Paradoxic uptake of Gd-EOB-DTPA by hepatocellular carcinoma in mice: quantitative image analysis

Gadoxetate Disodium-Enhanced MRI to Differentiate Dysplastic Nodules and Grade of Hepatocellular Carcinoma: Correlation With Histopathology

OBJECTIVE

The objective of our study was to determine quantitative differences to differentiate low-grade from high-grade dysplastic nodules (DNs) and low-grade from high-grade hepatocellular carcinomas (HCCs) using gadoxetate disodium-enhanced MRI.

MATERIALS AND METHODS

A retrospective study of 149 hepatic nodules in 127 consecutive patients who underwent gadoxetic acid-enhanced MRI was performed. MRI signal intensities (SIs) of the representative lesion ROI and of ROIs in liver parenchyma adjacent to the lesion were measured on unenhanced T1-weighted imaging and on dynamic contrast-enhanced MRI in the arterial, portal venous, delayed, and hepatobiliary phases. The relative SI of the lesion was calculated for each phase as the relative intensity ratio as follows: [mass SI / liver SI].

RESULTS

Of the 149 liver lesions, nine (6.0%) were low-grade DNs, 21 (14.1%) were high-grade DNs, 83 (55.7%) were low-grade HCCs, and 36 (24.2%) were high-grade HCCs. The optimal cutoffs for differentiating low-grade DNs from high-grade DNs and HCCs were an unenhanced to arterial SI of ≥ 0 or a relative SI on T2-weighted imaging of ≤ 1.5, with a positive predictive value (PPV) of 99.2% and accuracy of 88.6%. The optimal cutoffs for differentiating low-grade HCCs from high-grade HCCs were a relative hepatobiliary SI of ≤ 0.5 or a relative T2 SI of ≥ 1.5, with a PPV of 81.0% and an accuracy of 60.5%.

CONCLUSION

Gadoxetate disodium-enhanced MRI allows quantitative differentiation of low-grade DNs from high-grade DNs and HCCs, but significant overlap was seen between low-grade HCCs and high-grade HCCs.

Differentiation of small (≤2 cm) hepatocellular carcinomas from small benign nodules in cirrhotic liver on gadoxetic acid-enhanced and diffusion-weighted magnetic resonance images

OBJECTIVE

To identify imaging characteristics that differentiate small (≤2 cm) HCCs from small (≤2 cm) benign nodules in cirrhotic liver on gadoxetic acid-enhanced and diffusion-weighted (DW) magnetic resonance (MR) images.

MATERIALS AND METHODS

On gadoxetic acid-enhanced and DW MR images, we analysed signal intensity of 222 small HCCs and 61 benign nodules (diameter, 0.5-2 cm) at each sequence and rim enhancement during portal or equilibrium phases. Univariate and multivariate logistic regression analyses identified predictors of HCC. Combinations of significant MR findings in multivariate analysis were compared with American Association for the Study of Liver Disease (AASLD) practice guidelines.

RESULTS

In multivariate analysis, arterial enhancement (adjusted odds ratio [aOR], 8.6), T2 hyperintensity (aOR, 5.8), and hyperintensity on DW images (aOR, 3.8) were significant for differentiating small HCCs from benign nodules (p ≤ 0.004). When two or all three findings were applied as diagnostic criteria for differentiating small HCCs from benign nodules, sensitivity and accuracy were significantly higher compared with AASLD practice guidelines (91% vs. 78% and 89% vs. 81%, respectively; each p < 0.0001).

CONCLUSION

On gadoxetic acid-enhanced MR imaging, arterial enhancement and hyperintensity on T2-weighted and DW MR images are helpful for differentiating small HCCs from benign nodules in liver cirrhosis.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Gadoxetate acid-enhanced MRI of hepatocellular carcinoma in a c-myc/TGFα transgenic mouse model including signal intensity and fat content: initial experience

