Improved detection of focal liver lesions at MR imaging: multicenter comparison of gadoxetic acid-enhanced MR images with intraoperative findings

Breath-hold High-resolution T1-weighted Gradient Echo Liver MR Imaging with Compressed Sensing Obtained during the Gadoxetic Acid-enhanced Hepatobiliary Phase: Image Quality and Lesion Visibility Compared with a Standard T1-weighted Sequence

PURPOSE

To evaluate the feasibility of breath-hold (BH) high-resolution (HR) T1-weighted gradient echo hepatobiliary phase (HBP) imaging using compressed sensing (CS) in gadoxetic acid-enhanced liver MRI in comparison with standard HBP imaging using parallel imaging (PI).

METHODS

The study included 122 patients with liver tumors with hypointensity in the HBP who underwent both HR HBP imaging with CS and standard HBP imaging with PI. Two radiologists evaluated the liver edge sharpness, hepatic vessel conspicuity, bile duct conspicuity, image noise, and overall image quality, as well as the lesion conspicuity on HR and standard HBP imaging and the contrast-enhanced (CE) MR cholangiography (MRC) image quality reconstructed from HBP images. As a quantitative analysis, the SNR of the liver and the liver to lesion signal intensity ratio (LLSIR) were also determined.

RESULTS

The liver edge sharpness, hepatic vessel conspicuity, bile duct conspicuity, and overall image quality as well as the lesion conspicuity and the LLSIR on HR HBP imaging with CS were significantly higher than those on standard HBP imaging (all of P < 0.001). The image quality of CE-MRC reconstructed from HR HBP imaging with CS was also significantly higher than that from standard HBP imaging (P < 0.001). Conversely, the SNR of liver in standard HBP was significantly higher than that in HR HBP with CS (P < 0.001).

CONCLUSION

BH HR HBP imaging with CS provided an improved overall image quality, lesion conspicuity, and CE-MRC visualization when compared with standard HBP imaging without extending the acquisition time.

Apparent Variation in Measurement Size of Colorectal Cancer Metastases to the Liver on Dual Contrast MRI

PURPOSE

The aim of this study was to formally investigate the apparent variation in lesion size of hepatic metastatic lesions from colorectal cancer on hepatobiliary phase (HBP) and dual contrast images of magnetic resonance imaging performed with both hepatobiliary and extracellular contrast agents.

METHODS

Patients with known colorectal carcinoma who had undergone dual contrast liver magnetic resonance imaging were identified in our institutional database. Metastatic lesions were measured semiautomatically on both HBP and dual contrast images with a custom software tool that automatically identifies the lesion edge and thereby the lesion diameter. Lesion measurements from both sets of images were compared with a Student t test and Bland-Altman analysis. Lesions were also measured on both HBP and dual contrast images by 2 fellowship-trained abdominal radiologists. Measurements from the software and radiologists were compared with a Student t test and Bland-Altman analysis; interreader agreement was evaluated with the intraclass correlation coefficient.

RESULTS

A total of 70 liver lesions in 39 patients was identified. Software-based measurements were significantly larger on HBP than dual contrast images ( P < 0.001), with a mean lesion size of 10.9 ± 4.2 mm for HBP and 10.5 ± 4.2 mm for dual contrast measurements. Radiologist-based measurements showed a similar trend, with HBP measurements being significantly larger than dual contrast measurements ( P < 0.001). Bland-Altman analysis indicated a mean bias ± 2 SD of +0.4 ± 1.6 mm for software-based measurements and +0.9 ± 2.9 mm and +0.7 ± 2.1 mm for readers 1 and 2, respectively. The intraclass correlation coefficient for interreader agreement was 0.9.

CONCLUSIONS

Both software-based and radiologist-based measurements of colorectal cancer liver metastases are significantly larger on HBP than dual contrast images. Based on these findings, we recommend that longitudinal assessment be performed consistently on either HBP or dual contrast phases to avoid introduction of avoidable variability.

Impact of portal-phase signal intensity of dynamic gadoxetic acid-enhanced magnetic resonance imaging in hepatocellular carcinoma

PURPOSE

To evaluate the prognostic impact of dynamic gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) in patients with hepatocellular carcinoma (HCC).

METHODS

We retrospectively reviewed the data of 206 patients with HCC who underwent preoperative Gd-EOB-DTPA-enhanced MRI and hepatectomy and quantitatively evaluated the signal intensity ratio of the tumor to the surrounding liver tissue in the portal phase (SIRPP). We verified the survival rates and assessed the prognostic factors associated with overall survival (OS) and recurrence-free survival (RFS) using SIRPP.

RESULTS

Multivariate analysis revealed that the independent predictive factors for poorly-differentiated HCC were α-fetoprotein > 20 ng/mL (hazard ratio [HR]: 3.1909, 95% confidence interval [CI]: 1.3464-7.5622, p = .0084) and SIRPP ≤ 0.85 (HR: 3.7155, 95% CI: 1.521-9.076, p = .004). The 5-year OS and RFS rates in the high and low SIRPP groups were 83.2 and 52.1%, respectively (p < .0001) and 49.7 and 18.5%, respectively (p = .0003). Multivariate analysis revealed that SIRPP ≤ 0.68 was an independent prognostic factor related to OS (HR: 4.4537, 95% CI: 1.6581-11.9626, p = .003).

CONCLUSION

The SIRPP of preoperative Gd-EOB-DTPA-enhanced MRI might predict the histological differentiation and prognosis of HCC.

Liver functional assessment using time-associated change in the liver-to-spleen signal intensity ratio on enhanced magnetic resonance imaging: a retrospective study

BACKGROUND

Liver-to-spleen signal intensity ratio (LSR) is evaluated by magnetic resonance imaging (MRI) in the hepatobiliary phase and has been reported as a useful radiological assessment of regional liver function. However, LSR is a passive (non-time-associated) assessment of liver function, not a dynamic (time-associated) assessment. Moreover, LSR shows limitations such as a dose bias of contrast medium and a timing bias of imaging. Previous studies have reported the advantages of time-associated liver functional assessment as a precise assessment of liver function. For instance, the indocyanine green (ICG) disappearance rate, which is calculated from serum ICG concentrations at multiple time points, reflects a precise preoperative liver function for predicting post-hepatectomy liver failure without the dose bias of ICG or the timing bias of blood sampling. The aim of this study was to develop a novel time-associated radiological liver functional assessment and verify its correlation with traditional liver functional parameters.

METHODS

A total of 279 pancreatic cancer patients were evaluated to clarify fundamental time-associated changes to LSR in normal liver. We defined the time-associated radiological assessment of liver function, calculated using information on LSR from four time points, as the "LSR increasing rate" (LSRi). We then investigated correlations between LSRi and previous liver functional parameters. Furthermore, we evaluated how timing bias and protocol bias affect LSRi.

RESULTS

Significant correlations were observed between LSRi and previous liver functional parameters such as total bilirubin, Child-Pugh grade, and albumin-bilirubin grade (P < 0.001 each). Moreover, considerably high correlations were observed between LSRi calculated using four time points and that calculated using three time points (r > 0.973 each), indicating that the timing bias of imaging was minimal.

CONCLUSIONS

This study propose a novel time-associated radiological assessment, and revealed that the LSRi correlated significantly with traditional liver functional parameters. Changes in LSR over time may provide a superior preoperative assessment of regional liver function that is better for predicting post-hepatectomy liver failure than LSR using the hepatobiliary phase alone.

Contrast Agents for Hepatocellular Carcinoma Imaging: Value and Progression

Hepatocellular carcinoma (HCC) has the third-highest incidence in cancers and has become one of the leading threats to cancer death. With the research on the etiological reasons for cirrhosis and HCC, early diagnosis has been placed great hope to form a favorable prognosis. Non-invasive medical imaging, including the associated contrast media (CM)-based enhancement scan, is taking charge of early diagnosis as mainstream. Meanwhile, it is notable that various CM with different advantages are playing an important role in the different imaging modalities, or even combined modalities. For both physicians and radiologists, it is necessary to know more about the proper imaging approach, along with the characteristic CM, for HCC diagnosis and treatment. Therefore, a summarized navigating map of CM commonly used in the clinic, along with ongoing work of agent research and potential seeded agents in the future, could be a needed practicable aid for HCC diagnosis and prognosis.

