Liver-specific Contrast Agent Research Articles

Liver Lesion Characterization: The Wrong Choice of Contrast Agent Can Mislead the Diagnosis of Hemangioma

AJR 2012; 199:W662 0361–803X/12/1995–W662 © American Roentgen Ray Society Liver Lesion Characterization: The Wrong Choice of Contrast Agent Can Mislead the Diagnosis of Hemangioma Over the past few years, abdominal radiology experts studying the liver have increased the usage of liver-specific gadolinium-chelate contrast agents. These agents are gadobenate dimeglumine (MultiHance, Bracco) and gadoxetate (Primovist, Bayer HealthCare), with different biliary rate excretion (5% and 50%) and liver-specific phase acquisition time (120 and 20 minutes), respectively. This great difference in biliary clearance requires the radiologist’s consideration, especially in the study of focal lesions. In fact, with Primovist, the equilibrium phase (180 seconds) is an early-uptake stage because of the quick accumulation of the contrast agent in hepatic cells. Therefore, we must consider a false washout at the equilibrium phase, in which Primovist is retained in the hemangioma, which nonetheless appears isoor hypointense on T1-weighted images because of the increasing signal intensity of the surrounding healthy hepatic parenchyma. This implies that hemangiomas may have a misleading contrast imaging pattern with Primovist, without the usual, well-demonstrable fill in, as assessed by Gupta et al. [1] who showed the different contrast imaging pattern of hemangiomas with Primovist and MultiHance. This nontypical pattern of hemangiomas with Primovist does not represent a significant problem in detecting large masses, which are already well recognizable on unenhanced acquisitions. However, it can be difficult to properly characterize small lesions that may not be benign [2]. In particular, it can be complicated when we observe small multiple hemangiomas—sometimes with a prevalent fibrous component and relatively low signal intensity in heavily T2-weighted acquisitions—that have not been documented in previous examinations or, as often occurs in daily practice, in patients lacking an accurate clinical history or previous examination (e.g., occasional hepatic lesion seen on an ultrasound examination) (Fig. 1). These problems can be amplified if, to optimize examination time, the radiologist chooses to apply the Primovist inverse study protocol, in which only the T1-weighted sequences are acquired before the dynamic phase, and T2weighted and diffusion-weighted sequences are acquired in the contrast-enhanced phase before the hepatobiliary phase is acquired. Such an inverse modality is based on studies that have highlighted that Primovist does not influence the T2-weighted and diffusionweighted sequences, and our experience confirms these data [3]. Of course, the saving in time is relevant, but the risk of selecting an unsuitable contrast agent is increased. On the basis of these considerations, to avoid the risk of making mistakes or at least to deal with divergent patterns in patients without a clinical history or with a suspicion of hemangioma, we prefer the use of MultiHance, which can act as a non–liver-specific gadolinium chelate (with an appropriate dynamic phase) and, if necessary, make it possible to acquire a hepatobiliary phase. Silvia Pradella Silvia Lucarini Stefano Colagrande Azienda Ospedaliero-Universitaria Careggi, Florence, Italy DOI:10.2214/AJR.12.8951 WEB—This is a Web exclusive article.

Characterization of hepatic lesions (≤30 mm) with liver-specific contrast agents: A comparison between ultrasound and magnetic resonance imaging