Genetically engineered mouse models, such as double transgenic c-myc/TGFα mice, with specific pathway abnormalities might be more successful at predicting the clinical response of hepatocellular carcinoma (HCC) treatment. But a major drawback of the tumour models is the difficulty of visualizing endogenously formed tumours. The optimal imaging procedure should be brief and minimally invasive. Magnetic resonance imaging (MRI) satisfies these criteria and gadoxetate acid-enhanced MRI improves the detection of HCC. Fat content is stated to be an additional tool to help assess tumour responses, for example, in cases of radiofrequency ablation. Therefore the aim of this study was to investigate if gadoxetate acid-enhanced MRI could be used to detect HCC in c-myc/TGFα transgenic mice by determining the relation between the signal intensity of HCC and normal liver parenchyma and the corresponding fat content as a diagnostic marker of HCC. In our study, 20 HCC in c-myc/TGFα transgenic male mice aged 20–34 weeks were analyzed. On gadoxetate acid-enhanced MRI, the signal intensity was 752.4 for liver parenchyma and 924.5 for HCC. The contrast to noise ratio was 20.4, the percentage enhancement was 267.1% for normal liver parenchyma and 353.9% for HCC. The fat content was 11.2% for liver parenchyma and 16.2% for HCC. There was a correlation between fat content and signal intensity with r = 0.7791. All parameters were statistically significant with P < 0.05. Our data indicate that gadoxetate acid contrast enhancement allows sensitive detection of HCC in c-myc/TGFα transgenic mice and determination of the fat content seems to be an additional useful parameter for HCC.

Different signal intensity at Gd-EOB-DTPA compared with Gd-DTPA-enhanced MRI in hepatocellular carcinoma transgenic mouse model in delayed phase hepatobiliary imaging

PURPOSE

To evaluate hyperintense Gd-DTPA- compared with hyper- and hypointense Gd-EOB-DTPA-enhanced magnet resonance imaging (MRI) in c-myc/TGFα transgenic mice for detecting hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Twenty HCC-bearing transgenic mice with overexpression of the protooncogene c-myc and transforming growth factor-alpha (TGF-α) were analyzed. MRI was performed using a 3-T MRI scanner and an MRI coil. The imaging protocol included Gd-DTPA- and Gd-EOB-DTPA-enhanced T1-weighted images. The statistically evaluated parameters are signal intensity (SI), signal intensity ratio (SIR), contrast-to-noise ratio (CNR), percentage enhancement (PE), and signal-to-noise ratio (SNR).

RESULTS

On Gd-DTPA-enhanced MRI compared with Gd-EOB-DTPA-enhanced MRI, the SI of liver was 265.02 to 573.02 and of HCC 350.84 to either hyperintense with 757.1 or hypointense with 372.55 enhancement. Evaluated parameters were SNR of HCC 50.1 to 56.5/111.5 and SNR of liver parenchyma 37.8 to 85.8, SIR 1.32 to 1.31/0.64, CNR 12.2 to 26.1/-30.08 and PE 42.08% to 80.5/-98.2%, (P < 0.05).

CONCLUSION

Gd-EOB-DTPA is superior to Gd-DTPA for detecting HCC in contrast agent-enhanced MRI in the c-myc/TGFα transgenic mouse model and there was no difference between the hyperintense or hypointense appearance of HCC. Either way, HCCs can easily be distinguished from liver parenchyma in mice.

Magnetic resonance imaging of focal liver lesions: approach to imaging diagnosis

This article is a review of magnetic resonance imaging (MRI) of incidental focal liver lesions. This review provides an overview of liver MRI protocol, diffusion-weighted imaging, and contrast agents. Additionally, the most commonly encountered benign and malignant lesions are discussed with emphasis on imaging appearance and the diagnostic performance of MRI based on a review of the literature.

Gadoxetate disodium-enhanced hepatobiliary phase MRI of hepatocellular carcinoma: correlation with histological characteristics

OBJECTIVE

The purpose of this study was to assess whether gadoxetate disodium-enhanced hepatobiliary phase MRI could predict the histologic factors of hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

Fifty-three HCCs histopathologically proved by surgery in 51 patients were evaluated retrospectively. All patients underwent gadoxetate disodium-enhanced MRI before surgical resection. The differences in contrast enhancement ratio of the lesions and differences in contrast-to-noise ratio (CNR) among the histologic grades of HCC were compared by using the Kruskal-Wallis test. The Spearman method was used to determine the correlations among contrast enhancement ratio, CNR, cell density ratio, and positivity for anti-hepatocyte antibody, keratin 7, and keratin 19.

RESULTS

Of 53 HCCs, 50 showed low signal intensity on hepatobiliary phase images, whereas three HCCs were hyperintense on hepatobiliary phase images compared with surrounding hepatic parenchyma. Although well-differentiated HCCs tended to show higher contrast enhancement, there was no statistical significance between contrast enhancement ratio of the tumors and histologic grade (p = 0.414). No significant difference was observed between CNR and histologic grade (p = 0.965). The contrast enhancement ratios of the tumors were significantly lower in the keratin 19-positive group than in the keratin 19-negative group (p = 0.015). There was no significant correlation among contrast enhancement ratio, anti-hepatocyte antibody positivity, cell density ratio, and keratin 7 positivity (p > 0.05).

