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Aims: To investigate the prognostic value of baseline imaging features for overall survival (OS) and liver decompensation (LD) in patients with hepatocellular carcinoma (HCC)., Design: Patients with advanced HCC from the SORAMIC trial were evaluated in this post hoc analysis. Several radiological imaging features were collected from baseline computed tomography (CT) and magnetic resonance imaging (MRI) imaging, besides clinical values. The prognostic value of these features for OS and LD (grade 2 bilirubin increase) was quantified with univariate Cox proportional hazard models and multivariate Least Absolute Shrinkage and Selection Operator (LASSO) regression., Results: Three hundred and seventy-six patients were included in this study. The treatment arm was not correlated with OS. LASSO showed satellite lesions, atypical HCC, peritumoral arterial enhancement, larger tumour size, higher albumin-bilirubin (ALBI) score, liver-spleen ratio <1.5, ascites, pleural effusion and higher bilirubin values were predictors of worse OS, and higher relative liver enhancement, smooth margin and capsule were associated with better OS. LASSO analysis for LD showed satellite lesions, peritumoral hypointensity in hepatobiliary phase, high ALBI score, higher bilirubin values and ascites were predictors of LD, while randomisation to sorafenib arm was associated with lower LD., Conclusions: Imaging features showing aggressive tumour biology and poor liver function, in addition to clinical parameters, can serve as imaging biomarkers for OS and LD in patients receiving sorafenib and selective internal radiation therapy for HCC., (© 2021. The Author(s).)

Objectives: The 8th International Forum for Liver Magnetic Resonance Imaging (MRI), held in Basel, Switzerland, in October 2017, brought together clinical and academic radiologists from around the world to discuss developments in and reach consensus on key issues in the field of gadoxetic acid-enhanced liver MRI since the previous Forum held in 2013., Methods: Two main themes in liver MRI were considered in detail at the Forum: the use of gadoxetic acid for contrast-enhanced MRI in patients with liver cirrhosis and the technical performance of gadoxetic acid-enhanced liver MRI, both opportunities and challenges. This article summarises the expert presentations and the delegate voting on consensus statements discussed at the Forum., Results and Conclusions: It was concluded that gadoxetic acid-enhanced MRI has higher sensitivity for the diagnosis of hepatocellular carcinoma (HCC), when compared with multidetector CT, by utilising features of hyperenhancement in the arterial phase and hypointensity in the hepatobiliary phase (HBP). Recent HCC management guidelines recognise an increasing role for gadoxetic acid-enhanced MRI in early diagnosis and monitoring post-resection. Additional research is needed to define the role of HBP in predicting microvascular invasion, to better define washout during the transitional phase in gadoxetic acid-enhanced MRI for HCC diagnosis, and to reduce the artefacts encountered in the arterial phase. Technical developments are being directed to shortening the MRI protocol for reducing time and patient discomfort and toward utilising faster imaging and non-Cartesian free-breathing approaches that have the potential to improve multiphasic dynamic imaging., Key Points: • Gadoxetic acid-enhanced MRI provides higher diagnostic sensitivity than CT for diagnosing HCC. • Gadoxetic acid-enhanced MRI has roles in early-HCC diagnosis and monitoring post-resection response. • Faster imaging and free-breathing approaches have potential to improve multiphasic dynamic imaging.

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

Purpose: Benign insulinomas are the most prevalent cause of endogenous hyperinsulinaemic hypoglycaemia (EHH) in adults, and because of their small size are difficult to localise. The purpose of the study was to test the diagnostic accuracy and clinical impact of glucagon-like peptide-1 receptor (GLP-1R) PET/CT using 68 Ga-DOTA-exendin-4 in consecutive adult patients referred for localisation of insulinomas. The results were compared with 111 In-DOTA-exendin-4 SPECT/CT, study-MRI and previously performed external CT and/or MRI (prior external CT/MRI)., Methods: We prospectively enrolled patients with neuroglycopenic symptoms due to EHH. GLP-1R PET/CT, SPECT/CT and study-MRI were performed in a randomised, crossover order within 3-4 days. The reference standard was surgery with histology and treatment outcome., Results: From January 2014 until March 2017, 52 patients were recruited. All imaging and invasive procedures before recruitment identified suspicious lesions in 46.2% of patients. GLP-1R PET/CT, SPECT/CT and study-MRI detected suspicious lesions in 78.8%, 63.5% and 63.4% of patients, respectively. In 38 patients, conclusive histology was available for final analysis. Accuracy (95% confidence interval) for PET/CT, SPECT/CT, study-MRI and prior external CT/MRI was 93.9% (87.8-97.5%), 67.5% (58.1-76.0%), 67.6% (58.0-76.1%) and 40.0% (23.9-57.9%), respectively (all P values < 0.01, except comparison of SPECT/CT and study-MRI with a P value = 1.0). Impact on clinical management was 42.3%, 32.7% and 33.3% for PET/CT, SPECT/CT and study-MRI, respectively. Percentage reading agreement was 89.5%, 75.7%, and 71.1% for PET/CT, SPECT/CT and study-MRI, respectively., Conclusion: 68 Ga-DOTA-exendin-4 PET/CT performed significantly better than 111 In-DOTA-exendin-4 SPECT/CT and MRI in the localisation of benign insulinomas and should be considered in patients where localisation fails with CT/MRI ( ClinicalTrials.gov , NCT02127541).

