Liver-specific Contrast Agent Research Articles

Microwave ablation of large HCC lesions: Added value of CEUS examinations forablation success control.

To assess the value of dynamic contrast enhanced ultrasound (CEUS) for the detection of residual tumor tissue day 1 after microwave ablation (MWA) of large hepatocellular carcinoma (HCC) compared to MRI. 30 consecutive patients (5 females, 25 males, mean age 64 years, age range 54-73 years) with an untreated HCC lesion larger than or equal to 3 cm underwent percutaneous MWA between 03/2014 and 04/2016. 1 patient was excluded because of an artificial pacemaker. All remaining 29 patients underwent 3-T MRI with liver-specific contrast agent and CEUS 1 day after ablation to detect residual tumor tissue. The 6-week follow-up including CEUS and MRI was defined as the reference standard. Complete ablation was achieved in 23 of 29 treated lesions (79%). The sensitivities and specificities for the detection of residual tumor tissue on day 1 were 100% and 83% for CEUS and 87% and 67% for MRI resp. without the differences being statistically significant. CEUS allows a reliable assessment of therapeutic success of percutaneous ablation of large HCC lesions one day after the ablation. Its ability to visualize reactive periablation perfusion changes in real-time might be of advantage in the depiction of residual tumor tissue when compared to MRI imaging alone.

Is There Long-term Signal Intensity Increase in the Central Nervous System on T1-weighted Images after MR Imaging with the Hepatospecific Contrast Agent Gadoxetic Acid? A Cross-sectional Study in 91 Patients.

Purpose To evaluate whether there is T1-weighted signal intensity (SI) increase in the dentate nucleus (DN) and globus pallidus (GP) in relation to the middle cerebellar peduncle (MCP), pons, and thalamus after repeated administration of the liver-specific contrast agent gadoxetic acid. Materials and Methods This was an institutional review board-approved, prospectively conducted (written informed consent acquired), cross-sectional study performed in a consecutively selected patient group (n = 91; patients received one to 37 doses of gadoxetic acid) and a control group (n = 52; subjects had never received injections of gadolinium-based contrast agent) examined with a standard T1-weighted two-dimensional spin-echo pulse sequence of the brain at 1.5 T. DN/MCP, DN-to-pons, GP-to thalamus, and GP-to-cerebrospinal fluid ratios were measured and compared by using the nonparametric Kruskal-Wallis test, corresponding pairwise tests, and Spearman correlation. Results DN/MCP (ρ = 0.51, P < .0001) and DN-to-pons (ρ = 0.41, P = .0001) ratios correlated positively with the number of previous administrations of gadoxetic acid. DN/MCP and DN-to-pons ratios were significantly different between control subjects (medians of 1.016 and 1.034, respectively) and patients with more than 10 gadoxetic acid administrations (1.038 [P < .0001] and 1.053 [P = .0100], respectively), whereas no significant difference was found in the groups with five to 10 (1.029 [P = .053] and 1.044 [P = .072], respectively) and fewer than five (1.014 [P = .420] and 1.030 [P = .595], respectively) gadoxetic acid administrations. GP-to-thalamus ratios differed significantly between the study and control groups (P < .0001), whereas no significant correlation was found for GP-to-thalamus ratios and number of gadoxetic acid administrations (ρ = 0.13, P = .2304). Conclusion Results show a significant correlation between the number of gadoxetic acid administrations and the increase of SI in the DN, which is likely due to gadolinium retention. © RSNA, 2017.