CONCLUSION

The contrast enhancement ratio and CNR of HCCs were not correlated with histologic grades. The contrast enhancement ratio was significantly lower in keratin 19-positive HCCs.

Comparison of enhancement patterns of histologically confirmed hepatocellular carcinoma between gadoxetate- and ferucarbotran-enhanced magnetic resonance imaging

PURPOSE

To compare enhancenent patterns of hepatocellular carcinoma (HCC) and dysplastic nodule (DN) between gadoxetate- and ferucarbotran-enhanced MRI.

MATERIALS AND METHODS

Patients recruited from ultrasound surveillance for HCC in chronic liver diseases were enrolled in this prospective study approved by institutional review board. Thirty-six patients with 37 histologically proven HCC, including 22 well-differentiated HCCs (wHCC), 15 moderately to poorly differentiated HCCs (mpHCCs), and 4 DNs, underwent gadoxetate-enhanced and ferucarbotran-enhanced MRI. We compared hepatobiliary phase image of gadoxetate-enhanced MRI with ferucarbotran-enhanced MR image regarding signal intensity of HCC and DN relative to surrounding liver parenchyma. We calculated contrast ratios between tumor and liver on pre-enhancement, hepatobiliary phase of gadoxetate-enhanced MRI and ferucarbotran-enhanced MRI.

RESULTS

On ferucarbotran-enhanced MRI, all mpHCCs showed hyper-intensity, while 14 wHCCs (14/22;63%) showed iso-intensity. On hepatobiliary phase of gadoxetate-enhanced MRI, 13 mpHCCs (13/15;86%) and 20 wHCCs (20/22;91%) showed hypo-intensity. Two DNs and the other two showed iso- and hypo-intensity, respectively, on gadoxetate-enhanced MRI, whereas all DNs revealed iso-intensity on ferucarbotran-enhanced MRI. Gadoxetate-postcontrast ratio was significantly lower than ferucarbotran-postcontrast ratio in wHCC (P = 0.015).

CONCLUSION

The uptake function of hepatocytes that are targeted by gadoxetate is more sensitive than that of Kupffer cells targeted by ferucarbotran in stepwise hepatocarcinogenesis.

Uptake of Gd-EOB-DTPA by hepatocellular carcinoma: radiologic-pathologic correlation with special reference to bile production

PURPOSE

The aim of this study was to reveal the relationship between intratumoral uptake of gadoliniumethoxylbenzyldiethylenetriaminepentaacetic acid (Gd-EOB-DTPA) of hepatocellular carcinoma (HCC) in the hepatobiliary phase and pathological features.

MATERIALS AND METHODS

Sixty HCC nodules were confirmed at pathology in 56 patients who had undergone dynamic MRI. T1-weighted 3D gradient echo sequences before and 20 min (hepatobiliary phase) after the injection of Gd-EOB-DTPA were performed. Uptake of Gd-EOB-DTPA was defined as an increase in signal intensity in the hepatobiliary phase compared with the precontrast scan. All surgical specimens were fixed with formalin and then digitally photographed. The relationship between Gd-EOB-DTPA uptake and histological findings, including a macroscopic greenish area, was examined.

RESULTS

MR images showed uptake of Gd-EOB-DTPA in twenty-two nodules. Histological findings indicated twenty-six nodules contained a greenish area. There is a significant correlation between HCC showing Gd-EOB-DTPA uptake and the presence of a greenish area (p<0.001). On a nodule-by-nodule basis, more than two-thirds of the area of Gd-EOB DTPA uptake coincides with the greenish part in only 12 of 22 lesions (54.5%). More than two-thirds of the greenish area coincided with that of Gd-EOB-DTPA uptake in only 10 of 26 cases (38.5%).

CONCLUSION

The area of Gd-EOB-DTPA uptake does not always match the greenish part, but HCC with uptake of Gd-EOB-DTPA significantly correlated with green HCC.

Paradoxical high signal intensity of hepatocellular carcinoma in the hepatobiliary phase of Gd-EOB-DTPA enhanced MRI: initial experience

PURPOSE

To describe the paradoxical high signal intensity of hepatocellular carcinoma (HCC) in the hepatobiliary phase on gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI).