The liver is more often involved with metastatic disease than primary liver tumors. The accurate detection and characterization of liver metastases are crucial since patient management depends on it. The imaging options, mainly consisting of contrast-enhanced ultrasound (CEUS), multidetector computed tomography (CT), magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI), extra-cellular contrast media and liver-specific contrast media as well as positron emission tomography/computed tomography (PET/CT), are constantly evolving. PET/MRI is a more recent hybrid method and a topic of major interest concerning liver metastases detection and characterization. This review gives a brief overview about the spectrum of imaging findings and focus on an update about the performance, advantages and potential limitations of each modality as well as current developments and innovations., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Objectives: Liver-specific MRI is a fast-growing field, with technological and protocol advancements providing more robust imaging and allowing a greater depth of information per examination. This article reports the evidence for, and expert thinking on, current challenges in liver-specific MRI, as discussed at the 7th International Forum for Liver MRI, which was held in Shanghai, China, in October 2013., Methods: Topics discussed included the role of gadoxetic acid-enhanced MRI in the differentiation of focal nodular hyperplasia from hepatocellular adenoma and small hepatocellular carcinoma (HCC) from small intrahepatic cholangiocarcinoma (in patients with chronic liver disease), the differentiation of low-grade dysplastic nodule (DN) from pre-malignant high-grade DN and early HCC, and treatment planning and assessment of treatment response for patients with HCC and colorectal liver metastasis. Optimization of the gadoxetic acid-enhanced MRI protocol to gain robust arterial and hepatobiliary phase images was also discussed., Results and Conclusions: Gadoxetic acid-enhanced MRI demonstrates added value for the detection and characterization of focal liver lesions and shows promise in a number of new indications, including regional liver functional assessment and patient monitoring after therapy; however, more data are needed in some areas, and further developments are needed to translate cutting-edge techniques into clinical practice., Key Points: Liver-specific MRI is a fast-growing field, with many technological and protocol advancements. Gadoxetic acid-enhanced MRI demonstrates value for detecting and characterizing focal liver lesions. Gadoxetic acid-enhanced MRI shows promise in regional functional assessment and patient monitoring. Further developments are needed to translate cutting-edge techniques into clinical practice.

Purpose: To evaluate the diagnostic accuracy of dynamic-contrast-enhanced (DCE) MRI in comparison to both (18)F-FDG- and (68)Ga-DOTATATE-PET/CT in patients with liver metastases of neuroendocrine neoplasms (NEN)., Materials and Methods: Thirty-two patients with hepatic metastases from NEN were examined both in DCE-MRI and positron emission tomography/computed tomography (PET/CT), using either (18)F-fluorodeoxyglucose ((18)F-FDG) or (68)Ga-DOTATATE as tracer. DCE-MRI was performed at 3 Tesla with Gd-EOB-DTPA acquiring 48 slices every 2.2 s for 5 min. Three regions of interest (ROIs) representing liver background and liver metastases were defined in fat-saturated T1w three-dimensional GRE MRI sequences in the hepatobiliary phase. Corresponding ROIs were then defined in the DCE-MRI- and in the PET/CT-dataset. Area under the curve (AUC) was calculated for the differentiation between metastases and liver background for DCE-MRI and PET-CT parameters., Results: AUC was very high for SUVmean (mean standardized uptake value) derived from (68)Ga-DOTATATE- (AUC = 0.966), and (18)F-FDG-PET/CT (AUC = 0.989). For DCE-MRI parameters, arterial flow fraction and intracellular uptake fraction showed the highest AUCs (AUC = 0.826, AUC = 0.819, respectively). The combination of those two had an AUC of 0.949. The combination of DCE-MRI and PET-CT parameters resulted in the highest AUC., Conclusion: Both PET/CT parameters and DCE-MRI perfusion parameters show a high diagnostic accuracy in the distinction between liver metastases and liver tissue. Our data suggest that both modalities provide complementary information., (© 2013 Wiley Periodicals, Inc.)

Background: This multicentre international randomized trial compared the impact of gadoxetic acid-enhanced magnetic resonance imaging (MRI), MRI with extracellular contrast medium (ECCM-MRI) and contrast-enhanced computed tomography (CE-CT) as a first-line imaging method in patients with suspected colorectal cancer liver metastases (CRCLM)., Methods: Between October 2008 and September 2010, patients with suspected CRCLM were randomized to one of the three imaging modalities. The primary endpoint was the proportion of patients for whom further imaging after initial imaging was required for a confident diagnosis. Secondary variables included confidence in the therapeutic decision, intraoperative deviations from the initial imaging-based surgical plan as a result of additional operative findings, and diagnostic efficacy of the imaging modalities versus intraoperative and pathological extent of the disease., Results: A total of 360 patients were enrolled. Efficacy was analysed in 342 patients (118, 112 and 112 with gadoxetic acid-enhanced MRI, ECCM-MRI and CE-CT respectively as the initial imaging procedure). Further imaging was required in 0 of 118, 19 (17.0 per cent) of 112 and 44 (39.3 per cent) of 112 patients respectively (P < 0.001). Diagnostic confidence was high or very high in 98.3 per cent of patients for gadoxetic acid-enhanced MRI, 85.7 per cent for ECCM-MRI and 65.2 per cent for CE-CT. Surgical plans were changed during surgery in 28, 32 and 47 per cent of patients in the respective groups., Conclusion: The diagnostic performance of gadoxetic acid-enhanced MRI was better than that of CE-CT and ECCM-MRI as the initial imaging modality. No further imaging was needed in the gadoxetic acid-enhanced MRI group and comparison of diagnostic efficacy parameters demonstrated the diagnostic superiority of gadoxetic acid-enhanced MRI., Registration Number: NCT00764621(http://clinicaltrials.gov); EudraCT number: 2008-000583-16 (https://eudract.ema.europa.eu/)., (© 2014 The Authors. BJS published by John Wiley & Sons Ltd on behalf of BJS Society Ltd.)

Purpose: To investigate the effect of hepatic steatosis on enhancement of liver parenchyma with gadoxetate disodium-enhanced MR imaging., Materials and Methods: Gadoxetate disodium-enhanced MR images of 166 patients were analyzed. Liver-spleen contrast and liver-spleen relative enhancement ratio on three-dimensional gradient echo T1-weighted images with fat suppression 20 minutes after injection of gadoxetate disodium were evaluated in correlation with fat signal fraction using the Pearson correlation coefficient and also compared between patients with normal liver parenchyma (n = 115) and with liver steatosis (n = 51) using the Student t-test., Results: The liver-spleen contrast at hepatobiliary phase showed inverse correlations with the fat signal fraction (r = -0.36; P < 0.01), while the liver-spleen relative enhancement ratio showed no statistical correlation with the fat signal fraction (P = 0.80). The liver-spleen contrast in the group with steatotic liver was significantly lower than that in the group with normal livers (P < 0.001). There was no significant difference in the relative enhancement ratio between the two groups (P = 0.85)., Conclusion: Our results may suggest that hepatic steatosis does not affect the uptake of gadoxetate disodium into hepatocytes and are considered crucial as background knowledge in extending the use of gadoxetate disodium-enhanced MR imaging to quantitate liver function., (Copyright © 2013 Wiley Periodicals, Inc.)

