off of 485.73 and obtain an AUC of 0.867. The AUC of RHUI improved and was significantly different from that of MHUI, LHUI, and CHUI (P = 0.03, P = 0.007, and P < 0.001, respectively, Delong's test).

Conclusions

The RHUI could help quantitatively discriminate hepatitis B-related cirrhosis between compensated and decompensated statuses.

Structural and practical identifiability of contrast transport models for DCE-MRI

Contrast transport models are widely used to quantify blood flow and transport in dynamic contrast-enhanced magnetic resonance imaging. These models analyze the time course of the contrast agent concentration, providing diagnostic and prognostic value for many biological systems. Thus, ensuring accuracy and repeatability of the model parameter estimation is a fundamental concern. In this work, we analyze the structural and practical identifiability of a class of nested compartment models pervasively used in analysis of MRI data. We combine artificial and real data to study the role of noise in model parameter estimation. We observe that although all the models are structurally identifiable, practical identifiability strongly depends on the data characteristics. We analyze the impact of increasing data noise on parameter identifiability and show how the latter can be recovered with increased data quality. To complete the analysis, we show that the results do not depend on specific tissue characteristics or the type of enhancement patterns of contrast agent signal.

Diagnosis and differential diagnosis of dermatofibrosarcoma protuberans: Utility of high-resolution dynamic contrast-enhanced (DCE) MRI

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is a kind of low-grade malignant spindle cell neoplasm, the diagnosis, and treatment, which have markedly attracted clinicians' attention for its repeated recurrence. High-resolution magnetic resonance imaging (HR-MRI) has shown unique capabilities in diagnosis of various cutaneous tumors.

MATERIALS AND METHODS

Data of 29 patients with clinically suspected DFSPs and undergoing dynamic contrast-enhanced (DCE) HR-MRI preoperatively were prospectively collected. The HR-MRI qualitative features were evaluated and compared. The DCE-associated quantitative parameters and the time-signal intensity curve (TIC) types were provided using DCE sequences.

RESULTS

A total of 7 DFSPs, nine dermatofibromas (DF, including four cases of cellular variant [CDF]), 12 keloids, and one nodular fasciitis were enrolled. DFSP showed the largest major diameter and the deepest depth. Five DFSPs (71.4%) showed ill-defined margins as well as infiltration of peripheral adipose. All DFSPs showed irregular shape. Most DFSPs presented hyperintensity on T₂ WI (71.4%) and iso-intensity on T₁ WI (85.7%). Six cases (85.7%) had significant enhancement, and six cases (85.7%) had homogeneous enhancement. There were significant differences of K^trans , K_ep , V_e and iAUC values among DFSPs, DFs, and keloids, and DFSP had the highest values for these parameters. Six DFSPs (85.7%) and four CDFs (100%) showed type-III TICs, while the other lesions showed type-Ⅰor type-Ⅱ TICs.

CONCLUSIONS

DCE-HR-MRI could show the growth characteristics of DFSPs, which was of great value for the diagnosis and differential diagnosis of DFSPs and was helpful for the determination of treatment options, thereby to improve the prognosis of patients.

Pharmacological Effects and Molecular Protective Mechanisms of Astragalus Polysaccharides on Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) has been renamed metabolic dysfunction-associated fatty liver disease (MAFLD), a condition for which there is now no authorized treatment. The search for new medications to treat MAFLD made from natural substances is gaining traction. The function of anti-oxidant, anti-inflammation, hypoglycaemic, antiviral, hypolipidemic, and immunomodulatory actions of Astragalus polysaccharides (APS), a chemical molecule isolated from Astragalus membranaceus, has become the focus of therapeutic attention. We have a large number of papers on the pharmacological effects of APS on NAFLD that have never been systematically reviewed before. According to our findings, APS may help to slow the progression of non-alcoholic fatty liver disease (NAFL) to non-alcoholic steatohepatitis (NASH). Lipid metabolism, insulin resistance (IR), oxidative stress (OS), endoplasmic reticulum stress (ERS), inflammation, fibrosis, autophagy, and apoptosis are some of the pathogenic pathways involved. SIRT1/PPARα/FGF21, PI3K/AKT/IRS-1, AMPK/ACC, mTOR/4EBP-1/S6K1, GRP78/IRE-1/JNK, AMPK/PGC-1/NRF1, TLR4/MyD88/NF-κB, and TGF-β/Smad pathways were the most common molecular protective mechanisms. All of the information presented in this review suggests that APS is a natural medication with a lot of promise for NAFLD, but more study, bioavailability studies, medicine type and dosage, and clinical proof are needed. This review could be useful for basic research, pharmacological development, and therapeutic applications of APS in the management of MAFLD.