Indeterminate liver lesions on gadoxetic acid-enhanced magnetic resonance imaging of the liver: Case-based radiologic-pathologic review

Different histopathological manifestations of focal liver lesions show varying common and uncommon imaging findings and some pathologies may show similar appearance despite of different histopathology. It is necessary to characterise focal liver lesions accurately as not only benign and malignant lesions are managed differently, but also certain benign lesions have differing management. These lesions are increasingly being detected due to rapid growth of use of cross-sectional imaging as well as improvement in image quality and new imaging techniques. Contrast enhanced magnetic resonance imaging (MRI) is considered the gold standard technique in characterising focal liver lesions. Addition of gadoxetic acid has been shown to significantly increase diagnostic accuracy in the detection and characterization of liver abnormalities. Classic imaging characteristics of common liver lesions, including their behaviour on gadoxetic acid enhanced MRI, have been described in literature over recent years. It is important to be familiar with the typical aspects of these lesions as well as know the uncommon and overlapping imaging features to reach an accurate diagnosis. In this article, we will review the well-described characteristic imaging findings of common and rare focal liver lesions and present several challenging cases encountered in the clinical setting, namely hepatocellular adenoma, focal nodular hyperplasia, hepatic angiomyolipoma, hepatocellular carcinoma, intrahepatic cholangiocarcinoma, neuroendocrine tumours as well as a pleomorphic liposarcoma of the liver.

Is Gadoxetic Acid Disodium (Gd-EOB-DTPA)-Enhanced Magnetic Resonance Imaging an accurate diagnostic method for Hepatocellular Carcinoma? a systematic review with meta-analysis

Background： Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) has become a widely used liver-specific contrast agent worldwide, but its value and limitations as a diagnostic technique with hepatocellular carcinoma (HCC), have not been assessed.

INTRODUCTION

A review of the latest evidence available on the diagnostic value of Gd-EOB-DTPA-enhanced MRI for the evaluation of HCC is reported.

METHODS

A systematic, comprehensive literature search was conducted with PubMed, Scopus, EMBASE, the Web of Science, the Cochrane Library, CNKI, vip, wanfangdata and CBM from inception to June 31, 2020. The QUADAS-2 tool was used to evaluate the quality of the included studies. Pooled sensitivity (SEN), pooled specificity (SPE), pooled positive likelihood ratio (PLR), pooled negative likelihood ratio (NLR), pooled diagnostic odds ratio (dOR) and summary receiver operating characteristic (SROC) curves were calculated to assess the diagnostic value of the individual diagnostic tests.

RESULTS

A total of 47 articles were included, involving a total of 6362 nodules in 37 studies based on per-lesion studies. There were 13 per-patient studies, including a total of 1816 patients. The results of the meta-analysis showed that the per-lesion studies pooled weighted values were SEN 0.90 [95% confidence interval (CI): 0.87-0.92], SPE 0.92 (95%CI: 0.90-0.94), PLR 11.6 (95%CI: 8.8-15.2), NLR 0.11 (95%CI: 0.09-0.14) and dOR 107.0 (95%CI: 74.0-155.0). The AUC of the SROC curve was 0.96. The per-patient studies pooled weighted values were SEN 0.84 [95% confidence interval (CI): 0.78-0.89], SPE 0.92 (95%CI: 0.88-0.94), PLR 10.4 (95%CI: 7.4-14.6), NLR 0.17 (95%CI: 0.12-0.24) and dOR 61.0 (95%CI: 42.0-87.0). The AUC of the SROC curve was 0.95 and subgroup analyses were performed.

CONCLUSIONS

The diagnostic value of Gd-EOB-DTPA for HCC was quantitatively evaluated in a per-lesion study and a per-patient study using a systematic review of the literature. A positive conclusion was drawn: Gd-EOB-DTPA-enhanced imaging is a valuable diagnostic technique for HCC. The size of the nodules and the selection of the imaging diagnostic criteria may affect the diagnostic sensitivity.

Diagnosis of Hepatocellular Carcinoma Using Gd-EOB-DTPA MR Imaging

Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA; Gadoxetic acid; Gadoxetate disodium) is a hepatocyte-specific MR contrast agent. It acts as an extracellular contrast agent in the early phase after intravenous injection, and then is taken up by hepatocytes later. Using this contrast agent, we can evaluate the hemodynamics of the liver and liver tumors, and can therefore improve the detection and characterization of hepatocellular carcinoma (HCC). Gd-EOB-DTPA helps in the more accurate detection of hypervascular HCC than by other agents. In addition, Gd-EOB-DTPA can detect hypovascular HCC, which is an early stage of the multi-stage carcinogenesis, with a low signal in the hepatobiliary phase. In addition to tumor detection and characterization, Gd-EOB-DTPA contrast-enhanced MR imaging can be applied for liver function evaluation and prognoses evaluation. Thus, Gd-EOB-DTPA plays an important role in the diagnosis of HCC. However, we have to employ optimal imaging techniques to improve the diagnostic ability. In this review, we aimed to discuss the characteristics of the contrast media, optimal imaging techniques, diagnosis, and applications.

Expression of Organic Anion Transporting Polypeptides in an H-Ras 12V Transgenic Mouse Model of Spontaneous Hepatocellular Carcinoma

PURPOSE

Expression of organic anion transporting polypeptides (OATPs) 1B1/1B3 in hepatocellular carcinoma (HCC) induces a paradoxical enhancement of gadoxetic acid on liver magnetic resonance imaging (MRI). We examined the expression profile of OATPs with regard to tumor differentiation in a genetically modified H-Ras 12V mouse model of spontaneous HCC that undergoes multistep hepatocarcinogenesis with minimal inter-individual variation.

MATERIALS AND METHODS

Tumor nodules were harvested from transgenic H-Ras 12V mice. Hematoxylin and eosin-stained slides were examined for tumor differentiation and high-grade pathological components (tumor necrosis, thickened trabeculae, or vascular invasion). Immunohistochemistry of OATP 1B1/1B3 was performed, and OATP expression was assessed.

RESULTS

We examined well-differentiated HCCs (n=59) in which high-grade pathological components were absent (n=49) or present (n=10). Among the well-differentiated HCCs without high-grade pathological components (n=49), OATP expression was negative, weak positive, and moderate positive in 23, 17, and nine cases, respectively. Among the well-differentiated HCCs with high-grade pathological components (n=10), OATP expression was negative, weak positive, and moderate positive in one, two, and seven cases, respectively. The ratio of positive OATP 1B1/1B3 expressing tumors was higher in HCCs with high-grade pathological components than in those without high-grade pathological components (p=0.004).

CONCLUSION

Our findings support those of previous clinical studies that have reported the frequent appearance of gadoxetic acid-enhanced MRI in moderately differentiated HCC.

Corona enhancement can substitute enhancing capsule in the imaging diagnosis of small (≤ 3 cm) HCCs on gadoxetic acid-enhanced MRI

OBJECTIVES

This study aimed to elucidate the relationship between gadoxetic acid-enhanced magnetic resonance imaging (MRI) features-enhancing capsule, corona enhancement or hypointense rim-observed in hepatocellular carcinomas (HCCs).

METHODS

Of the HCCs surgically confirmed during a 5-year period (2013-2017), ≤ 3-cm lesions (n = 83) in 78 patients were evaluated. Presence of corona enhancement and enhancing capsule on multiphasic dynamic imaging and presence of hypointense rim on hepatobiliary phase imaging were determined retrospectively by two independent observers. The relationship among the three imaging features was statistically analysed and correlated with the presence of histologic fibrous capsules, tumour differentiation and gross morphologic type.

RESULTS

There was substantial overall interobserver agreement in determining the presence of the three imaging features. Sixty (72.3%) lesions had histologic fibrous capsule positively correlated with all three imaging features (p < 0.05). Corona enhancement was the most common (66.3%) feature followed by enhancing capsule (61.4%) and hypointense rim (33.7%), and the correspondence rate of enhancing capsule to corona enhancement was 68.6% (p = 0.004). Corona enhancement was more frequently observed in moderately differentiated HCCs than other lesions (p = 0.012) and not dependent (p = 0.465) on the tumour size, while enhancing capsule was significantly dependent on tumour size, as indicated by univariate (p < 0.001) and multivariate analyses (odds ratio, 4.241; p = 0.002).