Radiofrequency ablation for hepatocellular carcinoma - analysis of the clinical outcome

Introduction/Objective. Radiofrequency ablation (RFA) is a minimally invasive treatment modality for primary and metastatic liver tumors. It can be performed percutaneously or as a laparoscopic or open surgical procedure under ultrasound or computerized tomography guidance. The objective of the study was to evaluate the clinical outcome of the initial 16 patients with hepatocellular carcinoma (HCC) managed by percutaneous RFA at a tertiary institution and to assess the efficacy of this procedure in the management of selected patients with HCC. Method. From June 2011 until December 2013, 16 patients with early-stage HCC were managed by percutaneous radiofrequency ablation at the Clinic for Digestive Surgery, Clinical Center of Serbia, Belgrade. All the patients were treated by the same team composed of an interventional radiologist and a liver surgeon. We analyzed the clinical outcome and the biologic effect of this treatment by comparing the pre- and post-treatment levels of alpha-fetoprotein (AFP). Results. Post-treatment values of liver transaminase levels returned to the pre-treatment values from Day 3. Post-treatment hospital stay was two days. Post-procedural complications included mild pain in all patients, skin necrosis at the site of the electrode puncture in five patients, and transient hepatic decompensation in one patient. In all the patients the AFP level correlated with the findings of liver imaging (ultrasound and/or magnetic resonance imaging with liver-specific contrast agent) indicating viability of the treated tumor. Conclusion. RFA is a feasible and effective procedure providing favorable clinical outcome in patients with early-stage HCC.

A Dendritic Supramolecular Complex as Uniform Hybrid Micelle with Dual Structure for Bimodal In Vivo Imaging

In this study, a uniform complex dual micelle bearing a gadolinium-substituted polyoxometalate core, a hydrophobic middle, and a biocompatible organic shell, which exhibits a uniform size and definite molecular weight and chemical composition, is constructed through a simple two-step process for use as a fluorescence and magnetic resonance imaging (MRI) contrast agent. A paramagnetic polyoxometalate cluster, K13 [Gd(β2 -SiW11 O39 )2 ], is first encapsulated with a cationic 3-generation dendron (D-3) bearing triethylene glycol monomethyl ether terminal groups through ionic substitution. The formed electrostatic complex, (D-3)13 [Gd(β2 -SiW11 O39 )2 ] (D-GdSiW), which displays an ambivalent micellar structure, is then demonstrated to act as a suitable carrier for the uptake of cationic fluorescent dyes, forming a loaded complex. The dye-loaded complex D-GdSiW-D is thus proven to display high relaxivity as a contrast agent, maintaining its structural stability under physiological conditions with low cell cytotoxicity. Confocal laser scanning microscopic observation also demonstrates the fluorescence imaging property of the prepared complex upon consumption by MCF-7 cells. Both in vivo fluorescence imaging and MRI further confirm that the complex micelle with dual micellar structure may be a suitable liver-specific contrast agent for clinical diagnosis.

Synthesis and Evaluation of a Biocompatible Macromolecular Gadolinium Compound as a Liver-Specific Contrast Agent for MRI

A new macromolecular biocompatible gadolinium chelate complex (PAI-N2-DOTA-Gd) as a liver-specific magnetic resonance imaging (MRI) contrast agent was synthesised and evaluated. An aspartic acid–isoleucine copolymer was chemically linked with Gd-DOTA via ethylenediamine to give PAI-N2-DOTA-Gd. In vitro, the T1-relaxivity of PAI-N2-DOTA-Gd (14.38 mmol–1⋅L⋅s–1, 0.5 T) was much higher than that of the clinically used Gd-DOTA (4.96 mmol–1⋅L⋅s–1, 0.5 T), with obvious imaging signal enhancement. In the imaging experiments in vivo, PAI-N2-DOTA-Gd exhibited good liver selectivity, and had a greater intensity enhancement (68.8 ± 5.6 %) and a longer imaging window time (30–70 min), compared to Gd-DOTA (21.1 ± 5.3 %, 10–30 min). Furthermore, the in vivo histological studies of PAI-N2-DOTA-Gd showed a low acute toxicity and desirable biocompatibility. The results of this study indicate that PAI-N2-DOTA-Gd is a feasible liver-specific contrast agent for MRI.

GADOXETATE DISODIUM (GD-EOB-DTPA) CONTRAST ENHANCED MAGNETIC RESONANCE IMAGING CHARACTERISTICS OF HEPATOCELLULAR CARCINOMA IN DOGS.

