Gd-EOB-DTPA-enhanced MR imaging: evaluation of hepatic enhancement effects in normal and cirrhotic livers

Liver Biliary Function Evaluation on a 1.5T Magnetic Resonance Imaging Scan by T1 Reduction Rate Assessment Using Variable-Flip-Angle Sequences

OBJECTIVE

Magnetic resonance (MR) relaxometry is an absolute and reproducible quantitative method, compared with signal intensity for the evaluation of liver biliary function. This is obtainable by the T1 reduction rate (T1RR), as it carries a smaller systematic error than the pre/post contrast agent T1 measurement. We aimed to develop and test an MR T1 relaxometry tool tailored for the evaluation of liver T1RR after gadolinium ethoxybenzyl-diethylenetriaminepentaacetic acid administration on 1.5T MR.

METHODS

In vitro/vivo (liver) T1RR values with two 3D FLASH variable-flip-angle sequences were calculated by a MATLAB algorithm. In vitro measurements were done by 2 physicists, in consensus. The prospective in vivo study was approved by the local ethical committee and performed on 13 normal/26 cirrhotic livers. A supplemental test in 5 normal/5 cirrhotic livers, out of the studied series, was done to compare the results of our method (without B1 inhomogeneity correction) and those of a standardized commercial tool (with B1 inhomogeneity correction). All in vivo evaluations were performed by 2 radiologists with 7 years of experience in abdominal imaging. Open-source Java-based software ImageJ was used to draw the free-hand regions of interest on liver section and for the measurement of hepatic T1RR values. The T1RR values of each group of patients were compared to assess statistically significant differences. All statistical analyses were performed with IBM-SPSS Statistics. In vivo evaluations, the intrareader and interreader reliability was assessed by intraclass correlation coefficient.

RESULTS

Our method showed good accuracy in evaluating in vitro T1RR with a maximum percentage error of 9% (constant at various time points) with T1 values in the 200- to 1400-millisecond range. In vivo, a high concordance between the T1RR evaluated with the proposed method and that calculated from the standardized commercial software was verified ( P < 0.05). The median T1RRs were 74.8, 67.9, and 52.1 for the normal liver, Child-Pugh A, and Child-Pugh B cirrhotic groups, respectively. A very good agreement was found, both within intrareader and interreader reliability, with intraclass correlation coefficient values ranging from 0.88 to 0.95 and from 0.85 to 0.90, respectively.

CONCLUSIONS

The proposed method allowed accurate reliable in vitro/vivo T1RR assessment evaluation of the liver biliary function after gadolinium ethoxybenzyl-diethylenetriaminepentaacetic acid administration.

Comparison between CT volumetry, technetium99m galactosyl-serum-albumin scintigraphy, and gadoxetic-acid-enhanced MRI to estimate the liver fibrosis stage in preoperative patients

OBJECTIVES

To compare the efficacy of computed tomography volumetry (CTV), technetium99m galactosyl-serum-albumin (99mTc-GSA) scintigraphy, and gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic-acid-enhanced MRI (EOB-MRI) in estimating the liver fibrosis (LF) stage in patients undergoing liver resection.

METHODS

This retrospective study included 91 consecutive patients who had undergone preoperative dynamic CT and 99mTc-GSA scintigraphy. EOB-MRI was performed in 76 patients. CTV was used to measure the total liver volume (TLV), spleen volume (SV), normalised to the body surface area (BSA), and liver-to-spleen volume ratio (TLV/SV). 99mTc-GSA scintigraphy provided LHL15, HH15, and GSA indices. The liver-to-spleen ratio (LSR) was calculated in the hepatobiliary phase of EOB-MRI. Hyaluronic acid and type 4 collagen levels were measured in 65 patients. Logistic regression and receiver operating characteristic (ROC) analyses were performed to identify useful parameters for estimating the LF stage and laboratory data.

RESULTS

According to the multivariable logistic regression analysis, SV/BSA (odds ratio [OR], 1.01; 95% confidence interval [CI], 1.003-1.02; p = 0.011), LSR (OR, 0.06; 95%CI, 0.004-0.70; p = 0.026), and hyaluronic acid (OR, 1.01; 95%CI, 1.001-1.02; p = 0.024) were independent variables for severe LF (F3-4). Combined SV/BSA, LSR, and hyaluronic acid correctly estimated severe LF, with an AUC of 0.91, which was significantly larger than the AUCs of the GSA index (AUC = 0.84), SV/BSA (AUC = 0.83), or LSR (AUC = 0.75) alone.

CONCLUSIONS

Combined CTV, EOB-MRI, and hyaluronic acid analyses improved the estimation accuracy of severe LF compared to CTV, EOB-MRI, or 99mTc-GSA scintigraphy individually.

CLINICAL RELEVANCE STATEMENT

The combined analysis of spleen volume on CT volumetry, liver-to-spleen ratio on gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic-acid-enhanced MRI, and hyaluronic acid can identify severe liver fibrosis associated with a high risk of liver failure after hepatectomy and recurrence in patients with hepatocellular carcinoma.

KEY POINTS

• Spleen volume of CT volumetry normalised to the body surface area, liver-to-spleen ratio of EOB-MRI, and hyaluronic acid were independent variables for liver fibrosis. • CT volumetry and EOB-MRI enable the detection of severe liver fibrosis, which may correlate with post-hepatectomy liver failure and complications. • Combined CT volumetry, gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic-acid-enhanced MRI (EOB-MRI), and hyaluronic acid analyses improved the estimation of severe liver fibrosis compared to technetium99m galactosyl-serum-albumin scintigraphy.

Hepatobiliary phase imaging in cirrhotic patients using compressed sensing and controlled aliasing in parallel imaging results in higher acceleration

OBJECTIVE

We aimed to compare the image quality and focal lesion detection ability of hepatobiliary phase (HBP) images obtained using compressed sensing (CS) and controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) in patients with liver cirrhosis.

MATERIALS AND METHODS

We retrospectively included 244 gadoxetic acid-enhanced liver MRI from 244 patients with cirrhosis obtained by two HBP images using CS and CAIPIRINHA from July 2020 to December 2020. The optimized resolution and scan time for CS-HBP and CAIPIRINHA-HBP were 0.9 × 0.9 × 1.5 mm3 and 15 s and 1.3 × 1.3 × 3 mm3 and 16 s, respectively. We compared the image quality between the two sets of images in 244 patients and focal lesion (n = 294) analyses for 112 patients.

RESULTS

CS-HBP showed comparable overall image quality (3.7 ± 0.9 vs. 3.6 ± 0.8, p = 0.680), superior liver edge sharpness (3.9 ± 0.6 vs. 3.6 ± 0.5, p < 0.001), and fewer respiratory motion artifacts (4.0 ± 0.7 vs. 3.8 ± 0.5, p < 0.001), but higher non-respiratory artifacts (3.4 ± 0.7 vs. 3.6 ± 0.6, p < 0.001) and subjective image noise (3.5 ± 0.8 vs. 3.6 ± 0.7, p = 0.014) than CAIPIRINHA-HBP. CS-HBP showed a higher signal-to-noise ratio in the liver than CAIPIRINHA-HBP (20.9 ± 9.0 vs. 18.9 ± 7.1, p = 0.008). The pooled sensitivity, specificity, and AUC were 90.0%, 77.5%, and 0.84 for CS-HBP and 73.5%, 82.4%, and 0.78 for CAIPIRINHA-HBP, respectively.