CONCLUSIONS

Among the capsular features, corona enhancement might closely relate to enhancing capsule in HCCs. Corona enhancement was not dependent on tumour size and had the highest incidence of appearance on gadoxetic acid-enhanced multiphasic dynamic MRI.

KEY POINTS

• Enhancing capsule has a limited role in the LI-RADS categorisation during gadoxetic acid-enhanced MRI. • Appearance of corona enhancement is closely related to enhancing capsule and is not dependent on size of HCCs. • Corona enhancement can substitute enhancing capsule in the diagnosis of HCCs during multiple arterial and portal venous phase gadoxetic acid-enhanced MRI.

The Assessment of Regional Liver Function Before Major Hepatectomy Using Magnetic Resonance Imaging

BACKGROUND

The liver-to-spleen signal intensity ratio (LSR) on magnetic resonance imaging with gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid has been used as a parameter to assess liver function. LSR of the future remnant liver region (FR-LSR) is included in preoperative assessment of regional liver function. The aim of this study was to investigate the predictability of post-hepatectomy liver failure (PHLF) by FR-LSR.

METHODS

Between May 2013 and May 2019, 127 patients underwent standardized EOB-MRI for diagnosis of liver tumor before major hepatectomy. The FR-LSR on EOB-MRI was calculated by a semiautomated three-dimensional volumetric analysis system. The cutoff value of FR-LSR in association with clinically relevant PHLF was determined according to the areas under the receiver operating characteristic curves. Then, FR-LSR and clinical variables were analyzed to assess the risk of clinically relevant PHLF.

RESULTS

In patients with preoperative biliary drainage, metastatic liver tumor, estimated future remnant liver volume <50%, biliary reconstruction, operation time ≥ 480 min, estimated blood loss ≥ 1000 g, blood transfusion and a FR-LSR < 2.00 were associated with clinically relevant PHLF (P < .05 for all) in univariable analysis. The liver-to-spleen signal intensity ratio of the future remnant liver region < 2.00 was the only independent risk factor for clinically relevant PHLF in multivariable risk analysis (OR, 27.90; 95% CI: 7.99-136.40; P < .05).

DISCUSSION

The present study revealed that FR-LSR calculated using a 3-dimensional volumetric analysis system was an independent risk factor for clinically relevant PHLF. The liver-to-spleen signal intensity ratio of the future remnant liver region might be a reliable preoperative parameter in liver functional assessment, enabling safe performance of major hepatectomy.

The diagnostic performance of gadoxetic acid disodium-enhanced magnetic resonance imaging and contrast-enhanced ultrasound in detecting hepatocellular carcinoma: A meta-analysis

The purpose of this study was to identify and compare the diagnostic performance of gadolinium-ethoxybenzyl-diethyltriethylenetriacetic acid (Gd-EOB-DTPA) enhanced magnetic resonance imaging (MRI) and contrast-enhanced ultrasound (CEUS) in hepatocellular carcinoma (HCC).Two researchers searched PubMed, EMBASE, and Cochrane Library databases from the inception of each database to 10 February 2020, to find comparative studies of Gd-EOB-DTPA-MRI and CEUS in detection of HCC.The study included eight studies (374 patients). MRI is superior to CEUS in diagnostic sensitivity of HCC, P = .03. The diagnostic sensitivity of MRI in lesions with a diameter of less than 30 mm was significantly higher than that of CEUS, P = .04. MRI and CEUS had no significant difference in diagnostic specificity of HCC, P = .95. Summary Receiver Operating Characteristics (SROC) of MRI showed a larger than that of CEUS, but with P > .05.Gd-EOB-DTPA-MRI showed higher sensitivity than CEUS for hepatocellular carcinoma lesions, especially for lesions of less than 30 mm across.

Synthesis of gadolinium-enhanced liver tumors on nonenhanced liver MR images using pixel-level graph reinforcement learning

If successful, synthesis of gadolinium (Gd)-enhanced liver tumors on nonenhanced liver MR images will be critical for liver tumor diagnosis and treatment. This synthesis will offer a safe, efficient, and low-cost clinical alternative to eliminate the use of contrast agents in the current clinical workflow and significantly benefit global healthcare systems. In this study, we propose a novel pixel-level graph reinforcement learning method (Pix-GRL). This method directly takes regular nonenhanced liver images as input and outputs AI-enhanced liver tumor images, thereby making them comparable to traditional Gd-enhanced liver tumor images. In Pix-GRL, each pixel has a pixel-level agent, and the agent explores the pixels features and outputs a pixel-level action to iteratively change the pixel value, ultimately generating AI-enhanced liver tumor images. Most importantly, Pix-GRL creatively embeds a graph convolution to represent all the pixel-level agents. A graph convolution is deployed to the agent for feature exploration to improve the effectiveness through the aggregation of long-range contextual features, as well as outputting the action to enhance the efficiency through shared parameter training between agents. Moreover, in our Pix-GRL method, a novel reward is used to measure pixel-level action to significantly improve the performance by considering the improvement in each action in each pixel with its own future state, as well as those of neighboring pixels. Pix-GRL significantly upgrades the existing medical DRL methods from a single agent to multiple pixel-level agents, becoming the first DRL method for medical image synthesis. Comprehensive experiments on three types of liver tumor datasets (benign, cancerous, and healthy controls) with 325 patients (24,375 images) show that our novel Pix-GRL method outperforms existing medical image synthesis learning methods. It achieved an SSIM of 0.85 ± 0.06 and a Pearson correlation coefficient of 0.92 in terms of the tumor size. These results prove that the potential exists to develop a successful clinical alternative to Gd-enhanced liver MR imaging.

Value of gadoxetic acid-enhanced MR imaging and DWI in classification, characterization and confidence in diagnosis of solid focal liver lesions

OBJECTIVE

To assess gadoxetic acid (Gd-EOB-DTPA) and diffusion-weighted imaging (DWI) value in classification (benign vs. malignant) and characterization of solid focal liver lesions (SFLLs) and impact on confidence in diagnosis.

METHODS

A total of 195 lesions (46 hepatocellular carcinomas [HCCs], 45 metastases, 32 adenomas, 37 focal nodular hyperplasias [FNHs] and 35 hemangiomas) were retrospectively evaluated in 93 patients. Three imaging datasets were compared: DWI/ apparent diffusion coefficient (ADC) (set A), Gd-EOB-DTPA (set B) and combination of both (set C). Two radiologists (R) independently classified (on a five-point ordinal scale) and characterized each lesion. The accuracy in classification and characterization was compared, and the diagnostic confidence was assessed.

RESULTS

The classification accuracy on set A, B and C was 86.2%, 91.3% and 91.8% (R1), and 84.6%, 91.8% and 93.3% (R2); and characterization accuracy was 67.2%, 88.2% and 87.7% (R1), and 60.5%, 88.2% and 85.6% (R2). Classification by reader 1 showed no significant difference between set A and B (p=.09). For both readers, there was a significant difference between set A and C in both classification and characterization (all p < .05), but no significant difference between set B and C in neither classification nor characterization. No significant difference between the three datasets in classification and characterization of hemangiomas (all p > .05). The diagnostic confidence of the readers has increased progressively from set A to Set C (all p < .01).

CONCLUSIONS

DWI may suggest benignity or malignancy of solid liver lesions, while Gd-EOB-DTPA-enhanced imaging remains superior in lesions characterization and the combination of both increases the diagnostic confidence. DWI is very helpful in the diagnosis of hepatic hemangiomas.

Does Hepatic Steatosis Influence the Detection Rate of Metastases in the Hepatobiliary Phase of Gadoxetic Acid-Enhanced MRI?

