Cirrhotic rat liver: reference to transporter activity and morphologic changes in bile canaliculi--gadoxetic acid-enhanced MR imaging

The value of contrast-enhanced portal vein imaging at the hepatobiliary phase obtained with gadobenate dimeglumine for predicting decompensation and transplant-free survival in chronic liver disease

OBJECTIVES

To investigate the value of contrast-enhanced portal vein imaging at the hepatobiliary phase obtained with gadobenate dimeglumine for predicting clinical outcomes in patients with chronic liver disease (CLD).

METHODS

Three hundred and fourteen CLD patients who underwent gadobenate dimeglumine-enhanced hepatic magnetic resonance imaging were stratified into three groups: nonadvanced CLD (n = 116), compensated advanced CLD (n = 120), and decompensated advanced CLD (n = 78) groups. The liver-to-portal vein contrast ratio (LPC) and liver-spleen contrast ratio (LSC) at the hepatobiliary phase were measured. The value of LPC for predicting hepatic decompensation and transplant-free survival was assessed using Cox regression analysis and Kaplan-Meier analysis.

RESULTS

The diagnostic performance of LPC was significantly better than LSC in evaluating the severity of CLD. During a median follow-up period of 53.0 months, the LPC was a significant predictor for hepatic decompensation (p < 0.001) in patients with compensated advanced CLD. The predictive performance of LPC was higher than that of the model for end-stage liver disease score (p = 0.006). With the optimal cut-off value, patients with LPC ≤ 0.98 had a higher cumulative incidence of hepatic decompensation than patients with LPC > 0.98 (p < 0.001). The LPC was also a significant predictive factor for transplant-free survival in patients with compensated advanced CLD (p = 0.007) and those with decompensated advanced CLD (p = 0.002).

CONCLUSIONS

Contrast-enhanced portal vein imaging at the hepatobiliary phase obtained with gadobenate dimeglumine is a valuable imaging biomarker for predicting hepatic decompensation and transplant-free survival in CLD patients.

KEY POINTS

• The liver-to-portal vein contrast ratio (LPC) significantly outperformed liver-spleen contrast ratio in evaluating the severity of chronic liver disease. • The LPC was a significant predictor for hepatic decompensation in patients with compensated advanced chronic liver disease. • The LPC was a significant predictor for transplant-free survival in patients with compensated and those with decompensated advanced chronic liver disease.

Noninvasive Assessment of APAP (N-acetyl-p-aminophenol)-Induced Hepatotoxicity Using Multiple MRI Parameters in an Experimental Rat Model

BACKGROUND

Early detection and accurate assessment of N-acetyl-p-aminophenol (APAP)-induced hepatotoxicity can prevent further aggravation of liver injury and reduce the incidence of liver failure.

PURPOSE

To evaluate the potential of multiple MRI parameters for assessing APAP-induced hepatotoxicity in an experimental rat model.

STUDY TYPE

Prospective.

ANIMAL MODEL

Twenty-one APAP-treated rats and 12 control rats.

FIELD STRENGTH/SEQUENCE

A 3 T, T1 mapping, Gd-EOB-DTPA-enhanced MRI, and intravoxel incoherent motion (IVIM).

ASSESSMENT

The severity of histological changes was assessed by a liver pathologist. Rat livers were pathologically classified into three groups: normal (n = 12), mild necrosis (n = 13), and moderate necrosis (n = 8). T1 relaxation time (T1) and diffusion parameters were measured. The reduction rate of T1 (ΔT1%) at different time points, the maximum value of ΔT1%, time period to the maximum value of ΔT1%, and time period from ΔT1max (%) to 2/3 value of ΔT1max (%) (ΔT1-T2/3) were calculated. Transporters activities like organic anion-transporting polypeptide 1 (oatp1) and multidrug resistance-associated protein 2 (mrp2) were compared among different necrotic groups.

STATISTICAL TESTS

ANOVA/Kruskal-Wallis. Pearson/Spearman correlation. P < 0.05 was considered statistical significance.

RESULTS

T1 Precontrast and ΔT1-T2/3 were strongly correlated with the severity of necrosis (r = 0.9094; r = 0.7978, respectively) and showed significant differences between the two groups. The apparent diffusion coefficient (ADC) and tissue diffusivity (D) values were significantly lower in the moderate necrosis group than in the normal and mild necrosis groups. The oatp1 activity of the necrosis groups was significantly reduced compared to that of the normal group, but the differences between normal and mild (P = 0.21), normal and moderate group (P = 0.56) were not significant. Meanwhile, enlargement of bile canaliculi and sparse microvilli was observed in the necrotic groups.

CONCLUSION

MRI parameters such as precontrast T1 and ΔT1-T2/3 had promising potential in assessing the severity of early-stage hepatotoxicity in an APAP overdose rat model.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 1.

Gadolinium-free Magnetic Resonance Imaging of the Liver via an Oatp1-Targeted Manganese(III) Porphyrin

Controversy surrounding gadolinium-based contrast agents (GBCAs) has rendered their continued utility highly contentious, but the liver-specific GBCA Gd(III) ethoxybenzyl-diethylene triamine pentaacetic acid (Gd(III)-EOB-DTPA) remains in use because it provides unique diagnostic information that could not be obtained by any other means. To address the need for an alternate liver-specific MRI probe, we synthesized Mn(III) 20-(4-ethoxyphenyl) porphyrin-5,10,15-tricarboxylate (Mn(III)TriCP-PhOEt), which exhibited significantly higher r1 relaxivity than Gd(III)-EOB-DTPA in vitro, while also targeting hepatocyte-specific organic anion-transporting polypeptide 1 (Oatp1) channels as a marker of viability. In mice, Mn(III)TriCP-PhOEt resulted in significant and specific increases in liver signal intensity on T1-weighted images and significant decreases in liver T1 time relative to pre-contrast measurements. Our findings suggest that Mn(III)TriCP-PhOEt operates as a specific and sensitive MR probe for Oatp1-targeted imaging in vivo.

Evaluation of liver function in patients with chronic hepatitis B using Gd-EOB-DTPA-enhanced T1 mapping at different acquisition time points: a feasibility study

PURPOSE

This study aimed to explore the impact of different acquisition times on the evaluation of liver function levels in chronic hepatitis B using Gd-EOB-DTPA-enhanced T1 positioning technology under 3.0 Tesla magnetic resonance imaging (MRI).

METHODS

A total of 146 patients with chronic hepatitis B (CHB) were classified into four groups as follows: chronic hepatitis B without liver cirrhosis (CH, 22 cases), liver cirrhosis with Child-Pugh classification A (LCA 63 cases), Child-Pugh B (LCB 47 cases) and Child-Pugh C (LCC 14 cases). Normal liver function (NLF) group was composed of 23 persons who had healthy liver and no medical histories of hepatitis. T1 mapping images were performed before and after administration of Gd-EOB-DPTA using Look-Locker sequence. Changes in T1 relaxation time (T1rt), the reduction rate of T1 relaxation time (ΔT1) and the increase in T1 relaxation rate (ΔR1) of liver over time (at 5, 10, 15 and 20 min) were investigated and compared among all five groups using a one-way analysis of variance (ANOVA). The Spearman's rank correlation coefficient (r) was used to show the correlations of these parameters in different liver function groups.

RESULTS

In the NLF, CH, LCA and LCB groups, postT1 gradually decreased, while the ΔT1 and ΔR1 gradually increased with time. The parameters were compared between different liver function levels at the same time point, and the differences were statistically significant except for NLF-CH, NLF-LCA and CH-LCA. There was no significant difference in the area under the ROC curve of other parameters at 10, 15 and 20 min. At each time point, no correlation was found between preT1rt and the degrees of liver function. PostT1rt was positively correlated with liver function classification, while ΔT1 and ΔR1 were negatively correlated with liver function classification.

CONCLUSION

Gd-EOB-DTPA-enhanced T1 mapping magnetic resonance imaging is beneficial to assess liver function. Using the Gd-EOB-DTPA to enhance T1 mapping imaging to assess liver function can shorten the observation time of the hepatobiliary period and 10 min after enhancement may be the best time point.

Quantitative assessment of liver function with hepatocyte fraction: Comparison with T1 relaxation-based indices

PURPOSE

This study aimed to assess the use of hepatocyte fraction in gadoxetic acid-enhanced magnetic resonance imaging (MRI) for quantitatively evaluating the liver function in comparison with T1 relaxation-based indices.

METHODS

This retrospective study included 79 patients with chronic liver disease, who were divided into 2 groups based on the results of the indocyanine green retention test (ICG). All patients underwent a gadoxetic acid-enhanced MRI of the liver. Pre- and post-contrast Look-Locker sequences were used 20 min after gadoxetic acid administration to acquire T1 mapping. Two readers independently identified and measured the MRI parameters [five T1 relaxation-based indices (T1pre, T1post, rrT1, R1post/R1pre and ΔR1) and two hepatocyte fraction indices (HeF and K_Hep)]. An Independent-samples t test was used to compare each parameter for the two groups. Pearson correlation analysis was used to analyze the correction in each parameter and 15-minute ICG retention rate (ICG-R15). Receiver operating characteristic analyses were performed to differentiate the diagnostic performance of each parameter in ICG-R15 ≤ 20 % and ICG-R15 > 20 % groups.