PurposeImaging-based differentiation of hepatic lesions (≤30mm) between well-differentiated hepatocellular carcinomas (w-HCC) and regenerative nodules (RN) presents difficulties. The aim was to compare the diagnostic abilities to differentiate w-HCC from RN using contrast-enhanced ultrasound and magnetic resonance imaging (MRI) both with liver-specific contrast agents. Materials and methodsThis prospective study included 67 pathologically proven hepatic lesions (17.5±5.4mm, 54 w-HCCs, 13 RNs) in 56 patients with chronic hepatitis/cirrhosis (male 40, female 16; 29–79y). Hepatic-arterial/liver-specific phase enhancements were assessed quantitatively by ultrasound with perflubutane microbubble agent and MRI with gadolinium-ethoxybenzyl-diethylenetriamine with respect to the histological findings. ResultsSensitivity, specificity and accuracy of hepatic-arterial phase hyper-enhancement for w-HCC were 59.3%, 100% and 67.2% by ultrasound and 46.3%, 100% and 56.7% by MRI without significant difference. Meanwhile, those of liver-specific-phase hypo-enhancement for w-HCC were 44.4%, 100% and 55.2% by ultrasound and 87.0% (p<0.0001), 46.2% (p=0.0052) and 79.1% (p=0.0032) by MRI. Diagnostic accuracies for w-HCC by area under the receiver operating characteristic curves were higher in the hepatic-arterial phase in ultrasound (0.8316) than MRI (0.6659, p=0.0101) and similar in the liver-specific phase in ultrasound (0.7225) and MRI (0.7347, p=0.8814). ConclusionsHypervascularity is a significant feature which distinguishes w-HCC from RN, and ultrasound exerts a beneficial impact better than MRI for such characterization. However, both imaging have comparable abilities in the characterization of non-hypervascular lesions, compensating mutually for the poor sensitivity of ultrasound and the poor specificity of MRI in the liver-specific phase.

Gd complexes of diethylenetriaminepentaacetic acid conjugates of low-molecular-weight chitosan oligosaccharide as a new liver-specific MRI contrast agent

This study was to describe the synthesis of complexes of gadolinium diethylenetriaminepentaacetic acid conjugates of low-molecular-weight chitosan oligosaccharide Gd-DTPA-CSn (n=6, 8, 11) as a new class of contrast agent as well as its magnetic property in a pilot magnetic resonance imaging. The efficacy of the contrast agent was assessed by measuring the longitudinal relaxivity (r1), FLASH imaging in phantoms in vitro and signal intensity in vivo of the rat abdominal axial imaging. The r1 of Gd-DTPA-CS11 was up to 11.65mM−1·s−1, which was 3 times higher than that of the analogous MRI contrast agent Gd-DTPA in commercial use. In vivo MR images of rat obtained with Gd-DTPA-CS11 showed strong signal enhancement in liver and the vessels of the liver parenchyma during the extended period of time. The present study suggests that the new synthesized gadolinium complexes can be used as a new class of practical liver-specific MRI contrast agent because of its superior performance compared with Gd-DTPA.

Diagnosis of Hepatocellular Carcinoma: Newer Radiological Tools

With the recent dramatic advances in diagnostic modalities, the diagnosis of hepatocellular carcinoma (HCC) is primarily based on imaging. Ultrasound (US) plays a crucial role in HCC surveillance. Dynamic multiphasic multidetector-row CT (MDCT) and magnetic resonance imaging (MRI) are the standard diagnostic methods for the noninvasive diagnosis of HCC, which can be made based on hemodynamic features (arterial enhancement and delayed washout). The technical development of MDCT and MRI has made possible the fast scanning with better image quality and resolution, which enables an accurate CT hemodynamic evaluation of hepatocellular tumor, as well as the application of perfusion CT and MRI in clinical practice. Perfusion CT and MRI can measure perfusion parameters of tumor quantitatively and can be used for treatment response assessment to anti-vascular agents. Besides assessing the hemodynamic or perfusion features of HCC, new advances in MRI can provide a cellular information of HCC. Liver-specific hepatobiliary contrast agents, such as gadoxetic acid, give information regarding hepatocellular function or defect of the lesion, which improves lesion detection and characterization. Diffusion-weighted imaging (DWI) of the liver provides cellular information of HCC and also has broadened its role in lesion detection, lesion characterization, and treatment response assessment to chemotherapeutic agents. In this article, we provide an overview of the state-of-the art imaging techniques of the liver and their clinical role in management of HCC.

Gadoxetic acid-enhanced MRI: a method for the detection of hepatic metastases

Staging of malignant tumors is increasingly important as new therapeutic strategies develop. The presence of liver metastasis significantly changes the therapeutic approach; therefore, it is important to exclude metastasis with high confidence. Moreover, the proportion of patients with hepatic metastasis considered amenable to resection is increasing with improvements in surgical treatment. With improvements in surgical and medical management of hepatic metastasis comes an increasing need to provide accurate assessment of the exact number, size and location of metastases using imaging. The differentiation of liver metastases from benign lesions, such as hemangioma, focal nodular hyperplasia or adenoma, is very important. Gadoxetic acid is a liver-specific MR contrast agent that has both dynamic and hepatocytespecific properties. Once taken up by functioning hepatocytes, gadoxetic acid enhances hepatic parenchyma, whereas lesions with no hepatocytes or hepatocyte dysfunction, such as metastases, and most hepatocellular carcinomas, remain unenhanced.