The aim of this exploratory study was to evaluate the influence of hepatic steatosis on the detection rate of metastases in gadoxetic acid-enhanced liver magnetic resonance imaging (MRI). A total of 50 patients who underwent gadoxetic acid-enhanced MRI (unenhanced T1w in- and opposed-phase, T2w fat sat, unenhanced 3D-T1w fat sat and 3-phase dynamic contrast-enhanced (uDP), 3D-T1w fat sat hepatobiliary phase (HP)) were retrospectively included. Two blinded observers (O1/O2) independently assessed the images to determine the detection rate in uDP and HP. The hepatic signal fat fraction (HSFF) was determined as the relative signal intensity reduction in liver parenchyma from in- to opposed-phase images. A total of 451 liver metastases were detected (O1/O2, n = 447/411). O1/O2 detected 10.9%/9.3% of lesions exclusively in uDP and 20.2%/15.5% exclusively in HP. Lesions detected exclusively in uDP were significantly associated with a larger HSFF (area under curve (AUC) of receiver operating characteristic (ROC) analysis, 0.93; p < 0.001; cutoff, 41.5%). The exclusively HP-positive lesions were significantly associated with a smaller diameter (ROC-AUC, 0.82; p < 0.001; cutoff, 5 mm) and a smaller HSFF (ROC-AUC, 0.61; p < 0.001; cutoff, 13.3%). Gadoxetic acid imaging has the advantage of detecting small occult metastatic liver lesions in the HP. However, using non-optimized standard fat-saturated 3D-T1w protocols, severe steatosis (HSFF > 30%) is a potential pitfall for the detection of metastases in HP.

Hepatobiliary phase of gadoxetic acid-enhanced MRI in patients with HCC: prognostic features before resection, ablation, or TACE

OBJECTIVES

Patients with hepatocellular carcinoma (HCC) receiving different treatments might have specific prognostic factors that can be captured in the hepatobiliary phase (HBP) of gadoxetic acid-enhanced magnetic resonance imaging (GA-MRI). We aimed to identify the clinical findings and HBP features with prognostic value in patients with HCC.

METHODS

In this retrospective, single-institution study, we included patients with Barcelona Clinic Liver Cancer very early/early stage HCC who underwent GA-MRI before treatment. After performing propensity score matching, 183 patients received the following treatments: resection, radiofrequency ablation (RFA), and transarterial chemoembolization (TACE) (n = 61 for each). Cox regression models were used to identify clinical factors and HBP features associated with disease-free survival (DFS) and overall survival (OS).

RESULTS

In the resection group, large tumor size was associated with poor DFS (hazard ratio [HR] 4.159 per centimeter; 95% confidence interval [CI], 1.669-10.365) and poor OS (HR 8.498 per centimeter; 95% CI, 1.072-67.338). In the RFA group, satellite nodules on HBP images were associated with poor DFS (HR 5.037; 95% CI, 1.061-23.903) and poor OS (HR 9.398; 95% CI, 1.480-59.668). Peritumoral hypointensity on HBP images was also associated with poor OS (HR 13.062; 95% CI, 1.627-104.840). In addition, serum albumin levels and the prothrombin time-international normalized ratio were associated with DFS and/or OS. Finally, in the TACE group, no variables were associated with DFS/OS.

CONCLUSIONS

Different HBP features and clinical factors were associated with DFS/OS among patients with HCC receiving different treatments.

KEY POINTS

• In patients who underwent resection for HCC, a large tumor size on HBP images was associated with poor disease-free survival and overall survival. • In the RFA group, satellite nodules and peritumoral hypointensity on HBP images, along with decreased serum albumin levels and PT-INR, were associated with poor disease-free survival and/or overall survival. • In the TACE group, no clinical or HBP imaging features were associated with disease-free survival or overall survival.

Human Organic Anion Transporting Polypeptide 1B3 Applied as an MRI-Based Reporter Gene

Objective

Recent innovations in biology are boosting gene and cell therapy, but monitoring the response to these treatments is difficult. The purpose of this study was to find an MRI-reporter gene that can be used to monitor gene or cell therapy and that can be delivered without a viral vector, as viral vector delivery methods can result in long-term complications.

Materials and Methods

CMV promoter-human organic anion transporting polypeptide 1B3 (CMV-hOATP1B3) cDNA or CMV-blank DNA (control) was transfected into HEK293 cells using Lipofectamine. OATP1B3 expression was confirmed by western blotting and confocal microscopy. In vitro cell phantoms were made using transfected HEK293 cells cultured in various concentrations of gadoxetic acid for 24 hours, and images of the phantoms were made with a 9.4T micro-MRI. In vivo xenograft tumors were made by implanting HEK293 cells transfected with CMV-hOATP1B3 (n = 4) or CMV-blank (n = 4) in 8-week-old male nude mice, and MRI was performed before and after intravenous injection of gadoxetic acid (1.2 µL/g).

Results

Western blot and confocal microscopy after immunofluorescence staining revealed that only CMV-hOATP1B3-transfected HEK293 cells produced abundant OATP1B3, which localized at the cell membrane. OATP1B3 expression levels remained high through the 25th subculture cycle, but decreased substantially by the 50th subculture cycle. MRI of cell phantoms showed that only the CMV-hOATP1B3-transfected cells produced a significant contrast enhancement effect. In vivo MRI of xenograft tumors revealed that only CMV-hOATP1B3-transfected HEK293 tumors demonstrated a T1 contrast effect, which lasted for at least 5 hours.

Conclusion

The human endogenous OATP1B3 gene can be non-virally delivered into cells to induce transient OATP1B3 expression, leading to gadoxetic acid-mediated enhancement on MRI. These results indicate that hOATP1B3 can serve as an MRI-reporter gene while minimizing the risk of long-term complications.

Impact of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging on the prognosis of hepatocellular carcinoma after surgery

Background and Aim

Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (EOB-MRI) has been recognized as a useful imaging technique to distinguish the biological behavior of hepatocellular carcinoma (HCC).

Methods

We analyzed 217 hepatectomy recipients with HCCs measuring 10 cm or less. We divided the patients into a decreased intensity (DI) group (n = 189, 87%) and an increased or neutral intensity (INI) group (n = 28, 13%) according to the ratio of tumor intensity to liver intensity during the hepatobiliary phase (HBP). According to the ratio of the maximum tumor diameter (including peritumoral hypointensity) between HBP images and precontrast T1-weighted images (RHBPP), we divided the patients as follows: The group whose RHBPP was ≥1.036 was the high RHBPP group (n = 60, 28%), and the group whose RHBPP was <1.036 was the low RHBPP group (n = 157, 72%). We investigated the prognoses and clinicopathological characteristics of these patients.

Results

DI versus INI was not a prognostic factor for either survival or recurrence; however, a high RHBPP was an independent predictor of unfavorable survival and recurrence in patients. In addition, the INI group showed significantly lower α-fetoprotein (AFP) levels and higher rates of well-differentiated HCC and ICGR15 ≥15% than the DI group. The high RHBPP group showed significantly higher rates of vascular invasion and poorly differentiated HCC than the low RHBPP group.

Conclusions

A high RHBPP by EOB-MRI is a preoperative predictor of vascular invasion and an unfavorable prognostic factor for survival and recurrence. These patients might be considered for highly curative operations such as anatomical liver resection.

Diagnosis of Pre-HCC Disease by Hepatobiliary-Specific Contrast-Enhanced Magnetic Resonance Imaging: A Review

We first proposed a new concept, pre-hepatocellular carcinoma (HCC) disease, to describe the precancerous condition of HCC, which has received scant attention from clinicians. Pre-HCC disease is defined as chronic liver injury concurrent with hepatic low- or high-grade dysplastic nodular lesions. Precise diagnosis of pre-HCC disease may prevent or arrest HCC and contribute to relieving the HCC burden worldwide, although noninvasive diagnosis is difficult and biopsy is generally required. Fortunately, recent advances and extensive applications of hepatobiliary-specific contrast-enhanced magnetic resonance imaging will facilitate the noninvasive identification and characterization of pre-HCC disease. This review briefly discusses the new concept of pre-HCC disease and offers an overview of the role of hepatobiliary-specific contrast-enhanced magnetic resonance imaging for the diagnosis of pre-HCC disease.

Outcome of LR-3 and LR-4 observations without arterial phase hyperenhancement at Gd-EOB-DTPA-enhanced MRI follow-up

OBJECTIVE

The aim of this study was to retrospectively analyze the outcome of LR-3 and LR-4 without arterial phase hyperenhancement (APHE), and identify which features could predict LR-5 progression on serial Gd-EOB-DTPA-enhanced MRI follow-up.

METHODS

Forty-nine cirrhotic patients with 55 LR-3 and 19 LR-4 without APHE were evaluated. Observations were classified as decreased, stable or increased in category at follow-up. Observation size and LI-RADS major and ancillary features were evaluated.