Objectives: The objective of this study was to evaluate the correlation between dynamic gadoxetic acid-enhanced magnetic resonance imaging parameters and specific uptake values (SUVs) derived from ¹⁸fluorodeoxyglucose (¹⁸F-FDG) and ⁶⁸Ga-DOTA-Tyr(3)-octreotate (⁶⁸Ga-DOTATATE) positron emission tomography/computed tomography (PET/CT) in patients with liver metastases of neuroendocrine neoplasms., Methods: A total of 42 patients with hepatic metastases of neuroendocrine neoplasms were prospectively enrolled and underwent both dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and PET/CT, using either ¹⁸F-FDG or ⁶⁸Ga-DOTATATE as tracer. The DCE-MRI was performed at 3 T with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid acquiring 48 slices every 2.2 seconds for 5 minutes. Three regions of interest (ROIs) representing the liver background and up to 3 ROIs representing metastatic liver tissue were coregistered in the PET/CT and in the DCE-MRI data sets. For each patient, a dedicated dual-inlet, 2-compartment uptake model was fitted to the enhancement curves of DCE-MRI ROIs and perfusion parameters were calculated. Lesion-to-background ratios of SUVs were correlated with corresponding lesion-to-background ratios of the perfusion parameters arterial plasma flow, venous plasma flow, total plasma flow, extracellular mean transit time, extracellular volume, arterial flow fraction, intracellular uptake rate, and hepatic uptake fraction using the Spearman coefficient., Results: Whereas the lesion-to-background ratios of arterial plasma flow and arterial flow fraction of liver metastases correlated negatively with the lesion-to-background ratios of SUV(mean) derived from ⁶⁸Ga-DOTATATE PET/CT (r = -0.54, P < 0.001; r = -0.39, P < 0.001, respectively), they correlated positively with the lesion-to-background ratios of SUV(mean) derived from ¹⁸F-FDG-PET/CT (r = 0.51, P < 0.05; r = 0.68, P < 0.01, respectively). The lesion-to-background ratios of the DCE-MRI parameters extracellular mean transit time and extracellular volume correlated very weakly with the lesion-to-background ratios of SUV(mean) from ⁶⁸Ga-DOTATATE PET/CT, whereas venous plasma flow, total plasma flow, hepatic uptake fraction, and intracellular uptake rate showed no correlation between DCE-MRI and PET/CT., Conclusions: Both ⁶⁸Ga-DOTATATE and ¹⁸fluorodeoxyglucose PET/CT partially correlate with MRI perfusion parameters from the dual-inlet, 2-compartment uptake model. The results indicate that the paired imaging methods deliver complementary functional information.

Objective: This article reviews topics discussed during the Fifth International Forum for Liver MRI (with a focus on gadoxetic acid-enhanced MRI), which was held in Munich, Germany, in September 2011., Conclusion: Growing evidence shows that gadoxetic acid-enhanced MRI has high sensitivity and specificity for diagnosing liver tumors. Hepatobiliary phase imaging adds new information for the characterization of borderline lesions. However, there is a need to develop standardized criteria for interpretation of gadoxetic acid-enhanced MRI in patients with cirrhosis or other risk factors for hepatocellular carcinoma.

Objective: The aim of this study is to describe the imaging features of intrahepatic cholangiocarcinoma in Gd-EOB-DTPA-enhanced MRI and to determine whether it results in improved tumour conspicuity of cholangiocarcinoma., Materials and Methods: Fifty-four patients with histologically proven intrahepatic cholangiocarcinoma underwent MRI of the liver using a 1.5T MR-scanner with Gadoxetic acid disodium (Gd-EOB-DTPA; Eovist/Primovist, Bayer Healthcare, Berlin, Germany). The standard imaging protocol included a T2w multi-shot TSE sequence with fat saturation (fs), a T2w single shot sequence without fs and a T1w 3D GRE sequences with fs (unenhanced and arterial, portovenous, late venous and hepatobiliary phase). Two board certified radiologists experienced in liver MRI (5 and 10 years experience) evaluated retrospectively all MRI scans qualitatively and quantitatively. Signal was measured with region-of-interests (ROI) and signal-to-noise (SNR) as well as contrast-to-noise (CNR) was calculated. Statistical significance was tested with an ANOVA and a pairwise Wilcoxon rank test., Results: All intrahepatic cholangiocarcinomas presented as hypointense lesions in the late venous and hepatobiliary phase. Images in the hepatobiliary phase showed the highest lesion conspicuity, i.e. n=9 blurred (16.6%), n=31 moderate (57.4%) and n=14 sharp (26%). This was significantly higher than the lesion conspicuity of all other sequences or phases. Furthermore, the CNR was the highest in this sequence with 76.8±51.3, with significantly higher values than the CNR of the unenhanced T1w sequence (CNR: 35.6±21.0; p<0.0001) and the arterial phase images (CNR: 53.6±36.8; p<0.001). The hepatobiliary phase images showed a SNR of 97.3±59.7 (p<0.001) and thus was significantly different from the unenhanced T1w sequence (SNR: 60.4±35.3; p<0.001), whereas the increase in SNR from the late venous to hepatobiliary phase was neglectable, indicating that no liver-specific contrast uptake is present in cholangiocarcinoma., Conclusion: Intrahepatic cholangiocarcinoma presents as a hypointense lesion in Gd-EOB-DTPA-enhanced MRI in late venous phase images. The lesion conspicuity as well as CNR was highest in the hepatobiliary phase. Consequently, hepatobiliary phase images in Gd-EOB-DTPA-enhanced MRI images might be helpful for therapy planning due to the exact depiction of the tumour borders., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