CONTRAST AGENT Gd‐EOB‐DTPA (EOB·Primovist®) FOR LOW‐FIELD MAGNETIC RESONANCE IMAGING OF CANINE FOCAL LIVER LESIONS

Contrast-enhanced magnetic resonance (MR) imaging with a new liver-specific contrast agent gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA; EOB·Primovist®) was studied in 14 normal beagles and 9 dogs with focal liver lesions. Gd-EOB-DTPA accumulates in normally functioning hepatocytes 20 min after injection. As with Gd-DTPA, it is also possible to perform a dynamic multiphasic examination of the liver with Gd-EOB-DTPA, including an arterial phase and a portal venous phase. First, a reliable protocol was developed and the appropriate timings for the dynamic study and the parenchymal phase in normal dogs using Gd-EOB-DTPA were determined. Second, the patterns of these images were evaluated in patient dogs with hepatic masses. The optimal time of arterial imaging was from 15 s after injection, and the optimal time for portal venous imaging was from 40 s after injection. Meanwhile, the optimal time to observe changes during the hepatobiliary phase was from 20 min after injection. In patient dogs, 11 lesions were diagnosed as malignant tumors; all were hypointense to the surrounding normal liver parenchyma during the hepatobiliary phase. Even with a low-field MR imaging unit, the sequences afforded images adequate to visualize the liver parenchyma and to detect tumors within an appropriate scan time. Contrast-enhanced MR imaging with Gd-EOB-DTPA provides good demarcation on low-field MR imaging for diagnosing canine focal liver lesions.

MR prediction of liver fibrosis using a liver‐specific contrast agent: Superparamagnetic iron oxide versus Gd‐EOB‐DTPA

To examine whether the uptake of a liver-specific contrast agent in the liver parenchyma was correlated with the degree of liver fibrosis. This retrospective study included 54 and 63 patients who underwent superparamagnetic iron oxide (SPIO)- and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI before liver surgery, respectively. For each patient, we calculated ΔR2* and ΔR2, which represent differences in R2* and R2 values of the liver parenchyma before and after administration of SPIO; and the increase rate of liver-to-spleen signal intensity ratio (LSR) on the hepatobiliary phase compared with the precontrast image. The correlation of each MR parameter with the degree of liver fibrosis (F0 to F4) was assessed using Spearman's rank correlation test. The increase rate of LSR was best correlated with the degree of liver fibrosis and significantly decreased as the liver fibrosis progressed (rho = -0.641; P < 0.0001). It showed sensitivity of 76.9% and specificity of 83.3% in differentiating F3 or greater fibrosis when 1.126 or less was set up as a cut-off value. No significant correlation was obtained between ΔR2* or ΔR2 and the degree of liver fibrosis. The uptake of Gd-EOB-DTPA in the liver parenchyma decreased as the liver fibrosis progressed. J. Magn. Reson. Imaging 2012;36:664-671. © 2012 Wiley Periodicals, Inc.

A LC–MS/MS method to evaluate the hepatic uptake of the liver-specific magnetic resonance imaging contrast agent gadoxetate (Gd-EOB-DTPA) in vitro and in humans