CONCLUSIONS

CS-HBP showed better focal lesion detection ability, comparable overall image quality, and fewer respiratory motion artifacts, but higher non-respiratory artifacts and noise compared to CAIPIRINHA-HBP. Thus, CS-HBP could be recommended for liver MRI in patients with cirrhosis to improve diagnostic performance.

CLINICAL RELEVANCE STATEMENT

Thin-slice CS-HBP may be useful for detecting sub-centimeter hepatocellular carcinoma in cirrhotic patients with Child-Pugh classification A while maintaining comparable subjective image quality.

KEY POINTS

• Compared with controlled aliasing in parallel imaging results in higher acceleration, compressed sensing hepatobiliary phase yielded thinner slices and shorter scan time at a higher accelerating factor. • Compressed sensing hepatobiliary phase showed comparable overall image quality, superior liver edge sharpness, and fewer respiratory motion artifacts, but higher non-respiratory artifacts and subjective image noise than controlled aliasing in parallel imaging results in higher acceleration-hepatobiliary phase. • Compressed sensing hepatobiliary phase can detect sub-centimeter hepatocellular carcinoma in cirrhotic patients with Child-Pugh classification A.

How Much Is Enough? A Surgical Perspective on Imaging Modalities to Estimate Function and Volume of the Future Liver Remnant before Hepatic Resection

Liver resection is the first curative option for most hepatic primary and secondary malignancies. However, post-hepatectomy liver failure (PHLF) still represents a non-negligible postoperative complication, embodying the most frequent cause of hepatic-related mortality. In the absence of a specific treatment, the most effective way to deal with PHLF is its prevention through a careful preoperative assessment of future liver remnant (FLR) volume and function. Apart from the clinical score and classical criteria to define the safe limit of resectability, new imaging modalities have shown their ability to assist surgeons in planning the best operative strategy with a precise estimation of the FLR amount. New technologies leading to liver and tumor 3D reconstruction may guide the surgeon along the best resection planes combining the least liver parenchymal sacrifice with oncological appropriateness. Integration with imaging modalities, such as hepatobiliary scintigraphy, capable of estimating total and regional liver function, may bring about a decrease in postoperative complications. Magnetic resonance imaging with hepatobiliary contrast seems to be predominant since it simultaneously integrates hepatic function and volume information along with a precise characterization of the target malignancy.

Transitional phase Gd-EOB-DTPA-enhanced MRI: Visual assessment of hepatic function and fibrosis based on uptake rate of Gd-EOB-DTPA

PURPOSE

The aim of the study is to investigate the feasibility for hepatic function and fibrosis visual assessment using transitional phase imaging based on the uptake process of Gd-EOB-DTPA.

MATERIALS AND METHODS

We retrospectively selected 105 consecutive patients who underwent Gd-EOB-DTPA enhanced MRI examination at 1.5 Tesla for intrahepatic lesion evaluation from June 2020 to June 2022. Data were classified into two groups defined by the signal intensity (SI) difference in the hepatic vein against that of the hepatic parenchyma at transitional phase as follows: High and Iso-SI group: hepatic vein SI equal to or greater than the hepatic parenchymal SI; and Low-SI group: hepatic vein SI lower than hepatic parenchymal SI. We evaluated whether significant differences in ALBI score, FIB-4, APRI and LSR of hepatobiliary phase between two groups. We measured cut-off values between two groups in all items according to receiver operating characteristic analysis. Furthermore, the inter-reader reproducibility of the visual assessment on transitional phase images between two readers was evaluated using the ICC.

RESULTS

The visual assessment results were as follows: High and Iso- and Low-SI groups included 48, 57, patients, respectively. Significant differences were observed in ALBI score, FIB-4, APRI and LSR between two groups. The cut-off values of ALBI score, FIB-4, APRI and LSR were -2.69, 2.28, 0.49 and 2.15. ICC of transitional phase image visual assessment between two readers was 0.86.

CONCLUSIONS

Hepatic function and fibrosis might be assessed by visual assessment of transitional phase images in Gd-EOB-DTPA enhanced MRI.

Application of A U-Net for Map-like Segmentation and Classification of Discontinuous Fibrosis Distribution in Gd-EOB-DTPA-Enhanced Liver MRI

Highlights

Abstract

We aimed to evaluate whether U-shaped convolutional neuronal networks can be used to segment liver parenchyma and indicate the degree of liver fibrosis/cirrhosis at the voxel level using contrast-enhanced magnetic resonance imaging. This retrospective study included 112 examinations with histologically determined liver fibrosis/cirrhosis grade (Ishak score) as the ground truth. The T1-weighted volume-interpolated breath-hold examination sequences of native, arterial, late arterial, portal venous, and hepatobiliary phases were semi-automatically segmented and co-registered. The segmentations were assigned the corresponding Ishak score. In a nested cross-validation procedure, five models of a convolutional neural network with U-Net architecture (nnU-Net) were trained, with the dataset being divided into stratified training/validation (n = 89/90) and holdout test datasets (n = 23/22). The trained models precisely segmented the test data (mean dice similarity coefficient = 0.938) and assigned separate fibrosis scores to each voxel, allowing localization-dependent determination of the degree of fibrosis. The per voxel results were evaluated by the histologically determined fibrosis score. The micro-average area under the receiver operating characteristic curve of this seven-class classification problem (Ishak score 0 to 6) was 0.752 for the test data. The top-three-accuracy-score was 0.750. We conclude that determining fibrosis grade or cirrhosis based on multiphase Gd-EOB-DTPA-enhanced liver MRI seems feasible using a 2D U-Net. Prospective studies with localized biopsies are needed to evaluate the reliability of this model in a clinical setting.

Assessment of Liver Function With MRI: Where Do We Stand?

Liver disease and hepatocellular carcinoma (HCC) have become a global health burden. For this reason, the determination of liver function plays a central role in the monitoring of patients with chronic liver disease or HCC. Furthermore, assessment of liver function is important, e.g., before surgery to prevent liver failure after hepatectomy or to monitor the course of treatment. Liver function and disease severity are usually assessed clinically based on clinical symptoms, biopsy, and blood parameters. These are rather static tests that reflect the current state of the liver without considering changes in liver function. With the development of liver-specific contrast agents for MRI, noninvasive dynamic determination of liver function based on signal intensity or using T1 relaxometry has become possible. The advantage of this imaging modality is that it provides additional information about the vascular structure, anatomy, and heterogeneous distribution of liver function. In this review, we summarized and discussed the results published in recent years on this technique. Indeed, recent data show that the T1 reduction rate seems to be the most appropriate value for determining liver function by MRI. Furthermore, attention has been paid to the development of automated tools for image analysis in order to uncover the steps necessary to obtain a complete process flow from image segmentation to image registration to image analysis. In conclusion, the published data show that liver function values obtained from contrast-enhanced MRI images correlate significantly with the global liver function parameters, making it possible to obtain both functional and anatomic information with a single modality.