Objectives: The aim of this study is to determine MRI characteristics which indicate liver metastases of neuroendocrine tumors (NET) rather than metastases of other origin (non-NET)., Methods: Sixty-nine patients with histopathologically proven liver metastases from NET and 69 patients with known liver metastases of other origin underwent MRI of the liver using a 1.5 T MR-scanner. Two board certified radiologists assessed presence of fluid-fluid-levels, number and distribution pattern, signal intensity (SI) characteristics, lesion homogeneity, presence of central necrosis and intratumoral hemorrhage in T2w and T1w non-contrast imaging. A multivariate logistic regression analysis was performed to determine the independent association of image findings and occurrence of NET., Results: Fluid-fluid-levels were identified in 19/69 of patients with NET-metastases, and in none of the patients in the control group (p<0.0001). Hyperintense SI in T1w imaging, markedly hyperintense SI in T2w imaging, a disseminated distribution pattern and intratumoral hemorrhage were indicative of NET metastases (p<0.05). After statistical adjustment for all significant MRI findings, fluid-fluid-levels (OR: 17.6, 95% CI: 1.9-166.5), strongly hyperintense SI in T2w (OR: 4.7, 95% CI: 1.8-12.7) and a disseminated distribution pattern (OR: 2.9, 95% CI: 1.1-7.4) were independent predictors for NET metastases., Conclusions: The presence of fluid-fluid-levels is highly indicative of NET liver metastases and can be used as an independent predictor to distinguish them from metastases of other origin., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Clinical Problem: Diffuse liver diseases show an increasing prevalence. The diagnostic gold standard of liver biopsy has several disadvantages. There is a clinical demand for non-invasive imaging-based techniques to qualitatively and quantitatively evaluate the entire liver., Standard Radiological Methods: Ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) are routinely used., Methodical Innovations: Steatosis: chemical shift and frequency selective imaging, MR spectroscopy (MRS). Hemochromatosis: MR-based iron quantification. Fibrosis: MR elastography, diffusion, intravoxel incoherent motion (IVIM) and MR perfusion. PERFORMANCE/ACHIEVEMENTS/PRACTICAL RECOMMENDATIONS: T1-weighted in and opposed phase imaging is the clinically most frequently used MR technique to noninvasively detect and quantify steatosis. New methods for quantification that are not influenced by confounders like iron overload are under investigation. The most sensitive method to measure the fat content of the liver is MRS. As data acquisition and analysis remain complex and there is no whole organ coverage, MRS of the liver is not a routine method. With an optimized protocol incorporating T2* sequences, MRI is the modality of choice to quantify iron overload in hemochromatosis. Standard MR sequences cannot depict early stages of liver fibrosis. Advanced MR techniques (e.g. elastography, diffusion, IVIM and perfusion) for noninvasive assessment of liver fibrosis appear promising but their role has to be further investigated.

Purpose: To evaluate the feasibility of quantifying hepatic perfusion and function by using dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging with the hepatobiliary contrast agent gadoxetic acid and a dual-inlet two-compartment uptake model., Materials and Methods: The study was approved by the local institutional review board, and written informed consent was obtained from all patients. Data were acquired between October 2008 and November 2009 in 24 patients with hepatic metastases from neuroendocrine tumors (13 men, 11 women; mean age, 59.8 years). DCE MR imaging was performed at 3.0 T with a standard dose of gadoxetic acid and a three-dimensional sequence, with 48 sections of data acquired every 2.2 seconds for 5 minutes. For each patient, a plasma flow map was calculated by means of deconvolution and the model was fitted to six region-of-interest curves. Results were evaluated with goodness-of-fit analysis and, in normal-appearing liver tissue, by comparing perfusion parameters with those reported in the literature. Interobserver effects in the selection of arterial and venous input functions were assessed., Results: With an arterial delay parameter, the model provided a good fit to all data. Values for arterial and venous plasma flow and extracellular volume in normal-appearing liver tissue were comparable to those in the literature. The mean intracellular uptake rate is 3.4/100/min with a standard deviation of 1.9/100/min The model also provided a good fit in all tumor data, producing high arterial flow fraction (87%) and lower uptake (1.7/100/min) . Bias due to observer-dependent differences in the selection of the input functions was negligible., Conclusion: The analysis of dynamic gadoxetic acid-enhanced MR images with the dual-inlet two-compartment uptake model presents a new and practical approach for measuring arterial and venous perfusion and hepatic function in a single acquisition.

Liver imaging is an important clinical area in everyday practice. The clinical meaning of different lesion types in the liver can be quite different. Therefore, the result of imaging studies of the liver can change therapeutic concepts fundamentally. Contrast agents are used in the majority of MR examinations of the liver parenchyma-despite the already good soft-tissue contrast in plain MRI. This can be explained by the advantages in lesion detection and characterization of contrast-enhanced MRI of the liver. Beyond the qualitative evaluation of contrast-enhanced liver MR examinations, quantification of parameters will be the demand of the future. This can be achieved by perfusion MRI, also called dynamic contrast-enhanced MRI (DCE-MRI) of the liver. Its basic principles and different clinical applications will be discussed in this article. Definite cut-off values to determine disease or therapeutic response will help to increase the objectivity and reliability of liver MRI in future. This is especially important in the oncological setting, where modern therapies cannot be assessed based on changes in size only.

This paper reports on issues relating to the optimal use of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid magnetic resonance imaging (Gd-EOB-DTPA MR imaging) together with the generation of consensus statements from a working group meeting, which was held in Seoul, Korea (2010). Gd-EOB-DTPA has been shown to improve the detection and characterization of liver lesions, and the information provided by the hepatobiliary phase is proving particularly useful in differential diagnoses and in the characterization of small lesions (around 1-1.5 cm). Discussion also focused on advances in the role of organic anion-transporting polypeptide 8 (OATP8) transporters. Gd-EOB-DTPA is also emerging as a promising tool for functional analysis, enabling the calculation of post-surgical liver function in the remaining segments. Updates to current algorithms were also discussed.