Gadoxetate (Gd-EOB-DTPA, Primovist®) is a frequently used liver-specific magnetic resonance imaging (MRI) contrast agent which disposition is so far not fully understood in humans. Here, we describe the development and validation of a selective and sensitive quantification method to measure cellular in vitro concentrations as well as human serum concentrations of gadoxetate. The drug was measured after protein precipitation with acetonitrile and ethyl acetate-mediated sample concentration using amoxicillin as internal standard and liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) for detection. Hydrophilic interaction chromatography (HILIC) was performed by using the column Atlantis® HILIC Silica (2.1mm×100mm), a step-elution gradient with acetonitrile and ammonium acetate (5mM, pH 3.8) as mobile phases and a flow rate of 200μl/min. The MS/MS detection was done in the negative multiple reaction monitoring (MRM) mode by monitoring the m/z transitions 681.3/635.2 for gadotrexate and 363.8/222.7 for the internal standard. The method was validated between 5 and 4000ng/ml in serum and between 1.25 and 500ng/ml in cell lysates. The method was shown to possess sufficient specificity, accuracy, precision and stability without any matrix effects, thereby fulfilling current bioanalytical guidelines. The developed assay was successfully applied to quantify gadoxetate in cellular uptake studies in OATP1B1-transfected cell lines and to monitor serum concentrations-time profiles from a clinical pilot study performed in healthy volunteers carrying the wild-type or the functionally relevant variants T521C (*5) and A388G (*1b) of the hepatic uptake transporter OATP1B1.

Bioinspired synthesis of gadolinium-based hybrid nanoparticles as MRI blood pool contrast agents with high relaxivity

A unique biomineralization approach was developed to synthesize gadolinium-based hybrid (GH) nanoparticles for effective blood pool contrast agents. This approach is bioinspired, environmentally benign, and straightforward. As-prepared GH nanoparticles are biocompatible and well stable in serum. They exhibit much higher longitudinal relaxivity and transverse relaxivity in water (r1 and r2 values of 15.0 and 19.7 s−1 per mM of Gd3+, respectively) than those measured for Gd–DTPA solution (r1 and r2 values of 3.7 and 4.6 s−1 per mM of Gd3+, respectively). In vivo T1-weighted magnetic resonance imaging (MRI) in living mice shows that the GH nanoparticles have an intravascular half-life up to 1 h, much longer than that of Gd–DTPA (about 10 min). As the GH nanoparticles were found to be cleared gradually via hepatobiliary (HB) processing, they can also serve as ideal candidates for liver specific MR contrast agents. In particular, these GH nanoparticles are bioinspired and environmentally benign, therefore promising for medical imaging applications.

Diffusion/Perfusion MR Imaging of the Liver: Practice, Challenges, and Future

Diffusion-weighted (DWI) magnetic resonance (MR) imaging is useful in diagnosing various pathologic conditions in the liver, such as malignant tumors or hepatic fibrosis, and is now part of routine MR imaging protocols for the liver following the development of a parallel encoding technique that has markedly improved image quality. DWI is not very sensitive for detecting hepatocellular carcinomas (HCC) and is useless for characterizing border-line hepatocellular nodules in cirrhosis, but it complements gadolinium-enhanced MR imaging in detecting regional tumor recurrence or intrahepatic metastases of HCC following treatment. DWI is more useful for detecting hepatic metastasis, because histopathologic architecture of metastases does not resemble that of liver tissue and T(2) relaxation time of hepatic metasitasis is fairly longer than that of liver parenchyma. DWI is also useful for detecting moderate and advanced hepatic fibrosis. In cirrhosis, however, decreased blood flow in fibrotic liver is thought to lower apparent diffusion coefficient of the liver. For MR perfusion analysis, a dual-input one-compartment model is used to correlate various hepatic blood flow parameters that represent hepatic arterial/portal blood flow or fraction, mean transit time, and distribution volume with the severity of cirrhosis and portal hypertension. Conventional multisectional imaging and perfusion study can be combined using a 3-dimensional sequence with high temporal resolution, but spatial resolution is not sufficiently high to diagnose tiny hepatic lesions. The advent of liver-specific contrast agents, such as gadoxetic acid, may spur the development of a new analysis model that incorporates extracellular perfusion and hepatocyte function.

Liver-specific contrast agents

In the patient with cancer, magnetic resonance imaging is increasingly used as a diagnostic tool for disease detection, lesion characterization, as well as the assessment of treatment response. Although non-contrast T1-weighted and T2-weighted imaging, together with low molecular weight extracellular gadolinium contrast-enhanced T1-weighted magnetic resonance imaging remain the cornerstone for liver assessment, there is increasing recognition of the benefits of liver-specific contrast agents for disease evaluation.

