Impact of liver cirrhosis on liver enhancement at Gd-EOB-DTPA enhanced MRI at 3 Tesla

Influence of Gd-EOB-DTPA on proton-density fat fraction in the liver using chemical shift-encoded magnetic resonance imaging at 3-T

Non-alcoholic fatty liver disease (NAFLD) and its advanced stage, non-alcoholic steatohepatitis (NASH), have become increasingly prevalent owing to the rise in metabolic syndromes. Accurate assessment of hepatic fat deposition and inflammation is crucial for diagnosing and managing NAFLD/NASH. We investigated the influence of Gd-EOB-DTPA, (EOB) on proton-density fat fraction (PDFF) measurements using chemical shift-encoded magnetic resonance imaging (CSE-MRI) at 3-T. In total, 431 patients who underwent EOB contrast-enhanced MRI were included. PDFF measurements were obtained from pre- and post-contrast CSE-MRI. Linear regression and Bland-Altman analyses were performed to assess the correlation and agreement between pre- and post-EOB PDFF measurements. Relative enhancement (RE) of the liver was calculated as an EOB uptake index. There was a significant decrease in PDFF following EOB administration compared with the pre-contrast values (P < 0.0001), which was observed across all PDFF ranges (< 10% and ≥ 10%). Linear regression analysis revealed high correlation between pre- and post-EOB PDFF measurements. Bland-Altman analysis indicated a small bias between pre- and post-EOB PDFF values. Subgroup analysis based on RE showed a significant difference in ΔPDFF between patients with high RE (> 120%) and those with lower RE levels. EOB administration resulted in a slight decrease in PDFF measurements obtained using CSE-MRI at 3-T. We were able to generalize and clarify that the PDFF of the liver on 3D CSE-MRI at 3-T was slightly decreased after EOB administration as we used a larger group of patients compared to previous studies.

Relative enhancement index can be used to quantify liver function in cirrhotic patients that undergo gadoxetic acid-enhanced MRI

OBJECTIVES

To evaluate MRI with gadoxetic acid to quantify liver function in cirrhotic patients using the relative enhancement index (REI) compared with Child-Pugh score (CPS), MELD score, and indocyanine green plasma disappearance rate (ICG-PDR) and to establish cutoffs for REI to stratify cirrhotic patients into good and poor liver function groups.

METHODS

We prospectively evaluated 60 cirrhotic patients and calculated CPS, MELD score, ICG-PDR, and REI for each patient. Spearman's correlation coefficient was used to assess correlation between REI, CPS, MELD, and ICG-PDR. Good and poor liver function groups were created by k-means clustering algorithm using CPS, MELD, and ICG-PDR. ROC curve analysis was performed and optimal cutoff was identified for group differentiation.

RESULTS

Good correlations were found between REI and other liver function biomarkers: REI and CPS (rho =  - 0.816; p < 0.001); REI and MELD score (rho =  - 0.755; p < 0.001); REI and ICG-PDR (rho = 0.745; p < 0.001)]. REI correlation was stronger for patients with Child-Pugh A (rho = 0.642, p = 0.002) and B (rho = 0.798, p < 0.001) than for those with Child-Pugh C (rho = 0.336, p = 0.148). REI is significantly lower in patients with poor liver function (p < 0.001). ROC curve showed an AUC 0.94 to discriminate patients with poor liver function (REI cutoff < 100; 100% sensitivity; 76% specificity).

CONCLUSIONS

REI is a valuable non-invasive index for liver function quantification that has good correlations with other liver function biomarkers. REI can be easily calculated and can be used to estimate liver function in clinical practice in the routine evaluation of cirrhotic patients that undergo MR imaging with gadoxetic acid contrast.

KEY POINTS

• REI is a valuable non-invasive index for liver function quantification that has good correlations with other liver function biomarkers. • REI can be easily calculated in the routine evaluation of cirrhotic patients that undergo gadoxetic acid-enhanced MRI. • The REI enables stratification of cirrhotic patients into good and poor liver function groups and can be used as additional information, together with morphological and focal liver lesion evaluation.

T1 reduction rate with Gd-EOB-DTPA determines liver function on both 1.5 T and 3 T MRI

Magnetic resonance T1 mapping before and after Gd-EOB-DTPA administration allows quantification of the T1 reduction rate as a non-invasive surrogate marker of liver function. A major limitation of T1 relaxation time measurement is its dependency on MRI field strengths. Since T1 reduction rate is calculated as the relative shortening of T1 relaxation time before and after contrast administration, we hypothesized that the T1 reduction rate is comparable between 1.5 and 3 T. We thus compared liver T1 relaxation times between 1.5 and 3 T in a total of 243 consecutive patients (124, 1.5 T and 119, 3 T) between 09/2018 and 07/2019. T1 reduction rates were compared between patients with no cirrhosis and patients with cirrhosis Child-Pugh A-C. There was no significant difference of T1 reduction rate between 1.5 and 3 T in any patient group (p-value 0.126-0.861). On both 1.5 T and 3 T, T1 reduction rate allowed to differentiate between patients with no cirrhosis and patients with liver cirrhosis Child A-C (p < 0.001). T1 reduction rate showed a good performance to predict liver cirrhosis Child A (AUC = 0.83, p < 0.001), Child B (AUC = 0.83, p < 0.001) and Child C (AUC = 0.92, p < 0.001). In conclusion, T1 reduction rate allows to determine liver function on Gd-EOB-DTPA MRI with comparable values on 1.5 T and 3 T.

Prediction of insufficient hepatic enhancement during the Hepatobiliary phase of Gd-EOB DTPA-enhanced MRI using machine learning classifier and feature selection algorithms

PURPOSE

The purpose of this study was to reveal the usefulness of machine learning classifier and feature selection algorithms for prediction of insufficient hepatic enhancement in the HBP.

METHODS

We retrospectively assessed 214 patients with chronic liver disease or liver cirrhosis who underwent MRI enhanced with Gd-EOB-DTPA. Various liver function tests, Child-Pugh score (CPS) and Model for End-stage Liver Disease Sodium (MELD-Na) score were collected as candidate predictors for insufficient hepatic enhancement. Insufficient hepatic enhancement was assessed using liver-to-portal vein signal intensity ratio and 5-level visual grading. The clinico-laboratory findings were compared using Student's t-test and Mann-Whitney U test. Relationships between the laboratory tests and insufficient hepatic enhancement were assessed using Pearson's and Spearman's rank correlation coefficient. Feature importance was assessed by Random UnderSampling boosting algorithms. The predictive models were constructed using decision tree(DT), k-nearest neighbor(KNN), random forest(RF), and support-vector machine(SVM) classifier algorithms. The performances of the prediction models were analyzed by calculating the area under the receiver operating characteristic curve(AUC).