RESULTS

T1pre and T1post were significantly lower in the ICG-R15 ≤ 20 % group than in the ICG-R15 > 20 % group (P < 0.05). rrT1, R1post/R1pre, ΔR1, HeF, and K_Hep were significantly higher in the ICG-R15 ≤ 20 % group than in the ICG-R15 > 20 % group (P < 0.05). The correction coefficients between T1pre, T1post, rrT1, R1post/R1pre, ΔR1, HeF, K_Hep, and ICG-R15 were 0.343, 0.783, -0.833, -0.781, -0.803, -0.819, and -0.832, respectively. The area under the curves (AUCs) of T1pre, T1post, rrT1, R1post/R1pre, ΔR1, HeF, and K_Hep in assessing the ICG-R15＞20 % groups were 0.761, 0.945, 0.912, 0.912, 0.948, 0.945, and 0.950, respectively. K_Hep had the highest AUC, sensitivity, and specificity.

CONCLUSION

Hepatocyte fraction based on gadoxetic acid-enhanced T1-mapping MRI is an efficient diagnostic tool for the quantitative evaluation of liver function.

Ex vivo gadoxetate relaxivities in rat liver tissue and blood at five magnetic field strengths from 1.41 to 7 T

Quantitative mapping of gadoxetate uptake and excretion rates in liver cells has shown potential to significantly improve the management of chronic liver disease and liver cancer. Unfortunately, technical and clinical validation of the technique is currently hampered by the lack of data on gadoxetate relaxivity. The aim of this study was to fill this gap by measuring gadoxetate relaxivity in liver tissue, which approximates hepatocytes, in blood, urine and bile at magnetic field strengths of 1.41, 1.5, 3, 4.7 and 7 T. Measurements were performed ex vivo in 44 female Mrp2 knockout rats and 30 female wild-type rats who had received an intravenous bolus of either 10, 25 or 40 μmol/kg gadoxetate. T1 was measured at 37 ± 3°C on NMR instruments (1.41 and 3 T), small-animal MRI (4.7 and 7 T) and clinical MRI (1.5 and 3 T). Gadolinium concentration was measured with optical emission spectrometry or mass spectrometry. The impact on measurements of gadoxetate rate constants was determined by generalizing pharmacokinetic models to tissues with different relaxivities. Relaxivity values (L mmol-1 s-1 ) showed the expected dependency on tissue/biofluid type and field strength, ranging from 15.0 ± 0.9 (1.41) to 6.0 ± 0.3 (7) T in liver tissue, from 7.5 ± 0.2 (1.41) to 6.2 ± 0.3 (7) T in blood, from 5.6 ± 0.1 (1.41) to 4.5 ± 0.1 (7) T in urine and from 5.6 ± 0.4 (1.41) to 4.3 ± 0.6 (7) T in bile. Failing to correct for the relaxivity difference between liver tissue and blood overestimates intracellular uptake rates by a factor of 2.0 at 1.41 T, 1.8 at 1.5 T, 1.5 at 3 T and 1.2 at 4.7 T. The relaxivity values derived in this study can be used retrospectively and prospectively to remove a well-known bias in gadoxetate rate constants. This will promote the clinical translation of MR-based liver function assessment by enabling direct validation against reference methods and a more effective translation between in vitro findings, animal models and patient studies.

Feasibility of T1 mapping with histogram analysis for the diagnosis and staging of liver fibrosis: Preclinical results

PURPOSE

To compare the diagnostic accuracy of parameters derived from the histogram analysis of precontrast, 10-min hepatobiliary phase (HBP) and 20-min HBP T1 maps for staging liver fibrosis (LF).

METHODS

LF was induced in New Zealand white rabbits by subcutaneous injections of carbon tetrachloride for 4-16 weeks (n = 120), and 20 rabbits injected with saline served as controls. Precontrast, 10-min and 20-min HBP modified Look-Locker inversion recovery (MOLLI) T1 mapping was performed. Histogram analysis of T1 maps was performed, and the mean, median, skewness, kurtosis, entropy, inhomogeneity and 10th/25th/75th/90th percentiles of T1_native, T1_10min and T1_20min were derived. Quantitative histogram parameters were compared. For significant parameters, further receiver operating characteristic (ROC) analyses were performed to evaluate the potential diagnostic performance in differentiating LF stages.

RESULTS

Finally, 17, 20, 21, 21 and 20 rabbits were included for the F0, F1, F2, F3, and F4 pathological grades of fibrosis, respectively. The mean/75th of T1_native, entropy of T1_10min and entropy/mean/median/10th of T1_20min demonstrated a significant good correlation with the LF stage (|r| = 0.543-0.866, all P < 0.05). The 75th of T1_native, entropy_10min, and entropy_20min were the three most reliable imaging markers in reflecting the stage of LF. The area under the ROC curve of entropy_20min was larger than that of entropy_10min (P < 0.05 for LF ≥ F2, ≥F3, and ≥ F4) and the 75th of T1_native (P < 0.05 for LF ≥ F2 and ≥ F3) for staging LF.

CONCLUSION

Magnetic resonance histogram analysis of T1 maps, particularly the entropy derived from 20-min HBP T1 mapping, is promising for predicting the LF stage.

Combination of hepatocyte fraction and diffusion-weighted imaging as a predictor in quantitative hepatic fibrosis evaluation

OBJECTIVE

To investigate the performance of the combined hepatocyte fraction (HepF) and apparent diffusion coefficient (ADC) values to stage hepatic fibrosis (HF) in patients with hepatitis B/C.

MATERIALS AND METHODS

A total of 281 patients with hepatitis B/C prospectively underwent gadoxetate disodium-based T1 mapping and diffusion-weighted imaging. HepF was determined from pre and postcontrast T1 mapping with pharmacokinetics. The independent predictors of the HF stage (S0-4) were identified from HepF, ADC, conventional T1-based parameters, and age using a logistic regression analysis. The performances of independent and combined predictors in diagnosing various HF stages were compared by analyzing receiver operating characteristic curves. The intraclass correlation coefficient (ICC) was used to assess the interobserver reproducibility of each predictor.

RESULTS

In total, 167 patients with various stages of HF were included. All measurements had excellent interobserver agreement (ICC ≥ 0.75). The hepatic relative enhancement, HepF ,and ADC values were significantly different among various HF stages (p < 0.05). The HepF and ADC were independent predictors of > S0, > S1, > S2 , and > S3 disease (p < 0.05). T1_Liver, T1_Spleen, and T1_Liver/Spleen were independent predictors of S > 2 disease (p < 0.05). The performance of HepF combined with the ADC (area under the curve (AUC) = 0.84-0.95) was higher than HepF (AUC = 0.79-0.92) or ADC (AUC = 0.82-0.89) alone in diagnosing > S0, > S1, > S2 , and > S3 disease.

CONCLUSION

The combined predictor of HepF and ADC shows acceptable performance for staging HF.

Signal intensity in the dentate nucleus after cumulative dose of Gd-EOB-DTPA: First results of a prospective longitudinal study

Gadolinium ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) is a hepatocyte-specific, linear ionic contrast agent for MRI. In comparison to other linear contrast agents Gd-EOB-DTPA is excreted equally through liver and kidneys. This prospective longitudinal study investigates the signal intensity (SI) in the dentate nucleus (DN) on unenhanced T1-weighted images after repetitive application of Gd-EOB-DTPA. 46 patients were included into the study and 107 MRI examinations were performed. Statistical analysis of 25 patients showed no significant correlation between cumulative dose of Gd-EOB-DTPA and SI change and between the DN/Pons ratiolast and the mean DN/Pons ratiofirst. Subgroup analysis however revealed a significant correlation for one out of two readers. Gd-EOB-DTPA deposition could not be proven in the framework of this study.

Impaired lesion detectability on gadoxetic acid-enhanced MR imaging in indocyanine green excretory defect: case series of three patients

Indocyanine green (ICG) excretory defect is characterized by an ICG retention rate of more than 50% at 15 min without any other abnormal liver functions. The incidence of ICG excretory defect is 0.007% in the Japanese population. Due to its rarity, the imaging characteristics associated with ICG excretory defect remain unclear. Herein, we present three cases of ICG excretory defect, which showed impaired lesion detectability on gadoxetic acid-enhanced MR imaging (EOB-MRI). In the hepatobiliary phase (HBP) of EOB-MRI, diminished enhancement of the liver parenchyma, prolonged intravascular enhancement, and attenuated gadoxetic acid excretion to the bile duct were observed. Our study also investigated the expression level of organic anion transporting polypeptide (OATP) 1B3 and OATP1B1/1B3, which is related to the uptake of ICG and gadoxetic acid into hepatocytes. All cases showed decreased expression of OATP1B3, which was assumed to be characteristic of ICG excretory defect. The present study indicates that, when patients with ICG excretory defect are evaluated using EOB-MRI, attention should be paid to the impaired lesion detectability in the HBP due to the attenuated gadoxetic acid uptake into the liver parenchyma.

Systematic review: The diagnostic efficacy of gadoxetic acid-enhanced MRI for liver fibrosis staging

PURPOSE

To evaluate the diagnostic efficacy of gadoxetic acid-enhanced MRI for the staging of liver fibrosis by meta-analysis.

METHODS

PubMed/Medline, EMBASE, the Web of Science, and the Cochrane Library were searched. Studies were included according to their eligibility and the exclusion criteria. The Quality Assessment of Diagnostic Accuracy Studies 2 tool was used to assess the methodologic quality. The bivariate random-effects model was used to obtain the pooled summary estimates, heterogeneity, and the area under summary receiver operating characteristic curves (AUROC). Meta-regression was performed to discover the source of heterogeneity and compare certain some subsets for their capacity to stage hepatic fibrosis by AUROC comparison.

RESULTS

A total of 20 original articles (1936 patients) were included. Most studies had a low risk of bias and minimal concerns regarding applicability. The summary AUROC values of gadoxetic acid-enhanced MRI in staging the liver fibrosis ≥ F1, ≥ F2, ≥ F3, and F4 subsets were 0.92, 0.87, 0.89, and 0.91, respectively. Studies with populations equal to or more than 100 had a significantly higher sensitivity (84 %) and specificity (91 %) than those with populations less than 100 (70 % and 77 %, respectively, P < 0.01). Studies of a prospective design exhibited a significantly higher sensitivity (94 %) and specificity (94 %) than those of a retrospective design (75 % and 84 %, respectively, P < 0.01).