Hypervascular hepatocellular carcinomas: detection with gadoxetate disodium-enhanced MR imaging and multiphasic multidetector CT

To retrospectively compare the accuracy of detection of hypervascular hepatocellular carcinoma (HCC) by multiphasic multidetector CT and by gadoxetate disodium-enhanced MR imaging. After ethical approval, we analysed a total of 73 hypervascular HCC lesions from 31 patients suspected of having HCC, who underwent both gadoxetate disodium-enhanced MR imaging and multiphasic multidetector CT. Five blinded observers independently reviewed CT images, as well as dynamic MR images alone and combined with hepatobiliary phase MR images. Diagnostic accuracy (Az values), sensitivities and positive predictive values were compared by using the Scheffe post hoc test. The mean Az value for dynamic and hepatobiliary phase MR combined (0.81) or dynamic MR images alone (0.78) was significantly higher than that for CT images (0.67, P < 0.001, 0.005, respectively). The mean sensitivity of the combined MR images (0.67) was significantly higher than that of dynamic MR alone (0.52, P < 0.05) or CT images (0.44, P < 0.05). The mean positive predictive values were 0.96, 0.95 and 0.94, for CT, dynamic MR alone and combined MR images, respectively. Compared with multiphasic multidetector CT, gadoxetate disodium-enhanced MR imaging combining dynamic and hepatobiliary phase images results in significantly improved sensitivity and diagnostic accuracy for detection of hypervascular HCC. Gadoxetate disodium is a new liver-specific MR imaging contrast agent. Gadoxetate disodium-enhanced MRI helps the assessment of patients with liver disease. It showed high diagnostic accuracy for the detection of hepatocellular carcinoma.

Contrast-enhanced MR cholangiography (MRCP) with GD-EOB-DTPA in evaluating biliary complications after surgery

We assessed the usefulness of contrast-enhanced magnetic resonance cholangiography (CE-MRC) with liver-specific contrast agent in evaluating the biliary tree after hepatic surgery. A total of 142 patients with suspected biliary complications after liver surgery underwent hepatobiliary MR before and after administration of gadolinium ethoxy benzylic diethylenetriamine pentaacetic acid (Gd-EOB-DTPA). Unenhanced MR cholangiopancreatography (MRCP) and postcontrast MRC were obtained in all patients. Blinded image evaluation and semiquantitative analysis comparing MRCP and CE-MRC were performed by two experienced radiologists. In all cases, optimal postcontrast visualisation of the biliary tract was obtained. In 22 patients, a postsurgical biliary complication was confirmed. MRCP detected 64% of lesions, but in 36% of cases, an alteration was only suspected but not clearly defined. CE-MRC allowed definite diagnosis in 100% of cases. Hepatobiliary-specific contrast agents allow for accurate and extensive study of biliary tract alterations, especially in assessing postsurgical complications.

Quantifying differences in hepatic uptake of the liver specific contrast agents Gd-EOB-DTPA and Gd-BOPTA: a pilot study

To develop and evaluate a procedure for quantifying the hepatocyte-specific uptake of Gd-BOPTA and Gd-EOB-DTPA using dynamic contrast-enhanced (DCE) MRI. Ten healthy volunteers were prospectively recruited and 21 patients with suspected hepatobiliary disease were retrospectively evaluated. All subjects were examined with DCE-MRI using 0.025 mmol/kg of Gd-EOB-DTPA. The healthy volunteers underwent an additional examination using 0.05 mmol/kg of Gd-BOPTA. The signal intensities (SI) of liver and spleen parenchyma were obtained from unenhanced and enhanced acquisitions. Using pharmacokinetic models of the liver and spleen, and an SI rescaling procedure, a hepatic uptake rate, K (Hep), estimate was derived. The K (Hep) values for Gd-EOB-DTPA were then studied in relation to those for Gd-BOPTA and to a clinical classification of the patient's hepatobiliary dysfunction. K (Hep) estimated using Gd-EOB-DTPA showed a significant Pearson correlation with K (Hep) estimated using Gd-BOPTA (r = 0.64; P < 0.05) in healthy subjects. Patients with impaired hepatobiliary function had significantly lower K (Hep) than patients with normal hepatobiliary function (K (Hep) = 0.09 ± 0.05 min(-1) versus K (Hep) = 0.24 ± 0.10 min(-1); P < 0.01). A new procedure for quantifying the hepatocyte-specific uptake of T (1)-enhancing contrast agent was demonstrated and used to show that impaired hepatobiliary function severely influences the hepatic uptake of Gd-EOB-DTPA. • The liver uptake of contrast agents may be measured with standard clinical MRI. • Calculation of liver contrast agent uptake is improved by considering splenic uptake. • Liver function affects the uptake of the liver-specific contrast agent Gd-EOB-DTPA. • Hepatic uptake of two contrast agents (Gd-EOB-DTPA, Gd-BOPTA) is correlated in healthy individuals. • This method can be useful for determining liver function, e.g. before hepatic surgery.