RESULTS

Among four machine learning classifier algorithms using various feature combinations, SVM using total bilirubin(TB) and albumin(Alb) showed excellent predictive ability for insufficient hepatic enhancement(AUC = 0.93, [95% CI: 0.93-0.94]) and higher AUC value than conventional logistic regression(LR) model (AUC = 0.92, [95% CI; 0.92-0.93], predictive models using the MELD-Na (AUC = 0.90 [95% CI: 0.89-0.91]) and CPS (AUC = 0.89 [95% CI: 0.88-0.90]).

CONCLUSION

Machine learning-based classifier (i.e. SVM) and feature selection algorithms can be used to predict insufficient hepatic enhancement in the HBP before performing MRI.

Errors and Misinterpretations in Imaging of Chronic Liver Diseases

MRI is an important problem-solving tool for accurate characterization of liver lesions. Chronic liver disease alters the typical imaging characteristics and complicates liver imaging. Awareness of imaging pitfalls and technical artifacts and ways to mitigate them allows for more accurate and timely diagnosis.

A 3D Deep Neural Network for Liver Volumetry in 3T Contrast-Enhanced MRI

PURPOSE

 To create a fully automated, reliable, and fast segmentation tool for Gd-EOB-DTPA-enhanced MRI scans using deep learning.

MATERIALS AND METHODS

 Datasets of Gd-EOB-DTPA-enhanced liver MR images of 100 patients were assembled. Ground truth segmentation of the hepatobiliary phase images was performed manually. Automatic image segmentation was achieved with a deep convolutional neural network.

RESULTS

 Our neural network achieves an intraclass correlation coefficient (ICC) of 0.987, a Sørensen-Dice coefficient of 96.7 ± 1.9 % (mean ± std), an overlap of 92 ± 3.5 %, and a Hausdorff distance of 24.9 ± 14.7 mm compared with two expert readers who corresponded to an ICC of 0.973, a Sørensen-Dice coefficient of 95.2 ± 2.8 %, and an overlap of 90.9 ± 4.9 %. A second human reader achieved a Sørensen-Dice coefficient of 95 % on a subset of the test set.

CONCLUSION

 Our study introduces a fully automated liver volumetry scheme for Gd-EOB-DTPA-enhanced MR imaging. The neural network achieves competitive concordance with the ground truth regarding ICC, Sørensen-Dice, and overlap compared with manual segmentation. The neural network performs the task in just 60 seconds.

KEY POINTS

  · The proposed neural network helps to segment the liver accurately, providing detailed information about patient-specific liver anatomy and volume.. · With the help of a deep learning-based neural network, fully automatic segmentation of the liver on MRI scans can be performed in seconds.. · A fully automatic segmentation scheme makes liver segmentation on MRI a valuable tool for treatment planning..

CITATION FORMAT

· Winther H, Hundt C, Ringe KI et al. A 3D Deep Neural Network for Liver Volumetry in 3T Contrast-Enhanced MRI. Fortschr Röntgenstr 2021; 193: 305 - 314.

Structure guided deformable image registration for treatment planning CT and post stereotactic body radiation therapy (SBRT) Primovist® (Gd-EOB-DTPA) enhanced MRI

The purpose of this study was to assess the performance of structure‐guided deformable image registration (SG‐DIR) relative to rigid registration and DIR using TG‐132 recommendations. This assessment was performed for image registration of treatment planning computed tomography (CT) and magnetic resonance imaging (MRI) scans with Primovist^® contrast agent acquired post stereotactic body radiation therapy (SBRT). SBRT treatment planning CT scans and posttreatment Primovist^® MRI scans were obtained for 14 patients. The liver was delineated on both sets of images and matching anatomical landmarks were chosen by a radiation oncologist. Rigid registration, DIR, and two types of SG‐DIR (using liver contours only; and using liver structures along with anatomical landmarks) were performed for each set of scans. TG‐132 recommended metrics were estimated which included Dice Similarity Coefficient (DSC), Mean Distance to Agreement (MDA), Target Registration Error (TRE), and Jacobian determinant. Statistical analysis was performed using Wilcoxon Signed Rank test. The median (range) DSC for rigid registration was 0.88 (0.77–0.89), 0.89 (0.81–0.93) for DIR, and 0.90 (0.86–0.94) for both types of SG‐DIR tested in this study. The median MDA was 4.8 mm (3.7–6.8 mm) for rigid registration, 3.4 mm (2.4–8.7 mm) for DIR, 3.2 mm (2.0–5.2 mm) for SG‐DIR where liver structures were used to guide the registration, and 2.8 mm (2.1–4.2 mm) for the SG‐DIR where liver structures and anatomical landmarks were used to guide the registration. The median TRE for rigid registration was 7.2 mm (0.5–23 mm), 6.8 mm (0.7–30.7 mm) for DIR, 6.1 mm (1.1–20.5 mm) for the SG‐DIR guided by only the liver structures, and 4.1 mm (0.8–19.7 mm) for SG‐DIR guided by liver contours and anatomical landmarks. The SG‐DIR shows higher liver conformality as per TG‐132 metrics and lowest TRE compared to rigid registration and DIR in Velocity AI software for the purpose of registering treatment planning CT and post‐SBRT MRI for the liver region. It was found that TRE decreases when liver contours and corresponding anatomical landmarks guide SG‐DIR.

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.

Comparison between dynamic gadoxetate-enhanced MRI and 99mTc-mebrofenin hepatobiliary scintigraphy with SPECT for quantitative assessment of liver function

Objectives

To compare Gd-EOB-DTPA dynamic hepatocyte-specific contrast-enhanced MRI (DHCE-MRI) with ^99mTc-mebrofenin hepatobiliary scintigraphy (HBS) as quantitative liver function tests for the preoperative assessment of patients undergoing liver resection.

Methods

Patients undergoing liver surgery and preoperative assessment of future remnant liver (FRL) function using ^99mTc-mebrofenin HBS were included. Patients underwent DHCE-MRI. Total liver uptake function was calculated for both modalities: mebrofenin uptake rate (MUR) and Ki respectively. The FRL was delineated with both SPECT-CT and MRI to calculate the functional share. Blood samples were taken to assess biochemical liver parameters.

