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To perform an intra-individual comparison of the frequency of respiratory-motion artefacts on magnetic resonance imaging (MRI) in cirrhotic patients following injection of gadoxetate disodium and gadobenate dimeglumine.Ninety-five cirrhotic patients (61 men and 34 women, mean age 58 years) underwent liver MRI with intravenous administration of gadoxetate disodium and gadobenate dimeglumine at different times (interval between studies, 189±83 days). Three readers scored the severity of respiratory-motion artefacts on the three-dimensional (3D) gradient-echo (GRE) images acquired before and after contrast medium injection. McNemar's test was used to assess the difference in frequency of new respiratory-motion artefacts and transient severe motion (TSM) artefacts between gadoxetate disodium and gadobenate dimeglumine MRI studies. The association between clinical and technical features and the occurrence of TSM on gadoxetate disodium MRI studies was investigated.On arterial phase images, new respiratory-motion artefacts were present in 32/95 (34%) cases after injection of gadoxetate disodium, while only seen in 2/95 (2%) cases after injection of gadobenate dimeglumine (p0.0001). TSM was present in 6/95 (6%) cases after injection of gadoxetate disodium, and in 0/95 (0%) case after injection of gadobenate dimeglumine. No clinical or technical features were associated with the occurrence of TSM.In cirrhotic patients, respiratory-motion artefacts on arterial phase 3D GRE images are more frequently seen after injection of gadoxetate disodium than after injection of gadobenate dimeglumine.

Evaluation of enhancement characteristics of histopathologically confirmed focal nodular hyperplasias (FNHs) and hepatocellular adenomas (HCAs) with gadoxetic acid-enhanced MRI.Sixty-eight patients with 115 histopathologically proven lesions (FNHs, n=44; HCAs, n=71) examined with gadoxetic acid-enhanced MRI were retrospectively enrolled (standard of reference: surgical resection, n=53 patients (lesions: FNHs, n=37; HCAs, n=53); biopsy, n=15 (lesions: FNHs, n=7; HCAs, n=18)). Two radiologists evaluated all MR images regarding morphological features as well as the vascular and hepatocyte-specific enhancement in consensus.For the hepatobiliary phase, relative enhancement of the lesions and lesion to liver enhancement were significantly lower for HCAs (mean, 48.7 (±48.4)%and 49.4 (±33.9) %) compared to FNHs (159.3 (±92.5) %; and 151.7 (±79) %; accuracy of 89%and 90 %, respectively; P0.001). Visual strong uptake of FNHs vs. hypointensity of HCAs in the hepatobiliary phase resulted in an accuracy of 92 %. This parameter was superior to all other morphological and dynamic vascular criteria alone and in combination (accuracy, 54–85 %).For differentiation of FNHs and HCAs by means of MRI, gadoxetic acid uptake in the hepatobiliary phase was found to be superior to all other criteria alone and in combination.EOB-MRI is well suited to differentiate FNHs and hepatocellular adenomas. For this purpose hepatobiliary phase is superior to unenhanced and dynamic imaging. Hepatobiliary phase (peripheral) hyper- or isointensity is typical for FNH. Hepatobiliary phase hypointensity is typical for hepatocellular adenomas. EOB-MRI helps to avoid misinterpretations of benign hepatocellular lesions.

This chapter gives an overview of some of the important advances made in abdominal and pelvic magnetic resonance imaging. The chapter focuses on four specific areas in the body that have seen major advances in the last ten years; the gastro-intestinal tract, liver, kidney, and foetus and placenta in the female pelvis. It describes some of the MRI techniques utilised to measure organ volume, understand organ physiology and structure in health and disease, and determine potential disease biomarkers.