Comparing and combining MRE, T1ρ, SWI, IVIM, and DCE-MRI for the staging of liver fibrosis in rabbits: Assessment of a predictive model based on multiparametric MRI

PURPOSE

To establish and validate an optimal predictive model based on multiparametric MRI for staging liver fibrosis (LF) in rabbits with magnetic resonance elastography (MRE), spin-lattice relaxation time in the rotating frame (T1ρ imaging), SWI, intravoxel incoherent motion (IVIM), and DCE-MRI.

METHODS

The LF group included 120 rabbits induced by subcutaneous injections of carbon tetrachloride (CCl₄ ); 30 normal rabbits served as the control group. Multiparametric MRI was performed, including MRE, T1ρ, SWI, IVIM, and DCE-MRI. The quantitative parameters were analyzed in two groups, with histopathological results serving as the reference standard. The diagnostic performance of multiparametric MRI and the predictive model established by multivariable logistic regression analysis were evaluated by receiver operating characteristic (ROC) curve analysis.

RESULTS

In total, 32, 67, and 51 rabbits were histologically diagnosed as no fibrosis (stage F0), early-stage LF (F1-F2), and advanced-stage LF (F3-F4), respectively. The LF stages presented a strong correlation with liver stiffness (LS) on MRE (r = 0.90), signal-intensity ratio (SIR) on SWI (r = -0.84), and K^trans on DCE-MRI (r = 0.71; p < 0.05 for all). The LS and SIR parameters had higher AUC values for distinguishing early-stage LF from both no fibrosis (0.94 and 0.93, respectively) and advanced-stage LF (0.95 and 0.87, respectively). The predictive model showed a slightly higher AUC value of 0.97 (0.90-0.99) than LS and SIR in distinguishing early-stage LF from no fibrosis (p > 0.05), a significantly higher AUC value of 0.98 (0.93-0.99) than the SIR in distinguishing early-stage from advanced-stage LF (p < 0.05).

CONCLUSION

SWI, DCE-MRI, and MRE in particular showed improved performance for LF diagnosis and stage. The predictive model based on multiparametric MRI was found to further enhance diagnostic accuracy and could serve as an excellent imaging tool for staging LF.

Evaluation of Rabbits Liver Fibrosis Using Gd-DTPA-BMA of Dynamic Contrast-Enhanced Magnetic Resonance Imaging

Objective

To evaluate the different pharmacokinetic parameters of the DCE-MRI method on diagnosing and staging of rabbits' liver fibrosis.

Methods

We had performed DCE-MRI for rabbits that had been divided into the experiment group and the control group. Then, rabbits' images were transferred to a work station to get three parameters such as K _trans, K _ep, and V _e, which had been measured to calculate. After data were analyzed, ROC analyses were performed to assess the diagnostic performance of K _trans, K _ep, and V _e to judge liver fibrosis.

Results

The distribution of the different liver fibrosis group was as follows: F1, n = 8; F2, n = 9; F3, n = 6; F4, n = 5. No fibrosis was deemed as F0, n = 6. K _ep is statistically significant (P < 0.05) for F0 and mild liver fibrosis stage, and the K _ep shows AUC of 0.814. Three parameters are statistically significant for F0 and advanced liver fibrosis stage (K _trans and K _ep, P < 0.01; V _e, P < 0.05), and the K _trans shows AUC of 0.924; the K _ep shows AUC of 0.909; the V _e shows AUC of 0.848; K _trans and K _ep are statistically significant for mild and advanced liver fibrosis stages (K _trans, P < 0.01; K _ep, P < 0.05), and the K _trans shows AUC of 0.840; the K _ep shows AUC of 0.765. Both K _trans and K _ep are negatively correlated with the liver fibrosis stage. V _e is positively correlated with the liver fibrosis stage.