Results

A total of 20 patients were included. The HBS-derived MUR and the DHCE-MRI-derived mean Ki correlated strongly for both total and FRL function (Pearson r = 0.70, p = 0.001 and r = 0.89, p < 0.001 respectively). There was a strong agreement between the functional share determined with both modalities (ICC = 0.944, 95% CI 0.863–0.978, n = 20). There was a significant negative correlation between liver aminotransferases and bilirubin for both MUR and Ki.

Conclusions

Assessment of liver function with DHCE-MRI is comparable with that of ^99mTc-mebrofenin HBS and has the potential to be combined with diagnostic MRI imaging. This can therefore provide a one-stop-shop modality for the preoperative assessment of patients undergoing liver surgery.

Key Points

• Quantitative assessment of liver function using hepatobiliary scintigraphy is performed in the preoperative assessment of patients undergoing liver surgery in order to prevent posthepatectomy liver failure.

• Gd-EOB-DTPA dynamic hepatocyte-specific contrast-enhanced MRI (DHCE-MRI) is an emerging method to quantify liver function and can serve as a potential alternative to hepatobiliary scintigraphy.

• Assessment of liver function with dynamic gadoxetate-enhanced MRI is comparable with that of hepatobiliary scintigraphy and has the potential to be combined with diagnostic MRI imaging.

Electronic supplementary material

The online version of this article (10.1007/s00330-019-06029-7) contains supplementary material, which is available to authorized users.

Does gadoxetate disodium affect MRE measurements in the delayed hepatobiliary phase?

OBJECTIVES

To assess if the administration of gadoxetate disodium (Gd-EOB-DTPA) significantly affects hepatic magnetic resonance elastography (MRE) measurements in the delayed hepatobiliary phase (DHBP).

METHODS

A total of 47 patients (15 females, 32 males; age range 23-78 years, mean 54.28 years) were assigned to standard hepatic magnetic resonance imaging (MRI) with application of Gd-EOB-DTPA and hepatic MRE. MRE was performed before injection of Gd-EOB-DTPA and after 40-50 min in the DHBP. Liver stiffness values were obtained before and after contrast media application and differences between pre- and post-Gd-EOB-DTPA values were evaluated using a Bland-Altman plot and the Mann-Whitney-Wilcoxon test. In addition, the data were compared with regard to the resulting fibrosis classification.

RESULTS

Mean hepatic stiffness for pre-Gd-EOB-DTPA measurements was 4.01 kPa and post-Gd-EOB-DTPA measurements yielded 3.95 kPa. We found a highly significant individual correlation between pre- and post-Gd-EOB-DTPA stiffness values (Pearson correlation coefficient of r = 0.95 (p < 0.001) with no significant difference between the two measurements (p =0.49)). Bland-Altman plot did not show a systematic effect for the difference between pre- and post-stiffness measurements (mean difference: 0.06 kPa, SD 0.81). Regarding the classification of fibrosis stages, the overall agreement was 87.23% and the intraclass correlation coefficient was 96.4%, indicating excellent agreement.

CONCLUSIONS

Administration of Gd-EOB-DTPA does not significantly influence MRE stiffness measurements of the liver in the DHBP. Therefore, MRE can be performed in the DHBP.

KEY POINTS

• MRE of the liver can reliably be performed in the delayed hepatobiliary phase. • Gd-EOB-DTPA does not significantly influence MRE stiffness measurements of the liver. • MRE performed in the delayed hepatobiliary-phase is reasonable in patients with reduced liver function.

Hepatobiliary phase in cirrhotic patients with different Model for End-stage Liver Disease score: comparison of the performance of gadoxetic acid to gadobenate dimeglumine

OBJECTIVES

The purpose of this study was to compare the performance of gadobenate dimeglumine-enhanced MRI and gadoxetic acid-enhanced MRI in the hepatobiliary phase (HBP) in cirrhotic patients with different degrees of liver dysfunction.

METHODS

In this retrospective cross-sectional study, we analyzed the unenhanced phase and the HBP of 131 gadobenate dimeglumine-enhanced MRI examinations (gadobenate dimeglumine group) and 127 gadoxetic acid-enhanced MRI examinations (gadoxetic acid group) performed in 249 cirrhotic patients (181 men and 68 women; mean age, 64.8 years) from August 2011 to April 2017. For each MRI, the contrast enhancement index of the liver parenchyma was calculated and correlated to the Model For End-Stage Liver Disease (MELD) score (multiple linear regression analysis). A qualitative analysis of the adequacy of the HBP, adjusted for the MELD score (logistic regression analysis), was performed.

RESULTS

The contrast enhancement index was inversely related (r = - 0.013) with MELD score in both gadoxetic acid and gadobenate dimeglumine group. At the same MELD score, the contrast enhancement index in the gadoxetic acid group was increased by a factor of 0.23 compared to the gadobenate dimeglumine group (p < 0.001), and the mean odds ratio to have an adequate HBP with gadoxetic acid compared to gadobenate dimeglumine was 3.64 (p < 0.001). The adequacy of the HBP in the gadoxetic acid group compared to the gadobenate dimeglumine group increased with the increase of the MELD score (exp(b)interaction = 1.233; p = 0.011).

CONCLUSION

In cirrhotic patients, the hepatobiliary phase obtained with gadoxetic acid-enhanced MRI is of better quality in comparison to gadobenate dimeglumine-enhanced MRI, mainly in patients with high MELD score.

KEY POINTS

• In cirrhotic patients, the adequacy of the hepatobiliary phase with gadoxetic acid-enhanced MRI is better compared to gadobenate dimeglumine-enhanced MRI. • Gadoxetic acid-enhanced MRI should be preferred to gadobenate dimeglumine-enhanced MRI in cirrhotic patients with MELD score > 10, if the hepatobiliary phase is clinically indicated. • In patients with high MELD score (> 15), the administration of the hepatobiliary agent could be useless; even though, if it is clinically indicated, we recommend to use gadoxetic acid given the higher probability of obtaining clinically relevant information.

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.

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.

A New Model for MR Evaluation of Liver Function with Gadoxetic Acid, Including Both Uptake and Excretion

OBJECTIVES

Most existing models that are in use to model hepatic function through assessment of hepatic gadoxetic acid enhancement kinetics do not consider quantitative measures of gadoxetic excretion. We developed a model that allows a simultaneous quantitation of uptake and excretion of liver specific contrast agents. The aim was to improve the assessment of hepatic synthetic function, and provide quantitative measures of hepatic excretion function.