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.

Effect of type 2 diabetes on Gd-EOB-DTPA uptake into liver parenchyma: replication study in human subjects

PURPOSE

Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) is a contrast agent for magnetic resonance imaging (MRI), which specifically taken up by hepatocytes through organic anion-transporting polypeptides (OATPs). Previous research in mice has shown that type 2 diabetes is associated with reduced uptake of Gd-EOB-DTPA into the liver parenchyma, reflecting reduced expression of OATP. Since considerable differences in OATP expression exist between mice and humans, human studies are necessary to clarify the effect of diabetes to Gd-EOB-DTPA uptake. The purpose of this study was to validate the effect of diabetes to Gd-EOB-DTPA liver uptake by a confirmatory study in humans.

METHODS

Patients who underwent Gd-EOB-DTPA-enhanced MRI were retrospectively reviewed and divided into two groups: severe or uncontrolled diabetic group (patients with insulin therapy and/or HbA1c ≥ 8.4%) and the control group. Liver-to-spleen ratio (LSR) and relative enhancement of the liver (REL) were calculated to represent Gd-EOB-DTPA liver uptake.

RESULTS

A total of 94 patients fulfilled the criteria. The severe or uncontrolled diabetic group (n = 15) showed significantly lower LSR (1.74 ± 0.26 vs. 1.98 ± 0.31, p = 0.007) and REL (0.69 ± 0.23 vs. 0.87 ± 0.31, p = 0.005), compared to the control group (n = 79).

CONCLUSION

Our study revealed decreased uptake of Gd-EOB-DTPA into liver parenchyma in the severe or uncontrolled diabetic patients. Further studies to determine the impact of the reduced liver enhancement on clinical diagnostic practice will be needed.

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.

Uptake of gadoxetic acid in hepatobiliary phase magnetic resonance imaging and transporter expression in hypovascular hepatocellular nodules

AIMS

To evaluate the association between contrast patterns on gadoxetic acid-enhanced hepatobiliary phase (HBP) MR images and transporter expression in surgically resected hypovascular hepatocellular nodules including early hepatocellular carcinomas (HCCs).

METHODS

Forty-two hypovascular hepatic nodules and 43 hypervascular HCCs as a control were included in this retrospective study. Contrast of the nodules on HBP images was graded as hypo-, iso-, or hyperintense. Histopathological assessment was performed in the context of multistep hepatocarcinogenesis. Immunohistochemical staining of organic anion transporter 1B3 (OATP1B3) and multidrug resistance protein 2 (MRP2) was performed. Cramer's coefficient was used to determine the linear relationship between contrast grades and transporter expression, and the Cochran-Armitage trend test was used to determine the relationship between transporter expression and progression of multistep hepatocarcinogenesis.

RESULTS

Moderate linear relationships between contrast grades and OATP1B3 expression were observed for both hypo- and hypervascular nodules. OATP1B3 expression was negatively correlated with the progression of multistep hepatocarcinogenesis. MRP2 expression was not associated with the contrast grades or histopathological results.

CONCLUSION

OATP1B3 expression was associated with contrast grades of hepatocellular nodules observed in HBP image of gadoxetic acid-enhanced MRI in the hypovascular hepatocellular nodules and was negatively correlated with hepatocarcinogenesis.

Quantitative analysis of gadoxetic acid-enhanced MRI for the differential diagnosis of focal liver lesions: Comparison between estimated intralesional gadoxetic acid retention by T1 mapping and conventional processing methods

PURPOSE

To compare the estimated quantity of intratumor gadoxetic acid retention using T1 mapping of gadoxetic acid-enhanced magnetic resonance imaging (MRI) versus conventional processing methods for the differential diagnosis of focal liver lesions.

METHODS

Seventy patients with hepatic lesions (colorectal metastasis (CRM) [n = 28], hepatocellular carcinoma (HCC) [n = 20], hemangioma [n = 12], and intrahepatic cholangiocarcinoma (ICC) [n = 10]) underwent gadoxetic acid-enhanced MRI, including pre- and post-contrast T1-weighted imaging and T1 mapping. Quantitative analyses included the lesion-to-liver signal intensity ratio (SIR) on hepatobiliary phase images, the pre- and post-contrast lesion T1 value difference (ΔT1 [ms]), and the lesion retention index (LRI [%]), which was the estimated intralesional gadoxetic acid retention calculated on pre- and post-contrast T1 maps using a two-compartment pharmacokinetic model. Results were compared between the four subcategories of focal liver lesions using the Kruskal-Wallis test, followed by the post-hoc Dunn's test and receiver operating characteristic (ROC) analysis to distinguish between pairs of the four lesion subcategories.

RESULTS

This study identified significant differences in the LRI of the four lesion subcategories (p <  0.01), without significant differences in ΔT1 or SIR. Post-hoc analysis demonstrated significant differences in CRM vs. hemangioma (p <  0.01), hemangioma vs. ICC (p <  0.01), and HCC vs. ICC (p =  0.047) for the LRI.

CONCLUSIONS

The quantity of intratumor gadoxetic acid retention estimated using pre- and post- contrast T1 mapping could distinguish focal liver lesions, unlike conventional processing methods, and captured unique lesion characteristics.

Noninvasive diagnosis of portal hypertension using gadoxetate DCE-MRI of the liver and spleen

OBJECTIVES

To assess the performance of gadoxetate dynamic contrast-enhanced (DCE) MRI of the liver and spleen for noninvasive diagnosis of portal hypertension (PH).

METHODS

Thirty-five patients (M/F 22/13, mean age 55 years) with chronic liver disease who underwent hepatic venous pressure gradient (HVPG) measurements were prospectively enrolled in this IRB-approved study. All patients underwent multiparametric MRI including gadoxetate DCE-MRI acquisition. Model-based and model-free DCE-MRI analyses were performed. The correlation between DCE-MRI parameters and HVPG was assessed. ROC analysis was employed to determine the diagnostic performance of DCE-MRI parameters alone and in combination for prediction of PH and clinically significant (CS)PH (HVPG > 5 and ≥ 10 mmHg, respectively).

RESULTS

Mean HVPG was 7.0 ± 5.0 mmHg (range 0-18 mmHg). Twenty-one (60%) patients had PH, of whom 9 had CSPH. Modeled liver uptake fraction f_i and uptake rate k_i and model-free parameters liver upslope and uptake were all significantly negatively correlated with HVPG (r range - 0.490 to - 0.398, p value range 0.003-0.018), while spleen interstitial fraction v_e was significantly positively correlated with HVPG (r = 0.336, p = 0.048). For PH diagnosis, liver k_i showed the best diagnostic performance with an AUC, sensitivity, and specificity of 0.74 (confidence interval (CI) 0.57-0.91), 71.4%, and 78.6%. The combination of liver k_i and spleen v_e was selected as the best classifier for diagnosis of CSPH with an AUC, sensitivity, and specificity of 0.87 (CI 0.75-0.99), 100%, and 73.1%.