Conclusion

K _trans is shown to be the best DCE parameter to distinguish the fibrotic liver from the normal liver and mild and advanced fibrosis. On the contrary, K _ep is moderate and V _e is worst. And K _ep is a good DCE parameter to differentiate mild fibrosis from the normal liver.

Quantitative T2 mapping of rats with chronic hepatitis

The aim of the study was to explore the diagnostic value of T2 mapping in an experimental rat model of chronic liver disease. Chronic hepatitis was induced in Sprague-Dawley male rats (n=88) by intraperitoneal and abdominal subcutaneous injection of carbon tetrachloride in olive oil. The normal control rats (n=12) were similarly injected with the same dose of normal saline. All rats were randomly selected and subjected to T2-weighted/spectral adiabatic inversion recovery and multiple gradient- and spin-echo sequence. After scanning, rats were sacrificed immediately and livers removed for staining with hematoxylin and eosin, as well as Masson's trichrome, to determine the pathological stage of hepatic fibrosis, necroinflammatory activity and steatosis. The T2 values were measured and associated with histopathological findings. The T2 values were significantly associated with hepatic fibrosis (P<0.05), but not with hepatitis (P>0.05) or steatosis (P>0.05). By partial correlation analysis, a significant positive correlation was observed between the T2 values and stages of liver fibrosis (r=0.820; P<0.05). T2 values increased with progressive hepatic fibrosis. The differences between T2 values and stages of liver fibrosis were statistically significant. Statistically significant differences were observed between different stages of liver fibrosis (P<0.05), with an area under the curve value of 0.944 for predicting stage F1 or greater, 0.942 for stage F2 or greater, 0.958 for stage F3 or greater, and 0.948 for F4. Thus, the T2 value is one of the quantitative indices of imaging and accurately reflects the stages of liver fibrosis.

Integrated quantitative susceptibility and R2 * mapping for evaluation of liver fibrosis: An ex vivo feasibility study

To develop a method for noninvasive evaluation of liver fibrosis, we investigated the differential sensitivities of quantitative susceptibility mapping (QSM) and R2 * mapping using corrections for the effects of liver iron. Liver fibrosis is characterized by excessive accumulation of collagen and other extracellular matrix proteins. While collagen increases R2 * relaxation, measures of R2 * for fibrosis are confounded by liver iron, which may be present in the liver over a wide range of concentrations. The diamagnetic collagen contribution to susceptibility values measured by QSM is much less than the contribution of highly paramagnetic iron. In 19 ex vivo liver explants with and without fibrosis, QSM (χ), R2 * and proton density fat fraction (PDFF) maps were constructed from multiecho gradient-recalled echo (mGRE) sequence acquisition at 3 T. Median parameter values were recorded and differences between the MRI parameters in nonfibrotic vs. advanced fibrotic/cirrhotic samples were evaluated using Mann-Whitney U tests and receiver operating characteristic analyses. Logistic regression with stepwise feature selection was employed to evaluate the utility of combined MRI measurements for detection of fibrosis. Median R2 * increased in fibrotic vs. nonfibrotic liver samples (P = .041), while differences in χ and PDFF were nonsignificant (P = .545 and P = .395, respectively). Logistic regression identified the combination of χ and R2 * significant for fibrosis detection (logit [prediction] = -8.45 + 0.23 R2 * - 28.8 χ). For this classifier, a highly significant difference between nonfibrotic vs. advanced fibrotic/cirrhotic samples was observed (P = .002). The model exhibited an AUC of 0.909 (P = .003) for detection of advanced fibrosis/cirrhosis, which was substantially higher compared with AUCs of the individual parameters (AUC 0.591-0.784). An integrated QSM and R2 * analysis of mGRE 3 T imaging data is promising for noninvasive diagnostic assessment of liver fibrosis.