CONCLUSIONS

Our meta-analysis shows the high diagnostic efficacy of gadoxetic acid-enhanced MRI in the staging of liver fibrosis. A prospective study with more than one hundred patients showed higher diagnostic efficacy.

Quantitative Evaluation of Liver Fibrosis on T1 Relaxometry in Comparison with Fibroscan

Purpose

This study was performed to determine whether the T1 relaxation time of gadoxetic acid-enhanced liver MR imaging is useful for detecting and staging liver fibrosis in patients with chronic liver disease.

Materials and Methods

One hundred and three patients with suspected focal liver lesion underwent MR imaging and Fibroscan. Fibroscan was chosen as the reference standard for classifying liver fibrosis. T1 relaxation times were acquired before (preT1), 20 minutes after (postT1) contrast administration, and reduction rate of T1 relaxation time (rrT1) on transverse 3D VIBE (volumetric interpolated breath-hold examination) sequence using 3T MR imaging. The optimal cut-off values for the fibrosis staging were determined with ROC analysis.

Results

PreT1 and postT1 increased and rrT1 decreased constantly with increasing severity of liver fibrosis according to the METAVIR score (F0–F4). There were statistically significant differences between F2 and F3 in preT1 (F2, 836.0 ± 74.7 ms; F3, 888.6 ± 77.5 ms, p < 0.05) and between F3 and F4 in postT1 (F3, 309.0 ± 80.2 ms; F4, 406.6 ± 147.7 ms, p < 0.05) and rrT1 (F3, 65.4 ± 7.7%; F4, 57.3 ± 11.4%, p < 0.05). ROC analysis revealed that combination test (preT1 + postT1) was the best test for predicting liver fibrosis.

Conclusion

PreT1 and postT1 increased constantly with increasing severity of liver fibrosis. T1 mapping in gadoxetic acid-enhanced liver MR imaging could be a helpful complementary sequence to determine the liver fibrosis stage.

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.

Assessment of liver fibrosis with gadoxetic acid-enhanced MRI: comparisons with transient elastography, ElastPQ, and serologic fibrosis markers

OBJECTIVES

To compare the diagnostic performance of gadoxetic acid-enhanced magnetic resonance imaging (MRI), ultrasonography (US)-based elastography, and serologic fibrosis markers in assessing the stage of liver fibrosis.

MATERIALS AND METHODS

This retrospective study included 67 patients (55 male and 12 female; mean age 62.5 years) who underwent gadoxetic acid-enhanced MRI and liver stiffness measurements before liver biopsy or surgery between January 2014 and January 2018. Measurements were performed using transient elastography (TE), ultrasound shear wave elastography point quantification (ElastPQ), and blood tests. The following MRI-based fibrosis markers were assessed: contrast enhancement index (CEI), liver-spleen contrast ratio (LSC), liver-portal vein contrast ratio (LPC), and signal intensity ratio (SIR). The diagnostic performances of fibrosis markers were compared using the area under the receiver operating characteristic curve (AUC), with histopathologic fibrosis stage as the reference standard.

RESULTS

The fibrosis stages were F0-F1 (n = 17), F2 (n = 7), F3 (n = 20), and F4 (n = 23). MRI-based fibrosis markers negatively correlated with histologic stage: CEI (r = -0.786); LSC (r = - 0.718); LPC (r = - 0.448); and SIR (r = - 0.617; all P < 0.001). For diagnosis of either significant liver fibrosis (≥ F2) or cirrhosis (F4), the CEI provided better diagnostic accuracy (AUC = 0.898 and 0.881) than the aspartate aminotransferase-to-platelet ratio index (APRI) (AUC = 0.699 and 0.715; all P < 0.05). The CEI displayed similar diagnostic accuracy for ≥ F2 or F4 when using TE (AUC = 0.866 and 0.884, both P > 0.05) or ElastPQ [AUC = 0.751 (P = 0.021) and AUC = 0.786 (P = 0.234)].

CONCLUSIONS

The CEI measured by gadoxetic acid-enhanced MRI allows the staging of liver fibrosis, with a diagnostic accuracy comparable to that of TE and superior to that of ElastPQ or APRI.

Hepatocellular carcinoma grading and recurrence prediction using T1 mapping on gadolinium-ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging

The aim of the present study was to explore the value of T₁ mapping on gadolinium-ethoxybenzyl diethylenetriamine pentaacetic (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) for grading hepatocellular carcinoma (HCC) and predicting its recurrence rate. A retrospective study was performed that included 75 patients (66 men and 9 women; mean age, 52.89 years; age range, 23-79 years) with HCC who had undergone Gd-EOB-DTPA-enhanced MRI with T₁ mapping before surgery. The T₁ relaxation time of the 81 lesions and non-tumorous liver parenchyma in 75 patients with HCC were measured before Gd-EOB-DTPA was injected and then at 5, 10 and 20 min after administration, respectively. T_{1[lesion (L)-hepatic parenchyma (H)]/H} (%) was calculated as the increment rate of the T₁ value in the lesions relative to the non-tumorous liver parenchyma. One-way analysis of variance and Spearman's correlation analysis was used to compare the differences and relationship of T₁ mapping values among the three grades of HCC. A total of 81 lesions were divided into well-differentiated HCC (grades I; n=21), moderately differentiated HCC (grades II; n=40) and poorly differentiated HCC (grades III; n=20) according to the histopathology. The T_1(L-H)/H (%) value among grades I, II and III HCC on pre-contrast results and on post-contrast results at the 5-, 10- and 20-min hepatobiliary phase (HBP) were significantly different (P<0.05), and T_1(L-H)/H (%) was correlated with the histological grade of HCC at each time point (r=0.637, r=0.554, r=0.499 and r=0.560, respectively, P<0.001). A total of 41 recurrence cases [grade I (n=5), grade II (n=23) and grade III (n=13)] were verified by imaging (CT, MRI or ultrasound) or reoperation. Patients with grade III and grade II HCC had higher recurrence rates compared with that in patients with grade I HCC (P<0.05; median recurrence times were 258 days, 605 days and undefined, respectively). According to the optimal cut-off point for the T_1(L-H)/H (%) of the three grades of HCC, patients with HCC in the low T_1(L-H)/H (%) value group (≤155.15%) had lower cumulative recurrence rates compared with that in the medium (T_1(L-H)/H (%) >155.15% and T1_(L-H)/H (%) ≤241.20%) and high (T_1(L-H)/H (%) >241.20%) value groups at the 20-min HBP (P<0.05; median recurrence times were undefined, 530 days and 447 days, respectively). These results indicate that the parameters of T₁ mapping would be beneficial for predicting the grading and recurrence of HCC.

Model-inferred mechanisms of liver function from magnetic resonance imaging data: Validation and variation across a clinically relevant cohort

Estimation of liver function is important to monitor progression of chronic liver disease (CLD). A promising method is magnetic resonance imaging (MRI) combined with gadoxetate, a liver-specific contrast agent. For this method, we have previously developed a model for an average healthy human. Herein, we extended this model, by combining it with a patient-specific non-linear mixed-effects modeling framework. We validated the model by recruiting 100 patients with CLD of varying severity and etiologies. The model explained all MRI data and adequately predicted both timepoints saved for validation and gadoxetate concentrations in both plasma and biopsies. The validated model provides a new and deeper look into how the mechanisms of liver function vary across a wide variety of liver diseases. The basic mechanisms remain the same, but increasing fibrosis reduces uptake and increases excretion of gadoxetate. These mechanisms are shared across many liver functions and can now be estimated from standard clinical images.

Being able to accurately and reliably estimate liver function is important when monitoring the progression of patients with liver disease, as well as when identifying drug-induced liver injury during drug development. A promising method for quantifying liver function is to use magnetic resonance imaging combined with gadoxetate. Gadoxetate is a liver-specific contrast agent, which is taken up by the hepatocytes and excreted into the bile. We have previously developed a mechanistic model for gadoxetate dynamics using averaged data from healthy volunteers. In this work, we extended our model with a non-linear mixed-effects modeling framework to give patient-specific estimates of the gadoxetate transport-rates. We validated the model by recruiting 100 patients with liver disease, covering a range of severity and etiologies. All patients underwent an MRI-examination and provided both blood and liver biopsies. Our validated model provides a new and deeper look into how the mechanisms of liver function varies across a wide variety of liver diseases. The basic mechanisms remain the same, but increasing fibrosis reduces uptake and increases excretion of gadoxetate.

Influence of hepatic fibrosis and inflammation: Correlation between histopathological changes and Gd-EOB-DTPA-enhanced MR imaging

Objective

To evaluate the influence of an active inflammatory process in the liver on Gd-EOB-DTPA-enhanced MR imaging in patients with different degrees of fibrosis/cirrhosis.

Material and methods

Overall, a number of 91 patients (61 men and 30 women; mean age 58 years) were included in this retrospective study. The inclusion criteria for this study were Gd-EOB-DTPA-enhanced MRI of the liver and histopathological evaluation of fibrotic and inflammatory changes. T1-weighted VIBE sequences of the liver with fat suppression were evaluated to determine the relative signal change (RE) between native and hepatobiliary phase (20min). In simple and multiple linear regression analyses, the influence of liver fibrosis/cirrhosis (Ishak score) and the histopathological degree of hepatitis (Modified Hepatic Activity Index, mHAI) on RE were evaluated.