Multinodular pseudolymphoma of the liver: computed tomography and magnetic resonance imaging findings

A 60-year-old woman who had had a history of renal cell carcinoma with intraperitoneal recurrence presented with multiple liver masses. Computed tomography demonstrated multiple enhancing lesions in the both lobes of the liver, and there was an apparent small vessel coursing within one of the lesions. On magnetic resonance imaging, masses showed slight T1 and T2 prolongation, and restricted diffusion: On the hepatobiliary phase of liver-specific contrast agent enhancement, lesions were shown as low signal intensity of varying degree. Liver metastases from renal cell carcinoma were suspected, and partial hepatectomy was performed for the superficially located nodules to make a definitive diagnosis. The final pathological diagnosis was reactive lymphoid hyperplasia or pseudolymphoma of the liver.

Unenhanced fat fraction ratios obtained by MR and enhanced T2* values with liver-specific MR contrast agents for diagnosis of non-alcoholic steatohepatitis in rats

Non-invasive MR imaging is expected to be used for accurate diagnosis and quantification of non-alcoholic steatohepatitis (NASH), because NASH is a progressive fatty liver disease. New MR techniques, such as fat fraction ratio (FFR) and T2* value measurement, have attracted an increasing attention, because those techniques can measure quantitative parameters of fibrosis, fat and iron deposition in the liver. To investigate the potential of FFR and T2* value in NASH with pre-enhancement, gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) or super-paramagnetic iron oxide (SPIO)-enhanced MRI. Twenty-eight rats were divided equally into four groups (one control group and three NASH groups). All rats underwent unenhanced, Gd-EOB-DTPA, and SPIO-enhanced MRI. The T2* value of the liver was measured for each image sequence, and then changes in T2* values before and after each injection were analyzed using Dunnett's test. The reduction rate of T2* value before and 13 min after injection of Gd-EOB-DTPA or SPIO was analyzed using Mann-Whitney's U test. Moreover, FFR of the liver was measured before enhancement, and the relationship between fat fraction and the calculated fat area percentage on a pathological specimen was examined using Spearman's correlation test. On pre-enhancement, FFR and T2* value were 26.0% ± 12.0% and 21.5 ± 4.2 ms for all NASH groups, and 0.9% ± 0.5% and 30.8 ±-5.5 ms for control, respectively. Both FFR and T2* values were significantly different between the NASH and control groups. The reduction rate of T2* value was significantly lower in the NASH groups than in the control group on SPIO-enhanced MRI, though there was no significant difference on Gd-EOB-DTPA-enhanced MRI. FFR was correlated with the calculated fat area percentage for the pathological specimen. Pre-enhancement FFR, T2* value measurement and reduction rate of T2* value on SPIO-enhanced MRI may help estimate the progress of liver fat deposition and fibrosis in NASH.

Gadoxetate Acid-Enhanced MR Imaging for HCC: A Review for Clinicians

Hepatocellular carcinoma (HCC) is increasingly being detected at an earlier stage, owing to the screening programs and regular imaging follow-up in high-risk populations. Small HCCs still pose diagnostic challenges on imaging due to decreased sensitivity and increased frequency of atypical features. Differentiating early HCC from premalignant or benign nodules is important as management differs and has implications on both the quality of life and the overall survival for the patients. Gadoxetate acid (Gd-EOB-DTPA, Primovist®, Bayer Schering Pharma) is a relatively new, safe and well-tolerated liver-specific contrast agent for magnetic resonance (MR) imaging of the liver that has combined perfusion- and hepatocyte-specific properties, allowing for the acquisition of both dynamic and hepatobiliary phase images. Its high biliary uptake and excretion improves lesion detection and characterization by increasing liver-to-lesion conspicuity in the added hepatobiliary phase imaging. To date, gadoxetate acid-enhanced MRI has been mostly shown to be superior to unenhanced MRI, computed tomography, and other types of contrast agents in the detection and characterization of liver lesions. This review article focuses on the evolving role of gadoxetate acid in the characterization of HCC, differentiating it from other mimickers of HCC.