RESULTS

Seventeen/fifty-five (31%) LR-3 and 8/19 (42%) LR-4 progressed to LR-5 at follow-up. Baseline LI-RADS major and ancillary features were not significantly different among LR-3 and LR-4. A diameter ≥ 10 mm significantly increased LR-5 progression risk of LR-3 (OR = 6.07; 95% CI: 0.12; 60.28]; P < .001). LR-4 with a diameter ≥ 10 mm more likely become LR-5 at follow-up (OR = 8.95; 95% CI: 0.73; 111.8; P = .083]).

CONCLUSION

LR-3 and LR-4 without APHE were often downgraded or remained stable in category on Gd-EOB-DTPA-enhanced MRI follow-up.

Application of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is the most common malignant tumor of the liver, and its morbidity and mortality have been increasing in recent years. The early diagnosis and prompt treatment of small HCC are crucial to improve the prognosis and quality of life of patients. In China, hepatitis B virus infection is the main cause. HCC with a single tumor nodule of ≤ 3 cm in diameter, or HCC with a number of nodules, in which each nodule is ≤ 2 cm in diameter, with a total diameter of ≤ 3 cm, is considered as small HCC. The MRI liver-specific contrast agent can detect small HCC at the early stage. This has important clinical implications for improving the survival rate of patients.

MAIN BODY

Gd-EOB-DTPA-enhanced MRI can significantly improve the sensitivity and specificity of the detection of HBV-related small hepatocellular carcinoma, providing an important basis for the clinical selection of appropriate personalized treatment. Gd-EOB-DTPA-enhanced MRI can reflect the degree of HCC differentiation, and the evaluation of HCC on Gd-EOB-DTPA-enhanced MRI would be helpful for the selection of the treatment and prognosis of HCC patients. The present study reviews the progress of the application of Gd-EOB-DTPA in the early diagnosis of small HCC, its clinical treatment, the prediction of the degree of differentiation, and the assessment of recurrence and prognosis of HCC, including the pharmacoeconomics and application limitations of Gd-EOB-DTPA. The value of the application of HCC with the Gd-EOB-DTPA was summarized to provide information for improving the quality of life and prolonging the survival of patients.

CONCLUSION

Gd-EOB-DTPA-enhanced MRI has the diagnostic capability for small HCC with a diameter of ≤ 2 cm. This will have a broader application prospect in the early diagnosis of small liver cancer with a diameter of ≤ 1 cm in the future. The relationship between GD-EOB-DTPA-MRI and the degree of HCC differentiation has a large research space, and Gd-EOB-DTPA is expected to become a potential tool for the preoperative prediction and postoperative evaluation of HCC, which would be beneficial for more appropriate treatments for HCC patients.

The imaging findings of Peliosis hepatis on gadoxetic acid enhanced MRI

Peliosis hepatis involves multiple blood-filled cystic spaces in the hepatic parenchyma. Using conventional imaging, distinguishing PH from other malignancies can be difficult. The findings of Peliosis hepatis on gadoxetic acid (Gd-EOB) enhanced magnetic resonance imaging are not well reported. Therefore, we report the imaging features of pathologically proven PH. On the hepatobiliary phase of Gd-EOB magnetic resonance imaging, most lesions showed unenhanced areas, but some lesions showed central enhancement “halo sign.”

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

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

Additional value of gadoxetic acid-enhanced MRI to conventional extracellular gadolinium-enhanced MRI for the surgical management of colorectal and neuroendocrine liver metastases

BACKGROUND

Liver resection being the only potentially curative treatment for patients with liver metastasis, it is critical to select the appropriate preoperative imaging modality. The aim of this study was to assess the impact of preoperative gadoxetic acid-enhanced MRI compared to a conventional extracellular gadolinium-enhanced MRI on the surgical management of colorectal and neuroendocrine liver metastasis.

METHODS

We included 110 patients who underwent both a gadoxetic acid-enhanced MRI (hepatospecific contrast) and conventional extracellular gadolinium for the evaluation of colorectal or neuroendocrine liver metastases, from January 2012 to December 2015 at the CHU de Québec - Université Laval. When the number of lesions differed, a hepatobiliary surgeon evaluated if the gadoxetic acid-enhanced MRI modified the surgical management.

RESULTS

Gadoxetic acid-enhanced MRI found new lesions in 25 patients (22.7%), excluded lesions in 18 patients (16.4%) and identified the same number in 67 patients (60.9%). The addition of the gadoxetic acid-enhanced MRI directly altered the surgical management in 19 patients overall (17.3% (95% CI [10.73-25.65])).

CONCLUSION

Despite the additional cost associated with gadoxetic acid-enhanced MRI compared to conventional extracellular gadolinium-enhanced MRI, the use of this contrast agent has a significant impact on the surgical management of patients with liver metastases.

Assessment of Hepatic Perfusion Using GRASP MRI: Bringing Liver MRI on a New Level

PURPOSE

The aim of this study was to demonstrate the feasibility of hepatic perfusion imaging using dynamic contrast-enhanced (DCE) golden-angle radial sparse parallel (GRASP) magnetic resonance imaging (MRI) for characterizing liver parenchyma and hepatocellular carcinoma (HCC) before and after transarterial chemoembolization (TACE) as a potential alternative to volume perfusion computed tomography (VPCT).

METHODS AND MATERIALS

Between November 2017 and September 2018, 10 patients (male = 8; mean age, 66.5 ± 8.6 years) with HCC were included in this prospective, institutional review board-approved study. All patients underwent DCE GRASP MRI with high spatiotemporal resolution after injection of liver-specific MR contrast agent before and after TACE. In addition, VPCT was acquired before TACE serving as standard of reference. From the dynamic imaging data of DCE MRI and VPCT, perfusion maps (arterial liver perfusion [mL/100 mL/min], portal liver perfusion [mL/100 mL/min], hepatic perfusion index [%]) were calculated using a dual-input maximum slope model and compared with assess perfusion measures, lesion characteristics, and treatment response using Wilcoxon signed-rank test. To evaluate interreader agreement for measurement repeatability, the interclass correlation coefficient (ICC) was calculated.

RESULTS

Perfusion maps could be successfully generated from all DCE MRI and VPCT data. The ICC was excellent for all perfusion maps (ICC ≥ 0.88; P ≤ 0.001). Image analyses revealed perfusion parameters for DCE MRI and VPCT within the same absolute range for tumor and liver tissue. Dynamic contrast-enhanced MRI further enabled quantitative assessment of treatment response showing a significant decrease (P ≤ 0.01) of arterial liver perfusion and hepatic perfusion index in the target lesion after TACE.

CONCLUSIONS

Dynamic contrast-enhanced GRASP MRI allows for a reliable and robust assessment of hepatic perfusion parameters providing quantitative results comparable to VPCT and enables characterization of HCC before and after TACE, thus posing the potential to serve as an alternative to VPCT.

Hypovascular hepatic nodules as a predictive factor for transcatheter arterial chemoembolization refractoriness in hepatocellular carcinoma

AIM

Intermediate-stage hepatocellular carcinoma (HCC) targeted for transcatheter arterial chemoembolization (TACE) corresponds to a highly heterogeneous population for whom the factors predicting TACE efficacy have not been established. This study aimed to evaluate the impact of hypovascular hepatic nodules coexisting with intermediate-stage HCC as a significant predictive factor for TACE refractoriness.

METHODS

A total of 66 patients with intermediate-stage HCC who received initial TACE were retrospectively analyzed. Hypovascular hepatic nodules were detected by dynamic computed tomography or magnetic resonance imaging, as well as angiography, before all initial TACE. The time to TACE refractoriness (TTTR) was defined as the period from initial TACE until the diagnosis of TACE refractoriness.

RESULTS

Hypovascular hepatic nodules were detected in 36 patients (54.5%), 15 (41.7%) of whom had a single nodule, whereas 21 (58.3%) had multiple nodules, and the median size of the maximum nodule was 10 mm (range 5-80 mm). The median TTTR was 17.4 months for all patients, and 7.3 and 33.1 months for patients with and without hypovascular hepatic nodules, respectively. The TTTR was significantly shorter for patients with hypovascular hepatic nodules than that for the other patients. In the multivariate analysis, the presence of hypovascular hepatic nodules (HR 7.016, 95% CI 3.534-13.930; P < 0.001) and being out of the up-to-seven criteria (HR 2.861, 95% CI 1.493-5.486; P = 0.002) were independent risk factors for a short TTTR.