CONCLUSIONS

Our results demonstrate the potential utility of hepatocyte uptake parameters and spleen interstitial fraction obtained with gadoxetate DCE-MRI for the diagnosis of PH and CSPH.

KEY POINTS

• Liver uptake and spleen interstitial fraction estimates from gadoxetate DCE-MRI are significantly correlated with portal pressure measurements. • Liver uptake rate shows good diagnostic performance for the diagnosis of portal hypertension. • The combination of liver uptake rate with spleen interstitial fraction exhibits excellent diagnostic performance for the diagnosis of clinically significant portal hypertension.

Comparison of handcrafted features and convolutional neural networks for liver MR image adequacy assessment

We propose a random forest classifier for identifying adequacy of liver MR images using handcrafted (HC) features and deep convolutional neural networks (CNNs), and analyze the relative role of these two components in relation to the training sample size. The HC features, specifically developed for this application, include Gaussian mixture models, Euler characteristic curves and texture analysis. Using HC features outperforms the CNN for smaller sample sizes and with increased interpretability. On the other hand, with enough training data, the combined classifier outperforms the models trained with HC features or CNN features alone. These results illustrate the added value of HC features with respect to CNNs, especially when insufficient data is available, as is often found in clinical studies.

Quantification of liver function using gadoxetic acid-enhanced MRI

The introduction of hepatobiliary contrast agents, most notably gadoxetic acid (GA), has expanded the role of MRI, allowing not only a morphologic but also a functional evaluation of the hepatobiliary system. The mechanism of uptake and excretion of gadoxetic acid via transporters, such as organic anion transporting polypeptides (OATP1,3), multidrug resistance-associated protein 2 (MRP2) and MRP3, has been elucidated in the literature. Furthermore, GA uptake can be estimated on either static images or on dynamic imaging, for example, the hepatic extraction fraction (HEF) and liver perfusion. GA-enhanced MRI has achieved an important role in evaluating morphology and function in chronic liver diseases (CLD), allowing to distinguish between the two subgroups of nonalcoholic fatty liver diseases (NAFLD), simple steatosis and nonalcoholic steatohepatitis (NASH), and help to stage fibrosis and cirrhosis, predict liver transplant graft survival, and preoperatively evaluate the risk of liver failure if major resection is planned. Finally, because of its noninvasive nature, GA-enhanced MRI can be used for long-term follow-up and post-treatment monitoring. This review article aims to describe the current role of GA-enhanced MRI in quantifying liver function in a variety of hepatobiliary disorders.

The value of 99mTc-labeled galactosyl human serum albumin single-photon emission computerized tomography/computed tomography on regional liver function assessment and posthepatectomy failure prediction in patients with hilar cholangiocarcinoma

BACKGROUND

The aim was to evaluate the value of Tc-labeled galactosyl human serum albumin (Tc-GSA) with single-photon emission computerized tomography (SPECT) in the preoperative assessment of regional liver function and prediction of posthepatectomy liver failure (PHLF) in patients with hilar cholangiocarcinoma (hCCA).

METHODS

Patients with hCCA who underwent Tc-GSA SPECT/computed tomography (CT) before hepatectomy were included. The liver functional parameters of functional liver density (FLD) and predictive residual index (PRI) were calculated based on Tc-GSA SPECT/CT. PHLF was defined according to the International Study Group of Liver Surgery criteria. Univariate and multivariate analyses were used to analyze the risk factors for PHLF. The prediction of PHLF was calculated using receiver operating characteristic curve.

RESULTS

A total of 34 patients were included, 23 of whom underwent preoperative biliary drainage. FLD was significantly higher in patients with drained lobes than that in patients with undrained lobes (0.615 ± 0.190 versus 0.500 ± 0.211, P < 0.05). Sixteen patients suffered PHLF. The ratio of future remnant to total morphological liver volume, future remnant FLD, and PRI differed significantly in patients with and without PHLF according to univariate analysis. PRI was identified as the only independent factor for prediction of PHLF according to multivariate analysis. With a PRI of 0.78, it was possible to predict PHLF with a sensitivity of 83% and a specificity of 93%.

CONCLUSIONS

Tc-GSA SPECT/CT can accurately assess regional liver function and is better able to predict PHLF than conventional methods in patients with hCCA.

Patterns of enhancement in the hepatobiliary phase of gadoxetic acid-enhanced MRI

A variety of patterns of enhancement of liver lesions and liver parenchyma is observed in the hepatobiliary phase (HBP) of gadoxetic acid-enhanced MRI. It is becoming increasingly apparent that many lesions may exhibit HBP enhancement. Much of the literature regarding the role of gadoxetic acid-enhanced MRI in characterising liver lesions is dichotomous, focusing on whether lesions are enhancing or non-enhancing in the HBP, rather than examining the patterns of enhancement. We provide a pattern-based description of HBP enhancement of liver parenchyma and of liver lesions. The role of OATP1B3 transporters, hepatocyte function and lesion composition in influencing patterns of HBP hyperintensity are discussed.

Hyperintensity at fat spared area in steatotic liver on the hepatobiliary phase MRI

PURPOSE

We aimed to investigate the reasons for hyperintensity at fat spared area in steatotic liver at hepatobiliary phase (HBP) on gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) enhanced liver magnetic resonance imaging.

METHODS

Twenty-two patients with focal fat spared area demonstrating hyperintensity on HBP images were included. A region of interest was placed on in- and opposed-phase images at fat spared area and liver to measure the fat. The measurement was also performed on precontrast T1-weighted and HBP images. The signal intensities of spleen, kidney, muscle, intervertebral disc, and spinal cord were also recorded.

RESULTS

The mean fat fraction of liver and fat spared area was 24.86% (8%-46%) and 8.41% (1%-34%), respectively (P < 0.001). There was a significant positive correlation between liver parenchyma fat fraction and delta fat fraction (r=0.74, P < 0.001). The mean signal intensity values of fat spared areas were higher compared with liver on precontrast T1-weighted and HBP images (P < 0.001). The mean relative enhancement ratio of liver and fat spared areas were 0.98 (0.05-1.90) and 1.15 (0.22-2.03), respectively (P < 0.001). However, in 6 patients, the relative enhancement ratio of liver and fat spared areas were almost equal. The uptake of Gd-EOB at fat spared area was not correlated with the degree of steatosis (r = -0.01, P = 0.95).

CONCLUSION

Fat spared area in steatotic liver appears hyperintense on HBP images due to increased relative enhancement ratio and/or baseline hyperintensity on precontrast images.