METHODS

Sixteen patients underwent dynamic T1-weighted turbo gradient echo imaging at 1.5 T prior and after bolus injection of gadoxetic acid at 0.1 ml/kg. DCE-images were obtained for 30 min after injection. A dual-inlet two-compartment model was then used to fit the measured liver signal values. Four tissue parameters (extracellular volume fraction, arterial flow fraction, uptake rate and excretion half-time) were extracted for each liver segment.

RESULTS

The proposed model provided a good fit to acquired data. Mean values for arterial flow fraction (0.08+-0.04), extracellular volume (0.20±0.08) and uptake rate (4.02 ±1.32 /100 ml/min) were comparable to those obtained with the conventional model (0.08±0.05, 0.21±0.12, and 4.93±1.74), but exhibited significantly less variation and improved fit quality.

CONCLUSIONS

The proposed model is more accurate than existing conventional models and provides an additional excretion parameter.

KEY POINTS

• Models of hepatic contrast agent uptake can be extended to include excretion. • Including an additional excretion parameter improves accuracy of the model. • Standard diagnostic sequences can be extended to incorporate the model.

Hepatobiliary MRI: Signal intensity based assessment of liver function correlated to 13C-Methacetin breath test

Gadoxetic acid (Gd-EOB-DTPA) is a paramagnetic MRI contrast agent with raising popularity and has been used for evaluation of imaging-based liver function in recent years. In order to verify whether liver function as determined by real-time breath analysis using the intravenous administration of ¹³C-methacetin can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI using signal intensity (SI) values. 110 patients underwent Gd-EOB-DTPA-enhanced 3-T MRI and, for the evaluation of liver function, a ¹³C-methacetin breath test (¹³C-MBT). SI values from before (SI_pre) and 20 min after (SI_post) contrast media injection were acquired by T1-weighted volume-interpolated breath-hold examination (VIBE) sequences with fat suppression. The relative enhancement (RE) between the plain and contrast-enhanced SI values was calculated and evaluated in a correlation analysis of ¹³C-MBT values to SI_post and RE to obtain a SI-based estimation of ¹³C-MBT values. The simple regression model showed a log-linear correlation of ¹³C-MBT values with SI_post and RE (p < 0.001). Stratified by 3 different categories of ¹³C-MBT readouts, there was a constant significant decrease in both SI_post (p ≤ 0.002) and RE (p ≤ 0.033) with increasing liver disease progression as assessed by the ¹³C-MBT. Liver function as determined using real-time ¹³C-methacetin breath analysis can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI using SI-based indices.

Detecting liver fibrosis with Gd-EOB-DTPA-enhanced MRI: A confirmatory study

Strong correlations between the grade of fibrosis and cirrhosis, classified using the Ishak scoring system, and the uptake characteristics of Gd-EOB-DTPA with the relative enhancement (RE) of the liver parenchyma have been reported. To confirm the results of a retrospective analysis, patients undergoing liver surgery were prospectively examined with Gd-EOB-DTPA-enhanced liver 3 Tesla MRI to determine the degree of liver fibrosis. Correlations between the grade of fibrosis and cirrhosis, classified using the Ishak scoring system, and RE were investigated and compared with those derived from an initial retrospective study. After validating the cut-off values in the retrospective study (Ishak ≥ 1, RE-cut-off 0.90; Ishak ≥ 2, RE-cut-off 0.79; Ishak ≥ 4, RE-cut-off 0.60; and Ishak = 6, RE-cut-off 0.47), we showed that Gd-EOB-DTPA has a high sensitivity (≥86%) and a high positive predictive value (≥86%). These results support the use of Gd-EOB-DTPA-enhanced liver MRI as a non-invasive method for determining the degree of liver fibrosis and cirrhosis.

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.

Development and validation of a predictor of insufficient enhancement during the hepatobiliary phase of Gd-EOB-DTPA-enhanced magnetic resonance imaging

Background Insufficient enhancement of liver parenchyma negatively affects diagnostic accuracy of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI). Currently, there is no reliable method for predicting insufficient enhancement during the hepatobiliary phase (HBP) in Gd-EOB-DTPA-enhanced MRI. Purpose To develop a predictor for insufficient enhancement of liver parenchyma during HBP in Gd-EOB-DTPA-enhanced MRI. Material and Methods In order to formulate a HBP enhancement test (HBP-ET), clinical factors associated with relative enhancement ratio (RER) of liver parenchyma were retrospectively determined from the datasets of 156 patients (Development group) who underwent Gd-EOB-DTPA-enhanced MRI between November 2012 and May 2015. The independent clinical factors were identified by Pearson's correlation and multiple stepwise regression analysis; the performance of HBP-ET was compared to Child-Pugh score (CPS), Model for End-stage Liver Disease score (MELD), and total bilirubin (TBIL) using receiver operating characteristic (ROC) curve analysis. The datasets of 52 patients (Validation group), which were examined between June 2015 and Oct 2015, were applied to validate the HBP-ET. Results Six biochemical parameters independently influenced RER and were used to develop HBP-ET. The mean HBP-ET score of patients with insufficient enhancement was significantly higher than that of patients with sufficient enhancement ( P < 0.001) in both the Development and Validation groups. HBP-ET (area under the curve [AUC] = 0.895) had better performance in predicting insufficient enhancement than CPS (AUC = 0.707), MELD (AUC = 0.798), and TBIL (AUC = 0.729). Conclusion The HBP-ET is more accurate than routine indicators in predicting insufficient enhancement during HBP, which is valuable to aid clinical decisions.

Gd-EOB-DTPA-enhanced MRI for evaluation of liver function: Comparison between signal-intensity-based indices and T1 relaxometry

Gadolinium ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) is a paramagnetic hepatobiliary magnetic resonance (MR) contrast agent. Due to its OATP1B1/B3-dependent hepatocyte-specific uptake and paramagnetic properties increasing evidence has emerged to suggest that Gd-EOB-DTPA-enhanced MRI can be potentially used for evaluation of liver function. In this paper we compare the diagnostic performance of Gd-EOB-DTPA-enhanced relaxometry-based and commonly used signal-intensity (SI)-based indices, including the hepatocellular uptake index (HUI) and SI-based indices corrected by spleen or muscle, for evaluation of liver function, determined using the Indocyanin green clearance (ICG) test. Simple linear regression model showed a significant correlation of the plasma disappearance rate of ICG (ICG-PDR) with all Gd-EOB-DTPA-enhanced MRI-based liver function indices with a significantly better correlation of relaxometry-based indices on ICG-PDR compared to SI-based indices. Among SI-based indices, HUI achieved best correlation on ICG-PDR and no significant difference of respective correlations on ICG-PDR could be shown. Assessment of liver volume and consecutive evaluation of multiple linear regression model revealed a stronger correlation of ICG-PDR with both (SI)-based and T1 relaxometry-based indices. Thus, liver function can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI-based indices. Here, indices derived from T1 relaxometry are superior to SI-based indices, and all indices benefit from taking into account respective liver volumes.