Following the introduction of rapid, high-quality scan techniques and the development of new, tissue-specific contrast agents, the applications of magnetic resonance imaging (MRI) for liver imaging continue to grow. MRI using a T1-weighted sequence, T2-weighted sequence, and serial gadolinium-enhanced gradient echo sequences is very effective at both detecting and characterizing various hepatic lesions. The use of a growing number of contrast agents has the potential to increase the sensitivity and specificity of liver MRI in numerous pathological conditions by improving morphological and functional information. This article examines the current status of liver MRI, highlighting technical and methodological approaches, contrast agents, and main clinical applications. MRI appears to be an ideal diagnostic tool for the detection and characterization of liver disease.

The purpose of this study was to evaluate echo-train short inversion-time inversion recovery (STIR) sequences and compare the results obtained with breath-hold and non-breath-hold imaging strategies. Forty-one patients referred for hepatic magnetic resonance were imaged with both a breath-hold STIR (BH-STIR; acquisition time [TA] 16-20 seconds x 2) and a non-breath-hold STIR (NBH-STIR; TA 210-256 seconds). Quantitative analysis of the liver, spleen, and up to five hepatic lesions per patient was performed. Three blinded readers recorded the number of focal lesions depicted by each study and qualitatively evaluated overall image quality, lesion conspicuity, and image artifacts. The BH-STIR had greater sensitivity (98.8% vs. 91.6%) for detection of hepatic lesions than the NBH-STIR. The BH-STIR was statistically superior in four measures of image quality and had fewer image artifacts. The NBH-STIR images had statistically higher signal-to-noise (S/N, P < 0.001) and liver-lesion contrast-to-noise (C/N, P = 0.005) ratios. For the evaluation of focal hepatic lesions, a breath-hold echo-train STIR sequence provided superior overall image quality and allowed for detection of more lesions in a shorter amount of time than a non-breath-hold echo-train STIR sequence.

MRI of the liver is a powerful imaging modality for detection and characterization of liver pathology. MRI technology continues to evolve with developments in scanner hardware performance and refinements in imaging sequences, particularly in respect to fast imaging techniques, improving the quality of images that can be routinely achieved. Fast imaging techniques allow dynamic contrast-enhanced scanning to assist in lesion detection and characterization. An array of tissue-specific contrast agents are also becoming available; the clinical utility of some of these agents is yet to be fully established. An overview of scanning technique, contrast media, and the role of MRI in liver lesion detection and characterization is presented, with a review of the typical imaging characteristics of common focal and diffuse hepatic diseases. Where possible, emphasis has been placed on features that allow distinction between the various pathologic entities described.

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.

Magnetic resonance imaging (MRI) with magnetic resonance cholangiography (MRC) has become the radiologic standard of reference for diagnosis of primary sclerosing cholangitis (PSC). However, natural history of radiologic features of PSC is poorly known. In the current study, we aimed at analyzing the course of PSC using three-dimensional (3D) MRC and liver MRI to find predictive radiologic features of progression. PSC patients, followed up in our center, with at least two 3D MRCs performed in at least a 1-year interval, were retrospectively reviewed. We built an interpretation standard model to score precisely bile ducts and liver parenchyma features. The primary endpoint was overall radiologic course, including worsening, improvement, or stabilization. Radiologic features were analyzed by logistic regression. We reviewed 289 MRIs from 64 patients upon a mean radiologic follow-up of 4 years (range, 1-9). Radiologic features worsened in 37 patients (58%) and stabilized in 27 (42%); no patient showed improvement. Multivariate analysis resulted in two MRI progression risk scores, based on the combination of predictive radiologic features (score without gadolinium administration = 1 × dilatation of intrahepatic bile ducts + 2 × dysmorphy + 1 × portal hypertension; score with gadolinium administration = 1 × dysmorphy + 1 × parenchymal enhancement heterogeneity). These scores were associated with radiologic progression, with an area under the curve of 80 and 83% ± 4%. Conclusion: A majority of PSC patients develop radiologic aggravation upon MRI over 4 years. Two simple scores can predict radiologic progression.(Hepatology 2014;58:242–250)