Gadoxetate-enhanced dynamic contrast-enhanced MRI for evaluation of liver function and liver fibrosis in preclinical trials

Background

To facilitate translational drug development for liver fibrosis, preclinical trials need to be run in parallel with clinical research. Liver function estimation by gadoxetate-enhanced dynamic contrast-enhanced MRI (DCE-MRI) is being established in clinical research, but still rarely used in preclinical trials. We aimed to evaluate feasibility of DCE-MRI indices as translatable biomarkers in a liver fibrosis animal model.

Methods

Liver fibrosis was induced in Sprague-Dawley rats by thioacetamide (200 mg, 150 mg, and saline for the high-dose, low-dose, and control groups, respectively). Subsequently, DCE-MRI was performed to measure: relative liver enhancement at 3-min (RLE-3), RLE-15, initial area-under-the-curve until 3-min (iAUC-3), iAUC-15, and maximum-enhancement (Emax). The correlation coefficients between these MRI indices and the histologic collagen area, indocyanine green retention at 15-min (ICG-R15), and shear wave elastography (SWE) were calculated. Diagnostic performance to diagnose liver fibrosis was also evaluated by receiver-operating-characteristic (ROC) analysis.

Results

Animal model was successful in that the collagen area of the liver was the largest in the high-dose group, followed by the low-dose group and control group. The correlation between the DCE-MRI indices and collagen area was high for iAUC-15, Emax, iAUC-3, and RLE-3 but moderate for RLE-15 (r, − 0.81, − 0.81, − 0.78, − 0.80, and − 0.51, respectively). The DCE-MRI indices showed moderate correlation with ICG-R15: the highest for iAUC-15, followed by iAUC-3, RLE-3, Emax, and RLE-15 (r, − 0.65, − 0.63, − 0.62, − 0.58, and − 0.56, respectively). The correlation coefficients between DCE-MRI indices and SWE ranged from − 0.59 to − 0.28. The diagnostic accuracy of RLE-3, iAUC-3, iAUC-15, and Emax was 100% (AUROC 1.000), whereas those of RLE-15 and SWE were relatively low (AUROC 0.777, 0.848, respectively).

Conclusion

Among the gadoxetate-enhanced DCE-MRI indices, iAUC-15 and iAUC-3 might be bidirectional translatable biomarkers between preclinical and clinical research for evaluating histopathologic liver fibrosis and physiologic liver functions in a non-invasive manner.

Dynamic Contrast-Enhanced MRI of OATP Dysfunction in Diabetes

Diabetes is associated with hepatic metabolic dysfunction predisposing patients to drug-induced liver injury. Mouse models of type 2 diabetes (T2D) have dramatically reduced expression of organic anion transporting polypeptide (OATP)1A1, a transporter expressed in hepatocytes and in the kidneys. The effects of diabetes on OATP1B2 expression are less studied and less consistent. OATP1A1 and OATP1B2 both transport endogenous substrates such as bile acids and hormone conjugates as well as numerous drugs including gadoxetate disodium (Gd-EOB-DTPA). As master pharmacokinetic regulators, the altered expression of OATPs in diabetes could have a profound and clinically significant influence on drug therapies. Here, we report a method to noninvasively measure OATP activity in T2D mice by quantifying the transport of hepatobiliary-specific gadolinium-based contrast agents (GBCAs) within the liver and kidneys using dynamic contrast-enhanced MRI (DCE-MRI). By comparing GBCA uptake in control and OATP knockout mice, we confirmed liver clearance of the hepatobiliary-specific GBCAs, Gd-EOB-DTPA, and gadobenate dimeglumine, primarily though OATP transporters. Then, we measured a reduction in the hepatic uptake of these hepatobiliary GBCAs in T2D ob/ob mice, which mirrored significant reductions in the mRNA and protein expression of OATP1A1 and OATP1B2. As these GBCAs are U.S. Food and Drug Administration-approved agents and DCE-MRI is a standard clinical protocol, studies to determine OATP1B1/1B3 deficiencies in human individuals with diabetes can be easily envisioned.