Results

RE decreased significantly with increasing liver fibrosis/cirrhosis (p < 0.001) and inflammation (mHAI, p = 0.004). In particular, a correlation between RE and periportal or periseptal boundary zone hepatitis (moth feeding necrosis, mHAI A, p = 0.001) and portal inflammation (mHAI D, p < 0.001) was observed. In multiple linear regression analysis, both the degree of inflammation and the degree of fibrosis were significant predictors for RE (p < 0.01).

Conclusion

The results of this study suggest that the MR-based hepatic enhancement index RE is not only influenced by the degree of fibrosis, but also by the degree of inflammation.

Imaging biomarkers for well and moderate hepatocellular carcinoma: preoperative magnetic resonance image and histopathological correlation

Background

Our aim of the study is to investigate the feasibility of preoperative prediction for hepatocellular carcinoma (HCC) histological grading using gadoxetic acid-enhanced magnetic resonance imaging (MRI).

Methods

This study included one hundred and fifty-six patients with solitary HCC. Preoperative gadoxetic acid-enhanced MRI findings were retrospectively analyzed. MRI qualitative features such as tumor size, margin, capsule status, signal homogeneity, intratumoral vessels, peritumoral enhancement during mid-arterial phase, peritumoral hypointensity during the hepatobiliary phase (HBP) were investigated. Apparent diffusion coefficients (ADCs), T1 reduction ratio of pre- and post-contrast enhanced images of the tumors were calculated. HCC histological grading in surgical specimens were confirmed by Edmonson’s criteria. Correlations between these MRI features and HCC histological grading were analyzed using multivariate logistic regression. The receiver operating characteristic (ROC) curve was used to assess the predictive efficacy of the model.

Results

Univariate analysis showed that maximum tumor diameter (p = 0.004), tumor margin (p = 0.006), intratumoral vessels (p = 0.001) and peritumoral hypointensity during HBP (p = 0.000), were significantly correlated with HCC histological grading. There was no relationship between capsule, tumor signal, venous thrombosis, peritumoral enhancement during mid-arterial phase, ADC value, T1 reduction ratio, and HCC histological grading. Multivariate logistic regression analysis demonstrated that the maximum tumor diameter (p = 0.012, odds ratio = 1.002, 95% confidence interval: 1.007–1.046)) was an independent risk factor for high grade HCC.

Conclusions

Greater tumor size, a more irregular margin, presence of intratumoral vessels, and peritumoral hypointensity during HBP were indicators for high grade HCC. The maximum tumor diameter was an independent risk factor for high grade HCC.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5574-8) contains supplementary material, which is available to authorized users.

Noninvasive Assessment of Liver Fibrosis in Patients with Chronic Hepatitis B or C by Contrast-Enhanced Magnetic Resonance Imaging

Background and Aim. To develop a noninvasive magnetic resonance imaging (MRI) method for evaluation of liver fibrosis. We evaluate the utility of hepatocyte-phase Gadoxetate disodium-enhanced magnetic resonance (MR) imaging in staging hepatic fibrosis and compare it with histological analysis as the reference standard (liver biopsy). Methods. Prospective cohort of 78 patients, who received Gadoxetate disodium dynamic contrast-enhanced MRI (DCE-MRI), were divided into three groups. The first group (n=19) was a control group of healthy individuals without liver injury and remaining 59 subjects were chronic hepatitis B and C patients who underwent liver biopsy. These patients were divided into the mild fibrosis F1-F2 (n=32) and advanced fibrosis F3-F4 (n=27) groups. Patients were examined by generated DCE-MRI in 20th minute. Variables such as liver surface changes, homogeneities, and quantitative contrast liver/spleen ratio-Q-LSCR were evaluated and these results were consequently compared between the three groups. Results. Gd-EOB-DTPA contrast-enhanced dynamic liver MRI examination (DCE-MRI) can in the 20th minute differentiate mild stage of liver fibrosis (F1-F2) from severe stage of liver fibrosis (F3-F4) on the basis of liver surface changes, homogeneities, and quantitative contrast liver/spleen ratio-Q-LSCR. Diagnostic MRI criteria were created and named MRI Triple test. This test correctly identified 96% of patients with F3-F4 fibrosis and 91% of patients with the F1-F2 fibrosis in the liver biopsy. This test correctly identified 42,1% of patients in the control group (presumed F0 fibrosis without liver disease). Spearman's rank correlation coefficient (r = 0,86, P < .001) confirmed high agreement of biopsy and MR Triple test. MR Triple test's sensitivity was 96.30% (95%CI 81.03% to 99.91%), specificity 90.62% (95%CI 74.98% to 98.02%), positive predictive value 89.66% (95%CI 74.64% to 96.23%), and negative predictive value 96.67% (95%CI 80.86% to 99.50%) for discrimination between F3-4 and F1-2 fibrosis on liver biopsy. Conclusions. Gd-EOB-DTPA contrast-enhanced MRI liver examination in 20th minute is able to reliably differentiate mild stage of liver fibrosis (F1-F2) from severe stage fibrosis (F3-F4) on the basis of Triple test (liver surface changes, homogeneities, and quantitative contrast liver/spleen ratio-Q-LSCR).

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.

Diagnostic performance of Gd-EOB-DTPA-enhanced MRI for evaluation of liver dysfunction: a multivariable analysis of 3T MRI sequences

OBJECTIVE

The aim of this study was to evaluate the diagnostic performance of a multiparametric gadolinium ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced MRI examination for the estimation of liver dysfunction classified by the Model for End-Stage Liver Disease (MELD) score.

RESULTS

Liver dysfunction can be assessed by different methods. In a logistic regression analysis, T1- and T2-weighted images were affected by impaired liver function. In the assessment of liver dysfunction, the reduction rate in T1 mapping sequences showed a significant correlation in simple and multiple logistic regression.

CONCLUSION

Changes in Gd-EOB-DTPA-enhanced MRI between plain images and images obtained during the hepatobiliary phase allowed good prediction of liver dysfunction, especially when using T1 mapping sequences.

MATERIALS AND METHODS

A total of 199 patients underwent contrast-enhanced MRI with a hepatocyte-specific contrast agent at 3T. In the multivariable analysis, the full range of available MRI sequences was used to estimate the liver dysfunction of patients with various MELD scores.

Liver function correlates with liver-to-portal vein contrast ratio during the hepatobiliary phase with Gd-EOB-DTPA-enhanced MR at 3 Tesla

PURPOSES

To determine if liver-to-portal vein contrast ratio (LPC) correlates with liver function in patients with hepatitis B virus (HBV)-related cirrhosis on gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA)-enhanced MR imaging.

METHODS

A total of 92 patients with normal (n = 20) or HBV-related cirrhotic livers graded by Child-Pugh class A (n = 50), B (n = 17) or C (n = 5) who underwent Gd-EOB-DTPA-enhanced 3Tesla MR imaging were retrospectively reviewed. LPC was defined as the signal intensity ratio of liver parenchyma to portal vein on hepatobiliary phase (HBP) acquired at 20 min, and it was compared between normal and cirrhotic livers. The correlation between LPC and hepatic function parameters at HBP after injection was quantitatively analyzed as well.

RESULTS

LPC differed between normal and cirrhotic livers significantly (P < 0.001). LPC constantly and significantly decreased from normal to cirrhotic livers with Child-Pugh class C at HBP imaging (P < 0.001). Multiple regression analysis revealed that total bilirubin (P = 0.011), albumin (P < 0.001), and platelet count (P = 0.007) were independent predictors of LPC at HBP imaging. A receiver operating characteristic (ROC) curve analysis revealed that the optimal cutoff value for LPC to distinguish normal group from cirrhotic groups was 2.05 (AUC 0.98) with a sensitivity of 84.1% and a specificity of 100%.

CONCLUSION

The level of LPC on Gd-EOB-DTPA MR imaging can efficaciously indicate the severity of liver function in patients with HBV-related cirrhosis and was correlated with liver function parameters significantly. It might be used as an alternative imaging biomarker for assessing liver function.

Quantitative assessment of hepatic fibrosis in chronic hepatitis B and C: T1 mapping on Gd-EOB-DTPA-enhanced liver magnetic resonance imaging

AIM

To assess the accuracy of Look-Locker on gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) for staging liver fibrosis in chronic hepatitis B/C (CHB/C).

METHODS

We prospectively included 109 patients with CHB or CHC who underwent a 3.0-Tesla MRI examination, including T1-weighted and Look-Locker sequences for T1 mapping. Hepatocyte fractions (HeF) and relaxation time reduction rate (RE) were measured for staging liver fibrosis. A receiver operating characteristic analysis using the area under the receiver operating characteristic curve (AUC) was used to compare the diagnostic performance in predicting liver fibrosis between HeF and RE.

RESULTS

A total of 73 patients had both pathological results and MRI information. The number of patients in each fibrosis stage was evaluated semiquantitatively according to the METAVIR scoring system: F0, n = 23 (31.5%); F1, n = 19 (26.0%); F2, n = 13 (17.8%); F3, n = 6 (8.2%), and F4, n = 12 (16.4%). HeF by EOB enhancement imaging was significantly correlated with fibrosis stage (r = -0.808, P < 0.05). AUC values for diagnosis of any (≥ F1), significant (≥ F2) or advanced (≥ F3) fibrosis, and cirrhosis (F4) using HeF were 0.837 (0.733-0.913), 0.890 (0.795-0.951), 0.957 (0.881-0.990), and 0.957 (0.882-0.991), respectively. HeF measurement was more accurate than use of RE in establishing liver fibrosis staging, suggesting that calculation of HeF is a superior noninvasive liver fibrosis staging method.

CONCLUSION

A T1 mapping-based HeF method is an efficient diagnostic tool for the staging of liver fibrosis.