MATERIALS AND METHODS

A database search was performed to identify cases of HCC that showed unusual prolonged enhancement in the hepatobiliary phase of Gd-EOB-DTPA MRI. All patients received 3.0-T liver MRI including precontrast T1-weighted images, T2-weighted images and a post Gd-EOB-DTPA-enhanced dynamic study. The signal intensity of HCC was measured at pre-enhanced, arterial, portal, delayed and hepatobiliary phase using regions of interest. Radiologic and pathologic correlation was performed for the paradoxically prolonged enhancing portion of HCC in the hepatobiliary phase.

RESULTS

Four patients (all male, age range 44-70; mean 57.5 years) were included in this study. All patients showed HCC lesions that were low signal intensity (SI) on T1-WI, high SI on T2-WI, enhanced in arterial phase, and washed-out in delayed phase. All cases showed paradoxically high SI in hepatobiliary phase, which was unusual for HCC. Pathologically, they were all diagnosed as well-differentiated HCC with prominent cytoplasm and a bile secreting appearance.

CONCLUSION

HCC may demonstrate the prolonged high signal intensity at the hepatobiliary phase on Gd-EOB-DTPA enhanced MRI. These HCCs tended to be highly differentiated and to have prominent bile secretion.

Detection and characterization of liver lesions using gadoxetic acid as a tissue-specific contrast agent

The value of cross-sectional liver imaging is evaluated by the accuracy, sensitivity, and specificity of the specific imaging technique. Magnetic resonance imaging (MRI) has become a key technique for the characterization and detection of focal and diffuse liver disease. More recently, gadoxetic acid, the hepatocyte-specific MR contrast agent, was clinically approved and introduced in many countries. Gadoxetic acid may be considered a "molecular imaging" probe because the compound is actively taken into hepatocytes via the ATP-dependent organic anion transport system in the plasma membrane for the hepatic uptake. The transport of gadoxetic acid from the cytoplasm to the bile is mainly determined by the capacity of the transport protein glutathione-S-transferase. Gadoxetic acid enhances hepatocyte-containing lesions and improves detection of lesions devoid of normal hepatocytes, such as metastases. Innovative rapid MR acquisition techniques with near isotropic 3D pulse sequences with fat saturation parallel the technical progress made by multidetector computed tomography combined with an impressive improvement in tumor-liver contrast when used for gadoxetic acid-enhanced MRI. The purpose of this review is to provide an overview of the development, clinical testing, and applications of this novel MR contrast agent.

Distinguishing hypervascular pseudolesions of the liver from hypervascular hepatocellular carcinomas with gadoxetic acid-enhanced MR imaging

PURPOSE

To retrospectively determine findings at gadoxetic acid-enhanced magnetic resonance (MR) imaging in hypervascular pseudolesions that were observed at computed tomography (CT) during hepatic arteriography, with special focus on distinguishing these pseudolesions from hypervascular hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

The institute ethics committee deemed study approval unnecessary. The study population comprised 80 patients (55 men, 25 women) with chronic liver disease who underwent CT during hepatic arteriography and arterial portography, gadoxetic acid-enhanced MR imaging, and follow-up dynamic contrast material-enhanced CT. The diagnosis of 104 pseudolesions and 123 HCCs was confirmed by means of histopathologic or multimodality evaluation. Two radiologists assessed the MR imaging findings of HCCs and pseudolesions in consensus, including the signal intensities (SIs) of the lesions on T2-weighted, diffusion-weighted (DW), and contrast-enhanced hepatocyte-phase images. The findings of nodular pseudolesions and HCCs were compared with the Fisher exact test. Additionally, the hepatocyte-phase SI ratio (ratio of lesion SI to liver SI) for HCCs and pseudolesions was compared by means of the Mann-Whitney U test.

RESULTS

There were 62 wedge-shaped, 32 nodular, and 10 linear pseudolesions. On gadoxetic acid-enhanced hepatocyte-phase MR images, 15% of pseudolesions (16 of 104) were hypointense compared with surrounding liver tissue. The mean hepatocyte-phase SI ratio of HCCs (0.65 +/- 0.14 [standard deviation]) was significantly lower (P < .01) than that of the nodular pseudolesions (0.95 +/- 0.11). The optimal cutoff value of hepatocyte-phase SI ratio for distinguishing between HCC and nodular pseudolesion was 0.84. No nodular pseudolesions were visible on DW images.

CONCLUSION

Gadoxetic acid-enhanced hepatocyte-phase MR imaging and DW imaging could be used to distinguish hypervascular pseudolesions from hypervascular HCCs; a hepatocyte-phase SI ratio below 0.84 and visibility on DW images were findings specific for HCCs rather than pseudolesions.