Visual liver assessment using Gd-EOB-DTPA-enhanced magnetic resonance imaging of patients in the early post-Fontan period

No imaging modality can be used to evaluate Fontan-associated liver disease (FALD). We retrospectively reviewed hepatic gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (EOB-MRI) characteristics of patients within 1 year post-Fontan procedure, and we evaluated the association between hepatic imaging abnormalities and clinical parameters, including follow-up cardiac catheterization and laboratory test findings. The EOB-MR images were graded, based on the extent of the decreased enhancement, as “normal” (Grade 1), “segmental” (Grade 2), “regional” (Grade 3), and “diffuse” (Grade 4). We enrolled 37 patients (mean age, 3.5 ± 1.0 years): 9 patients had Grade 1 or 2; 14 patients, Grade 3; and 14 patients, Grade 4. EOB-MRI revealed characteristic reticular or mosaic patterns of diminished enhancement (i.e. “frog spawn” appearance). Ultrasonography did not detect diminished enhancement or “frog spawn” appearance. A trend existed toward increased grade severity in imaging with increased central venous pressure, pulmonary vascular resistance, and gamma-glutamyltransferase levels. Noninvasive EOB-MRI revealed the characteristic pattern of diminished enhancement, which was correlated with certain clinical parameters indicative of Fontan physiology and liver dysfunction. Early-stage FALD may occur soon after the Fontan procedure and is associated with increased pressure in the inferior vena cava and hepatic veins.

Convolutional neural network-automated hepatobiliary phase adequacy evaluation may optimize examination time

PURPOSE

To develop and evaluate the performance of a fully-automated convolutional neural network (CNN)-based algorithm to evaluate hepatobiliary phase (HBP) adequacy of gadoxetate disodium (EOB)-enhanced MRI. Secondarily, we explored the potential of the proposed CNN algorithm to reduce examination length by applying it to EOB-MRI examinations.

METHODS

We retrospectively identified EOB-enhanced MRI-HBP series from examinations performed 2011-2018 (internal and external datasets). Our algorithm, comprising a liver segmentation and classification CNN, produces an adequacy score. Two abdominal radiologists independently classified series as adequate or suboptimal. The consensus determination of HBP adequacy was used as ground truth for CNN model training and validation. Reader agreement was evaluated with Cohen's kappa. Performance of the algorithm was assessed by receiver operating characteristics (ROC) analysis and computation of the area under the ROC curve (AUC). Potential examination duration reduction was evaluated descriptively.

RESULTS

1408 HBP series from 484 patients were included. Reader kappa agreement was 0.67 (internal dataset) and 0.80 (external dataset). AUCs were 0.97 (0.96-0.99) for internal and 0.95 (0.92-96) for external and were not significantly different from each other (p = 0.24). 48 % (50/105) examinations could have been shorter by applying the algorithm.

CONCLUSION

A proposed CNN-based algorithm achieves higher than 95 % AUC for classifying HBP images as adequate versus suboptimal. The application of this algorithm could potentially shorten examination time and aid radiologists in recognizing technically suboptimal images, avoiding diagnostic pitfalls.

Gd-EOB-DTPA-enhanced MRI T1 relaxometry as an imaging-based liver function test compared with 13C-methacetin breath test

Background

Gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) can be used as an imaging-based liver function test. This study aims to further corroborate its validity.

Purpose

To compare Gd-EOB-DTPA-enhanced MRI as an imaging-based liver function test with the 13C-methacetin breath test.

Material and Methods

Fifty-three patients who underwent Gd-EOB-DTPA-enhanced MRI T1 relaxometry before and 20 min after intravenous Gd-EOB-DTPA administration as well as a 13C-methacetin breath test (LiMAx test) were retrospectively analyzed. T1 relaxation times of liver parenchyma, total liver volume (TLV), and functional liver volume (FLV) were determined. Pearson correlations, multiple linear regression analysis, and receiver operating characteristic curve analysis were performed with indices derived from T1 relaxometry, liver volumetry, and laboratory parameters to identify the best predictor of liver function as determined by the LiMAx test.

Results

T1 reduction rate (T1 RR), T1 RR × TLV, T1 RR × FLV, and T1 relaxation time 20 min after intravenous Gd-EOB administration showed a statistically significant correlation with LiMAx and discriminatory capacity between patients with LiMAx of > and < 315 µg/kg/h. Of the indices investigated, T1 RR showed the best discriminatory capacity and proved to be the only statistically significant parameter in multiple linear regression analysis.

Conclusion

Gd-EOB-DTPA-enhanced MRI as an imaging-based liver function test also correlates with the LiMAx test which in turn reflects cytochrome P450 function. The T1 reduction rate of the liver on Gd-EOB-DTPA-enhanced MRI allows prediction of liver function as determined by the LiMAx test both for 1.5 and 3.0 T.

Gadobenate dimeglumine-enhanced magnetic resonance imaging can accurately predict the severity of esophageal varices and portal vein pressure in patients with hepatitis B cirrhosis

OBJECTIVE

To explore the effectiveness of gadobenate dimeglumine (Gd-BOPTA)-enhanced magnetic resonance imaging (MRI) in predicting portal hypertension and high-risk esophageal varices (EV) in patients with hepatitis B cirrhosis.

METHODS

In total, 71 and 30 patients comprising the training and validation groups, respectively, were enrolled in the study. Univariate and multivariate analyses were performed to detect their risk of developing high-risk EV to generate a formula for scoring EV. The relationships between the relative enhancement ratio (RE) of Gd-BOPTA-enhanced MRI and portal vein pressure were explored.

RESULTS

Platelet count, portal vein width and RE were identified as independent predictors of high-risk EV. Based on these parameters, the EV score model were calculated as: -6.483 + 15.612 × portal vein width + 2.251 × RE - 0.176 × platelet count. The area under the receiver operating characteristic curve was 0.903. At a cut-off value of ≤ -2.74, the negative predictive value was 94.00%, while the positive predictive value was as high as 93.80% when the cut-off was set at > 4.00. Gd-BOPTA-enhanced MRI was effective in predicting portal pressure. Its accuracy was confirmed with the validation set.

CONCLUSIONS

Gd-BOPTA-enhanced MRI was successfully applied to evaluate high-risk EV and portal hypertension. These results represent an accurate, non-invasive model for detecting high-risk EV, based on which we propose a cost-effective algorithm for EV management, eliminating the need to perform an endoscopy in all patients with cirrhosis.

MRI-Based Upper Abdominal Organs-at-Risk Atlas for Radiation Oncology

PURPOSE

The purpose of our study was to provide a guide for identification and contouring of upper abdominal organs-at-risk (OARs) in the setting of online magnetic resonance imaging (MRI)-guided radiation treatment planning and delivery.

METHODS AND MATERIALS

After a needs assessment survey, it was determined that an upper abdominal MRI-based atlas of normal OARs would be of benefit to radiation oncologists and radiation therapists. An anonymized diagnostic 1.5T MRI from a patient with typical upper abdominal anatomy was used for atlas development. Two MRI sequences were selected for contouring, a T1-weighted gadoxetic acid contrast-enhanced MRI acquired in the hepatobiliary phase and axial fast imaging with balanced steady-state precession. Two additional clinical MRI sequences from commercial online MRI-guided radiation therapy systems were selected for contouring and were included in the final atlas. Contours from each data set were completed and reviewed by radiation oncologists, along with a radiologist who specializes in upper abdominal imaging, to generate a consensus upper abdominal MRI-based OAR atlas.