Coefficient of variation on Gd-EOB MR imaging: Correlation with the presence of early-stage hepatocellular carcinoma in patients with chronic hepatitis B

PURPOSE

To study whether the measurement of hepatic fibrosis on gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) magnetic resonance (MR) imaging using the coefficient of variation (CV) might be correlated with the presence of hepatocellular carcinoma (HCC) in patients with chronic hepatitis B (CHB).

MATERIALS AND METHODS

This study included 104 patients with and without CHB, who were divided into 4 groups: control group, CHB without liver cirrhosis (LC; Group I), CHB with LC (Group II), and CHB with LC and HCC (Group III). MR images were analyzed to measure the inhomogeneity of signal intensities calculated using the CV map of the liver parenchyma. Intergroup comparisons of CV values were performed using ANOVA. The diagnostic performance of the CV map and alpha-fetoprotein (AFP) for diagnosing HCC was evaluated using the receiver operating characteristic (ROC) curve.

RESULTS

On the hepatobiliary phase of Gd-EOB-DTPA-enhanced T1-weighted imaging, the mean CV values of the control group and Groups I, II, and III were 3.9 ± 0.99, 3.97 ± 1.09, 5.58 ± 2.05, and 6.80 ± 2.34, respectively (P = 0.000). On ROC analysis of the CV value for predicting HCC, the value of the area under the curve (AUC) on Gd-EOB-DTPA MR imaging was 0.788 (95% CI: 0.697-0.862). The sensitivity and specificity were 84.2% and 63.6%, respectively, at a CV cutoff value >4.75. The value of AUC determined using AFP was 0.766.

CONCLUSION

The CV value for hepatic fibrosis on Gd-EOB-DTPA MR imaging may be correlated with the presence of HCC in patients with CHB, and shows comparable diagnostic performance to AFP analysis.

Quantitative Assessment of Liver Function Using Gadoxetate-Enhanced Magnetic Resonance Imaging: Monitoring Transporter-Mediated Processes in Healthy Volunteers

Objective

The objective of this study was to use noninvasive dynamic contrast-enhanced magnetic resonance imaging (MRI) techniques to study, in vivo, the distribution and elimination of the hepatobiliary contrast agent gadoxetate in the human body and characterize the transport mechanisms involved in its uptake into hepatocytes and subsequent efflux into the bile using a novel tracer kinetic model in a group of healthy volunteers.

Materials and Methods

Ten healthy volunteers (age range, 18–29 years), with no history of renal or hepatic impairment, were recruited via advertisement. Participants attended 2 MRI visits (at least a week apart) with gadoxetate as the contrast agent. Dynamic contrast-enhanced MRI data were acquired for approximately 50 minutes with a 3-dimensional gradient-echo sequence in the axial plane, at a temporal resolution of 6.2 seconds. Data from regions of interest drawn in the liver were analyzed using the proposed 2-compartment uptake and efflux model to provide estimates for the uptake rate of gadoxetate in hepatocytes and its efflux rate into the bile. Reproducibility statistics for the 2 visits were obtained to examine the robustness of the technique and its dependence in acquisition time.

Results

Eight participants attended the study twice and were included into the analysis. The resulting images provided the ability to simultaneously monitor the distribution of gadoxetate in multiple organs including the liver, spleen, and kidneys as well as its elimination through the common bile duct, accumulation in the gallbladder, and excretion in the duodenum. The mean uptake (k_i) and efflux (k_ef) rates in hepatocytes, for the 2 visits using the 50-minute acquisition, were 0.22 ± 0.05 and 0.017 ± 0.006/min, respectively. The hepatic extraction fraction was estimated to be 0.19 ± 0.04/min. The variability between the 2 visits within the group level (95% confidence interval; k_i: ±0.02/min, k_ef: ±0.004/min) was lower compared with the individual variability (repeatability; k_i: ±0.06/min, k_ef: ±0.012/min). Data truncation demonstrated that the uptake rate estimates retained their precision as well as their group and individual reproducibility down to approximately 10 minutes of acquisition. Efflux rate estimates were underestimated (compared with the 50-minute acquisition) as the duration of the acquisition decreased, although these effects were more pronounced for acquisition times shorter than approximately 30 minutes.

Conclusions

This is the first study that reports estimates for the hepatic uptake and efflux transport process of gadoxetate in healthy volunteers in vivo. The results highlight that dynamic contrast-enhanced MRI with gadoxetate can provide novel quantitative insights into liver function and may therefore prove useful in studies that aim to monitor liver pathology, as well as being an alternative approach for studying hepatic drug-drug interactions.

Combining hyperpolarized 13 C MRI with a liver-specific gadolinium contrast agent for selective assessment of hepatocyte metabolism

PURPOSE

Hyperpolarized 13 C MRI is a powerful tool for studying metabolism, but can lack tissue specificity. Gadoxetate is a gadolinium-based MRI contrast agent that is selectively taken into hepatocytes. The goal of this project was to investigate whether gadoxetate can be used to selectively suppress the hyperpolarized signal arising from hepatocytes, which could in future studies be applied to generate specificity for signal from abnormal cell types.

METHODS

Baseline gadoxetate uptake kinetics were measured using T1 -weighted contrast enhanced imaging. Relaxivity of gadoxetate was measured for [1-13 C]pyruvate, [1-13 C]lactate, and [1-13 C]alanine. Four healthy rats were imaged with hyperpolarized [1-13 C]pyruvate using a three-dimensional (3D) MRSI sequence prior to and 15 min following administration of gadoxetate. The lactate:pyruvate ratio and alanine:pyruvate ratios were measured in liver and kidney.

RESULTS

Overall, the hyperpolarized signal decreased approximately 60% as a result of pre-injection of gadoxetate. In liver, the lactate:pyruvate and alanine:pyruvate ratios decreased 42% and 78%, respectively (P < 0.05) following gadoxetate administration. In kidneys, these ratios did not change significantly. Relaxivity of gadoxetate for [1-13 C]alanine was 12.6 times higher than relaxivity of gadoxetate for [1-13 C]pyruvate, explaining the greater selective relaxation effect on alanine.

CONCLUSIONS

The liver-specific gadolinium contrast-agent gadoxetate can selectively suppress normal hepatocyte contributions to hyperpolarized 13 C MRI signals. Magn Reson Med 77:2356-2363, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Measuring hepatic functional reserve using T1 mapping of Gd-EOB-DTPA enhanced 3T MR imaging: A preliminary study comparing with 99mTc GSA scintigraphy and signal intensity based parameters

PURPOSE

To determine the utility of liver T1-mapping on gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic acid (Gd-EOB-DTPA) enhanced magnetic resonance (MR) imaging for the measurement of liver functional reserve compared with the signal intensity (SI) based parameters, technetium-99m-galactosyl serum albumin (^99mTc-GSA) scintigraphy and indocyanine green (ICG) clearance.

MATERIALS AND METHODS

This retrospective study included 111 patients (Child-Pugh-A 90; -B 21) performed with both Gd-EOB-DTPA enhanced liver MR imaging and ^99mTc-GSA (76 patients with ICG). Receiver operating characteristic (ROC) curve analysis was performed to compare diagnostic performances of T1-relaxation-time parameters [pre-(T1pre) and post-contrast (T1hb) Gd-EOB-DTPA], SI based parameters [relative enhancement (RE), liver-to-muscle-ratio (LMR), liver-to-spleen-ratio (LSR)] and ^99mTc-GSA scintigraphy blood clearance index (HH15)] for Child-Pugh classification. Pearson's correlation was used for comparisons among T1-relaxation-time parameters, SI-based parameters, HH15 and ICG.

RESULTS

A significant difference was obtained for Child-Pugh classification with T1hb, ΔT1, all SI based parameters and HH15. T1hb had the highest AUC followed by RE, LMR, LSR, ΔT1, HH15 and T1pre. The correlation coefficients with HH15 were T1pre 0.22, T1hb 0.53, ΔT1 -0.38 of T1 relaxation parameters; RE -0.44, LMR -0.45, LSR -0.43 of SI-based parameters. T1hb was highest for correlation with HH15. The correlation coefficients with ICG were T1pre 0.29, T1hb 0.64, ΔT1 -0.42 of T1 relaxation parameters; RE -0.50, LMR -0.61, LSR -0.58 of SI-based parameters; 0.64 of HH15. Both T1hb and HH15 were highest for correlation with ICG.

CONCLUSION

T1 relaxation time at post-contrast of Gd-EOB-DTPA (T1hb) was strongly correlated with ICG clearance and moderately correlated HH15 with ^99mTc-GSA. T1hb has the potential to provide robust parameter of liver functional reserve.