Diagnostic Accuracy of Gd-EOB-DTPA for Detection Hepatocellular Carcinoma (HCC): A Comparative Study with Dynamic Contrast Enhanced Magnetic Resonance Imaging (MRI) and Dynamic Contrast Enhanced Computed Tomography (CT)

Background

To compare the diagnostic accuracy of hepato-biliary (HB) phase with gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic acid (Gd-EOB-DTPA) with dynamic contrast-enhanced MR imaging (DCEMRI) and contrast-enhanced CT (DCECT) for hepatocellular carcinoma (HCC) detection.

Material/Methods

73 patients underwent DCECT and Gd-EOB-DTPA-3T-MR. Lesions were classified using a five-point confidence scale. Reference standard was a combination of pathological evidence and tumor growth at follow-up CT/MR at 12 months. Receiver Operating Characteristic (ROC) curves were obtained.

Results

A total of 125 lesions were confirmed in 73 patients. As many as 74 were HCCs and 51 were benign. Area under the curve (AUC) was 0.984 for DCEMRI+HB phase vs. 0.934 for DCEMRI (p<0.68) and 0.852 for DCECT (p<0.001). For lesions >20 mm (n.40), AUC was 0.984 for DCEMRI+HB phase, 0.999 for DCEMRI, and 0.913 for DCECT, (p=n.s.). For lesions <20 mm (n.85) AUC was 0.982 for DCEMRI+HB phase vs. 0.910 for DCEMRI (p<0.01) and 0.828 for DCECT (p<0.001).

Conclusions

The addition of HB phase to DCEMRI provides an incremental accuracy of 4.5% compared to DCEMRI and DCECT for HCC detection. The accuracy of Gd-EOB-DTPA-3T-MR significantly improves for lesions <20 mm. No significant improvement is observed for lesions >20 mm and patients with Child-Pugh class B or C.

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.

Feasibility of 10-Minute Delayed Hepatocyte Phase Imaging Using a 30° Flip Angle in Gd-EOB-DTPA-Enhanced Liver MRI for the Detection of Hepatocellular Carcinoma in Patients with Chronic Hepatitis or Cirrhosis

Objectives

To compare 10-minute (min) delayed hepatocyte phase imaging (HPI) using a 30° flip angle (FA) (10m-FA30) and 20-min delayed HPI using a 10° FA (20m-FA10) or 30° FA (20m-FA30) in Gd-EOB-DTPA-enhanced MRI in patients with chronic hepatitis or cirrhosis, in terms of lesion-to-liver contrast-to-noise ratio (CNR) for hepatocellular carcinoma (HCC) and detection sensitivity for focal hepatic lesions (FHLs).

Materials and Methods

One hundred and four patients with 168 HCCs and 55 benign FHLs who underwent Gd-EOB-DTPA-enhanced MRI with 10m-FA30, 20m-FA10, and 20m-FA30 were enrolled. Patients were divided into two groups according to the Child-Pugh classification: group A with chronic hepatitis or Child-Pugh A cirrhosis and group B with Child-Pugh B or C cirrhosis. Lesion-to-liver CNR for HCCs was compared between 10m-FA30 and 20m-FA10 or 20m-FA30 for each group. The presence of FHLs was evaluated using a four-point scale by two independent reviewers, and the detection sensitivity was analyzed.

Results

In group A, the CNR for HCCs (n = 86) on 10m-FA30 (165.8 ± 99.7) was significantly higher than that on 20m-FA10 (113.4 ± 71.4) and lower than that of 20m-FA30 (210.2 ± 129.3). However, there was no significant difference in the sensitivity of FHL detection between 10m-FA30 (mean 95.0% for two reviewers) and 20m-FA10 (94.7%) or 20m-FA30 (94.7%). In group B, the CNR (54.0 ± 36.4) for HCCs (n = 57) and the sensitivity (94.2%) of FHL detection for 10m-FA30 were significantly higher than those for 20m-FA10 (41.8 ± 36.4 and 80.8%, respectively) and were not different from those for 20m-FA30 (62.7 ± 44.4 and 93.3%, respectively).

Conclusion

The diagnostic performance of 10m-FA30 was similar to or higher than 20m-FA10 or 20m-FA30 in both groups A and B. This finding indicates that 10m-FA30 could replace 20-min delayed HPI regardless of patient liver function and reduce the delay time by 10 minutes.

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.

Hepatobiliary phase images using gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid-enhanced MRI as an imaging surrogate for the albumin-bilirubin grading system

OBJECTIVES

To clarify the correlation between hepatobiliary phase (HBP) images using gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) and albumin-bilirubin (ALBI) grading system.

MATERIALS AND METHODS

We evaluated 220 consecutive patients who underwent liver magnetic resonance imaging with Gd-EOB-DTPA. Quantitative liver-spleen contrast ratio (Q-LSC) was calculated in HBP images approximately 20min after Gd-EOB-DTPA administration. To evaluate the degree of association between Q-LSC and ALBI grade, the Child-Pugh (C-P) score was used for comparison. Correlation coefficients were calculated, and median Q-LSC values were compared with the C-P scores and ALBI grades. The Steel-Dwass multiple comparison test was used for statistical analysis.

RESULTS

The correlation coefficient between Q-LSC and C-P score was -0.35, P<0.0001, and the ALBI grade was -0.61, P<0.0001. Q-LSC of overall median, C-P A, B, and C were 1.94, 1.91, 1.96, and 1.33, respectively. The differences between C-P A and C-P B, C-P B and C-P C, and C-P A and C-P C were P=0.999, 0.126, and 0.149, respectively. Q-LSC of the overall median, ALBI grade 1, 2, and 3 were 1.94, 2.12, 1.69, and 1.30, respectively. The differences between ALBI grades 1 and 2, 2 and 3, and 1 and 3 were P<0.0001, P=0.0466, and P=0.0035, respectively. Q-LSC was better correlated and discriminated by ALBI grade than C-P score.