Purpose: To compare enhancement of liver parenchyma in MR imaging after injection of hepatocyte-specific contrast media., Materials and Methods: Patients (n = 295) with known/suspected focal liver lesions randomly received 0.025 mmol gadoxetic acid/kg body weight or 0.05 mmol gadobenate dimeglumine/kg body weight by means of bolus injection. MR imaging was performed before and immediately after injection, and in the delayed phase at approved time points (20 min after injection of gadoxetic acid and 40 min after injection of gadobenate dimeglumine). The relative liver enhancement for the overall population and a cirrhotic subgroup was compared in T1-weighted GRE sequences. An independent radiologist performed signal intensity measurements. Enhancement ratios were compared using confidence intervals (CIs)., Results: The relative liver enhancement in the overall population was superior with gadoxetic acid (57.24%) versus gadobenate dimeglumine (32.77%) in the delayed-imaging phase. The enhancement ratio between the contrast media was statistically significant at 1.75 (95% CI: 1.46-2.13). In the delayed phase, the enhancement of cirrhotic liver with gadoxetic acid (57.00%) was comparable to that in the overall population. Enhancement with gadobenate dimeglumine was inferior in cirrhotic liver parenchyma (26.85%)., Conclusion: In the delayed, hepatocyte-specific phase, liver enhancement after injection of gadoxetic acid was superior to that obtained with gadobenate dimeglumine.

The purpose of this study was to perform an economic evaluation of hepatocyte-specific Gd-EOB-DTPA enhanced MRI (PV-MRI) compared to extracellular contrast-media-enhanced MRI (ECCM-MRI) and three-phase-MDCT as initial modalities in the work-up of patients with metachronous colorectal liver metastases. The economic evaluation was performed with a decision-tree model designed to estimate all aggregated costs depending on the initial investigation. Probabilities on the need for further imaging to come to a treatment decision were collected through interviews with 13 pairs of each a radiologist and a liver surgeon in Germany, Italy and Sweden. The rate of further imaging needed was 8.6% after initial PV-MRI, 18.5% after ECCM-MRI and 23.5% after MDCT. Considering the cost of all diagnostic work-up, intra-operative treatment changes and unnecessary surgery, a strategy starting with PV-MRI with 959 Euro was cost-saving compared to ECCM-MRI (1,123 Euro) and MDCT (1,044 Euro) in Sweden. In Italy and Germany, PV-MRI was cost-saving compared to ECCM-MRI and had total costs similar to MDCT. In conclusion, our results indicate that PV-MRI can lead to cost savings by improving pre-operative planning and decreasing intra-operative changes. The higher cost of imaging with PV-MRI is offset in such a scenario by lower costs for additional imaging and less intra-operative changes.

Renal cell cancer is the most frequently encountered malignant tumor of the kidney. The modern imaging techniques computed tomography (CT) and magnetic resonance imaging (MRI) play a vital role in the diagnostic work-up of renal masses. Contrast-enhanced ultrasound (CEUS) is able to visualize subtle enhancement in hypovascular tumors with high sensitivity. Recent advances in multidetector CT (MDCT) enable high resolution imaging of local findings. CT is able to provide large volume coverage of the chest and abdomen within seconds for the assessment of lymph node and distant metastasis staging. Local renal cell cancer staging can be achieved with similar diagnostic accuracy using CT or MRI. Both modalities allow visualization of a tumor's relationship to the renal collecting system and pelvis, the renal artery and veins including the IVC. It is the radiologist's task to accurately detect and stage renal malignances in order that each individual patient receives the therapy best suited to them.

Purpose: To determine the value of MR enteroclysis (MRE) in the localization and characterization of primary carcinoid tumors of the small bowel and to describe typical imaging features., Material and Methods: Twenty patients with suspicion of primary small bowel carcinoid tumors (pCT) were recruited to undergo MRE following nasojejunal intubation and small bowel filling with 2.5 l of 0.5% methylcellulose solution under MR fluoroscopic guidance. MRE was performed on a 1.5 T MR scanner including T2w SSFSE, SSFP and contrast enhanced T1w GRE sequences with fat saturation. Fifteen patients, who subsequently had surgery for resection of their pCT, were retrospectively included in the study. All MRE were analyzed as for the presence, location, number, size, multiplicity and morphologic appearance of the pCT by two board certified radiologists in consensus. The conspicuity of the tumors was rated for each sequence type separately, according to a 4-point rating scale. Signal intensity measurements were performed in tumor and muscle. The presence of desmoplastic reaction, vascular involvement and lymph node metastases was also analyzed., Results: pCT were correctly identified and localized in 14/15 patients. Due to their hyperenhancement tumors was best detected on contrast-enhanced T1w fat saturated GRE sequences. SSFSE was clearly inferior with the tumors being either hyperintense or isointense to muscle. pCT appeared as nodular intraluminal masses in 40% of the cases, as focal wall thickening in 33.3% and in 20% with both. Mean size was 25 (7-46 mm) with a tendency to smaller size for ileal tumors. MRE failed to depict superficial micronodular peritoneal spread in one patient. Desmoplastic reaction was observed in 73.3% of the cases with mesenteric masses exhibiting lower signal than the pCT due to fibrotic changes., Conclusion: MRE is a valuable method for the detection and localization of primary carcinoid tumors, provided that appropriate bowel distension is achieved. Various characteristic morphologic features could be identified which may contribute to characterize pCT and their loco-regional metastases.