MRI of the abdomen has been under development for well over a decade. In the past, considerable work was directed toward identification and suppression of the artifacts caused by motion. However, within the last several years, image quality has further improved, particularly as various fast-scan techniques have been adapted for abdominal imaging. The purpose of this work is to review these technical developments. Specific methods include adaptation of the acquisition time to breath-holding, acquisition over multiple respiratory cycles, adjustment of the contrast of various sequences, and development of more sensitive receiver coils and faster gradient systems. Opportunities for future development are also identified, including improved slice sampling, increased in-plane spatial resolution, real-time means for monitoring respiration, and expanded applications. As these technical advances are implemented, it is expected that the overall sensitivity and specificity of abdominal MRI will further improve.

Objective(s) To describe the different patterns of gallbladder lumen opacification on gadoxetate disodium-enhanced liver magnetic resonance imaging (MRI). Methods One hundred eighty-seven MRI examinations were reviewed by two abdominal imaging radiologists who described the different patterns of gallbladder opacification, based on comparing the post-contrast to the pre-contrast images. Results Four patterns of gallbladder opacification were identified, all based on the anti-dependent distribution of the excreted biliary contrast inside the gallbladder lumen. Contrast was identified at the level of the gallbladder neck, anti-dependant wall, and gallbladder fundus. One gallbladder completely filled with contrast. Conclusion(s) The opacification of the gallbladder lumen follows a distinctive anti-dependent distribution.

To investigate whether it is possible to develop a dual magnetic resonance (MR) contrast agent, Fe(3)O(4)/MnO hybrid nanocrystals were modified to integrate the T(1) and T(2) contrast-enhancing abilities of each compound, and their characteristics as MR contrast agents were investigated. In vitro and in vivo investigations revealed that the Fe(3)O(4)/MnO dumbbell-shaped nanocrystal exerted a negative T(2) contrast effect in its intact form and also gave rise to a positive contrast effect in T(1)-weighted MR imaging by releasing Mn(2+) ions in a low pH environment. This induced organ-specific contrast enhancement for both T(1)- and T(2)-weighted in vivo MR imaging. The usefulness of the Fe(3)O(4)/MnO hybrid nanocrystals as dual contrast agents was evaluated by in vivo MR imaging of an orthotopic xenograft model of human hepatocellular carcinoma (HCC). After injection of the Fe(3)O(4)/MnO hybrid nanocrystals, dual contrast-enhanced MR images that synergistically combined the T(2) and T(1) contrast effects from the Fe(3)O(4) grain and released Mn(2+) ions were obtained by a single acquisition of MR imaging. This facilitated the detection of HCC with a high degree of conspicuity that could not be achieved with any single contrast agent.

OBJECTIVE We evaluated the effect of particle size on MR contrast-enhancing properties of arabinogalactan-coated superparamagnetic iron oxide (AG-SPIO) in tumor-bearing rats. MATERIALS AND METHODS T2*-weighted gradient-recalled echo MR studies were performed on rats with surgically implanted liver tumors before and after AG-SPIO administration. Contrast-to-noise ratio (CNR) and percent contrast enhancement (PCE) were calculated for animals given small (15.7 +/- 9.5 nm: n = 6), medium (49.1 +/- 19.7 nm; n = 4), and large (86.9 +/- 27.5 nm; n = 4) particles intravenously (10 mumol Fe/kg). RESULTS Postcontrast CNRs were 15.8 +/- 6.9, 8.9 +/- 4.1, and 10.0 +/- 1.8 for small, medium, and large particle groups, respectively. The PCE was -60.0 +/- 3.3, -75.5 +/- 7.9, and -80.5 +/- 1.2%. There was a significant difference in preversus postcontrast CNR for all particle sizes (p < 0.001) and in PCE for small particles as compared with the two larger sizes (p < 0.001). There was no between-group statistical difference in postcontrast CNR for any particle size. CONCLUSION Larger AG-SPIO particles slightly improve liver contrast enhancement, but have no significant effect on hepatic lesion detection as assessed by CNR.