Staging of liver fibrosis using Gd-EOB-DTPA and Gd-BOPTA enhanced magnetic resonance imaging

The severity of cirrhosis is closely related to its clinical treatment. Therefore, it is important to stage liver fibrosis accurately. Although liver biopsy can accurately stage the degree of cirrhosis, it has certain limitations in clinical application because of its invasive nature. Magnetic resonance imaging (MRI) has been used in the diagnosis of liver diseases. In recent years, two new contrast agents, gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) and gadobenate dimeglumine (Gd-BOPTA), have been successfully used for noninvasive liver imaging. They can be used for liver fibrosis staging and assessment of liver function. Cirrhotic patients with different liver function levels have a statistical difference in the liver parenchyma enhancement after giving contrast agents. This article briefly summarizes the progress of Gd-EOB-DTPA and Gd-BOPTA enhanced MRI in staging liver fibrosis stage.

Prospective comparison of diffusion-weighted MRI and dynamic Gd-EOB-DTPA-enhanced MRI for detection and staging of hepatic fibrosis in primary sclerosing cholangitis

PURPOSE

To assess the diagnostic value of multiparametric magnetic resonance imaging (MRI) including dynamic Gd-EOB-DTPA-enhanced (DCE) and diffusion-weighted (DW) imaging for diagnosis and staging of hepatic fibrosis in primary sclerosing cholangitis (PSC) using transient elastography as a standard reference.

MATERIAL AND METHODS

Multiparametric MRI was prospectively performed on a 3.0-Tesla scanner in 47 patients (age 43.9±14.3 years). Transient elastography derived liver stiffness measurements (LSM), DCE-MRI derived parameters (hepatocellular uptake rate (Ki), arterial (Fa), portal venous (Fv) and total (Ft) blood flow, mean transit time (MTT), and extracellular volume (Ve)) and the apparent diffusion coefficient (ADC) were calculated. Correlation and univariate analysis of variance with post hoc pairwise comparison were applied to test for differences between LSM derived fibrosis stages (F0/F1, F2/3, F4). ROC curve analysis was used as a performance measure.

RESULTS

Both ADC and Ki correlated significantly with LSM (r= -0.614; p<0.001 and r= -0.368; p=0.01). The ADC significantly discriminated fibrosis stages F0/1 from F2/3 and F4 (p<0.001). Discrimination of F0/1 from F2/3 and F4 reached a sensitivity/specificity of 0.917/0.821 and 0.8/0.929, respectively. Despite significant inter-subject effect for classification of fibrosis stages, post hoc pairwise comparison was not significant for Ki (p>0.096 for F0/1 from F2/3 and F4). LSM, ADC and Ki were significantly associated with serum-based liver functional tests, disease duration and spleen volume.

CONCLUSION

DW-MRI provides a higher diagnostic performance for detection of hepatic fibrosis and cirrhosis in PSC patients in comparison to Gd-EOB-DTPA-enhanced DCE-MRI.

KEY POINTS

• Both ADC and hepatocellular uptake rate (Ki) correlate significantly with liver stiffness (r= -0.614; p<0.001 and r= -0.368; p=0.01). • The DCE-imaging derived quantitative parameter hepatocellular uptake rate (Ki) fails to discriminate pairwise intergroup differences of hepatic fibrosis (p>0.09). • DWI is preferable to DCE-imaging for discrimination of fibrosis stages F0/1 to F2/3 (p<0.001) and F4 (p<0.001).