Hepatocellular carcinoma is the most common primary hepatic tumor in dogs and is amenable to surgical resection in many cases. Unfortunately, overlap of sonographic findings between benign and malignant hepatic lesions typically requires more invasive diagnostic tests to be performed (e.g., biopsy for histopathology). The availability of a noninvasive diagnostic test to identify hepatocellular carcinoma would be beneficial. The use of a liver-specific magnetic resonance imaging (MRI) contrast agent such as gadoxetate disodium (Gd-EOB-DTPA; Eovist® or Primovist®) has improved lesion detection in human patients. In this descriptive study, gadoxetate disodium contrast-enhanced MRI characteristics in dogs were evaluated in seven dogs (total of eight lesions). The imaging characteristics were variable with the exception of all lesions being hypointense to surrounding normal hepatic parenchyma on 3D T1-weighted gradient recalled echo images at all postcontrast time points. All lesions displayed signal intensity ratios less than 1, consistent with retained but impaired hepatocyte function. Hepatic lesions not identified on previous imaging were found in 3/7 patients which may affect surgical planning. In two patients, several hepatic nodules were identified during surgery which had not been visualized on MRI and were found to be benign on histopathology. This descriptive study reports the MRI characteristics of hepatocellular carcinoma in dogs using the liver-specific contrast agent gadoxetate disodium.

Combining hyperpolarized 13 C MRI with a liver-specific gadolinium contrast agent for selective assessment of hepatocyte metabolism.

Hyperpolarized 13 C MRI is a powerful tool for studying metabolism, but can lack tissue specificity. Gadoxetate is a gadolinium-based MRI contrast agent that is selectively taken into hepatocytes. The goal of this project was to investigate whether gadoxetate can be used to selectively suppress the hyperpolarized signal arising from hepatocytes, which could in future studies be applied to generate specificity for signal from abnormal cell types. Baseline gadoxetate uptake kinetics were measured using T1 -weighted contrast enhanced imaging. Relaxivity of gadoxetate was measured for [1-13 C]pyruvate, [1-13 C]lactate, and [1-13 C]alanine. Four healthy rats were imaged with hyperpolarized [1-13 C]pyruvate using a three-dimensional (3D) MRSI sequence prior to and 15 min following administration of gadoxetate. The lactate:pyruvate ratio and alanine:pyruvate ratios were measured in liver and kidney. Overall, the hyperpolarized signal decreased approximately 60% as a result of pre-injection of gadoxetate. In liver, the lactate:pyruvate and alanine:pyruvate ratios decreased 42% and 78%, respectively (P < 0.05) following gadoxetate administration. In kidneys, these ratios did not change significantly. Relaxivity of gadoxetate for [1-13 C]alanine was 12.6 times higher than relaxivity of gadoxetate for [1-13 C]pyruvate, explaining the greater selective relaxation effect on alanine. The liver-specific gadolinium contrast-agent gadoxetate can selectively suppress normal hepatocyte contributions to hyperpolarized 13 C MRI signals. Magn Reson Med 77:2356-2363, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Colorectal Cancer Liver Metastases: Diagnostic Performance and Prognostic Value of PET/MR Imaging.