Objective To evaluate the image findings of focal fat deposition (FFD) in the liver on gadobenate dimeglumine (Gd-BOPTA)- and gadoxetic acid (Gd-EOB-DTPA)-enhanced MRI, particularly during the hepatobiliary phase (HBP), and the relationship between relative enhancement (RE) and fat signal fraction (FSF) of FFD. Subjects and Methods Twenty-one patients with 27 FFDs (mean diameter, 21.9 mm), which showed low signal intensity on opposed-phase compared with in-phase MRI, were retrospectively evaluated. RE of the liver (REliver) and FFD (REFFD) and liver-to-lesion contrast-to-noise ratio (CNR) of FFD were measured on dynamic phases and HBP images with fat-saturated in-phase gradient-echo sequence. The FSF of each FFD was measured on in- and opposed-phase dual gradient-echo images. We qualitatively analyzed imaging findings of FFDs, including signal intensity, shape, margin, and homogeneity on HBP images, and enhancement pattern during dynamic phases. The correlations between REFFD and FSF and between CNR and FSF on HBP images were evaluated using Pearson’s correlation tests and a simple linear regression model. Results There were no significant differences between REFFD and REliver in dynamic phases and HBP, regardless of contrast agents (p ≥ 0.075). On HBP images, CNR (p = 0.008) but not REFFD (p = 0.122) was significantly correlated with FSF of FFDs (mean FSF, 19%). On HBP images, 21 of the 27 (77.8%) FFDs were hypointense, and 17 (63%) were homogeneous. Of the 21 hypointense FFDs, 12 (57.1%) had an ovoid shape and 11 (52.4%) were well margined. Although the 27 FFDs showed various enhancement patterns, 17 (63%) showed no enhancement. Conclusion Most FFDs appeared as hypointense lesions on Gd-BOPTA- and Gd-EOB-DTPA-enhanced MRI during HBP, with various enhancement patterns during dynamic contrast-enhanced phases. REFFD on HBP images was not significantly correlated with FSF of low grade FFDs.

Manganese is one of the most abundant metals on earth and is found as a component of more than 100 different minerals. Besides being an essential trace element in relation to the metabolic processes in the body, manganese is also a paramagnetic metal that possesses similar characteristics to gadolinium with regards to T1-weighted (T1-w) magnetic resonance imaging (MRI). Manganese, in the form of manganese (II) chloride tetrahydrate, is the active substance in a new targeted oral contrast agent, currently known as CMC-001, indicated for hepatobiliary MRI. Under physiological circumstances manganese is poorly absorbed from the intestine after oral intake, but by the use of specific absorption promoters, L-alanine and vitamin D3, it is possible to obtain a sufficiently high concentration in the liver in order to achieve a significant signal enhancing effect. In the liver manganese is exposed to a very high first-pass effect, up to 98%, which prevents the metal from reaching the systemic circulation, thereby reducing the number of systemic side-effects. Manganese is one of the least toxic trace elements, and due to its favorable safety profile it may be an attractive alternative to gadolinium-based contrast agents for patients undergoing an MRI evaluation for liver metastases in the future. In this review the basic pharmacological and pharmaceutical aspects of this new targeted oral hepatobiliary specific contrast agent will be discussed.