A multi-center preclinical study of gadoxetate DCE-MRI in rats as a biomarker of drug induced inhibition of liver transporter function

Drug-induced liver injury (DILI) is a leading cause of acute liver failure and transplantation. DILI can be the result of impaired hepatobiliary transporters, with altered bile formation, flow, and subsequent cholestasis. We used gadoxetate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), combined with pharmacokinetic modelling, to measure hepatobiliary transporter function in vivo in rats. The sensitivity and robustness of the method was tested by evaluating the effect of a clinical dose of the antibiotic rifampicin in four different preclinical imaging centers. The mean gadoxetate uptake rate constant for the vehicle groups at all centers was 39.3 +/- 3.4 s^-1 (n = 23) and 11.7 +/- 1.3 s^-1 (n = 20) for the rifampicin groups. The mean gadoxetate efflux rate constant for the vehicle groups was 1.53 +/- 0.08 s^-1 (n = 23) and for the rifampicin treated groups was 0.94 +/- 0.08 s^-1 (n = 20). Both the uptake and excretion transporters of gadoxetate were statistically significantly inhibited by the clinical dose of rifampicin at all centers and the size of this treatment group effect was consistent across the centers. Gadoxetate is a clinically approved MRI contrast agent, so this method is readily transferable to the clinic. Conclusion: Rate constants of gadoxetate uptake and excretion are sensitive and robust biomarkers to detect early changes in hepatobiliary transporter function in vivo in rats prior to established biomarkers of liver toxicity.

Contrast agents in dynamic contrast-enhanced magnetic resonance imaging

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a noninvasive method to assess angiogenesis, which is widely used in clinical applications including diagnosis, monitoring therapy response and prognosis estimation in cancer patients. Contrast agents play a crucial role in DCE-MRI and should be carefully selected in order to improve accuracy in DCE-MRI examination. Over the past decades, there was much progress in the development of optimal contrast agents in DCE-MRI. In this review, we describe the recent research advances in this field and discuss properties of contrast agents, as well as their advantages and disadvantages. Finally, we discuss the research perspectives for improving this promising imaging method.

Assessment of Nonalcoholic Fatty Liver Disease in Rats Using Quantitative Dynamic Contrast-Enhanced MRI

PURPOSE

To evaluate the usefulness of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in the assessment of nonalcoholic fatty liver disease (NAFLD) severity.

MATERIALS AND METHODS

Liver DCE-MRI at 3.0T was performed in 36 adult Sprague-Dawley rats with methionine choline-deficient diet-induced NAFLD and 10 untreated control rats. Pharmacokinetic parameters of DCE-MRI including Ktrans , Kep , Ve , Vp , and hepatic portal index (HPoI) were measured using the dual-input extended Tofts model. Animals were categorized as normal (n = 10), simple steatosis (SS, n = 11), borderline nonalcoholic steatohepatitis (bNASH, n = 20), and NASH (n = 5) subgroups according to the NAFLD activity score system, and classified into F0 (n = 24), F1 (n = 11), F2 (n = 7), and F3 (n = 4) subgroups according to an established scoring system. DCE-MRI parameters were compared. Receiver operating characteristic analyses were performed to assess the diagnostic performance of various DCE-MRI parameters in grading NAFLD activity and staging liver fibrosis.

RESULTS

Ktrans and HPoI were elevated with increasing severity of NAFLD activity and increased fibrosis stage. The areas under the receiver operating characteristic curve (AUROCs) of HPoI ranged from 0.895-0.951 for discriminating between different grades of NAFLD activity, and the AUROC was 0.852 for discriminating F0 stage from overall F1-F3 stages. The AUROC of Ktrans for discriminating non-NASH from bNASH and NASH groups was 0.968, and 0.898 for discriminating between normal and overall fibrosis groups.

CONCLUSION

DCE-MRI may play a role in assessing NAFLD severity.

LEVEL OF EVIDENCE

1 J. MAGN. RESON. IMAGING 2017;45:1485-1493.

Comparison of the DWI and Gd-EOB-DTPA-enhanced MRI on assessing the hepatic ischemia and reperfusion injury after partial hepatectomy

OBJECTIVE

To compare two different imaging media, diffusion weighted imaging (DWI) with apparent diffusion coefficient (ADC) and Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) with perfusion parameters K^trans, K^ep, and relative contrast enhancement index (RCEI), in assessing the liver function via ischemia/perfusion injury (IRI) + partial hepatectomy rat model.