CONCLUSIONS

The presence of hypovascular hepatic nodules with intermediate-stage HCC represents a significant predictive risk factor for TACE refractoriness.

Gadoxetic acid-enhanced MR imaging for hepatocellular carcinoma: molecular and genetic background

Gadoxetic acid-enhanced magnetic resonance imaging (MRI) plays important roles in diagnosis of hepatic lesions because of its superiority in the detectability of small lesions, its differentiation ability, and its utility for the early diagnosis of hepatocellular carcinoma (HCC). In HCC, expression of organic anion transporting polypeptide (OATP) 1B3 correlates with the enhancement ratio in the hepatobiliary phase. Gadoxetic acid-enhanced MRI, an indirect molecular imaging method, reflects OATP1B3 expression in HCC. OATP1B3 expression gradually decreases from the dysplastic nodule stage to advanced HCC. Decreased expression is a sensitive marker of multistep hepatocarcinogenesis, especially in the early stages. Hypervascular HCCs commonly show hypointensity in the hepatobiliary phase corresponding to a decrease in OATP1B3; however, approximately 10% of HCCs show hyperintensity due to OATP1B3 overexpression. This hyperintense HCC shows less aggressive biological features and has a better prognosis than hypointense HCC. Hyperintense HCC can be classified into a genetic subtype of HCC with a mature hepatocyte-like molecular expression. OATP1B3 expression and the less aggressive nature of hyperintense HCC are regulated by the molecular interaction of β-catenin signaling and hepatocyte nuclear factor 4α, a tumor suppressor factor. Gadoxetic acid-enhanced MR imaging has the potential to be an imaging biomarker for HCC. KEY POINTS: • The hepatobiliary phase is a sensitive indirect indicator of organic anion transporting polypeptide1B3 (OATP1B3) expression in hepatocellular carcinoma (HCC). • The OATP1B3 expression, namely, enhancement in the hepatobiliary phase, decreases from the very early stage of hepatocarcinogenesis, contributing to early diagnosis of HCC. • HCC showing hyperintensity on the hepatobiliary phase is a peculiar genetic subtype of HCC with OATP1B3 overexpression, a less aggressive nature, and mature hepatocyte-like molecular/genetic features.

Combined gadoxetic acid and gadobenate dimeglumine enhanced liver MRI: a parameter optimization study

PURPOSE

To demonstrate the feasibility of combined delayed-phase gadoxetic acid (GA) and gadobenate dimeglumine (GD) enhanced liver MRI for improved detection of liver metastases, and to optimize contrast agent dose, timing, and flip angle (FA).

METHODS

Fourteen healthy volunteers underwent liver MRI at 3.0T at two visits during which they received two consecutive injections: 1. GA (Visit 1 = 0.025 mmol/kg; Visit 2 = 0.05 mmol/kg) and 2. GD (both visits = 0.1 mmol/kg) 20 min after GA administration. Two sub-studies were performed: Experiment-1 Eight subjects underwent multi-phase breath-held 3D-fat-saturated T1-weighted spoiled gradient echo (SGRE) imaging to determine the optimal imaging window for the combined GA + GD protocol to create a homogeneously hyperintense liver and vasculature ("plain-white-liver") with maximum contrast to muscle which served as a surrogate for metastatic lesions in both experiments. Experiment-2 Six subjects underwent breath-held 3D-fat-saturated T1-weighted SGRE imaging at three different FA to determine the optimal FA for best image contrast. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were evaluated.

RESULTS

Experiment-1 The combined GA + GD protocol created a homogeneously hyperintense liver and vasculature with maximum CNR liver/muscle at approximately 60-120 s after automatic GD-bolus detection. Experiment-2 Flip angles between 25° and 35° at a dose of 0.025 mmol/kg GA provided the best combination that minimized liver/vasculature CNR, while maximizing liver/muscle CNR. CNR performance to achieve a "plain-white-liver" was superior with 0.025 mmol/kg GA compared to 0.05 mmol/kg.

CONCLUSION

Combined GA + GD enhanced T1-weighted MRI is feasible to achieve a homogeneously "plain-white-liver". Future studies need to confirm that this protocol can improve sensitivity of liver lesion detection in patients with metastatic liver disease.

[Examination of Gd-EOB-DTPA Liver Dynamic Contrast-enhanced MRI Using Radial VIBE with k-space Weighted Image Contrast Method]

Dynamic contrast-enhanced magnetic imaging (DCE-MRI) is a useful method for detection and diagnosis of liver lesions. However, DCE-MRI using Gd-EOB-DTPA has some problems with arterial phase images. Radial volumetric imaging breath-holding examination (r-VIBE) with k-space weighted image contrast reconstruction (KWIC), which is a modification of Cartesian VIBE (c-VIBE), is a new 3D-gradient echo sequence with a number of advantages compared with c-VIBE, including lower motion sensitivity. This study was performed to evaluate image contrast, blurring, and temporal phase division effects of r-VIBE in comparison with c-VIBE. Image contrast using diluted Gd-EOB-DTPA aqueous solution showed no significant difference between r-VIBE and c-VIBE. Imaging was performed with r-VIBE and c-VIBE during injection of a Gd-EOB-DTPA solution into a serpentine tube. r-VIBE showed a smaller half-width of the signal intensity profile of the tube and less image artifacts by blurring when compared to c-VIBE. The arrival times and durations of the maximum signal strengths of r-VIBE and c-VIBE images during injection of Gd-EOB-DTPA solution into the tube were almost identical. r-VIBE improved the temporal resolution without degradation of liver DCE-MRI using Gd-EOB-DTPA.

Overview of organic anion transporters and organic anion transporter polypeptides and their roles in the liver

Organic anion transporters (OATs) and organic anion transporter polypeptides (OATPs) are classified within two SLC superfamilies, namely, the SLC22A superfamily and the SLCO superfamily (formerly the SLC21A family), respectively. They are expressed in many tissues, such as the liver and kidney, and mediate the absorption and excretion of many endogenous and exogenous substances, including various drugs. Most are composed of 12 transmembrane polypeptide chains with the C-terminus and the N-terminus located in the cell cytoplasm. OATs and OATPs are abundantly expressed in the liver, where they mainly promote the uptake of various endogenous substrates such as bile acids and various exogenous drugs such as antifibrotic and anticancer drugs. However, differences in the locations of glycosylation sites, phosphorylation sites, and amino acids in the OAT and OATP structures lead to different substrates being transported to the liver, which ultimately results in their different roles in the liver. To date, few articles have addressed these aspects of OAT and OATP structures, and we study further the similarities and differences in their structures, tissue distribution, substrates, and roles in liver diseases.

Predicting Therapeutic Efficacy of Vascular Disrupting Agent CA4P in Rats with Liver Tumors by Hepatobiliary Contrast Agent Mn-DPDP-Enhanced MRI

To evaluate hepatobiliary-specific contrast agent (CA) mangafodipir trisodium (Mn-DPDP)–enhanced magnetic resonance imaging (MRI) for predicting the therapeutic efficacy of the vascular disrupting agent combretastatin A4 phosphate (CA4P) in rats with primary and secondary liver tumors, 36 primary hepatocellular carcinomas (HCCs) were raised by diethylnitrosamine gavage in 16 male rats, in 6 of which one rhabdomyosarcomas (R1) was intrahepatically implanted as secondary liver tumors. On a 3.0T MR scanner with a wrist coil, tumors were monitored weekly by T2-/T1-weighted images (T2WI/T1WI) and characterized by Mn-DPDP-enhanced MRI. CA4P-induced intratumoral necrosis was depicted by nonspecific gadoterate meglumine (Gd-DOTA)–enhanced MRI before and 12 h after therapy. Changes of tumor-to-liver contrast (ΔT/L) on Mn-DPDP-enhanced images were analyzed. In vivo MRI findings were verified by postmortem microangiography and histopathology. Rat models of primary HCCs in a full spectrum of differentiation and secondary R1 liver tumors were successfully generated. Mn-DPDP-enhanced ΔT/L was negatively correlated with HCC differentiation grade (P < 0.01). After treatment with CA4P, more extensive tumoral necrosis was found in highly differentiated HCCs than that in moderately and poorly differentiated ones (P < 0.01); nearly complete necrosis was induced in secondary liver tumors. Mn-DPDP-enhanced MRI may help in imaging diagnosis of primary and secondary liver malignancies of different cellular differentiations and further in predicting CA4P therapeutic efficacy in primary HCCs and intrahepatic metastases.