RESULTS

A normal OAR atlas was developed, including recommendations for contouring. The atlas and contouring guidance are described, and high-resolution MRI images and contours are displayed. OARs, such as the bile duct and biliary tree, which may be better seen on MRI than on computed tomography, are highlighted. The full DICOM/DICOM-RT MRI images from both the diagnostic and clinical online MRI-guided radiation therapy systems data sets have been made freely available, for educational purposes, at econtour.org.

CONCLUSIONS

This MRI contouring atlas for upper abdominal OARs should provide a useful reference for contouring and education. Its routine use may help to improve uniformity in contouring in radiation oncology planning and OAR dose calculation. Full DICOM/DICOM-RT images are available online and provide a valuable educational resource for upper abdominal MRI-based radiation therapy planning and delivery.

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.

Qualitative assessment of EOB-GD-DTPA and Gd-BT-DO3A MR contrast studies in HCC patients and colorectal liver metastases

Aim

To compare liver-specific EOB-GD-DTPA and liver-non-specific Gd-BT-DO3A MR, in hepatocellular carcinoma (HCC) and liver colorectal metastases.

Material and methods

Seventy HCC patients with 158 nodules and 90 colorectal liver metastases (mCRC) with 370 lesions were included in the retrospective analysis. HCC patients underwent MR at 0 time (MR0), after 3 (MR3) and 6 months (MR6) using two different CM; 69 mCRC patients underwent MR with Gd-EOB-BTPA and 21 mCRC patients with Gd-BT-DO3A. We evaluated arterial phase hyperenhancement, lesion-to-liver contrast during portal phase, hepatobiliary phase parenchymal hyperenhancement.

Results

In HCC patients arterial phase hyperenhancement degree was statistically higher (p = 0.03) with Gd-BT-DO3A (mean 4) than GD-EOB-DTPA (mean 2.6), while we found no significant statistical differences among mean (2.6) values at MR0 and MR6 using GD-EOB-DTPA. For all 209 patients underwent Gd-EOB-DTPA, we found that lesion-to-liver contrast during portal phase mean value was 4 while for patients underwent MR with Gd-BT-DO3A was 3 (p = 0.04). For HCC hepatobiliary phase parenchymal hyperenhancement mean value was 2.4. For mCRC patients: among 63 patients underwent previous chemotherapy hepatobiliary phase parenchymal hyperenhancement mean value was 3.1 while for 6 patients no underwent previous chemotherapy was 4 (p = 0.05).

Conclusions

Gd-EOB-DTPA should be chosen in pre surgical setting in patients with colorectal liver metastases.

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.

Early detection and staging of chronic liver diseases with a protein MRI contrast agent

Early diagnosis and noninvasive detection of liver fibrosis and its heterogeneity remain as major unmet medical needs for stopping further disease progression toward severe clinical consequences. Here we report a collagen type I targeting protein-based contrast agent (ProCA32.collagen1) with strong collagen I affinity. ProCA32.collagen1 possesses high relaxivities per particle (r₁ and r₂) at both 1.4 and 7.0 T, which enables the robust detection of early-stage (Ishak stage 3 of 6) liver fibrosis and nonalcoholic steatohepatitis (Ishak stage 1 of 6 or 1 A Mild) in animal models via dual contrast modes. ProCA32.collagen1 also demonstrates vasculature changes associated with intrahepatic angiogenesis and portal hypertension during late-stage fibrosis, and heterogeneity via serial molecular imaging. ProCA32.collagen1 mitigates metal toxicity due to lower dosage and strong resistance to transmetallation and unprecedented metal selectivity for Gd³⁺ over physiological metal ions with strong translational potential in facilitating effective treatment to halt further chronic liver disease progression.

Non-invasive early diagnosis of liver fibrosis is important to prevent disease progression and direct treatment strategies. Here the authors developed a collagen-targeting contrast agent for the detection of early stage fibrosis and non-alcoholic steatohepatitis by magnetic resonance and tested it in animal models.

Estimating liver function in a large cirrhotic cohort: Signal intensity of gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid-enhanced MRI

BACKGROUND

To assess whether gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid-enhanced MRI study is useful to estimate liver function in comparison to the presence or absence of cirrhosis, Child Pugh (CP), Model for End-stage Liver Disease (MELD), ALBI scores and biochemical test.

METHODS

We retrospectively reviewed all consecutive Gd-EOB-DTPA-enhanced-MRI studies performed between 2010 and 2016 in patients with focal liver lesions undergoing clinical evaluation. Patients were divided in study and control group according to the presence of cirrhosis, and then classified by CP, MELD and ALBI. Signal intensity was calculated through the liver-to-muscle ratio in portal- (SI-POR) and hepatobiliary-phase(SI-HEP).

RESULTS

Three-hundred-three Gd-EOB-DTPA liver-enhanced-MRI studies were included. One-hundred-ninety-one patients (63%) were cirrhotic. SI-HEP was significantly lower in cirrhotic group (0.55 ± 0.29 vs 0.66 ± 0.40, p = 0.004).The SI-HEP progressively decreased from CP-A to CP-C (0.59 ± 0.28 to 0.25 ± 0.19, p < 0.0001) and a significant difference was found between MELD ≤ 9 and MELD > 9 groups (0.61 ± 0.31 vs 0.49 ± 0.28, p = 0.007). No differences between ALBI grades were evident. Among biochemical parameters a moderate correlation was found among SI-HEP and total bilirubin, AST and albumin.

CONCLUSION

SI-HEP after Gd-EOB-DTPA-enhanced-MRI effectively stratified patients with different Child Pugh grades and MELD scores. This technique could hence be useful as a novel radiological marker to estimate the underlying liver function.

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.

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).

Assessing liver function: diagnostic efficacy of parenchymal enhancement and liver volume ratio of Gd-EOB-DTPA-enhanced MRI study during interstitial and hepatobiliary phase

AIM

To assess the efficacy of signal intensity in interstitial and hepatobiliary phase normalized for liver volume, on gadolinium-ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) study, for the evaluation of liver function through the comparison with Child-Pugh (CP), model for end-stage liver disease (MELD), and biochemical tests.

METHODS

All dynamic Gd-EOB-DTPA MRI studies performed in patients with suspected liver lesions were retrospectively reviewed. The rate of liver-to-muscle ratio on T1 sequence 70 s (interstitial phase) and 20 min (hepatobiliary phase) after injection of Gd-EOB-DTPA was calculated for each MRI study and then normalized for liver volume (irINTnorm and irHEPnorm). Pearson correlation coefficient was computed to assess the correlation among these values and CP and MELD scores, and biochemical tests.