Quantitative dynamic contrast-enhanced magnetic resonance imaging in a VX2 rabbit liver tumour model using different gadolinium-based contrast agents: comparison of DCE-MRI quantitative results between Magnevist and Eovist

Quantitative dynamic contrast enhanced MRI (DCE-MRI) can offer information related to tumour perfusion and permeability (K^trans), rate constant (K_ep), extravascular extracellular volume fraction (V_e) and distribution volume (V_d). Different types of gadolinium-based contrast agents (GBCAs) may traverse the vascular wall with different velocities owing to their physicochemical characteristics. The purpose of this article was to compare the DCE-MRI quantitative results (K^trans, K_ep, V_e and V_d) between Magnevist and Eovist in a VX2 rabbit liver tumour model. Sixteen rabbits (body weight, 3 Kg; random gender) containing implanted hepatic VX2 carcinomas were randomly divided into two groups based on the regimen of MRI contrast agent administered, eight rabbits in each group. All rabbits underwent a liver DCE-MRscan before tumour transplantation. Fourteen days after tumour transplantation, the eight rabbits in Group A (Magnevist group) underwent a liver DCE-MR scan in a 3.0 T Magnetom Verio MR scanner (Siemens Healthcare, AD, Germany) after the administration of Magnevist at the flow rate of 1 ml s^–1. The Group B rabbits underwent the same scan except for the administration of Eovist at the same flow rate. Twenty-four hours after the initial DCE-MRI, repeat DCE-MRI was performed with the cross-over GBCA at the same flow rate in each group. Every rabbit received 0.6 ml GBCA (0.2 ml Kg^–1) during each DCE-MRI. K^trans, K_ep, V_e and V_d were measured in the tumour lesion and compared with normal liver tissue in the same slice. A pathologic examination was also performed. Hepatocellular carcinoma was diagnosed in all 16 rabbits by pathologic examination. There were no significant differences in K^trans, V_e, K_ep and V_d between the two groups of rabbits (p > 0.05). The K^trans, V_e, K_ep and V_d of the VX2 rabbit liver tumour model were significantly higher than the normal liver parenchyma (0.742 ± 0.086 vs 0.027 ± 0.002, 7.345 ± 0.043 vs 6.721 ± 0.035, 0.101 ± 0.005 vs 0.101 ± 0.005, 0.419 ± 0.083 vs 0.037 ± 0.005, respectively; p < 0.01). The K^trans, V_e and V_d of Eovist group were significantly higher compared with the values in the Magnevist group (0.116 ± 0.016 vs 0.010 ± 0.002, respectively, p < 0.01; 0.101 ± 0.005 vs 0.004 ± 0.0009, respectively, p < 0.01; 0.419 ± 0.083 vs 0.037 ± 0.005, respectively, p < 0.001). There was no significant difference in K_ep between the Eovist and Magnevist groups (7.345 ± 0.043 vs 6.721 ± 0.035, respectively; p > 0.05). In the VX2 rabbit liver tumour model, DCE-MRI performed with different types of GBCA can develop different quantitative results with respect to K^trans, V_e and V_d. The liver-specific GBCA, Eovist, is more sensitive than the general GBCA, Magnevist, in detecting tumour perfusion and permeability.

Quantitative Measurement of Hepatic Fibrosis with Gadoxetic Acid-Enhanced Magnetic Resonance Imaging in Patients with Chronic Hepatitis B Infection: A Comparative Study on Aspartate Aminotransferase to Platelet Ratio Index and Fibrosis-4 Index

Objective

To quantitatively measure hepatic fibrosis on gadoxetic acid-enhanced magnetic resonance (MR) in chronic hepatitis B (CHB) patients and identify the correlations with aspartate aminotransferase-to-platelet ratio index (APRI) and fibrosis-4 index (FIB-4) values.

Materials and Methods

This study on gadoxetic acid-enhanced 3T MR imaging included 81 patients with CHB infection. To quantitatively measure hepatic fibrosis, MR images were analyzed with an aim to identify inhomogeneous signal intensities calculated from a coefficient of variation (CV) map in the liver parenchyma. We also carried out a comparative analysis between APRI and FIB-4 based on metaregression results. The diagnostic performance of the CV map was evaluated using a receiver-operating characteristic (ROC) curve.

Results

In the MR images, the mean CV values in control, groups I, II, and III based on APRI were 4.08 ± 0.92, 4.24 ± 0.80, 5.64 ± 1.11, and 5.73 ± 1.28, respectively (p < 0.001). In CHB patients grouped by FIB-4, the mean CV values of groups A, B, and C were 4.22 ± 0.95, 5.40 ± 1.19, and 5.71 ± 1.17, respectively (p < 0.001). The mean CV values correlated well with APRI (r = 0.392, p < 0.001) and FIB-4 (r = 0.294, p < 0.001). In significant fibrosis group, ROC curve analysis yielded an area under the curve of 0.875 using APRI and 0.831 using FIB-4 in HB, respectively.

Conclusion

Gadoxetic acid-enhanced MR imaging for calculating a CV map showed moderate correlation with APRI and FIB-4 values and could be employed to quantitatively measure hepatic fibrosis in patients with CHB.

Gd-EOB-DTPA-enhanced MR relaxometry for the detection and staging of liver fibrosis

Gd-EOB-DTPA, a liver-specific contrast agent with T1-shortening effects, is routinely used in clinical routine for detection and characterization of focal liver lesions and has recently received increasing attention as a tool for the quantitative analyses of liver function. We report the relationship between the extent of Gd-EOB-DTPA- induced T1 relaxation and the degree of liver fibrosis, which was assessed according to the METAVIR score. For the T1 relaxometry, a transverse 3D VIBE sequence with inline T1 calculation was acquired prior to and 20 minutes after Gd-EOB-DTPA administration. The reduction rates of the T1 relaxation time (rrT1) between the pre- and postcontrast images were calculated, and the optimal cutoff values for the fibrosis stages were determined with receiver operating characteristic (ROC) curve analyses. The rrT1 decreased with the severity of liver fibrosis and regression analysis revealed a significant correlation of the rrT1 with the stage of liver fibrosis (r = -0.906, p < 0.001). ROC analysis revealed sensitivities ≥78% and specificities ≥94% for the differentiation of different fibrosis stages. Gd-EOB-DTPA-enhanced T1 relaxometry is a reliable tool for both the detection of initial hepatic fibrosis and the staging of hepatic fibrosis.

Hepatic gadoxetic acid uptake as a measure of diffuse liver disease: Where are we?

MRI has emerged as the most comprehensive noninvasive diagnostic tool for focal liver lesions and diffuse hepatobiliary disorders. The introduction of hepatobiliary contrast agents, most notably gadoxetic acid (GA), has expanded the role of MRI, particularly in the functional imaging of chronic liver diseases, such as nonalcoholic fatty liver disease (NAFLD). GA-enhanced MRI (GA-MRI) may help to distinguish between the two subgroups of NAFLD, simple steatosis and nonalcoholic steatohepatitis. Furthermore, GA-MRI can be used to stage fibrosis and cirrhosis, predict liver transplant graft survival, and preoperatively estimate the risk of liver failure should major resection be undertaken. The amount of GA uptake can be estimated, using static images, by the relative liver enhancement, hepatic uptake index, and relaxometry of T1-mapping during the hepatobiliary phase. On the contrary, the hepatic extraction fraction and liver perfusion can be measured on dynamic imaging. Importantly, there is currently no clear consensus as to which of these MR-derived parameters is the most suitable for assessing liver dysfunction. This review article aims to describe the current role of GA-enhanced MRI in quantifying liver function, primarily in diffuse hepatobiliary disorders.

LEVEL OF EVIDENCE

3 J. Magn. Reson. Imaging 2017;45:646-659.

Pre-Hepatectomy Assessment of Bile Transporter Expression by Gadoxetic Acid-Enhanced MRI in a Rat Model of Liver Cirrhosis

BACKGROUND

Gadoxetic acid is a liver-specific intravenous T1 magnetic resonance (MR) contrast agent that is excreted via the hepatobiliary system. We hypothesize that hepatocyte expressions of bile transporters (OATP1 and MRP2) correlate with dynamic profile of Gadoxetic acid enhanced (GE)-MR imaging (MRI).

METHODS

Two groups of rats, control (n = 6) and cirrhosis (n = 12), received gadoxetic acid enhanced MRI followed by 70% hepatectomy. The change in MR signal intensity from the baseline before the contrast injection (ΔSI) was analyzed every minute for 30 min. Dynamic signal intensity retention ratio (DSR) was defined as the mean ΔSI of the third 10-minmin period divided by the first 10-minmin period. Real-time PCR was utilized to quantify mRNA expressions.

RESULTS

Compared to the control, cirrhosis group demonstrated lower mRNA levels of OATP1 (0.038 ± 0.020 vs. 0.232 ± 0.0979; p = 0.004), MRP2 (0.201 ± 0.084 vs. 0.7567 ± 0.254; p = 0.002), and OATP1/MRP2 mRNA ratio (0.193 ± 0.065 vs. 0.342 ± 0.206; p = 0.032). DSR was higher in the cirrhosis group (0.678 ± 0.554 vs -0.125 ± 0.839; p = 0.033). In the cirrhosis group, there was an inverse correlation between the ratios of OATP1/MRP2 mRNA and DSR (R = -0.709, p = 0.01).

CONCLUSION

Bile transporters OATP1/MRP2 mRNA expression ratio in rat liver tissue decreased with DMN-induced liver injury. The expressions of bile transporters correlated with GE-MRI DSR. The GE-MRI DSR has potential utility in qualifying OATP1/MRP2 mRNA expression.

Staging liver fibrosis in chronic hepatitis B with T1 relaxation time index on gadoxetic acid-enhanced MRI: Comparison with aspartate aminotransferase-to-platelet ratio index and FIB-4

PURPOSE

To assess the accuracy of the T₁ relaxation time index on gadoxetic acid-enhanced magnetic resonance imaging (MRI) for staging liver fibrosis in chronic hepatitis B (CHB), in comparison and combination with the aspartate aminotransferase-to-platelet ratio index (APRI) and fibrosis-4 (FIB-4).

MATERIALS AND METHODS

A retrospective study of gadoxetic acid-enhanced T₁ mapping and serum biochemical tests was performed on 126 CHB patients who underwent gadoxetic acid-enhanced 1.5T MRI, and the histological score used as the gold standard. The reduction rate of T₁ relaxation time before and 20 minutes after gadoxetic acid injection (ΔT₁ , ΔR1%), the contrast uptake rate (K_Hep ), APRI, and FIB-4 were calculated. The diagnostic efficacy of ΔT₁ , ΔR1%, K_Hep , APRI, and FIB-4 for predicting stage 2 or greater (≥S2), stage 3 or greater (≥S3), and stage 4 (S4) was compared.