CONCLUSION

A strong correlation was observed between Q-LSC of an HBP image with Gd-EOB-DTPA and ALBI grade; HBP imaging could be a surrogate for the ALBI grade.

Application of magnetic resonance imaging-based liver function assessment in hepatic surgery

Liver function is often assessed before liver surgery for surgical planning and prognosis prediction. The commonly used methods are not accurate as desired and cannot fully meet the clinical requirements. The advancement of imaging technology and contrast agents has made it possible to use liver-specific contrast agent-enhanced magnetic resonance imaging (MRI) to estimate the total and segmental liver function. Herein, we summarize several evaluation methods currently used and their shortcomings, and describe the principle of hepatic tissue-specific MRI contrast agents, a variety of relevant methods and the latest technological advances. The hepatic tissue-specific contrast-based MRI holds a promise to become a quantitative method for preoperative evaluation of liver function, and achieve the precise assessment of liver function that is needed for precise hepatic surgery.

Non-focal liver signal abnormalities on hepatobiliary phase of gadoxetate disodium-enhanced MR imaging: a review and differential diagnosis

Gadoxetate disodium (Gd-EOB-DTPA) is a linear, non-ionic paramagnetic MR contrast agent with combined extracellular and hepatobiliary properties commonly used for several liver indications. Although gadoxetate disodium is commonly used for detection and characterization of focal lesions, a spectrum of diffuse disease processes can affect the hepatobiliary phase of imaging (i.e., when contrast accumulates within the hepatocytes). Non-focal signal abnormalities during the hepatobiliary phase can be seen with multiple disease processes such as deposition disorders, infiltrating tumors, vascular diseases, and post-treatment changes. The purpose of this paper is to review the different processes which result in non-focal signal alteration during the hepatobiliary phase and to describe imaging patterns that may order a differential diagnosis and facilitate patient management.

MRI-based estimation of liver function by intravoxel incoherent motion diffusion-weighted imaging

PURPOSE

To explore the usefulness of intravoxel incoherent motion (IVIM) to evaluate the hepatic functional reserve as expressed by the model for Child-Pugh class.

MATERIALS AND METHODS

IVIM diffusion-weighted imaging (DWI) using 10 different b values were performed on a Philips 3.0T MR scanner in 70 patients with liver cirrhosis and 60 healthy volunteers as the control group. Patients with liver cirrhosis were subdivided into three groups: Child-Pugh class A: 29 cases; Child-Pugh class B: 19 cases; Child-Pugh class C: 22 cases. Pure molecular diffusion (D), pseudo-diffusion (D*), perfusion fraction (f) and apparent diffusion coefficient (ADC) values were calculated, and used to determine liver function, as indicated by the Child-Pugh class.

RESULTS

The ICC values of D, D*, f and ADC between two radiologists were 0.997, 0.986, 0.985 and 0.995, respectively. D*, f and ADC values of liver cirrhosis group were significantly lower than control group (P<0.001, P=0.016, P=0.042, respectively). D*, f and ADC values significantly decreased with increasing Child-Pugh scores (p<0.05). Child-Pugh scores were inversely correlated with D* and f values (r=-0.423, r=-0.620, respectively). The areas under the curve (AUCs) of D* and f for evaluating liver function were 0.67-0.90 and 0.78-0.89, respectively.

CONCLUSION

IVIM DWI may be a useful image-based method for assessing liver function.

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.

Liver surgery in cirrhosis and portal hypertension

The prevalence of hepatic cirrhosis in Europe and the United States, currently 250 patients per 100000 inhabitants, is steadily increasing. Thus, we observe a significant increase in patients with cirrhosis and portal hypertension needing liver resections for primary or metastatic lesions. However, extended liver resections in patients with underlying hepatic cirrhosis and portal hypertension still represent a medical challenge in regard to perioperative morbidity, surgical management and postoperative outcome. The Barcelona Clinic Liver Cancer classification recommends to restrict curative liver resections for hepatocellular carcinoma in cirrhotic patients to early tumor stages in patients with Child A cirrhosis not showing portal hypertension. However, during the last two decades, relevant improvements in preoperative diagnostic, perioperative hepatologic and intensive care management as well as in surgical techniques during hepatic resections have rendered even extended liver resections in higher-degree cirrhotic patients with portal hypertension possible. However, there are few standard indications for hepatic resections in cirrhotic patients and risk stratifications have to be performed in an interdisciplinary setting for each individual patient. We here review the indications, the preoperative risk-stratifications, the morbidity and the mortality of extended resections for primary and metastatic lesions in cirrhotic livers. Furthermore, we provide a review of literature on perioperative management in cirrhotic patients needing extrahepatic abdominal surgery and an overview of surgical options in the treatment of hepatic cirrhosis.

Evaluation of hypointense liver lesions during hepatobiliary phase MR imaging in normal and cirrhotic livers: is increasing flip angle reliable?

Gd-EOB-DTPA is a newly developed liver specific magnetic resonance contrast agent, which is widely used for focal liver lesion (FLL) detection and liver function evaluation. However, it has been demonstrated that hepatocytes uptake of Gd-EOB-DTPA obviously decreased in cirrhotic liver, and cirrhotic liver parenchyma may show reduced enhancement in hepatobiliary phase, which would result in decreased liver-to-lesion contrast (LLC) and liver to lesion signal intensity ratio (LLSIR). Therefore, it is important to improve the image quality in cirrhotic liver, as it may alter therapeutic strategy. In this paper, we have shown adjustments of the flip angle (FA) provides a simple step to achieve better image quality for evaluation of FLLs, especially to those patients with severe liver cirrhosis. On the basis of our quantitative analysis, both of the LLC and the LLSIR with high FA protocol were always higher than those of low FA protocol. Additionally, on high FA images, more FLLs were detected, peritumoral invasion was found, boundary of the tumor was more remarkably, and better visualization of bile duct was observed. In conclusion, for the patient with severe liver cirrhosis, increasing FA can obviously improve the image quality, which is helpful for FLLs depiction.

MR liver imaging with Gd-EOB-DTPA: The need for different delay times of the hepatobiliary phase in patients with different liver function

PURPOSE

To determine the optimal hepatobiliary delay time after Gd-EOB-DTPA injection for lesion characterization in cirrhosis patients with different liver function.