Purpose To evaluate the diagnostic performance of combined positron emission tomography (PET) and magnetic resonace (MR) imaging (hereafter, PET/MR imaging) in the detection of liver metastases and to assess its prognostic value in patients with colorectal cancer liver metastases (CRLMs). Materials and Methods Institutional review board approval was obtained for this retrospective study, with waiver of informed consent. A total of 55 patients with 98 CRLMs who underwent PET/MR imaging and multidetector computed tomography (CT) between January 2013 and June 2014 comprised the study population. Of these patients, 34 underwent hepatic resection, 18 of whom also underwent neoadjuvant chemotherapy (NAC). Two board-certificated radiologists independently assessed the four image sets (ie, multidetector CT, whole-body PET, MR imaging with a liver-specific contrast agent [hereafter, EOB MR imaging], and PET/MR imaging). To compare the diagnostic performance of each imaging modality, jackknife alternative free-response receiver operating characteristic and generalized estimating equations were used. To assess prognostic value, recurrence-free survival of the 18 patients who underwent NAC followed by hepatic resection was analyzed by using the Kaplan-Meier method and log-rank test. Results The reader-averaged figure of merit of PET/MR imaging was significantly higher than that of either multidetector CT (P = .003) or PET (P = .020) in the detection of CRLMs. However, no significant difference was observed between figure of merit for PET/MR imaging and that for EOB MR imaging (P = .231). After NAC, six of the 18 patients had isometabolic CRLMs on PET images, and 12 patients had hypermetabolic CRLMs. The 1-year recurrence-free survival rate was 80% in patients with isometabolic CRLMs and 14% in patients with hypermetabolic CRLMs, showing a significant difference (P = .026). Conclusion PET/MR imaging can yield significantly higher diagnostic performance in the detection of CRLMs when compared with the performance of multidetector CT or PET. However, no significant difference in diagnostic performance was observed between PET/MR imaging and EOB MR imaging. In addition, the degree of fluorodeoxyglucose uptake after NAC may have the potential to yield prognostic information for recurrence-free survival after hepatic resection. (©) RSNA, 2016 Online supplemental material is available for this article.

Current evidence for the diagnostic value of gadoxetic acid-enhanced magnetic resonance imaging for liver metastasis.

A variety of imaging techniques, including ultrasonography (US), multidetector computed tomography (MDCT), magnetic resonance imaging (MRI) and positron emission tomography combined with CT scan (PET/CT), are available for diagnosis and treatment planning in liver metastasis. Contrast-enhanced MDCT is a relatively non-invasive, widely available and standardized method for hepatic work-up. Gadoxetic acid (gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid; EOB Primovist®]) is a recently developed liver-specific hepatobiliary MR contrast agent that offers both dynamic imaging as well as liver-specific static hepatocyte imaging, referred to as the hepatobiliary phase. Following contrast injection, this technique reveals dynamic vascular phases (arterial, portal venous and delayed phases), in addition to the hepatobiliary phase upon uptake by functional hepatocytes. The overall sensitivity of gadoxetic acid-enhanced MRI was significantly higher than that of contrast-enhanced CT. Specifically, the higher sensitivity of gadoxetic acid-enhanced MRI was observed in lesions smaller than 1cm in diameter. Gadoxetic acid-enhanced MRI is considered an extremely useful tool for the diagnosis of liver metastases. Future studies will focus on diagnostic algorithms involving combinations of modalities such as MRI, MDCT and/or (18) F-fluorodeoxyglucose PET/CT, which may impact the treatment plan for these patients.

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

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

Diagnosis and treatment of benign liver nodules: Brazilian Society of Hepatology (SBH) recommendations.

Space-occupying lesions of the liver may be cystic or solid. Ultrasonography is an extremely useful method for initial screening, and suffices for diagnosis of simple hepatic cysts. Complex cysts and solid masses require computed tomography or magnetic resonance imaging for confirmation. Wide surgical excision is indicated in cystadenoma or cystadenocarcinoma. Clinical and epidemiological data are important, as nodules in noncirrhotic livers are more likely to be benign. Hemangiomas, the most common benign tumors, require no follow-up after diagnostic confirmation if they are small and asymptomatic. Patients with giant, symptomatic hemangiomas or compression of adjacent structures should be referred to hepatobiliary centers for potential surgery. The genetic heterogeneity of hepatocellular adenomas and their epidemiology and prognosis prompted classification of these tumors into four subtypes based on histology and immunohistochemistry. The major complications of hepatocellular adenomas are rupture with bleeding and malignant transformation. Rupture occurs in approximately 30% of cases. The main risk factors are tumors size >5 cm and inflammatory subtype. Hepatocellular adenomas may enlarge during pregnancy due to marked hormonal stimulation. As oral contraceptive pills and anabolic steroids have associated with hepatocellular adenomas growth, particularly of the hepatocyte nuclear factor-1alfa subtype, these drugs should be discontinued. Focal nodular hyperplasia is the second most common benign tumor of the liver. It is most frequent in women aged 20 to 60, and 70% to 90% of cases are asymptomatic. In the absence of a central scar and/or other hallmarks of Focal nodular hyperplasia, with uncertainty between this diagnosis and hepatocellular adenoma, liver-specific contrast agents are indicated.