Purpose Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) enhanced liver MRI is widely used for detection and differentiation of focal liver lesions. Diffusion weighted imaging (DWI) including apparent diffusion coefficient (ADC) measurements is increasingly utilised as a fast and, with limitations, quantitative method for liver lesion detection and characterisation. Herein we investigate whether the administration of Gd-EOB-DTPA affects DWI. Materials and methods 31 consecutive patients referred to standardised liver MRI (1.5 T, Gd-EOB-DTPA, 0.025 mmol/kg) were retrospectively reviewed. All underwent a breathhold DWI sequence before and after contrast agent administration (EPI-DWI, TR/TE (effective): 2100/62 ms, b -values: 0 and 800 s/mm 2 ). Patients with previously treated liver lesions were excluded. Signal intensity of lesion, parenchyma and noise on DWI images as well as the ADC value were measured after identification by two observers in consensus using manually placed regions of interest. The reference standard was imaging follow-up determined separately by two radiologists. Data analysis included signal-to-noise (SNR) ratio and contrast-to-noise ratio (CNR) calculations, comparisons were drawn by employing multiple Bonferroni corrected Wilcoxon signed-rank tests. Results 50 malignant and 39 benign lesions were identified. Neither SNR, CNR nor ADC values showed significant differences between pre- and postcontrast DWI. Both pre- and postcontrast ADC values differed significantly between benign and malignant lesions ( P Conclusion We did not identify a significant influence of Gd-EOB-DTPA on DWI of liver lesions. This allows for individual tailoring of imaging protocols according to clinical needs.

Purpose Diffusion weighted imaging (DWI) is an emerging technique for abdominal MR and usually performed before intravenous contrast injection. Recent studies performed in patients with normal liver function have shown that DWI can be performed after gadolinium administration. Aim of this study was to compare DWI before and after administration of different gadolinium compounds in patients with HCC and liver cirrhosis. Materials and methods 15 patients with known HCC and liver cirrhosis underwent liver MRI at 1.5 T (Magnetom Avanto, Siemens) including DWI on day 1 before and after administration of gadobutrol (Gadovist ® ) and on day 2 after administration of EOB-Gadolinium-DTPA (Primovist ® ). Signal to noise ratios (SNR) and contrast to noise ratios (CNR) of HCC lesions were determined for all DWI data sets. Furthermore, ADC values were compared using a Wilcoxon test. A p -value Results There were no statistically significant differences regarding SNR pre-contrast (mean: 48.1), after gadobutrol (mean: 47.7) or after EOB-Gadolinium-DTPA (mean: 50.0; values for b = 50 s/mm 2 ). Similarly, no significant differences were found for CNR (average values:34.4 vs. 32.3 vs. 30.7; b = 50 s/mm 2 ) nor for ADC-values (mean: 1.5 vs. 1.4 vs. 1.5 × 10 −3 mm 2 /s) of HCC. Conclusion There is no significant difference regarding DWI in patients with cirrhosis before and after contrast injection. Hence, it is reliable to run DWI after gadolinium either as an alternative for unsuccessful pre-contrast DWI or as a gap filler to spare time in EOB-Gadolinium-DTPA imaging.

We report in this communication a simple, facile surface modification strategy to transfer hydrophobic manganese oxide nanoparticles (MONPs) into water by using polyaspartic acid (PASP). We systematically investigated the effect of the size of PASP-MONPs on MRI of normal liver and found that the particles with a core size of 10 nm exhibited greater enhancement than those with larger core sizes.

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

DWI has expanded its applications outside the brain in the last years because of technological improvements in gradient strengths and sequences. Nowadays, DWI forms part of “state-of-the-art” liver MRI protocols, although lack of standardization limits its widespread use. In this chapter, we analyze the main technical parameters of DWI of the liver in order to choose the most appropriate type of sequence according to the magnet and patient status. The characteristics on DWI of focal and diffuse liver disease are also summarized, outlining the currently established and potential clinical applications of this functional technique. DWI is probably the best noninvasive imaging test for detection of focal liver lesions using black-blood DWI sequences with low b values. DWI may help along with other MRI sequences in focal liver characterization. As in other organs, the potential of DWI in post-treatment monitorization and prediction of response to treatment have not been fully explored, with recent data supporting a growing role in this task. Besides, the role of this functional technique in diffuse liver disease is currently under evaluation.