MATERIALS AND METHODS

Ninety consecutive patients with liver cirrhosis who underwent Gd-EOB-DTPA-enhanced MRI for the evaluation of known or suspected focal liver lesions were enrolled in this retrospective study. The patients were divided into Child-Pugh A, B and C groups depending on their liver function through the Child-Pugh classification. Hepatobiliary phase images obtained at 5, 10, 15, and 20min were assessed in each group by the following items: parenchymal enhancement, contrast agent excretion into the bile ducts and ureter, and contrast- and signal-to-noise ratios for lesions.

RESULTS

In the Child-Pugh A group, parenchymal enhancement increased significantly from 5min to 15min (P<0.05), and stabilized at 20min (P=0.22). However, there was no significant difference in parenchymal enhancement among all of the hepatobiliary phases in the Child-Pugh B and C groups. The biliary contrast agent excretion was first observed before 20min in all of the patients in the Child-Pugh A group, at 20min in 4 patients (25%) in the Child-Pugh B group, and after 20min in 11 patients (78.6%) in the Child-Pugh C group. The numbers of patients whose urethral contrast agent excretion was first observed at 5min in the Child-Pugh A, B and C groups were 38 (63.3%), 12 (75.0%) and 11 (78.6%), respectively. The CNR of the lesions increased significantly (P<0.05), up to 15min after enhancement without a further increase at 20min in the Child-Pugh A group; however, no significant change was found from 5min to 20min in the Child-Pugh B and C groups. For the SNR of lesions, there was no significant difference at 5, 10, 15 and 20min in all of the groups.

CONCLUSIONS

A delay time of 15min for the hepatobiliary phase was sufficient for patients with mild liver dysfunction who were classified as Child-Pugh A. Nevertheless, for the patients with moderate or severe liver dysfunction who were classified as Child-Pugh B or C, a delay time longer than 5min is meaningless for lesion characterization.

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.

Value of gadoxetate biliary transit time in determining hepatocyte function

OBJECTIVE

To determine if transit time for excretion of gadoxetate into major bile ducts and duodenum correlates with clinical models of hepatocellular function.

METHODS

This retrospective research was approved by the Institutional Review Board with waiver of informed consent. Search of the radiology database from January 1, 2013 to March 4, 2014 revealed 84 patients with chronic liver disease (65 males, mean age 47 years). Eighteen control subjects with no known liver disease or risk factors were also enrolled for analysis (9 males, mean age 43 years). MRI was performed with hepatobiliary phases at 10, 15, 20, and 25 min after injection of 0.025 mmol/kg of gadoxetate (Primovist, Bayer HealthCare, Shanghai, China). The time of excreted contrast appearing in the biliary tree and in the duodenum was recorded. Linear trend analysis was performed to determine the relationship between excretion time and hepatic function.

RESULTS

The patient cohort was stratified by Child-Pugh classification (A, B, and C with n = 53, 27, and 4, respectively). Arrival of gadoxetate in the gall bladder at 10-min hepatobiliary phase was seen in 87% of control group and 45% of Child-Pugh A group (p = 0.02). There was no difference between these groups for later hepatobiliary phases. The arrival of biliary contrast in the right hepatic duct, common bile duct, and gall bladder were significantly earlier in the Child-Pugh A group compared to the Child-Pugh B/C group at all hepatobiliary phases after 10 min (p < 0.05). Linear trend analysis showed that biliary transit times were significantly delayed with worsening liver function (p = 0.01). There was no difference in entry time of gadoxetate into the duodenum between the normal, Child-Pugh A, and Child-Pugh B/C groups.

CONCLUSIONS

The transit time for gadoxetate to appear in extrahepatic duct is a reasonable indicator of liver function, and may be included in radiology reports. The appearance in the duodenum, however, may depend on factors other than liver function, such as the physiology of the gallbladder and sphincter of Oddi.

ESGAR consensus statement on liver MR imaging and clinical use of liver-specific contrast agents

Objectives

To develop a consensus and provide updated recommendations on liver MR imaging and the clinical use of liver-specific contrast agents.

Methods

The European Society of Gastrointestinal and Abdominal Radiology (ESGAR) formed a multinational European panel of experts, selected on the basis of a literature review and their leadership in the field of liver MR imaging. A modified Delphi process was adopted to draft a list of statements. Descriptive and Cronbach’s statistics were used to rate levels of agreement and internal reliability of the consensus.

Results

Three Delphi rounds were conducted and 76 statements composed on MR technique (n = 17), clinical application of liver-specific contrast agents in benign, focal liver lesions (n = 7), malignant liver lesions in non-cirrhotic (n = 9) and in cirrhotic patients (n = 18), diffuse and vascular liver diseases (n = 12), and bile ducts (n = 13). The overall mean score of agreement was 4.84 (SD ±0.17). Full consensus was reached in 22 % of all statements in all working groups, with no full consensus reached on diffuse and vascular diseases.

Conclusions

The consensus provided updated recommendations on the methodology, and clinical indications, of MRI with liver specific contrast agents in the study of liver diseases.

Key points

• Liver-specific contrast agents are recommended in MRI of the liver.

• The hepatobiliary phase improves the detection and characterization of hepatocellular lesions.

• Liver-specific contrast agents can improve the detection of HCC.

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.

Improved parenchymal liver enhancement with extended delay on Gd-EOB-DTPA-enhanced MRI in patients with parenchymal liver disease: associated clinical and imaging factors

AIM

To establish the effect of prolonged hepatobiliary phase (HBP) delay time on hepatic enhancement in patients with parenchymal liver disease (PLD).

MATERIALS AND METHODS

Gadoxetate disodium (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) examinations with HBP were obtained after 20- (HBP-20) and 30-minute (HBP-30) delays in patients with PLD. For each patient, the Model for End-Stage Liver Disease (MELD) score, total and direct bilirubin, aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), prothrombin time (PT), and partial thromboplastin time (PTT) were recorded. Signal intensities of the liver, main portal vein, and spleen on pre-contrast, HBP-20, and HBP-30 were documented. Signal intensities were used to calculate liver relative enhancement (LRE), liver-spleen index (LSI), and liver-portal vein index (LPI) for HBP-20 and HBP-30. Improved hepatic enhancement was considered if two or more indices were higher on HBP-30 than HBP-20. A logistic regression model was constructed with improved hepatic enhancement as the outcome.