Liver-specific gadoxetic acid-enhanced magnetic resonance for focal lesion evaluation

Gadolinium-enhanced magnetic resonance for the evaluation of hepatic lesions is increasingly being used in clinical practice, especially in patients with suspicious focal lesions, whether benign or malignant. In regard to hepatocellular carcinoma, the diagnostic performance of magnetic resonance through the «conventional» protocols and multi-detector computerized tomography consisting of multiphase evaluation with intravenous contrast, largely depends on the size of the lesion. They are more reliable in lesions>2cm. However, in lesions measuring 1-2cm, establishing the definitive diagnosis is a real challenge, with sensitivity values of 45-65%, but generally with excellent specificity (>95%). Furthermore, if the lesion has a diameter<1cm, diagnosis is usually unreliable. In these last 2 settings, the complementary use of liver-specific contrast agents can be advantageous. The aim of our article was to review the current evidence on the usefulness of this new non-invasive diagnostic method in hepatic lesions.

Liver-specific gadoxetic acid-enhanced magnetic resonance for focal lesion evaluation.

Gadolinium-enhanced magnetic resonance for the evaluation of hepatic lesions is increasingly being used in clinical practice, especially in patients with suspicious focal lesions, whether benign or malignant. In regard to hepatocellular carcinoma, the diagnostic performance of magnetic resonance through the «conventional» protocols and multi-detector computerized tomography consisting of multiphase evaluation with intravenous contrast, largely depends on the size of the lesion. They are more reliable in lesions>2cm. However, in lesions measuring 1-2cm, establishing the definitive diagnosis is a real challenge, with sensitivity values of 45-65%, but generally with excellent specificity (>95%). Furthermore, if the lesion has a diameter<1cm, diagnosis is usually unreliable. In these last 2 settings, the complementary use of liver-specific contrast agents can be advantageous. The aim of our article was to review the current evidence on the usefulness of this new non-invasive diagnostic method in hepatic lesions.

Modern possibilities of liver surgery for colorectal cancer metastases.

In recent years there has been a significant improvement in the approaches of the treatment of patients with liver metastases of colorectal cancer. This is caused by improved diagnostics modalities. Modern possibilities of CT and MRI in combination with liver-specific contrast agents enable to localize tumor very precise, evaluate its location relative to blood vessels and other anatomic structures and, thus, carefully plan surgery. Ultrasound with contrast agents can add some important information. Multidisciplinary approach in treatment. Current chemotherapeutic drugs are becoming more specific, thereby increasing their effectiveness. Currently used regimens can be effective in about 60% of patients. Individual approach to chemotherapy using mutational analysis in some cases, makes possible to estimate beforehand efficacy and thus reduce the probability of treatment failure, followed by a high load for the patient. A good example in this case can serve K-Ras gene mutation that caused ineffectiveness therapy with Cetuximab. Conversely, wild forms of K-Ras oncogene allow to carry out this kind of treatment. Advances in chemotherapy make possible to perform complete removal of the tumor in approximately 20% of patients with primary inoperable tumors.

Activity-based cost analysis of contrast-enhanced ultrasonography (CEUS) related to the diagnostic impact in focal liver lesion characterisation.