Optimal imaging of focal liver lesions

Modern diagnostic imaging allows the accurate identification of different focal liver lesions. Ultrasound and contrast-enhanced ultrasound are widely available, and contrast injection allows the classification of most lesions as benign or malignant. CT is a robust, widely available and easy-to-use imaging technique that allows studies to be conducted in uncooperative patients. Owing to different sequences and liver-specific contrast agents, MRI is able to not only provide morphological and vascular information of the focal liver lesions, but also functional information on the capacity of the lesion to uptake the liver-specific contrast agent. The main drawback of the technique is the requirement for state-of-the-art equipment and a good knowledge of the different contrast mechanisms. Owing to the different costs and availability of the imaging techniques, their correct utilization permits a precise, accurate and fast way to gain the most significant information, thus allowing correct management of the dif...

Orally Administered Manganese With and Without Ascorbic Acid as a Liver-Specific Contrast Agent and Bowel Marker for Magnetic Resonance Imaging

The objectives of this clinical trial of orally administered manganese in magnetic resonance imaging (MRI) of the liver were to assess signal enhancements in the liver with and without the addition of an uptake promoter, ascorbic acid, and to evaluate acute safety. A total of 18 healthy adult males were enrolled in the present trial. Contrast medium: MnCl2, doses: 25, 50, and 100 micromoL/kg bw, respectively, and promoting agent: Ascorbic acid, doses: 50, 100, and 200 micromoL/kg bw, respectively, were used. All imaging was performed on a 1.5 T clinical MRI system. Three pulse-sequences in the abdomen were used: (1) T1-weighted axial gradient-echo (GRE), (2) T1-weighted coronal gradient-echo, and (3) T1-weighted axial spin-echo (SE). Time-points for imaging were precontrast, 1 hour, 2.5, 4, 6, 9, and 24 hours after MnCl2 intake. Safety parameters assessed were clinical examinations and vital signs, including heart rate and blood pressure. Hematology and clinical chemistry were assessed with standard laboratory procedures. All pulse-sequences showed a clear dose-response in liver-enhancement. Temporally, high enhancements in the liver were seen between 2.5 and 6 hours after MnCl2 intake. At the manganese dose 50-micromoL/kg bw, with ascorbic acid and at the dose 100-micromoL/kg bw, both with and without ascorbic acid, the hepatic enhancements were higher than 100% with the GRE pulse-sequence. The promoting effect of ascorbic acid was significant at a manganese-dose of 100-micromoL/kg bw. The contrast media distributed well in the small intestine, delineating intra-abdominal organs well. No serious or unexpected adverse events were encountered. The drug was generally well tolerated, except for minor gastrointestinal adverse events. No significant alteration in hematology or clinical chemistry was seen. Oral manganese is easy to use, and has few side effects. Besides the liver-specific effect, an additional benefit is the delineation of the intestine.

Contrast-enhanced MR cholangiography with gadoxetic-acid-disodium (Gd-EOB-DTPA) for the evaluation of post-gunshot traumatic bile duct injury: A case report

Bile duct injury is a common complication after hepatobiliary surgery, but may also occur in post-traumatic patients. Early diagnosis and treatment are crucial to prevent long-term morbidity. We present a case with a liver laceration and biliary leakage following a gunshot incident, which was demonstrated on MR cholangiography using gadoxetic-acid-disodium (Primovist). This liver-specific contrast agent provides excellent demonstration of bile leakage as well as the intrahepatic bile tree, being a safe, non-invasive and accurate technique for contrast-enhanced cholangiography without use of ionizing radiation.