RESULTS

A total of 303 MRI studies, performed on 221 patients, were included. Mean age was 63.8 years ± 12.9 with a majority of male patients (186; 61.4%). A total of 186 out of 303 (61.4%) were cirrhotic patients. The irHEPnorm was significantly lower in cirrhotic than non-cirrhotic patients (0.0004 ± 0.0002 to 0.0005 ± 0.0003, p = 0.010). This value had a moderate, significant correlation with Child-Pugh and MELD scores (R = - 0.292, p < 0.0001 and R = - 0.192, p = 0.010, respectively). In particular, irHEPnorm progressively decreased from Child-Pugh A to C (0.0004-0.0002, p < 0.0001) and from MELD ≤ 10 to 19-24 (0.0004-0.0003, p = 0.018). Among biochemical parameters, total bilirubin, GOT, and albumin had the strongest correlation with irHEPnorm (R = - 0.258, - 0.291, and 0.262, p < 0.0001, respectively). No correlations were found between irINTnorm and CP and MELD scores.

CONCLUSION

irHEPnorm value derived from Gd-EOB-DTPA-enhanced MRI is a reliable, non-invasive, useful tool to quantify liver function and to assess the degree of cirrhosis, offering a strict relationship with clinical scores and biochemical parameters. This could help surgeons in clinical decision-making, allowing them to choose the more suitable surgical approach for cirrhotic patients.

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.

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.

In vivo confirmation of altered hepatic glucose metabolism in patients with liver fibrosis/cirrhosis by 18F-FDG PET/CT

OBJECTIVE

The aim of this study was to assess the value of ¹⁸F-FDG PET/CT for quantitative assessment of hepatic metabolism in patients with different stages of liver fibrosis/cirrhosis.

MATERIALS AND METHODS

¹⁸F-FDG PET/CT scans of 37 patients either with or without liver fibrosis/cirrhosis, classified according to the METAVIR score (F0-F4) obtained from histopathological analysis of liver specimen, were analyzed retrospectively and classified as follows: no liver fibrosis (F0, n = 6), mild liver fibrosis (F1, n = 11), advanced liver fibrosis (F2, n = 6), severe liver fibrosis (F3, n = 5), and liver cirrhosis (F4, n = 11). The liver-to-blood ratio (LBR, scan time corrected for a reference time of 75 min) was compared between patient groups.

RESULTS

Patients with liver fibrosis or cirrhosis (≥ F1; LBR 1.53 ± 0.35) showed a significant higher LBR than patients with normal liver parenchyma (F0, 1.08 ± 0.23; P = 0.004). In direct comparison, LBR increased up to the advanced stage of liver fibrosis (F2; 2.00 ± 0.40) and decreased until liver cirrhosis is reached (F4, 1.32 ± 0.14).

CONCLUSION

Functional changes in liver parenchyma during liver fibrosis/cirrhosis affect hepatic glucose metabolism and significantly differ between stages of liver fibrosis/cirrhosis, classified according to the METAVIR scoring system, as demonstrated by LBR quantification by ¹⁸F-FDG PET/CT.

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.

Imaging of Hepatic Fibrosis

PURPOSE OF REVIEW

The purpose of this review is to discuss the current imaging techniques for non-invasive assessment of liver fibrosis (LF).

RECENT FINDINGS

Elastography-based techniques are the most widely used imaging methods for the evaluation of LF. Currently, MR elastography (MRE) is the most accurate non-invasive method for detection and staging of LF. Ultrasound-based vibration-controlled transient elastography (VCTE) is the most widely used as it can be easily performed at the point of care but has technical limitations especially in the obese. Innovations and technical improvements continue to evolve in elastography for improving accuracy and avoiding misinterpretation from confounding factors. Other imaging methods including diffusion-weighted imaging (DWI), hepatocellular contrast-enhanced (HCE) MRI, T1 relaxometry, T1ρ imaging, textural analysis, liver surface nodularity, susceptibility-weighted imaging, and perfusion imaging are promising but need further evaluation and clinical validation. MRE is the most accurate imaging technique for assessment of LF.

A radiologist's point of view in the presurgical and intraoperative setting of colorectal liver metastases

Multidisciplinary management of patients with metastatic colorectal cancer requires in each phase an adequate choice of the most appropriate imaging modality. The first challenging step is liver lesions detection and characterization, using several imaging modality ultrasound, computed tomography, magnetic resonance and positron emission tomography. The criteria to establish the metastases resectability have been modified. Not only the lesions number and site but also the functional volume remnant after surgery and the quality of the nontumoral liver must be taken into account. Radiologists should identify the liver functional volume remnant and during liver surgical procedures should collaborate with the surgeon to identify all lesions, including those that disappeared after the therapy, using intraoperative ultrasound with or without contrast medium.

The role of imaging in prediction of post-hepatectomy liver failure

Post-hepatectomy liver failure (PHLF) is not only a leading cause of mortality but also a leading cause of life-threatening complications in patients undergoing liver resection. The ability to accurately detect the emergence of PHLF represents a crucially important step. Currently, PHLF can be predicted by a comprehensive evaluation of biological, clinical, and anatomical parameters. With the development of new technologies, imaging methods including elastography, diffusion-weighted magnetic resonance imaging, and gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid-enhanced MRI play a more significant role in the pre-operative prediction and assessment of PHLF. In this review, we summarize the mainstream studies, with the aim of evaluating the role of imaging and improving the clinical value of existing scoring systems for predicting PHLF.

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.

Post-hepatectomy liver failure after major hepatic surgery: not only size matters

Objectives

To compare the value of functional future liver remnant (functFLR) to established clinical and imaging variables in prediction of post-hepatectomy liver failure (PHLF) after major liver resection.

Methods

This retrospective, cross-sectional study included 62 patients, who underwent gadoxetic acid enhanced MRI and MDCT within 10 weeks prior to resection of ≥ 4 liver segments. Future liver remnant (FLR) was measured in MDCT using semi-automatic software. Relative liver enhancement for each FLR segment was calculated as the ratio of signal intensity of parenchyma before and 20 min after i.v. administration of gadoxetic acid and given as mean (remnantRLE). Established variables included indocyanine green clearance, FLR, proportion of FLR, weight-adapted FLR and remnantRLE. functFLR was calculated as FLR multiplied by remnantRLE and divided by patient’s weight. The association of measured variables and PHLF was tested with univariate and multivariate logistic regression analysis and receiver operator characteristics (ROC) curves compared with the DeLong method.

Results

Sixteen patients (25.8%) experienced PHLF. Univariate logistic regression identified FLR (p = 0.015), proportion of FLR (p = 0.004), weight-adapted FLR (p = 0.003), remnantRLE (p = 0.002) and functFLR (p = 0.002) to be significantly related to the probability of PHLF. In multivariate logistic regression analysis, a decreased functFLR was independently associated with the probability of PHLF (0.561; p = 0.002). Comparing ROC curves, functFLR showed a significantly higher area under the curve (0.904; p < 0.001) than established variables.

Conclusions

functFLR seems to be superior to established variables in prediction of PHLF after major liver resection.