PurposeThis study was done to assess the clinical-diagnostic impact and cost of contrast-enhanced ultrasound (CEUS) versus computed tomography (CT) and magnetic resonance (MR) imaging in the characterisation of focal liver lesions.Materials and methodsCEUS with sulphur hexafluoride-filled microbubbles (SonoVue bolus 2.4 ml) was performed in 157 patients with 160 focal liver lesions identified by other diagnostic techniques. CEUS images were obtained during the arterial (15 to 35 s from contrast injection), portal venous (40 to 70 s) and late phase (up to 300 s from microbubble injection). Contrast-enhanced CT was performed with a 64-row multidetector CT. MRI was performed before and after administration of the liver-specific contrast agent gadobenate dimeglumine (Gd-BOPTA). A patient-by-patient activity-based cost analysis was performed.ResultsCEUS led to a change in the diagnostic workup in 131/157 patients (83.4 %) and in the therapeutic workup in 93/157 patients (59.2 %). CEUS allowed for the final diagnosis to be established in 133/157 patients (84.7 %). The full cost of CEUS was lower than that of contrast-enhanced CT and MR imaging.ConclusionsCEUS determined a change in the diagnostic and therapeutic workup in the characterisation of focal liver lesions and reduced the full costs of the diagnostic process.Main messages: • CEUS allows a correct diagnosis in more than 80 % of focal liver lesions. • CEUS has a significant impact on the diagnosis of focal liver lesions. • CEUS examination of focal liver lesions reduces total costs. • Dynamic MR with hepato-specific contrast medium remains the reference standard for lesion characterisation. • CEUS is low-cost, versatile and accurate in the characterisation of focal liver lesions.

Consensus statements from a multidisciplinary expert panel on the utilization and application of a liver-specific MRI contrast agent (gadoxetic acid).

OBJECTIVE. This systematic review presents evidence-based consensus statements as reported by a multidisciplinary expert panel (six abdominal radiologists, four hepatobiliary surgeons, and two hepatologists) regarding the use of gadoxetic acid for liver MRI. CONCULSION. Although this review highlights the incremental diagnostic value of hepatobiliary phase imaging with gadoxetic acid-enhanced liver MRI in multiple clinical scenarios, there remains a need for further impact studies for some clinical applications, such as hepatocellular carcinoma in cirrhosis.

Evaluation of Early-Stage Hepatocellular Carcinoma by Magnetic Resonance Imaging With Gadoxetic Acid Detects Additional Lesions and Increases Overall Survival

Hepatocellular carcinoma (HCC) has a high rate of intrahepatic recurrence after curative treatment, possibly because metastases are not always identified before treatment. Magnetic resonance (MR) imaging with a liver-specific contrast agent, gadoxetic acid, can detect small HCCs with high levels of sensitivity. We investigated whether MR imaging with gadoxetic acid increases overall and recurrence-free survival of patients initially assessed by computed tomography (CT). We performed a retrospective study of data from 700 patients diagnosed with a single-nodular HCC by dynamic 4-phase CT in Seoul, Korea, from January 2009 through December 2010. Of these patients, 323 underwent additional evaluation with gadoxetic acid-enhanced MR imaging (CT+MR group). The 377 patients who did not undergo MR imaging analysis are referred to as the CT group. The CT and CT+MR groups were comparable in most baseline characteristics (Child-Pugh class A, 93.1% vs 94.7%; and median size of the primary HCCs, 2.8 vs 2.6 cm, respectively). Seventy-four additional HCC nodules were detected in 53 (16.4%) of the patients who underwent MR evaluation after CT (CT+MR group). These detections increased the Barcelona Clinic Liver Cancer stages for 43 patients (13.3%) and modified their treatment plans. On multivariable analyses, the CT+MR group had a significantly lower rate of HCC recurrence (hazard ratio [HR], 0.72; 95% confidence interval [CI], 0.54-0.96) and lower overall mortality (HR, 0.65; 95% CI, 0.44-0.96) than the CT group. In an analysis of 285 pairs of patients matched on the basis of the propensity score, the CT+MR group had significantly lower overall mortality (HR, 0.66; 95% CI, 0.44-0.99). Among patients who underwent dynamic CT analysis of a single-nodular HCC, additional evaluation by MR imaging with gadoxetic acid led to the detection of additional HCC nodules in 16% of patients, reduced the risk of disease recurrence, and decreased overall mortality.

A Hyaluronic Acid-Conjugated Gadolinium Hepatocyte-Specific T1 Contrast Agent for Liver Magnetic Resonance Imaging.