Purpose: To compare conspicuity and detection rate of hypointense lesions on T1-weighted (T1w) gradient echo (GRE) sequences with low and high flip angles (FA) in hepatocyte phase magnetic resonance imaging (MRI) using gadoxetate disodium. Materials and Methods: This Health Insurance Portability and Accountability Act (HIPAA)-compliant study was Institutional Review Board (IRB)-approved. The study population consisted of patients with hypointense liver lesions undergoing MRI with gadoxetate disodium, with hepatocyte-phase fat suppressed 3D T1w GRE sequences at both low (10–12°) and high (30–35°) FA. Contrast-to-noise ratios (CNRs) were calculated for liver parenchyma vs. large lesions and common bile duct (CBD) vs. liver. Three radiologists each assigned a conspicuity score (CS) for each lesion detected at low or high FA. Paired Student's t-tests compared the lesion detection (LD) rate using only the hepatocyte phase data set compared with the entire MRI examination, and CS for low and high FA. Results: In all, 57 large and 70 small lesions were identified in 18 patients. Average LD and CS were significantly greater at high FA versus low FA overall (LD 89.0% vs. 79.5%; CS 2.8 vs. 2.2; P < 0.05) and for small lesions (81.4% vs. 65.7%; 2.5 vs. 1.8; P < 0.05). Average liver-to-lesion CNR for large lesions and CBD-to-liver CNR was significantly greater at high FA (P < 0.05). Conclusion: Increasing the FA in hepatocyte phase MRI with gadoxetate disodium improves hypointense lesion detection and conspicuity, particularly for small lesions. J. Magn. Reson. Imaging 2012;35:611-616. © 2011 Wiley Periodicals, Inc.

To compare free-breathing radially sampled 3D fat suppressed T1-weighted gradient-echo acquisitions (radial volumetric interpolated breath-hold examination [VIBE]) with breath-hold (BH) and free-breathing conventional (rectilinearly sampled k-space) VIBE acquisitions for postcontrast imaging of the liver.: Eighteen consecutive patients referred for clinically indicated liver magnetic resonance imaging were imaged at 3 T. Three minutes after a single dose of gadolinium contrast injection, free-breathing radial VIBE, BH VIBE, and free-breathing VIBE with 4 averages were acquired in random order with matching sequence parameters. Radial VIBE was acquired with the "stack-of-stars" scheme, which uses conventional sampling in the slice direction and radial sampling in-plane.All image data sets were evaluated independently by 3 radiologists blinded to patient and sequence information. Each reader scored the following parameters: overall image quality, respiratory motion artifact, pulsation artifact, liver edge sharpness, and hepatic vessel clarity using a 5-point scale, with the highest score indicating the most optimum examination. Mixed model analysis of variance was used to compare sequences in terms of each measure of image quality.: When scores were averaged over readers, there was no statistically significant difference between radial VIBE and BH VIBE regarding overall image quality (P = 0.1015), respiratory motion artifact (P = 1.0), and liver edge sharpness (P = 0.2955). Radial VIBE demonstrated significantly lower pulsation artifact (P0.0001), but had lower hepatic vessel clarity (P = 0.0176), when compared with BH VIBE. Radial VIBE had significantly higher image quality scores for all parameters when compared with free-breathing VIBE (P0.0001). Acquisition time for BH VIBE was 14 seconds and that of free-breathing radial VIBE and conventional VIBE with multiple averages was 56 seconds each.: Radial VIBE can be performed during free breathing for contrast-enhanced imaging of the liver with comparable image quality to BH VIBE. However, further work is necessary to shorten the acquisition time to perform dynamic imaging.

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.

OBJECTIVE. This article illustrates an approach to MRI for hepatobiliary imaging in children. The indications, patient preparation, protocols, pulse sequences, and contrast agents will be highlighted.CONCLUSION. Significant advances in hepatobiliary MRI have allowed reliable, high quality imaging in a pediatric population.