Key Points

• functFLR is a parameter combining volumetric and functional imaging information, derived from MDCT and gadoxetic acid enhanced MRI.

• In comparison to other established methods, functFLR is superior in prediction of post-hepatectomy liver failure.

• functFLR could help to improve patient selection prior major hepatic surgery.

Predicting post-hepatectomy liver failure by combined volumetric, functional MR image and laboratory analysis

BACKGROUND & AIMS

To assess the efficacy of functional MR image with volumetric, liver function test and indocyanine green clearance (ICG) in identifying the patients who are at risk of post-hepatectomy liver failure (PHLF).

METHODS

We retrospectively included 115 patients undergoing gadoxetic acid-enhanced MR imaging before hepatectomy at one medical centre from January 2013 to December 2015. Contrast enhancement ratio (CER) between transitional and hepatobiliary phases (3 and 30 minutes post-contrast) was calculated. Total liver volume (TLV) and spleen volume (Sp) were measured. Post-operatively, the histological Ishak fibrosis score was collected. Potential risk factors for liver failure were analysed, and the performance was examined by receiver operating characteristic curve.

RESULTS

Post-hepatectomy liver failure (PHLF) occurred in 16 patients (13.9%). TLV/SLV, ADC value, CER_HBP/TP and total liver contrast enhancement ratio (tCER) were associated with PHLF (P < .05). Between PHLF and non-PHLF groups, remnant liver volume (RLV), RLV/SLV, Sp/RLV, remnant liver contrast enhancement ratio (rCER) and Ishak fibrosis score showed statistical difference. rCER showed superiority in diagnostic performance (AUC = 0.78) with the optimal cut-off value of 1.23.

CONCLUSIONS

Gadoxetic acid-enhanced MR imaging with volumetric is a reliable method for evaluating functional liver volume and determining the risk of PHLF.

Prediction of high-stage liver fibrosis using ADC value on diffusion-weighted imaging and quantitative enhancement ratio at the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI at 1.5 T

Background Recently, diffusion-weighted imaging (DWI) and quantitative enhancement ratio measured at the hepatobiliary phase (HBP) of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) has been established as an effective method for evaluating liver fibrosis. Purpose To evaluate which is a more favorable surrogate marker in predicting high-stage liver fibrosis, apparently diffusion coefficient (ADC) value or quantitative enhancement ratio measured on HBP. Material and Methods Eighty-three patients with 99 surgically resected hepatic lesions were enrolled in this study. DWI was performed with b-values of 100 and 800 s/mm². Regions of interest were set on ADC map, and the HBP of Gd-EOB-DTPA-enhanced MRI, to calculate ADC value, liver-to-muscle ratio (LMR), liver-to-spleen ratio (LSR), and contrast enhancement index (CEI) of liver. We compared these parameters between low-stage fibrosis (F0, F1, and F2) and high-stage fibrosis (F3 and F4). Receiver operating characteristic analysis was performed to compare the diagnostic performance when distinguishing low-stage fibrosis from high-stage fibrosis. Results LMR and CEI were significantly lower at high-stage fibrosis than at the low stage ( P < 0.01 and P = 0.04, respectively), whereas LSR did not show a significant difference ( P = 0.053). No significant difference was observed in diagnostic performance between LMR and CEI ( P = 0.185). The best sensitivity and specificity, when an LMR of 2.80 or higher was considered to be low-stage fibrosis, were 82.4% and 75.6%, respectively. ADC value showed no significant differences among fibrosis grades ( P = 0.320). Conclusion LMR and CEI were both adequate surrogate parameters to distinguish high-stage fibrosis from low-stage fibrosis.

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.

Optimization of hepatobiliary phase delay time of Gd-EOB-DTPA-enhanced magnetic resonance imaging for identification of hepatocellular carcinoma in patients with cirrhosis of different degrees of severity

AIM

To optimize the hepatobiliary phase delay time (HBP-DT) of Gd-EOB-DTPA-enhanced magnetic resonance imaging (GED-MRI) for more efficient identification of hepatocellular carcinoma (HCC) occurring in different degrees of cirrhosis assessed by Child-Pugh (CP) score.

METHODS

The liver parenchyma signal intensity (LPSI), the liver parenchyma (LP)/HCC signal ratios, and the visibility of HCC at HBP-DT of 5, 10, 15, 20, and 25 min (i.e., DT-5, DT-10, DT-15, DT-20, and DT-25 ) after injection of Gd-EOB-DTPA were collected and analyzed in 73 patients with cirrhosis of different degrees of severity (including 42 patients suffering from HCC) and 18 healthy adult controls.

RESULTS

The LPSI increased with HBP-DT more significantly in the healthy group than in the cirrhosis group (F = 17.361, P < 0.001). The LP/HCC signal ratios had a significant difference (F = 12.453, P < 0.001) among various HBP-DT points, as well as between CP-A and CP-B/C subgroups (F = 9.761, P < 0.001). The constituent ratios of HCC foci identified as obvious hypointensity (+++), moderate hypointensity (++), and mild hypointensity or isointensity (+/-) kept stable from DT-10 to DT-25: 90.6%, 9.4%, and 0.0% in the CP-A subgroup; 50.0%, 50.0%, and 0.0% in the CP-B subgroup; and 0.0%, 0.0%, and 100.0% in the CP-C subgroup, respectively.

CONCLUSION

The severity of liver cirrhosis has significant negative influence on the HCC visualization by GED-MRI. DT-10 is more efficient and practical than other HBP-DT points to identify most of HCC foci emerging in CP-A cirrhosis, as well as in CP-B cirrhosis; but an HBP-DT of 15 min or longer seems more appropriate than DT-10 for visualization of HCC in patients with CP-C cirrhosis.

Transient severe motion during arterial phase in patients with Gadoxetic acid administration: Can a five hepatic arterial subphases technique mitigate the artifact?

Gadoxetic acid (Gd-EOB-DTPA) is a hepatocyte-specific magnetic resonance (MR) contrast agent, which has been increasingly used in recent years. However, it has been reported that Gd-EOB-DTPA related transient severe motion (TSM) is sometimes observed during the hepatic arterial phase of MR imaging, which may influence image quality. Since the hepatic arterial phase of contrast enhancement is used for the diagnosis of hepatocellular carcinoma, it is crucial to obtain a decent arterial phase imaging. The present study analyzed motion in patients receiving Gd-EOB-DTPA, comparing a single arterial phase acquisition to a five arterial phase acquisition to determine whether the multiphase acquisition was able to alleviate the TSM-related hepatic arterial MR imaging artifact. It was demonstrated that the single-phase acquisition failed to provide adequate diagnostic image quality in patients with TSM, whereas the multiphase arterial acquisition provided acceptable image quality in 20/22 (90.9%) patients with TSM. In conclusion, the results of the present study demonstrated that multiphase arterial acquisition is superior to single-phase arterial acquisition, mitigating arterial MR imaging artifacts caused by TSM after the administration of Gd-EOB-DTPA.