Significance of hypovascular lesions on dynamic computed tomography and/or gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging in patients with hepatocellular carcinoma

BACKGROUND AND AIM

The natural course and clinical implications of hypovascular lesions on dynamic computed tomography and/or gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging were investigated.

METHODS

We followed the patients with hepatocellular carcinoma (HCC) who underwent hepatectomy between April 2009 and August 2012 to determine whether new classical HCCs developed from these unresected borderline lesions or emerged in different areas.

RESULTS

One hundred and eleven patients with HCC were identified to have undergone examinations using both imaging methods before hepatic resection. A total of 54 hypovascular lesions were detected. Gadolinium ethoxybenzyl-enhanced magnetic resonance imaging detected 51 lesions, while dynamic computed tomography identified 21 lesions. Eleven lesions were resected at the time of the hepatectomy together with the main HCCs. Classical HCCs had developed from 52.5% of the 43 unresected lesions at 3 years after hepatic resection. Subsequently, we conducted a patient-by-patient analysis to compare the development of classical HCC from these hypovascular lesions and the emergence of de novo classical HCC in other areas. The 3-year occurrence rate was 62.2% for the former group and 55.0% for the latter group (P = 0.83). Thus, although 52.2% of these hypovascular lesions had developed into classical HCCs at 3 years after the initial hepatectomy, de novo HCCs also occurred at other sites. Furthermore, new hypovascular lesions emerged after hepatectomy in 18-29% of patients irrespective of the presence or absence of hypovascular lesions at hepatectomy.

CONCLUSIONS

It remains uncertain whether these hypovascular lesions should be resected together with the main tumors at the time of hepatectomy.

The diagnostic performance of gadoxetic acid disodium-enhanced magnetic resonance imaging and contrast-enhanced multi-detector computed tomography in detecting hepatocellular carcinoma: a meta-analysis of eight prospective studies

AIM

The purpose of this study was to determine the relative diagnostic benefit of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) over contrast-enhanced multi-detector computed tomography (CEMDCT) for the detection of hepatocellular carcinoma (HCC).

METHODS

Two investigators searched multiple databases from inception to January 8, 2019, for studies comparing Gd-EOB-DTPA-enhanced MRI with CEMDCT in adults suspected of HCC. Two reviewers independently selected studies and extracted data.

RESULTS

Eight studies were included enrolling 498 patients. MRI showed significantly higher sensitivity than CT (0.85 vs. 0.68). There was no significant difference in the specificity of MRI and CT (0.94 vs. 0.93). The negative likelihood ratio and positive likelihood ratio of MRI and CT were not significantly different (0.16 vs. 0.15 and 14.7 vs. 11.2, respectively). The summary receiver operating characteristics (SROC) of MRI was higher than that of CT at 0.96 vs. 0.91. In the subgroup analysis with a lesion diameter below 2 cm, the sensitivity of MRI was significantly higher than that of CT (0.79 vs. 0.46).

CONCLUSION

Gd-EOB-DTPA-enhanced MRI showed higher sensitivity and overall diagnostic accuracy than CEMDCT especially for hepatocellular carcinoma lesions smaller than 2 cm.

KEY POINTS

• Gd-EOB-DTPA-enhanced MRI can detect small lesions of hepatocellular carcinoma. • Gd-EOB-DTPA-enhanced MRI showed higher sensitivity and overall diagnostic accuracy than CEMDCT in patients with hepatocellular carcinoma. • Eight prospective studies showed that Gd-EOB-DTPA-enhanced MRI provides greater diagnostic confidence.

Predicting Patients With Insufficient Liver Enhancement in the Hepatobiliary Phase Before the Injection of Gadoxetic Acid: A Practical Approach Using the Bayesian Method

BACKGROUND

Gadoxetic acid-enhanced hepatobiliary phase (HBP) is useful in liver MRI, but sometimes shows insufficient liver enhancement. There is no established method to predict insufficient liver enhancement before the contrast injection.

PURPOSE

To reveal the utility of the Bayesian method for predicting patients with insufficient liver enhancement in the gadoxetic acid-enhanced HBP.

STUDY TYPE

Retrospective.

SUBJECTS

In all, 576 patients with chronic liver disease.

FIELD STRENGTH/SEQUENCE

3T/3D gradient-echo T₁ -weighted imaging and MR elastography (MRE).

ASSESSMENT

The patients were divided into two groups: insufficient and sufficient liver enhancement in HBP according to the liver-to-portal vein signal intensity ratio. Various parameters, including liver function tests and liver stiffness by MRE, were evaluated as predictors of insufficient liver enhancement.

STATISTICAL TESTS

We used Chi-square/Student's t-test/logistic regression analysis to determine independent associates, and Bayes' theorem to estimate the probability of insufficient (or sufficient) liver enhancement. The feasibility of Bayesian prediction of insufficient liver enhancement was tested by leave-one-out cross-validation to calculate sensitivity and specificity for single variables and combinations of some variables in all patients and in a subpopulation showing a confidence level of >80%.

RESULTS

Independent associates of insufficient liver enhancement in HBP included: serum albumin (odds ratio [OR] = 4.82, P < 0.001), total bilirubin (OR = 0.30, P < 0.00), platelet count (OR = 1.54, P < 0.00), and liver stiffness by MRE (OR = 0.59, P < 0.00). The accuracy of Bayesian prediction of insufficient liver enhancement was 80.9% (466/576) for the single parameter of albumin and 79.0% (455/576) for total bilirubin, and was increased to 85.2% (487/576) for a combination of albumin, total bilirubin, and liver stiffness. In patients who showed a confidence level of >80%, the accuracy was 89.0% (439/493) for the above combination.

DATA CONCLUSION

Bayesian prediction was useful to predict patients with insufficient enhancement by combining serum liver function tests and liver stiffness by MRE.

LEVEL OF EVIDENCE

3 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2020;51:62-69.

Intrahepatic diffuse periportal enhancement patterns on hepatobiliary phase gadoxetate disodium-enhanced liver MR images: Do they correspond to periportal hyperintense patterns on T2-weighted images?

The purpose of this study was to investigate the findings of diffuse periportal enhancement in the liver on hepatobiliary phase gadoxetate disodium-enhanced magnetic resonance images by comparing with the finding of periportal hyperintensity on T2-weighted images and to reveal their clinical significance.Nineteen consecutive patients with diffuse periportal enhancement on hepatobiliary phase images constituted the study population. The intrahepatic diffuse periportal enhancement finding was assessed on whether it corresponded to periportal hyperintense patterns on T2-weighted images or not in the location, and the cases were classified into 2 groups according to this characteristic. Signal intensities at the periportal areas were also assessed on T1-, T2-, diffusion-weighted and dynamic images. Furthermore, possible associations between these image findings and the final diagnoses were explored.In 7 of the 19 patients, periportal enhancement area corresponded with the periportal hyperintensity area on T2-weighted images. In the remaining 12 patients, the finding of periportal T2-hyperintensity was absent or the periportal enhancement differed from the periportal T2-hyperintensity in the location. Diseases of the former group comprised autoimmune hepatitis, acute exacerbation of chronic hepatitis and acute alcoholic steatohepatitis, and those of the latter group primary sclerosing cholangitis, autoimmune hepatitis-primary biliary cirrhosis overlap syndrome, and liver cirrhosis with miscellaneous etiology.Diffuse periportal enhancement during the hepatobiliary phase did not always correspond to periportal hyperintensity on T2-weighted images. In the classification based on whether enhancement area corresponded or not, each enhancement pattern appeared in different groups of liver diseases. Specifically, the former (corresponding) was associated with active inflammation such as hepatitis and the latter (not corresponding) was predominantly associated with a chronic change such as cirrhosis. Appropriate recognition of these periportal enhancement patterns may contribute to the improved diagnosis of diffuse liver diseases.