Gadoxetate disodium-enhanced MRI of the liver: part 2, protocol optimization and lesion appearance in the cirrhotic liver

OBJECTIVE

The purpose of this article is to review the use of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (gadoxetate disodium [Gd-EOB-DTPA]) in the cirrhotic liver and illustrate the imaging appearance of lesions commonly encountered in the cirrhotic liver.

CONCLUSION

Gd-EOB-DTPA shows promise as a problem-solving tool in the cirrhotic liver because it provides additional information that may be helpful in lesion detection and characterization. Further research is needed to optimize Gd-EOB-DTPA imaging protocols in cirrhosis and develop diagnostic criteria for liver lesions in the cirrhotic liver.

Expression of OATP1B3 determines uptake of Gd-EOB-DTPA in hepatocellular carcinoma

BACKGROUND

Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) is an MRI contrast agent with perfusion and hepatoselective properties. The purpose of the study was to examine uptake of Gd-EOB-DTPA in the hepatobiliary phase in hepatocellular carcinoma (HCC).

METHODS

A retrospective analysis of 22 patients with HCC who underwent preoperative Gd-EOB-DTPA-enhanced MRI was performed. Enhancement ratios (ERs) and expression levels of the organic anion transporter (OATP) 1B3 protein were examined.

RESULTS

Gd-EOB-DTPA accumulated in the hepatobiliary phase in 6 of the 22 cases. All 6 Gd-EOB-DTPA-positive cases were moderately differentiated HCC, but 11 other moderately differentiated HCCs did not show Gd-EOB-DTPA uptake. Histopathologically, 4 Gd-EOB-DTPA-positive HCCs and 5 Gd-EOB-DTPA-negative HCCs produced bile. HCCs with Gd-EOB-DTPA uptake overexpressed OATP1B3 compared with HCCs without Gd-EOB-DTPA uptake, and OATP1B3 levels were significantly correlated with ERs (r=0.91, P<0.0001).

CONCLUSIONS

Uptake of Gd-EOB-DTPA in HCC is determined by expression of OATP1B3 rather than by tumor differentiation or bile production.

Tumor models and specific contrast agents for small animal imaging in oncology

Despite the widespread use of various imaging modalities in clinical and experimental oncology without or with combined application of commercially available nonspecific contrast agents (CAs), development of tissue- or organ- or disease-specific CAs has been a continuing effort for pursuing ever-improved sensitivity, specificity, and applicability. This is particularly true with magnetic resonance imaging (MRI) due to its intrinsic superb spatial/temporal/contrast resolutions and adequate detectability for tiny amount of substances. In this context, research using small animal tumor models has played an indispensible role in preclinical exploration of tissue specific CAs. Emphasizing more on methodological and practical aspects, this article aims to share our cumulated experiences on how to create tumor models for evaluation and development of new tissue specific MRI CAs and how to apply such models in imaging-based research studies. With the results that are repeatedly confirmed by later clinical applications in cancer patients, some of our early preclinical studies have contributed to the designs of subsequent clinical trials on the new CAs, some studies have predicted new utilities of these CAs; and other studies have led to the discoveries of new tissue- or disease-specific CAs with novel diagnostic or even therapeutic potentials. Among commonly adopted tumor models, the chemically induced and surgically implanted nodules in the liver prove very useful to simulate primary and metastatic intrahepatic tumors, respectively in clinical patients. The methods to create tumor models have eased procedures and yielded high success rates. The specific properties of the new CAs could be outshined by intraindividual comparison to the commercial CAs as nonspecific controls. Meticulous imaging-microangiography-histology matching techniques guaranteed colocalization of the lesion on in vivo MRI and postmortem tissue specimen, hence correct imaging interpretation and longstanding conclusions. As exemplified in the real study cases, the present experimental set-up proves applicable in small animals for imaging-based oncological investigations, and may provide a platform for the currently booming molecular imaging in a multimodality environment.

[Current status of MRI diagnostics with liver-specific contrast agents. Gd-EOB-DTPA and Gd-BOPTA]

The contrast agents Gd-EOB-DTPA and Gd-BOPTA can be administered by bolus injection and are appropriate for use in MRI both as vascularization markers and markers of hepatobiliary excretion. This contribution presents an overview of the specific characteristics of contrast media and the status of clinical development. In comparison to CT and to MRI with unspecific extracellular Gd-chelates, liver-specific contrast agents offer advantages in differentiating unclear liver lesions, increasing the detection rate, and examining the bile duct system.