Objective: To evaluate the diagnostic efficacy (accuracy, sensitivity, specificity) of 1.0 M gadobutrol versus 0.5 M gadopentetate for the classification of lesions as either benign or malignant in patients with known or suspected liver lesions., Methods and Materials: A multicenter, phase-III, randomized, interindividually controlled comparison study with blinded reader evaluation was performed to investigate the diagnostic efficacy of a bolus injection of 1.0 M gadobutrol compared with 0.5 M gadopentetate at a dose of 0.1 mmol Gd/kg BW. The imaging protocol included a dynamic 3D-evaluation, static conventional, and fat saturated T1-weighted sequences. MR datasets were evaluated by 3 independent radiologists. The standard of reference was defined by an independent truth panel (radiologist or hepatologist). The safety evaluation included adverse events, vital signs, and physical examination., Results: A total of 497 of 572 patients were eligible for the final efficacy analysis. Noninferiority of gadobutrol-enhanced magnetic resonance imaging (MRI) for the classification of liver lesions was demonstrated on the basis of diagnostic accuracy determined by the on-site investigators (-0.098, 0.021) as well as for the average reader of the blinded evaluation (-0.096, 0.014) (95% confidence interval), compared with the predefined standard of reference. Very similar increases in sensitivity (ranging from approximately 10% to approximately 55%) and specificity (ranging from approximately 1% to approximately 18%) compared with precontrast MRI were also observed for the 2 contrast agent groups, with maximum differences of 4%.Very similar, low rates of adverse events were recorded for each of the 2 groups. No clinically relevant changes in vital signs or the results of the physical examination were observed in any patient., Conclusion: This study documents evidence for the noninferiority of a single i.v. bolus injection of 1.0 M gadobutrol (0.1 mmol/kg body weight) to 0.5 M gadopentetate (0.1 mmol/kg body weight) in the diagnostic assessment of liver lesions with contrast-enhanced MRI. The known excellent safety profile of gadobutrol was confirmed in this clinical trial and is similar to that of gadopentetate.

Solid pseudopapillary tumors of the pancreas (SPTP) are rare tumors of the pancreas with low malignancy potential and a very good prognostic outcome after surgery. They typically occur in young women or adolescents and consist of solid, cystic and cystic-hemorrhagic components.Imaging findings in these tumors are characteristic and include a fibrotic capsule with a clear delineation and exhibit solid and cystic-hemorrhagic signal and density characteristics. Calcifications may be present in the periphery of the tumor. The tumor capsule shows contrast enhancement, the solid components in the periphery enhance in the early phase and gradually and inhomogeneously in late phases. MRI is superior to CT and other imaging modalities for characterization of SPTP. Awareness and knowledge of this tumor entity with an excellent prognosis is crucial to guide the patient towards effective, predominantly organ-sparing surgical treatment.

Objectives: The aim of this prospective study was to evaluate the diagnostic performance of magnetic resonance imaging (MRI) of the liver with the hepatocellular-specific contrast agent gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) in comparison to precontrast MRI and spiral computed tomography (CT) in the specific diagnosis of focal nodular hyperplasia (FNH) and to describe morphologic features and enhancement pattern of FNH., Materials and Methods: In 176 patients from a phase III multicenter trial, 59 confirmed FNHs were present (13 = histopathology; 46 = imaging follow-up within 12 months before or 3 months after the MRI study). MR examination consisted of precontrast T1- and T2-w sequences, T1-weighted (w) dynamic sequences after bolus-injection of 0.025 mmol Gd-EOB-DTPA (Primovist; Bayer Schering Pharma)/kg bodyweight and T1-w sequences with fat saturation in the hepatocyte-phase after 20 minutes. The number of correctly characterized FNHs was evaluated and compared with that determined on spiral CT in an on-site reading (clinical study) and an off-site reading (3 blinded readers). The morphologic appearance and enhancement patterns of the FNHs were evaluated., Results: Characterization with combined pre- and post-MRI (88.1%) was superior to that achieved with biphasic-enhanced spiral CT (84.7%, not significant) and precontrast MRI (67.8%, P < 0.05) in the clinical study and significantly superior to both precontrast MRI and spiral CT for 2 of 3 blinded readers. Complete or partial enhancement of the lesions was present in the early dynamic phase (arterial and portovenous dynamic phase) in 94% and 85%, respectively. The pattern of lesion enhancement in the early dynamic phase was mainly homogenous (78%-80%); the median contrast-to-noise ratio was -5.9 in T1-w precontrast images, 14.0 in the arterial phase, 2.4 in the portovenous phase, and 2.9 in the equilibrium phase. Enhancement in the hepatocyte-phase after 10 and 20 minutes was observed in 88% and 90% of lesions, respectively., Conclusions: Characterization of FNH provided by Gd-EOB-DTPA-enhanced MRI is superior to that provided by precontrast MRI alone or spiral CT. FNHs show very similar enhancement characteristics to those of other extracellular contrast agents in the early dynamic phase after bolus injection of Gd-EOB-DTPA, after 20 minutes in the liver-specific phase enhancement is regularly seen.

Objectives: To evaluate the performance of black-blood diffusion-weighted (DW)-EPI sequences with parallel imaging for the detection of focal liver lesions in comparison with a standard T2-weighted (T2-w) sequence., Materials and Methods: Twenty patients with known or suspected focal liver lesions underwent liver MRI using a DW-EPI sequence with a b-value of 50 S/mm2 (TR/TE 2200/50 ms) and a standard fat-saturated T2-w sequence (TR/TE 2800/107 ms) with 6-mm slice thickness on a 1.5-T MRI system. Both sequences used parallel imaging with an acceleration factor of 2. Overall image quality and degree of artifacts were compared on a 5-point scale with 5 being the most desirable score. The detection rate and the level of confidence with regard to lesion detection were evaluated for both sequences in comparison to a contrast-enhanced (Gadolinium and SPIO) MR examination, which was used as the standard of reference., Results: The DW-EPI sequence showed significantly (P < 0.05) improved overall image quality (average score 4.15 vs. 3.63) and fewer artifacts (average score 4.2 vs. 3.5) in comparison with the T2-w sequence. The sensitivity for lesion detection was superior in the DW-EPI sequence (83% vs. 61%). The level of confidence in the detection of focal liver lesions was also superior for the DW-EPI sequence in comparison with the T2-w sequence (average score 3.9 vs. 3.2)., Conclusions: DW-EPI sequences for liver-imaging are feasible with parallel imaging and show excellent image quality. They may contribute to more easy and confident lesion detection in comparison with T2-w sequences.