Gd-EOB-DTPA is a new liver specific MRI contrast media. In the hepatobiliary phase, contrast media is trapped in normal liver tissue, a normal liver shows high intensity, tumor/liver contrast becomes high, and diagnostic ability improves. In order to indicate the degree of uptake of the contrast media, the enhancement ratio (ER) is calculated. The ER is obtained by calculating (signal intensity (SI) after injection-SI before injection) / SI before injection. However, because there is no linearity between contrast media concentration and SI, ER is not correctly estimated by this method. We discuss a method of measuring ER based on SI and T(1) values using the phantom. We used a column phantom, with an internal diameter of 3 cm, that was filled with Gd-EOB-DTPA diluted solution. Moreover, measurement of the T(1) value by the IR method was also performed. The ER measuring method of this technique consists of the following three components: 1) Measurement of ER based on differences in 1/T(1) values using the variable flip angle (FA) method, 2) Measurement of differences in SI, and 3) Measurement of differences in 1/T(1) values using the IR method. ER values calculated by these three methods were compared. In measurement made using the variable FA method and the IR method, linearity was found between contrast media concentration and ER. On the other hand, linearity was not found between contrast media concentration and SI. For calculation of ER using Gd-EOB-DTPA, a more correct ER is obtained by measuring the T(1) value using the variable FA method.

One of the advantages of using hepatobiliary contrast agents in liver MRI is the ability to acquire a delayed, “hepatocyte phase” dataset. This phase highlights many types of lesions as hypointense compared with the liver, because of the accumulation of contrast material in functioning hepatocytes and non-retention within most lesions. Increasing the flip angle of the T1-weighted pulse sequence used to acquire the hepatocyte phase is a simple parameter change that increases the contrast-to-noise ratio of focal lesions compared with the hepatic parenchyma. This technique increases the sensitivity for detection and conspicuity of focal liver lesions. High flip angle delayed hepatocyte phase imaging is a useful adjunct to standard enhanced MRI of the liver. It allows for better sensitivity in focal lesion detection, particularly for small lesions. Secondarily, this technique increases the conspicuity of the biliary system, which is an additional benefit of delayed imaging with hepatobiliary contrast agents.

To assess the utility of a T2*-weighted, multi-echo data imaging combination sequenced on superparamagnetic iron oxide (SPIO)-enhanced liver magnetic resonance imaging (MRI) using a 3 T system.Fifty patients underwent SPIO-enhanced MRI at 3 T using T2*-weighted, single-echo, gradient-recalled echo (GRE) sequences [fast imaging with steady precession; repetition time (TR)/echo time (TE), 126 ms/9 ms; flip angle, 30°] and multi-echo GRE (multi-echo data image combination) sequences (TR/TE, 186 ms/9 ms; flip angle, 30°). Three radiologists independently reviewed the images in a random order. The sensitivity and accuracy for the detection of focal hepatic lesions (a total of 76 lesions in 33 patients; 48 solid lesions, 28 non-solid lesions) were compared by analysing the area under the receiver operating characteristic curves. Image artefacts (flow artefacts, susceptibility artefacts, dielectric artefacts, and motion artefacts), lesion conspicuity, and overall image quality were evaluated according to a four-point scale: 1, poor; 2, fair; 3, good; 4, excellent. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the lesions were compared.Image artefacts were more frequent with single-echo GRE (p0.05). The mean scale of image quality assessment for flow, susceptibility, dielectric, and motion artefacts were 2.76, 3.13, 3.42, and 2.89 with single-echo, respectively, compared with 3.47, 3.43, 3.47, and 3.39, respectively, with multi-echo GRE. There was no significant difference in lesion conspicuity between single-echo (3.15) and multi-echo (3.30) GRE sequences. The overall image quality was significantly (p0.05) better with multi-echo (3.37) than with single-echo GRE (2.89). The mean SNR and CNR of the lesions were significantly (p0.05) higher on multi-echo (79±23 and 128±59, respectively) images than on single-echo (38±11 and 102±44, respectively) images. Lesion detection accuracy and sensitivity were not significantly different between the two sequences. Mean accuracies and sensitivities were 0.864 and 0.785 for single-echo and 0.847 and 0.785 for multi-echo GRE, respectively.At 3 T, the T2*-weighted, multi-echo data image combination sequence performs comparably to the T2*-weighted, single-echo GRE sequence for SPIO-enhanced MRI with good overall image quality and a decrease in undesired artefacts.