RESULTS

ΔT₁ (r = -0.513, P < 0.001), ΔR1% (r = -0.626, P < 0.001), K_Hep (r = -0.527, P < 0.001), APRI (r = 0.519, P < 0.001), and FIB-4 (r = 0.476, P < 0.001) correlated significantly with fibrosis stages. Areas under the curves (AUCs) of ΔR1% for detecting ≥S2, ≥S3, and S4 were 0.849, 0.827, and 0.809, which were greater than that of APRI (0.763, 0.745, 0.787) and FIB-4 (0.727, 0.738, 0.772), but significant difference was found only in discriminating ≥S2 between ΔR1% and FIB-4 (P = 0.027). The combination of all five indices performed best, with AUC, sensitivity, and specificity of 0.860, 87.21%, and 72.50% for diagnosing ≥S2, 0.878, 82.81%, and 85.48% for ≥S3, and 0.867, 80.00%, and 83.95% for S4.

CONCLUSION

The gadoxetic acid-enhanced T₁ relaxation time index appears to be superior to APRI and FIB-4 for predicting hepatic fibrosis. The combined use of gadoxetic acid-enhanced T₁ mapping, APRI, and FIB-4 may be more reliable for staging liver fibrosis in CHB.

LEVEL OF EVIDENCE

4 J. Magn. Reson. Imaging 2017;45:1186-1194.

Age dependence of spleen- and muscle-corrected hepatic signal enhancement on hepatobiliary phase gadoxetate MRI

OBJECTIVES

To identify correlations of signal enhancements (SE) and SE normalized to reference tissues of the spleen, kidney, liver, musculus erector spinae (MES) and ductus hepatocholedochus (DHC) on hepatobiliary phase gadoxetate-enhanced MRI with patient age in non-cirrhotic patients.

METHODS

A heterogeneous cohort of 131 patients with different clinical backgrounds underwent a standardized 3.0-T gadoxetate-enhanced liver MRI between November 2008 and June 2013. After exclusion of cirrhotic patients, a cohort of 75 patients with no diagnosed diffuse liver disease was selected. The ratio of signal intensity 20 min post- to pre-contrast administration (SE) in the spleen, kidney, liver, MES and DHC, and the SE of the kidney, liver and DHC normalized to the reference tissues spleen or MES were compared to patient age.

RESULTS

Patient age was inversely correlated with the liver SE normalized to the spleen and MES SE (both p < 0.001) and proportionally with the SE of the spleen (p = 0.043), the MES (p = 0.030) and the kidney (p = 0.022). No significant correlations were observed for the DHC (p = 0.347) and liver SE (p = 0.606).

CONCLUSION

The age dependence of hepatic SE normalized to the enhancement in the spleen and MES calls for a cautious interpretation of these quantification methods.

KEY POINTS

• Patient age was inversely correlated with spleen- and MES-corrected liver rSE (p < 0.001). • Patient age was correlated with spleen (p = 0.043) and MES SE (p = 0.030). • Patient age may confound quantitative liver function assessment using gadoxetate-enhanced liver MRI.

Hepatic enhancement of Gd-EOB-DTPA-enhanced 3 Tesla MR imaging: Assessing severity of liver cirrhosis

PURPOSE

To evaluate the usefulness of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MR imaging in assessing the severity of cirrhosis and liver function.

MATERIALS AND METHODS

This retrospective study included 120 patients who underwent Gd-EOB-DTPA-enhanced 3 Tesla (T) MR imaging (normal liver, n = 30; Child-Pugh class A, n = 30; B, n = 30; and C, n = 30). Groups were matched for underlying disease, age (±5 years), gender, and creatinine (±0.05 mg/dL). Contrast enhancement index (CEI) was calculated and compared between normal and cirrhosis groups. We analyzed the correlation between hepatic function parameters and CEI at hepatobiliary phase (HP).

RESULTS

The degree and time course of hepatic enhancement significantly differed between normal and each cirrhosis group (P < 0.001). Mean CEI at HP constantly and significantly decreased as the severity of cirrhosis increased (P < 0.001). Total bilirubin (P = 0.022), albumin (P < 0.001), platelet count (P = 0.04), and Model for End Stage Liver Disease score (P = 0.01) were independent predictors of hepatic enhancement at HP.

CONCLUSION

The degree of hepatic enhancement on Gd-EOB-DTPA indicates the severity of cirrhosis and is correlated with hepatic function parameters. J. Magn. Reson. Imaging 2016;44:1339-1345.

Gadoxetic acid: pearls and pitfalls

Gadoxetic acid is a hepatocyte-specific magnetic resonance imaging contrast agent with the ability to detect and characterize focal liver lesions and provide structural and functional information about the hepatobiliary system. Knowledge of the pharmacokinetics of gadoxetic acid is paramount to understanding imaging protocol and lesion appearance and facilitates identification and avoidance of undesired effects with use of this intravenous contrast agent. This article reviews the utility of gadoxetic acid in liver and biliary imaging, with emphasis on the hepatobiliary phase.

Use of gadoxetate disodium for functional MRI based on its unique molecular mechanism

Gadolinium ethoxybenzyl dimeglumine (gadoxetate) is a recently developed hepatocyte-specific MRI contrast medium. Gadoxetate demonstrates unique pharmacokinetic and pharmacodynamic properties, because its uptake in hepatocytes occurs via the organic anion transporting polypeptide (OATP) transporter expressed at the sinusoidal membrane, and its biliary excretion via the multidrug resistance-associated proteins (MRPs) at the canalicular membrane. Based on these characteristics, gadoxetate-enhanced MRI can provide functional information on hepatobiliary diseases, including liver function estimation, biliary drainage evaluation and characterization of hepatocarcinogenesis. In addition, understanding its mode of action can provide an opportunity to use gadoxetate for cellular and molecular imaging. Radiologists and imaging scientists should be familiar with the basic mechanism of gadoxetate and OATP/MRP transporters.

Novel Imaging Diagnosis for Hepatocellular Carcinoma: Consensus from the 5th Asia-Pacific Primary Liver Cancer Expert Meeting (APPLE 2014)

Current novel imaging techniques in the diagnosis of hepatocellular carcinoma (HCC), with the latest evidence in this field, was discussed at the Asia-Pacific Primary Liver Cancer Expert (APPLE) meeting held in Taipei, Taiwan, in July 2014. Based on their expertise in a specific area of research, the novel imaging group comprised 12 participants from Japan, South Korea, Taiwan, and China and it included 10 abdominal radiologists, one hepatologist, and one pathologist. The expert participants discussed topics related to HCC imaging that were divided into four categories: (i) detection method, (ii) diagnostic method, (iii) evaluation method, and (iv) functional method. Consensus was reached on 10 statements; specific comments on each statement were provided to explain the rationale for the voting results and to suggest future research directions.

Liver fibrosis and Gd-EOB-DTPA-enhanced MRI: A histopathologic correlation

Gadolinium ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) is a hepatocyte-specific MRI contrast agent. Because the hepatic uptake of Gd-EOB-DTPA depends on the integrity of the hepatocyte mass, this uptake can be quantified to assess liver function. We report the relationship between the extent of Gd-EOB-DTPA uptake and the degree of liver fibrosis. T1-weighted volume-interpolated breath-hold examination (VIBE) sequences with fat suppression were acquired before and 20 minutes after contrast injection. Strong correlations of the uptake characteristics of Gd-EOB-DTPA with the relative enhancement (RE) of the liver parenchyma and the grade of fibrosis/cirrhosis, classified using the Ishak scoring system, were observed. The subdivisions between the grades of liver fibrosis based on RE were highly significant for all combinations, and a ROC revealed sensitivities ≥82% and specificities ≥87% for all combinations. MR imaging is a satisfactorily sensitive method for the assessment of liver fibrosis/cirrhosis.

Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging as a useful detection method for advanced primary biliary cirrhosis

AIM

In primary biliary cirrhosis (PBC), damaged hepatocytes resulting from chronic cholestasis follow a compensatory mechanism that alters hepatobiliary transporter expression to reduce the accumulation of potentially toxic compounds such as bile acid. Organic anion transporter peptide 1B3 (OATP1B3), which transports agents such as gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA), has reduced expression in the late stages of PBC. Therefore, we investigated the use of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) as a useful detection method for the advanced staging of PBC.

METHODS

Stage I-III PBC (non-liver cirrhosis [LC]-PBC, n = 12), stage IV (LC-PBC, n = 6), and non-PBC patients (control group, n = 4) were included in this study. We obtained liver tissue samples by percutaneous liver biopsy. Hepatic OATP1B3 expression was determined immunohistochemically, and OATP1B3 mRNA levels were assessed using real-time reverse transcription polymerase chain reaction. The relative enhancement (RE) in the hepatobiliary phase was calculated using the signal intensity of Gd-EOB-DTPA-enhanced MRI.

RESULTS

Immunohistochemistry revealed markedly reduced expression of OATP1B3 in hepatocytes around the central vein in LC-PBC patients. Hepatic OATP1B3 mRNA expression in LC-PBC patients was significantly lower than that in non-LC-PBC patients (P < 0.05). The RE on MRI was significantly decreased in the LC-PBC group (0.33 ± 0.14) compared with the non-LC-PBC (0.91 ± 0.15, P < 0.01) and control (0.92 ± 0.20, P < 0.01) groups.

CONCLUSION

Gd-EOB-DTPA-enhanced MRI may provide a useful detection method for liver disease in patients with LC-PBC.