The aim of this study was to evaluate the diagnostic value of different magnetic resonance (MR) techniques for the diagnosis of nodular regenerative hyperplasia (NRH). Thirty-one patients with inflammatory bowel disease, who received 6-thioguanin, underwent liver biopsy and liver MRI on a 1.5-T MR system, with gadolinium and superparamagnetic iron oxide particles (SPIO). MR imaging (MRI) was evaluated independently as well as in consensus by two blinded readers, who received the following image sets: pre-contrast; pre-contrast and gadolinium-enhanced; pre-contrast and SPIO-enhanced and all images. The results were correlated with histopathology and diagnostic efficacy parameters were calculated. NRH was found in 13/31 patients. The set "all images" showed the highest sensitivity (84.6%), accuracy (77.4%) and negative predictive value (86.7%). However, results for gadolinium were only slightly inferior. The highest specificity (76.5%) was found for SPIO. The A(z) values of both readers were highest for gadolinium (mean A(z) = 0.824). It can be concluded that gadolinium-enhanced and SPIO-enhanced MRI enable an accurate diagnosis of NRH. Since gadolinium-enhanced MRI is very sensitive, it should be used for screening high-risk patients. SPIO-enhanced MRI is less sensitive, but more specific. The combination of both guarantees a high sensitivity and specificity and, therefore, is the diagnostic procedure of choice.

Purpose: To evaluate the efficacy of ferucarbotran in T2-weighted (T2W) fast spin-echo (FSE) and T2*W gradient-echo (GRE) sequences for characterizing focal liver lesions., Materials and Methods: In 68 patients, 46 malignant and 22 benign focal liver lesions were evaluated. Precontrast (NCE) T2W FSE images and contrast-enhanced (CE) T2W FSE and T2*W GRE images were obtained on a 1.5T MR system. Based on signal intensity (SI) measurements in focal lesions and liver parenchyma, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for all sequences. The percentage of SI loss (PSIL) in focal lesions after contrast agent (CA) application was calculated for the T2W FSE sequence. Qualitative analyses were performed to assess image quality and lesion conspicuity obtained with the CE-T2W FSE and CE-T2*W GRE sequences., Results: The mean PSIL was higher in solid benign lesions than in malignant lesions (39.6% vs. 3.2%, P<0.05). With a threshold PSIL of 25%, the sensitivity and specificity for characterizing malignant lesions were 97.8% and 92.9%, respectively. The mean CNR of the malignant lesions was higher in the CE-T2*W sequence than in the CE- and NCE-T2W FSE sequences (29.9 vs. 22.7 (P<0.01) vs. 12.8 (P<0.01)). CE-T2*W images showed a superior image quality and lesion conspicuity (P<0.05) compared to the CE-T2W FSE sequence., Conclusion: The PSIL can be an accurate tool for characterizing benign and malignant lesions. The addition of a CE-T2*W GRE sequence is helpful for the detection and characterization of malignant lesions., (Copyright (c) 2007 Wiley-Liss, Inc.)

The appropriate staging of malignant tumors is increasingly important as new therapeutic strategies develop. Because metastatic involvement of the liver in extrahepatic malignant disease may significantly change therapeutic approach, it is important to rule out such involvement with high confidence. Moreover, the differentiation between incidental benign lesions, such as hemangioma, focal nodular hyperplasia (FNH), or adenoma, is of high interest. Magnetic resonance (MR) imaging has proved reliable for diagnostic work-up of the liver. Liver-specific contrast agents have been especially helpful in detecting and precisely characterizing focal liver lesions, but the use of these agents has been limited because it has not been possible to perform both proper vascular phase and liver-specific phase within a reasonable time frame and in a single examination after a single injection of contrast agent. However, the hepatobiliary contrast agent gadolinium-ethoxybenzyl (Gd-EOB)-DTPA now allows combined dynamic imaging and hepatocyte-specific imaging in one examination. Gd-EOB-DTPA can be injected as a bolus and shows the enhancement characteristics and vascularity of liver lesions. In the delayed phase, which is acquired most appropriately 20 min after injection, Gd-EOB-DTPA is taken up selectively by functioning hepatocytes. Thus, malignant liver lesions, e.g. metastases, are spared from contrast uptake of the surrounding liver parenchyma. These lesions are hypointense in contrast to the surrounding bright liver. We review the current literature and present a practical approach to Gd-EOB-enhanced MR imaging using imaging examples of patients with liver metastases.

Internal fistulas (IFs) and abscesses are the most common complications of Crohn disease (CD). To reliably diagnose and clearly distinguish inflammatory or fibrostenotic manifestations of CD from its complications is of paramount importance to appropriately guide therapeutic decisions. Magnetic resonance enteroclysis (MRE), a recently introduced technique for small bowel imaging, has proved a high efficacy in the depiction of luminal and extraluminal manifestations of CD and holds great promise as a powerful diagnostic tool in the comprehensive diagnostic workup of this disease. As of yet, the characteristic imaging appearance of IFs on MRE has not been described in detail. This article reviews the performance of conventional imaging techniques and the current potential of MRE in the depiction of IFs in CD. Typical imaging morphology and characteristic imaging findings of IFs on MRE are described in detail and a newly defined and highly indicative imaging finding, the "star-sign," is presented and discussed.