In this study, we synthesized hyaluronic acid-conjugated gadolinium (HA-diethylene triamine pentaacetic acid (DTPA)-Gd) and evaluated as hepatocyte-specific magnetic resonance imaging (MRI) contrast agent for the diagnosis of hepatic metastasis. We conducted Fourier transform (FT)-IR analysis to determine the conjugation of HA and DTPA and performed cell viability assays using NIH3T3 and FL83B cell lines. We also conducted T1-weighted MRI of HA-DTPA-Gd and gadoxetic acid to compare the paramagnetic properties of both. HA-DTPA-Gd had a higher efficiency in liver MRI compared with the commercially available liver-specific contrast agent (p < 0.001). HA-DTPA-Gd, which possessed a higher T1 relaxivity, showed excellent capability for the diagnosis of hepatic metastasis through an in vivo MRI study in comparison with gadoxetic acid (p < 0.001). Based on this study, we believe that HA-DTPA-Gd has promising potential for use as a contrast agent for liver MRI of hepatic metastases.

Imaging findings of mimickers of hepatocellular carcinoma.

Radiological imaging plays a crucial role in the diagnosis of hepatocellular carcinoma (HCC) as the noninvasive diagnosis of HCC in high-risk patients by typical imaging findings alone is widely adopted in major practice guidelines for HCC. While imaging techniques have markedly improved in detecting small liver lesions, they often detect incidental benign liver lesions and non-hepatocellular malignancy that can be misdiagnosed as HCC. The most common mimicker of HCC in cirrhotic liver is nontumorous arterioportal shunts that are seen as focal hypervascular liver lesions on dynamic contrast-enhanced cross-sectional imaging. Rapidly enhancing hemangiomas can be easily misdiagnosed as HCC especially on MR imaging with liver-specific contrast agent. Focal inflammatory liver lesions mimic HCC by demonstrating arterial-phase hypervascularity and subsequent washout on dynamic contrast-enhanced imaging. It is important to recognize the suggestive imaging findings for intrahepatic cholangiocarcinoma (CC) as the management of CC is largely different from that of HCC. There are other benign mimickers of HCC such as angiomyolipomas and focal nodular hyperplasia-like nodules. Recognition of their typical imaging findings can reduce false-positive HCC diagnosis.

The do’s and dont’s of liver CT and MR imaging

Contrast enhanced multi-detector CT (MD CT) is now the most commonly used imaging modality for detection of liver metastases and work-up of equivocal lesions found at ultrasound. MR imaging is an established technique for non-invasive characterisation of liver masses and for preoperative potentially resectable liver tumours. Diagnostic value of each modality strongly depends on the scan technique. With MDCT, the role of thin slice imaging has been well established, with slice thicknesses of 5–7.5 mm being inferior to thinner slices in terms of lesion detection [1]. The amount of contrast material as well as the flow rate influence enhancement of hypervascular lesions in the arterial phase and the magnitude of liver parenchyma enhancement in the venous phase, respectively [2,3]. The number of CT scans varies with the local indication, with single-phasic venous scans to 4-phasic scans, as recommended by European and US guidelines for HCC detection and characterisation. For MR imaging, a multi-point DIXON technique has replaced conventional T1-weighted GRE pulse sequences; with this technique in one breathhold in-phase, opposed-phase, fat-suppressed, and water-suppressed images can be obtained, without any spatial misregistration. Diffusion-weighted pulse sequences significantly improve detection of metastases [4,5]. As a black-blood technique with T2-weighted image impression, it demonstrates small lesions without any blurring by an adjacent high signal intensity of vessels of bile ducts [6]. Administration of contrast agents is mandatory for liver MRI, with the choice of either non-specific gadolinium chelates or liver specific contrast agents. Indications for liver-specific contrast agents include preoperative evaluation of liver metastases and characterisation of hepatocellular lesions (FNH, adenoma), whereas non-specific gadolinium chelates are used for characterisation of haemangiomas, after liver resection or tumour ablation. The choice of the imaging techniques and the scan or contrast agent protocol should be tailored according to the clinical question.