Quantitative assessment of hepatic function: modified look-locker inversion recovery (MOLLI) sequence for T1 mapping on Gd-EOB-DTPA-enhanced liver MR imaging

OBJECTIVES

To determine whether multislice T1 mapping of the liver using a modified look-locker inversion recovery (MOLLI) sequence on gadoxetic acid-enhanced magnetic resonance imaging (MRI) can be used as a quantitative tool to estimate liver function and predict the presence of oesophageal or gastric varices.

METHODS

Phantoms filled with gadoxetic acid were scanned three times using MOLLI sequence to test repeatability. Patients with chronic liver disease or liver cirrhosis who underwent gadoxetic acid-enhanced liver MRI including MOLLI sequence at 3 T were included (n = 343). Pre- and postcontrast T1 relaxation times of the liver (T1liver), changes between pre- and postcontrast T1liver (ΔT1liver), and adjusted postcontrast T1liver (postcontrast T1liver-T1spleen/T1spleen) were compared among Child-Pugh classes. In 62 patients who underwent endoscopy, all T1 parameters and spleen sizes were correlated with varices.

RESULTS

Phantom study showed excellent repeatability of MOLLI sequence. As Child-Pugh scores increased, pre- and postcontrast T1liver were significantly prolonged (P < 0.001), and ΔT1liver and adjusted postcontrast T1liver decreased (P < 0.001). Adjusted postcontrast T1liver and spleen size were independently associated with varices (R (2) = 0.29, P < 0.001).

CONCLUSIONS

T1 mapping of the liver using MOLLI sequence on gadoxetic acid-enhanced MRI demonstrated potential in quantitatively estimating liver function, and adjusted postcontrast T1liver was significantly associated with varices.

KEY POINTS

• T1 mapping using MOLLI sequence can be achieved within a breath-hold. • T1liver measured by MOLLI sequence provided excellent short-term repeatability. • Precontrast and postcontrast T1liver were significantly prolonged as Child-Pugh scores increased. • Adjusted postcontrast T1liver and spleen size were independently associated with varices.

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

Purpose

To investigate the utility of dynamic contrast-enhanced MRI (DCE-MRI) with Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) for detecting liver fibrosis induced by carbon tetrachloride (CCl₄) in rats.

Methods

This study was approved by the institutional animal care and use committee. Liver fibrosis in rats was induced by intraperitoneal injection of 1 mL/kg 50% CCl₄ twice a week for 4-13 weeks. Control rats were injected with saline. Liver fibrosis was graded using the Metaviar score: no fibrosis (F0), mild fibrosis (F1-F2) and advanced fibrosis (F3-F4). DCE-MRI with Gd-EOB-DTPA was performed for all rats. K^trans, K_ep, V_e and iAUC of the liver parenchyma were measured. Relative enhancement (RE) value of the liver was calculated on T₁-weighted images at 15, 20 and 25 min after Gd-EOB-DTPA administration.

Results

Thirty-five rats were included: no fibrosis (n=13), mild fibrosis (n=11) and advanced fibrosis (n=11). K^trans and iAUC values were highest in advanced fibrosis group and lowest in no fibrosis group (P＜0.05). The area under the receiver operating characteristic curve (AUROC) for fibrosis (stages F1 and greater) were 0.773 and 0.882 for K^trans and iAUC, respectively. AUROC for advanced fibrosis were 0.835 and 0.867 for K^trans and iAUC, respectively. K_ep and RE values were not able to differentiate fibrosis stages (all P＞0.05).

Conclusion

K^trans and iAUC obtained from DCE-MRI with Gd-EOB-DTPA are useful for the detection and staging of rat liver fibrosis induced by CCl₄.

The diagnostic efficacy of quantitative liver MR imaging with diffusion-weighted, SWI, and hepato-specific contrast-enhanced sequences in staging liver fibrosis--a multiparametric approach

PURPOSE

To assess the diagnostic efficacy of multiparametric MRI using quantitative measurements of the apparent diffusion coefficient (ADC) of the liver parenchyma on diffusion-weighted imaging (DWI), signal intensity (SI) on susceptibility-weighted imaging (SWI), and gadoxetic acid-enhanced T1-weighted imaging during the hepatobiliary phase for the staging of liver fibrosis.

MATERIALS AND METHODS

Seventy-seven patients underwent a 3T MRI examination, including DWI/SWI sequences and gadoxetic acid-enhanced T1-weighted MRI. Liver fibrosis according to liver biopsy was staged using the Metavir fibrosis score: F0 (n = 21, 27.3%); F1 (n = 7, 9.1%); F2 (n = 8, 10.4%); F3 (n = 12, 15.6%); and F4 (n = 29, 37.7%). SI of the liver was defined using region-of-interest measurements to calculate the ADC values, the relative enhancement (RE) in the hepatobiliary phase, and the liver-to-muscle ratio (LMR) measurements for SWI.

RESULTS

The values of RE, LMR, and ADC measurements were statistically significantly different among the five fibrosis stages (p < 0.004). Combining the three parameters in a multiparametric approach, the AUC for detecting F1 stage or greater (≥ F1) was 94%, for F2 or greater (≥F2) was 95%, for F3 or greater (≥F3) was 90%, and for stage F4 was 93%.

CONCLUSIONS

Multiparametric MRI is an efficient non-invasive diagnostic tool for the staging of liver fibrosis.

KEY POINTS

• Multiparametric MRI has high accuracy in predicting moderate or greater liver fibrosis. • Relative enhancement post- gadoxetic acid is an independent predictor of liver fibrosis. • Liver SWI signal intensity and ADC values enhance the diagnostic ability.

Appearance of hepatocellular carcinoma on gadoxetic acid-enhanced hepato-biliary phase MR imaging: a systematic review

OBJECTIVE

To perform a systematic review of the contrast behaviour of HCC on Gd-EOB-DTPA hepato-biliary phase MRI.

MATERIALS AND METHODS

This review was completed in accordance with the recommendations outlined in the preferred reporting items for systematic reviews statement. In all reports, qualitative analysis of signal intensity (SI) of HCC on hepato-biliary phase was performed: the relative SI of HCC. When available, a quantitative analysis of tumour enhancement was evaluated.

RESULTS

A total of 106 studies were retrieved, of which 41 met the inclusion criteria. The total number of patients was 2550, with 3132 HCC. MRI showed 3110 HCC (22 non-detected). 2692/3110 (87 %) HCC were hypointense on Gd-EOB-DTPA-enhanced hepatocyte-phase MRI, 134 (4 %) isointense; 106 (3 %) hyperintense and 178 (6 %) iso-hyperintense. In 26 articles, 1653 HCCs were classified as follows: 519 well-differentiated, 883 moderately differentiated, 251 poorly differentiated. Among well-differentiated HCC, 445 (86 %) were hypointense, 12 isointense (2 %), 9 hyperintense (2 %), 53 iso/hyperintense (10 %). Among moderately differentiated HCC, 774 (88 %) were hypointense, 8 isointense (1 %), 27 hyperintense (3 %), 74 iso/hyperintense (8 %). Among poorly differentiated HCCs, 245 (98 %) were hypointense, one isointense, one hyperintense and four iso-hyperintense (2 %). We found a Chi-square (χ (2)) equivalent to 25,082 (p < 0.001).

CONCLUSION

The percentage of lesions iso/hyper/iso-hyper is the same when considering well-differentiated and moderately differentiated HCC; when considering poorly differentiated HCC, the percentage of lesions iso/hyper/iso-hyper is significantly lower. Conversely, the percentage of lesions hypointense is significantly more represented in poorly differentiated HCC compared to well-differentiated and moderately differentiated HCC.

Gadoxetic acid-enhanced MRI and sonoelastography: non-invasive assessments of chemoprevention of liver fibrosis in thioacetamide-induced rats with Sho-Saiko-To

Background

This study aimed to compare the performance of gadoxetic acid -enhanced magnetic resonance imaging (MRI) and sonoelastography in evaluating chemopreventive effects of Sho-Saiko-To (SST) in thioacetamide (TAA)-induced early liver fibrosis in rats.

Materials and Methods

Ten of Sprague-Dawley rats receiving TAA (200 mg/kg of body weight) intraperitoneal injection were divided into three groups: Group 1 (TAA only, n = 3), Group 2 (TAA +0.25 g/kg SST, n = 4) and Group 3 (TAA+1 g/kg SST, n = 3). Core needle liver biopsy at week 2 and liver specimens after sacrifice at week 6 confirmed liver fibrosis using histological examinations, including Sirius red staining, Ishak and Metavir scoring systems. Gadoxetic acid-enhanced MRI and shear-wave sonoelastography were employed to evaluate liver fibrosis. The expression of hepatic transporter organic anion transporter 1 (Oatp1), multidrug-resistant protein 2 (Mrp2) and alpha-smooth muscle actin (α-Sma) were also analyzed in each group by immunohistochemistry (IHC) and Western blot.

Results

According to histological grading by Sirius red staining, Ishak scores of liver fibrosis in Groups 1, 2 and 3 were 3, 2 and 1, respectively. As shown in gadoxetic acid-enhanced MRI, the ratio of relative enhancement was significantly lower in Group 1 (1.87±0.21) than in Group 2 of low-dose (2.82±0.25) and Group 3 of high-dose (2.72±0.12) SST treatment at 10 minutes after gadoxetic acid intravenous injection (p<0.05). Sonoelastography showed that the mean difference before and after experiments in Groups 1, 2 and 3 were 4.66±0.1, 4.4±0.57 and 3±0.4 KPa (p<0.1), respectively. Chemopreventive effects of SST reduced the Mrp2 protein level (p<0.01) but not Oatp1 and α-Sma levels.

Conclusion

Sonoelastography and gadoxetic acid-enhanced MRI could monitor the treatment effect of SST in an animal model of early hepatic fibrosis.