METHODS

Rats underwent 0, 30 and 60min of ischemia/reperfusion with 30% of hepatectomy before subjected to Gd-EOB-DTPA-enhanced MRI in addition to ^99mTc-GSA scintigraphy. For ^99mTc-GSA scintigraphy test, the receptor index LHL15, modified receptor index and the blood clearance index HH15 were recorded. Apparent diffusion coefficient (ADC) was evaluated by using both mono- and bi-exponential models, and perfusion parameters K^trans, K^ep, and RCEI were measured. Liver function is tested by measuring activity of serum ALT, AST and PT. Histological analysis was performed by H&E and Ki-67 staining.

RESULTS

^99mTc-GSA dynamic imaging analysis demonstrated that LHL15 was increased and HH15 was decreased as the extension of ischemia/reperfusion time. ADC value estimated by MRI was significantly increased (P<0.05) in 30min IRI group compared with 0min and 60min IRI groups, respectively. K^trans value was gradually and significantly decreased (P<0.05) as the extension of IRI time, but there was no significant difference (P>0.05) in K^ep value between at 30min and 60min IRI, and RCEI value was significantly higher (P<0.05) in 30min IR compared with 0min and 60min IRI group. Serum level of ALT, AST and PT were gradually and significantly (P<0.05) increased as the extension of IRI time. Histological analysis showed that there was a remarkable difference between 30min and 60min IRI, as protein expression of Ki-67 was significantly higher (P<0.05) in 30min IRI group.

CONCLUSION

Fast ADC bi-exponential model in DWI and RCEI in Gd-EOB-DTPA-enhanced MRI showed the good correlation in assessment of liver function after partial hepatectomy, showing consistency with our histological findings. The K^trans in Gd-EOB-DTPA-enhanced MRI could be a potent parameter for assessing the early ischemic injury, but not the severity of the hepatic injury, in accordance with the correlation with our biochemical findings.

Assessment of liver fibrosis using pharmacokinetic parameters of dynamic contrast-enhanced magnetic resonance imaging

PURPOSE

To evaluate the pharmacokinetic parameters of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in diagnosing and staging liver fibrosis in rabbits.

MATERIALS AND METHODS

DCE-MRI with gadodiamide (Gd-DTPA-BMA) was performed on a 3.0 Tesla, 60 cm bore MR scanner for rabbits with CCl4 -induced liver fibrosis, and an untreated control group. Fibrosis was staged according to the METAVIR system: control (F0; n = 13), nonadvanced fibrosis (F1-2; n = 15), and advanced fibrosis (F3-4; n = 12). The DCE-MRI parameters K(trans) , kep , Ve , and vp were measured with a dual-input extended Tofts model. Receiver operating characteristic analyses were performed to assess the diagnostic performance of K(trans) , Ve , and vp in staging liver fibrosis.

RESULTS

Both K(trans) and Ve decreased with increasing fibrosis stage. K(trans) of the control group was significantly different from that of the overall fibrosis group, nonadvanced group, and advanced group (P < 0.001 for all). Significant differences were found between Ve of the control group and that of the overall fibrosis and advanced groups (P = 0.019 and P = 0.009, respectively). For K(trans) , the areas under the receiver operating characteristic curve (AUROCs) for discriminating the control group from the overall fibrosis and advanced fibrosis groups were 0.909 (95% confidence interval [CI], 0.809-1.000), and 0.936 (95% CI,0.847-1.000), respectively. For discriminating between the control and nonadvanced fibrosis groups, the AUROC of K(trans) was 0.887 (95% CI, 0.762-1.000). The AUROCs of K(trans) were higher than those of Ve and vp for discriminating between the control and overall fibrosis groups, the control and nonadvanced fibrosis groups, and the control and advanced fibrosis groups. Pharmacokinetic parameters were negatively correlated with fibrosis stage (K(trans) , rho = -0.668, P < 0.001; Ve , rho = -0.438, P = 0.005; vp , rho = -0.360, P = 0.023).

CONCLUSION

Among pharmacokinetic parameters of DCE-MRI in our study, K(trans) was an excellent predictor for differentiating fibrotic livers from normal livers, and differentiating normal livers from nonadvanced or advanced fibrosis livers. J. Magn. Reson. Imaging 2016;44:98-104.