Gd-EOB-DTPA Enhanced MRI for Hepatocellular Carcinoma: Quantitative Evaluation of Tumor Enhancement in Hepatobiliary Phase

OBJECTIVE

The purpose of this study was to evaluate the utility of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) for the quantitative evaluation of hepatocellular carcinoma (HCC) and dysplastic nodules in the hepatobiliary phase.

MATERIAL AND METHODS

The subjects comprised 12 patients with 27 lesions (22 HCCs and 5 dysplastic nodules). Chemical-shift-selective fat-suppressed T1-weighted sequences were obtained before and 10, 20, and 40 min after the injection of Gd-EOB-DTPA. Quantitative analyses were performed with the enhancement ratio of the lesion and the contrast-to-noise (C/N) ratio.

RESULTS

The enhancement ratios of the HCCs were 44.0+/-36.5, 44.7+/-46.8, and 47.7+/-52.8 (%) at 10, 20, and 40 min, respectively, after the injection of Gd-EOB-DTPA. The enhancement ratios of the dysplastic nodules were 36.2+/-34.3, 44.3+/-37.3, and 40.1+/-46.8 (%). The C/N ratios of the HCCs were 0.2+/-6.6 for the precontrast image, and -9.2+/-12.6, -9.9+/-14.8, and -12.7+/-15.7 at 10, 20, and 40 min, respectively, after the injection of Gd-EOB-DTPA. The C/N ratios of the dysplastic nodules were 1.4+/-8.0, -13.7+/-11.1, -13.3+/-7.6, and -13.1+/-10.4. No significant differences were found between the HCCs and the dysplastic nodules in the enhancement ratio and the C/N ratio. Only two HCCs showed a positive C/N ratio value, and these HCCs were pathologically confirmed to be a well differentiated and a moderately differentiated carcinoma, respectively.

CONCLUSION

HCCs and some of the dysplastic nodules showed hypointensity in the hepatobiliary phase in Gd-EOB-DTPA-enhanced MRI. No specific enhancement was observed, regardless of tumor differentiation.

Potential for Differential Diagnosis with Gadolinium-Ethoxybenzyl-Diethylenetriamine Pentaacetic Acid-Enhanced Magnetic Resonance Imaging in Experimental Hepatic Tumors

RATIONALE AND OBJECTIVES

To investigate whether dynamic and delayed magnetic resonance imaging (MRI) with gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA), a hepatobiliary MRI contrast agent, has potential for the differential diagnosis of experimental hepatic tumors.

METHODS

Twelve male rats received N-nitrosomorpholine solution as drinking water to induce hepatic tumors. After injection of Gd-EOB-DTPA, rats were subjected to dynamic and delayed MRI. The relative enhancement (RE) was calculated, and the time of the maximum RE (Tmax) was evaluated. After MRI, liver was histologically analyzed.

RESULTS

One hundred sixty-three hepatic tumors 3-12 mm in diameter were induced after 18 weeks of treatment with 0.01 wt/vol% of N-nitrosomorpholine, and 81 of them were evaluated. The RE in hyperplastic nodules (HPNs) was significantly higher than that in moderately or poorly differentiated hepatocellular carcinomas (HCCs) in the late phase, whereas there was no significant difference in RE between well-differentiated HCCs and HPNs. The average Tmax in HPNs was about 13 minutes, whereas that of each differentiated HCCs was about 1 minute.

CONCLUSIONS

It was possible to differentiate benign HPNs and malignant HCCs (especially well-differentiated HCCs) by evaluating the change of RE or comparison of Tmax with Gd-EOB-DTPA-enhanced MRI.

MR contrast agents in hepatic cirrhosis and chronic hepatitis

Chronic liver disease alters the gross architecture of the liver and its arterial and portal blood supply. The relative proportion of regenerative hepatocytes, necrosis, extracellular interstitial space, and fibrosis is responsible for liver enhancement after the administration of a contrast agent. Because contrast agents can be directed toward either the extracellular or the intracellular spaces, knowledge of the different parenchymal enhancement alterations seen after the administration of these agents is necessary to understand how chronic liver disease pathologic changes influence contrast-enhanced magnetic resonance (MR) images. This article reviews the effect of chronic liver disease on MR contrast enhancement, as well as the effect of altered enhancement on lesion detection and characterization. Both extracellular and intracellular contrast agents are considered.