Objective: The objective of this study was to improve delineation of small and large bowel (SB, LB) anatomy and pathology with postoperative or complex multisegmental inflammatory changes using dual-contrast-technique (DCT) for magnetic resonance enteroclysis (MRE) with luminal contrast media of opposed signal characteristics., Materials and Methods: Sixty patients underwent MRE with iron oxide-based negative contrast in the SB. Thirty patients received additional rectal instillation of water for positive contrast (DCT). Two observers evaluated the degree of distention and the ease of identification of bowel anatomy and pathologies (none n=22, stenosis n=16, abscess n=4, fistulae n=5, postoperative changes and adhesions n=13) using a 4-point scale. Mann-Whitney U-test and kappa statistics were applied., Results: LB and the terminal ileum were significantly better distended and identified with DCT (P

Background/aims: Although 6-thioguanine (6-TG) has been suggested as an effective treatment option for patients with inflammatory bowel disease (IBD), the recent description of its hepatotoxicity has led to the recommendation not to consider this drug. We initiated a multicenter safety study in IBD-patients treated with 6-TG to investigate hepatic changes by liver biopsy and magnetic resonance imaging (MRI)., Methods: Forty-five patients from three European centers treated with 6-TG (40-80 mg/d) at least for 8 weeks were enrolled. In all patients liver biopsy and MRI were performed. Slides and MR images were independently read by two pathologists and radiologists, respectively, and interpreted according to predefined criteria by consent., Results: In 8 patients nodular regenerative hyperplasia (NRH) was diagnosed by liver biopsy, in 8 additional patients NRH could not be excluded due to equivocal pathological findings. MRI demonstrated a sensitivity of 77% and a specificity of 72% in the detection of pathohistological findings consistent with and/or possibly related to NRH., Conclusions: Our study suggests that 6-TG therapy in IBD patients is associated with NRH of the liver. Based on a special MRI protocol, non-invasive diagnosis of NRH with promising sensitivity and specificity was demonstrated.

Purpose: To detect hepatocyte-selective enhancement of focal lesions with gadoxetic acid at magnetic resonance (MR) imaging and to correlate enhancement in hepatocyte-selective phases with histopathologic findings and in arterial and portal venous phases with biphasic computed tomographic (CT) findings., Materials and Methods: Study was supported by local ethics committee; all patients gave written informed consent. In 19 men and 14 women recruited in three clinical studies, histopathologic correlation and CT scans of 41 focal lesions (13 primary malignant lesions, 21 metastases, three adenomas, three cases of focal nodular hyperplasia [FNH], and one cystadenoma) and ultrasonographic confirmation of five cysts were available. MR was performed before and during arterial and portal venous phases and in hepatocyte-selective phases 10 and 20 minutes after injection of gadoxetic acid. Enhancement was evaluated in consensus by two observers. Enhancement pattern and morphologic features during arterial and portal venous phases were correlated between gadoxetic acid-enhanced MR and CT images by means of adjusted chi(2) test., Results: Hepatocyte-selective uptake was observed 10 and 20 minutes after injection in FNH (three of three), adenoma (two of three), cystadenoma (one of one), and highly differentiated hepatocellular carcinoma (HCC [grade G1], two of four). Uptake was not detected in metastases (21 of 21), cholangiocarcinoma (three of three), combined hepatocellular cholangiocarcinoma (one of one), undifferentiated carcinoma (one of one), moderately or poorly differentiated HCC (grade G2-G3) (four of four), HCC (grade G1, two of four), adenoma with atypia (one of three), or cysts (five of five). During arterial and portal venous phases, there was high overall agreement rate of 0.963 between gadoxetic acid-enhanced MR and CT (simultaneous 95% confidence interval: 0.945, 0.981)., Conclusion: Liver-specific enhancement of focal lesions is hepatocyte selective and correlates with various histopathologic diagnoses regarding presence of certain hepatocytic functions. Arterial and portal venous MR images obtained with gadoxetic acid are comparable to those of CT., ((c) RSNA, 2004.)

This contribution provides an overview and imparts basic knowledge on pertinent technical developments in magnetic resonance imaging (MRI) of the liver: 3D sequences, respiratory triggering, parallel imaging, and 3 Tesla (3T). 3D sequences can be used as T1-weighted (T1w) sequences for analyzing dynamics of contrast enhancement or as T2w sequences for MR cholangiography. Consistent improvements in respiratory triggering make it possible to obtain good image quality on T2w scans even in patients unable to hold their breath. Parallel imaging as a universal technique to accelerate image acquisition is particularly appropriate for MRI of the liver, and it has been shown that the reduced acquisition time is not achieved at the expense of image quality. Further progress in MRI of the liver can be expected with use of the 3T systems, but hitherto irrelevant problems must still be solved. Overall the innovations presented here, applied alone or in combination, facilitate rapid, robust, and high-quality MRI diagnostic assessment of the liver.

Purpose: To compare high-resolution T2-weighted images of the liver with and without integrated parallel acquisition techniques (iPAT) using either breath-hold sequences in combination with prospective acquisition motion correction (PACE) or respiratory triggering., Materials and Methods: Ten volunteers and 10 patients underwent each four different high-resolution fast spin echo (FSE) T2-weighted sequences with 5 mm slice thickness and a full 320 matrix: a multi-breath-hold FSE sequence with and without iPAT and PACE and a respiratory-triggered FSE sequence with and without iPAT. Image quality was rated with a five-point scale by two independent readers. Signal intensity measurements were performed on a water phantom., Results: The sequences with iPAT required a substantially shorter acquisition time without loss of image quality. Overall image quality was rated equal for all sequences by both readers. Image time for nine slices with iPAT was 13 seconds (19 seconds without iPAT) with multi-breath-hold and on average 4:00 minutes (7:02 minutes without iPAT) with respiratory triggering. Imaging with the PACE technique resulted in more correct positioning of the image stacks., Conclusion: T2-weighted fast imaging with iPAT is feasible and results in high-quality images within a short acquisition time. Overall image quality is not negatively affected by iPAT., (Copyright 2004 Wiley-Liss, Inc.)

Objective: This paper describes the value of various imaging modalities for diagnostic work-up of tumors of the adrenal gland., Methods: Results of the literature are reviewed. An optimized examination protocol for computed tomography (CT) and magnetic resonance imaging (MRI) is shown for assessment and differentiation of unclear lesions of the adrenal gland., Results: Measurements of attenuation in the native examination as well as delayed enhancement are the cornerstones in the CT diagnostics of tumors of the adrenal gland. In MRI, chemical-shift imaging and evaluation of signal characteristics in T1- and T2-weighted images are most important for characterization even in unclear cases., Conclusion: CT and MRI play the major role in imaging of adrenal gland tumors. Whereas CT is less expensive and widely available,MRI provides advantages in unclear cases because of the excellent tissue contrast and the superior characterization.