Gd-EOB-DTPA dynamic contrast-enhanced magnetic resonance imaging is more effective than enhanced 64-slice CT for the detection of small lesions in patients with hepatocellular carcinoma

This study aimed to compare the sensitivity and accuracy for the detection of small lesions in patients with hepatocellular carcinoma (HCC) using gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and 64-slice computed tomography (CT) enhanced scanning, and to evaluate the necessity to perform MRI in patients diagnosed with HCC by CT.The clinical data from 209 patients with HCC diagnosed prior to surgery in the Affiliated Hospital of Guilin Medical University, China were retrospectively analyzed. The 64-slice dynamic contrast-enhanced multi-detector CT (MDCT) and 3.0 T Gd-EOB-DTPA DCE MRI procedures were successively carried out on all patients who were enrolled in a self-controlled study including detection and diagnosis of HCC lesions by MRI and CT, respectively.A total of 243 lesions were detected and both imaging methods could accurately detect lesions of diameter >2 cm. For lesions <2 cm, MRI detected 47, while CT detected 25 lesions indicating that the detection rate of MRI was 88% higher than that of CT. In addition, MRI detected lesions in 15 cases (7.81% in the total of 209 cases) that were not diagnosed by CT. Among these cases, 2 patients were diagnosed to have no lesion by CT.Gd-EOB-DTPA DCE-MRI performed as a routine check prior to surgery in HCC patients can improve the detection of small HCC lesions.

Peri-tumoral hyperintensity on hepatobiliary phase of gadoxetic acid-enhanced MRI in hepatocellular carcinomas: correlation with peri-tumoral hyperplasia and its pathological features

PURPOSE

Peri-tumoral hyperintensity (P-hyperintensity) is occasionally seen in hepatocellular carcinoma (HCC) on the hepatobiliary (HB) phase of gadoxetic acid-enhanced MRI (EOB-MRI). A recent study reported peri-tumoral hyperplasia (P-hyperplasia) associated with over-expression of glutamine synthetase (GS) in HCC or metastatic carcinoma. The aim of this study was to analyze the correlation between P-hyperintensity on the HB phase and GS expression indicating P-hyperplasia and reveal its pathological features.

METHODS

Seventy-seven surgically resected HCCs from 68 patients were analyzed. The grade of P-hyperintensity on HB phase was divided according to the degree of the peri-tumoral hyperintense signal: grade 0 (no P-hyperintensity), grade 1 (less than 50% of the tumor border), grade 2 (50%-80%), grade 3 (80%-100%). Immunohistochemical staining for GS and organic anion transporter polypeptides (OATP)1B3 was performed. The relationships among P-hyperplasia (peri-tumoral GS expression) and OATP1B3 expression, P-hyperintensity, and pathological features of the tumor were analyzed.

RESULTS

Thirty-four HCCs were classified as P-hyperintensity grade 0, 29 HCCs as grade 1,10 nodules as grade 2, and 4 HCCs as grade 3. P-hyperplasia was observed in 3/34 (8.8%) P-hyperintensity grade 0, 16/29 (55.2%) grade 1, 9/10 (90%) grade 2, and 4/4 (100%) grade 3. The incidence of P-hyperplasia was significantly increased in P-hyperintensity grades 1-3 compared with grade 0 (p < 0.0001). Hepatocytes in all P-hyperplasia sites demonstrated definite OATP1B3 expression. Microscopic hepatic venous invasion was significantly increased in P-hyperintensity-positive HCCs compared with negative HCCs (p = 0.0017).

CONCLUSIONS

P-hyperintensity on HB phase in HCC may indicate p-hyperplasia with GS and OATP1B3 expression and a higher incidence of microscopic hepatic venous invasion.

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.

Evaluation of liver function using gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid enhanced magnetic resonance imaging based on a three-dimensional volumetric analysis system

Background

Magnetic resonance imaging with gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (EOB-MRI) is a diagnostic modality for liver tumors. Three-dimensional (3D) volumetric analysis systems using EOB-MRI data are used to simulate liver anatomy for surgery. This study was conducted to investigate clinical utility of a 3D volumetric analysis system on EOB-MRI to evaluate liver function.

Methods

Between August 2014 and December 2015, 181 patients underwent laboratory and radiological exams as standardized preoperative evaluation for liver surgery. The liver-spleen contrast-enhanced ratio (LSR) was measured by a semi-automated 3D volumetric analysis system on EOB-MRI. First, the inter-evaluator variability of the calculated LSR was evaluated. Additionally, a subset of liver surgical specimens was evaluated histologically by using immunohistochemical staining. Finally, the correlations between the LSR and grading systems of liver function, laboratory data, or histological findings were analyzed.

Results

The inter-evaluator correlation coefficient of the measured LSR was 0.986. The mean LSR was significantly correlated with the Child–Pugh score (p = 0.014) and the ALBI score (p < 0.001). Significant correlations were also observed between the LSR and indocyanine green retention rate at 15 min (r = − 0.601, p < 0.001), between the LSR and liver fibrosis stage (r = − 0.556, p < 0.001), and between the LSR and liver steatosis grade (r = − 0.396, p < 0.001).

Conclusion

The LSR calculated by a 3D volumetric analysis system on EOB-MRI was highly reproducible and was shown to be correlated with liver function parameters and liver histology. These data suggest that this imaging modality can be a reliable tool to evaluate liver function.

Electronic supplementary material

The online version of this article (10.1007/s12072-018-9874-x) contains supplementary material, which is available to authorized users.

The inhibitory effect of gadoxetate disodium on hepatic transporters: a study using indocyanine green

OBJECTIVES

To assess the inhibitory effect of gadoxetate disodium on the transporter system using indocyanine green (ICG).

MATERIALS AND METHODS

Groups of six female B6 Albino mice were injected with the test agent (0.62 mmol/kg gadoxetate disodium) or phosphate-buffered saline (control) 10 min before injection of ICG. Identical fluorescence images were subsequently obtained to create time-efficiency curves of liver parenchymal uptake. The study was performed on hypothermic and normothermic mice. The logarithms of the absorption rate constants (logKa values) and of the elimination rate constants (logKe values) were calculated for each experimental condition, and between-group differences were compared using Student's t-test.

RESULTS

The logKe values of the test group were lower than those of the control group at both temperatures (-6.52 vs. -5.87 under hypothermic conditions and -4.54 vs. -4.14 under normothermic conditions), and both differences were statistically significant (p = 0.037, 0.015 respectively). In terms of the logKa values, although the difference did not reach statistical significance (p = 0.052), the test group had lower values than the control group under hypothermic conditions (-0.771 vs. -0.376). In normothermic mice, the logKa values for the test and control groups were 0.037 and 0.277 respectively, thus not significantly different (p = 0.404).

CONCLUSIONS

Gadoxetate disodium inhibited ICG excretion. Thus, gadoxetate disodium inhibited the ATP-binding cassette sub-family C member 2 transporter.

KEY POINTS

• Gadoxetate disodium inhibited ICG excretion. • Gadoxetate disodium tended to inhibit hepatic ICG uptake. • Drug-drug interactions of gadoxetate disodium need further investigation.

ACR Appropriateness Criteria® Suspected Liver Metastases

Liver metastases are the most common malignant liver tumors. The accurate and early detection and characterization of liver lesions is the key to successful treatment strategies. Increasingly, surgical resection in combination with chemotherapy is effective in significantly improving survival if all metastases are successfully resected. MRI and multiphase CT are the primary imaging modalities in the assessment of liver metastasis, with the relative preference toward multiphase CT or MRI depending upon the clinical setting (ie, surveillance or presurgical planning). The optimization of imaging parameters is a vital factor in the success of either modality. PET/CT, intraoperative ultrasound are used to supplement CT and MRI. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Reducing artifacts of gadoxetate disodium-enhanced MRI with oxygen inhalation in patients with prior episode of arterial phase motion: intra-individual comparison

PURPOSE

To determine whether oxygen inhalation reducing artifacts in patients with previous transient severe motion (TSM) on gadoxetate-disodium-enhanced MRI.

MATERIALS AND METHODS

Fifty-one patients with TSM on previous gadoxetate-disodium-enhanced MRI (Baseline examination) were evaluated. Image quality in the examination with oxygen inhalation (Oxygen examination) and that in Baseline examination and the examination before Baseline examination without oxygen inhalation (Past examination) were qualitatively compared in dynamic study.

RESULTS

Image quality was significantly higher in Oxygen examination than Baseline examination in arterial phase, but there was no statistical difference between Baseline and Past examinations.

CONCLUSION

Oxygen inhalation improved image quality in patients with a prior episode of arterial phase TSM.