RESULTS

One hundred and twenty-nine patients underwent 142 MRIs. Mean LRE, LSI, and LPI each increased from HBP-20 to HBP-30 (p = 0.004, p < 0.001, and p < 0.001, respectively). Seventy-two point five percent of cases demonstrated improved hepatic enhancement. The odds ratios for improved hepatic enhancement were 0.85 for MELD score (p = 0.02) and 3.2 for the 3 T scanner (p = 0.02), adjusted for age and sex.

CONCLUSION

Increasing HBP delay to 30 minutes improves hepatic enhancement in patients with PLD, particularly if using a 3 T scanner. This effect is attenuated with higher MELD scores.

[Operative therapy of hepatocellular carcinoma]

BACKGROUND

Curative surgical strategies for hepatocellular carcinoma are liver resection and transplantation.

METHODS

This overview is based on a selective literature search on therapeutic strategies for hepatocellular carcinoma. The new German S3 guidelines are outlined in detail but guidelines from other societies were also taken into consideration.

RESULTS

The question of resectability is of utmost importance and should not only be evaluated in an interdisciplinary tumor board but also in an experienced liver center. Primary resectable hepatocellular carcinoma in patients without portal hypertension should be resected. Most patients without cirrhosis qualify for resection. In patients with Child grade A cirrhosis but without severe portal hypertension and a stable health status, a liver resection should be considered. At resection intraoperative ultrasound is standard. Intrahepatic tumor recurrences also can be re-resected or thermally ablated. New techniques for extended liver resections or minimally invasive liver resections are commonly used and have to be studied further.

CONCLUSION

In addition to liver resection, liver transplantation now represents a standard therapy for hepatocellular carcinoma in cirrhosis. Observing the Milan selection criteria 5-year survival rates of 70-90 % can be achieved; however, increasing organ shortage leads to longer waiting times and thus higher risk of tumor progression. Therefore, patients on the waiting list should have follow-up imaging and bridging with surgical resection, radiofrequency ablation (RFA) or transarterial chemoembolization (TACE) by interventional radiology. Living donor liver transplantation should be considered in all these patients with expected longer waiting times.

Assessment of liver function and liver fibrosis with dynamic Gd-EOB-DTPA-enhanced MRI

RATIONALE AND OBJECTIVES

To evaluate the ability of segmental linear fitting analysis of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid liver perfusion magnetic resonance imaging (MRI) to assess liver function and liver fibrosis.

MATERIALS AND METHODS

Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid liver perfusion MRI was performed in 41 patients, and perfusion estimates were generated by segmental linear fitting analysis of the time-intensity curves. The relationships of Tin, Tout, Kup, and the ratio between the signal intensities of the peak and the last phase with liver fibrosis stage and laboratory measurements of liver function were evaluated.

RESULTS

Serum prealbumin concentration was significantly positively correlated with Kup and the signal intensity ratio and was significantly negatively correlated with Tin and Tout. Tin and Tout were significantly higher and Kup and the signal intensity ratio were significantly lower in patients with advanced fibrosis than those without. Tout was the best predictor of advanced fibrosis, with an area under the receiving operating characteristic curve of 0.843, a sensitivity of 100%, and a specificity of 80%.

CONCLUSIONS

A new procedure of quantifying the hepatocyte-specific uptake of a T1-enhancing contrast agent can be used to assess impaired hepatobiliary function. The parameters obtained from perfusion MRI have the potential to predict advanced fibrosis.

State-of-the-art cross-sectional liver imaging: beyond lesion detection and characterization

Cross-sectional imaging with computed tomography or magnetic resonance imaging is routinely used to detect and diagnose liver lesions; however, these examinations can provide additional important information. The improvement of equipment and techniques has allowed outstanding evaluation of the vascular and biliary anatomy, which is practicable in most routine examinations. Anatomical variants may exclude patients from certain therapeutic options and may be the cause of morbidity or mortality after surgery or interventional procedures. Diffuse liver disease, such as steatosis, hemochromatosis, or fibrosis, must be diagnosed and quantified. Usually these conditions are silent until the late stages, and imaging plays an important role in detecting them early. Additionally, a background of diffuse disease may interfere in a focal lesion systematic reasoning. The diagnostic probability of a particular nodule varies according to the background liver disease. Nowadays, most diffuse liver diseases can be easily and accurately quantified by imaging, which has allowed better understanding of these diseases and improved patient management. Finally, cross-sectional imaging can calculate total and partial liver volumes and estimate the future liver remnant after hepatectomy. This information helps to select patients for portal vein embolization and reduces postoperative complications. Use of a specific hepatic contrast agent on magnetic resonance imaging, in addition to improving detection and characterization of focal lesions, provides functional global and segmental information about the liver parenchyma.

Hepatocellular carcinoma: clinical significance of signal heterogeneity in the hepatobiliary phase of gadoxetic acid-enhanced MR imaging

OBJECTIVES

To clarify the relationship between the biological behaviour of hepatocellular carcinomas (HCCs) and their signal intensity in the hepatobiliary phase of gadoxetic acid-enhanced MR imaging with a special focus on the signal heterogeneity.

METHODS

A total of 68 patients with 70 pathologically proven HCCs were enrolled. On the basis of the signal intensity in the hepatobiliary phase, the lesions were classified into three groups: group 1, homogeneous hypointensity (n = 44); group 2, heterogeneous hyperintensity (n = 20); and group 3, homogeneous hyperintensity (n = 6). The clinicopathological findings were compared among the three groups.

RESULTS

The tumour size and the serum level of protein induced by vitamin K absence or antagonist-II (PIVKA-II) were significantly higher in group 2 compared to group 1 (p = 0.0155, p = 0.0215, respectively) and compared to group 3 (p = 0.0330, p = 0.0220, respectively). The organic anion transporting polypeptide 8 (OATP8) expression in group 2 and group 3 was significantly higher than in group 1 (p < 0.0001, p < 0.0001, respectively). Group 2 showed a significantly lower disease-free survival rate compared to group 1 (p = 0.0125), and group 2 was an independent prognostic factor for disease-free survival (p = 0.0308).

CONCLUSIONS

HCCs in the hepatobiliary phase that are heterogeneously hyperintense on gadoxetic acid-enhanced MR imaging have more malignant potential than other types of HCCs.

KEY POINTS

• Heterogeneous uptake of gadoxetic acid suggests more malignant potential in HCC • Uptake of gadoxetic acid does not suggest less malignancy in HCC • Evaluation of signal heterogeneity on gadoxetic acid-enhanced MR imaging is useful.