Magnetic resonance imaging (MRI) has now been used for about three decades to characterize the human liver in a non-invasive way, that is without the need of using ionizing radiation or removing tissue samples. During the past few years, technical progress has been considerable and novel applications of MRI have been implemented in the clinic. The beginning of a new decade offers an excellent opportunity for having five experts to present their view on the current status of MRI (and magnetic resonance spectroscopy) in the study of perfusion, fat and iron contents, diffusion and the metabolism of diffuse liver diseases. This topic highlight series thus provides an update of current knowledge in the field of liver MRI. (C) 2010 Baishideng. All rights reserved.

Measurement of liver MRI T2* and R2* is emerging as a reliable alternative to liver biopsy for the quantitation of liver iron content. A systematic investigation of the influence of the region-of-interest size and placement has not been conducted.To compare small and whole liver region-of-interest (ROI) MRI R2* values to each other and to biopsy liver iron content in patients with iron overload.Forty-one iron-overloaded patients, ages 7-35 years, underwent biopsy for liver iron content quantitation and MRI for liver R2* measurement within 30 days. Three reviewers independently used small and whole liver ROIs to measure R2*. Inter-reviewer agreement was assessed with the intra-class correlation coefficient (ICC). Associations between R2* and liver iron content were investigated using Spearman's rank-order correlation and Monte Carlo estimated exact P values.Biopsy liver iron content and small and whole liver ROI R2* measurements were strongly associated for all reviewers (all P0.0001). Although inter-reviewer agreement was excellent for both ROI methods (ICC = 0.98-0.99), the small ROI technique more frequently led to inter-reviewer differences larger than 75 Hz, slightly higher R2* values, larger standard errors and greater range in values.Small and whole liver ROI techniques are strongly associated with biopsy liver iron content. We found slightly greater inter-reviewer variability in R2* values using the small ROI technique. Because such variability could adversely impact patient management when R2* values are near a threshold of iron chelation therapy, we recommend using a whole liver ROI.

Contrast-enhanced liver MR image sequences acquired at multiple times before and after contrast administration have been shown to be critically important for the diagnosis and monitoring of liver tumors and may be used for the quantification of liver inflammation and fibrosis. However, over multiple acquisitions, the liver moves and deforms due to patient and respiratory motion. In order to analyze contrast agent uptake one first needs to correct for liver motion. In this paper we present a method for the motion correction of dynamic contrastenhanced liver MR images. For this purpose we use a modified version of the Local Correlation Coefficient (LCC) Demons non-rigid registration method. Since the liver is nearly incompressible its displacement field has small divergence. For this reason we add a divergence term to the energy that is minimized in the LCC Demons method. We applied the method to four sequences of contrast-enhanced liver MR images. Each sequence had a pre-contrast scan and seven post-contrast scans. For each post-contrast scan we corrected for the liver motion relative to the pre-contrast scan. Quantitative evaluation showed that the proposed method improved the liver alignment relative to the non-corrected and translation-corrected scans and visual inspection showed no visible misalignment of the motion corrected contrast-enhanced scans and pre-contrast scan.

To compare the arterial enhancement of hypervascular hepatic lesions by T1-weighted 3D-GRE (gradient-recalled echo) fat-sat sequence after slow (0.5 mL/sec) and fast (2 mL/sec) RESOVIST infusion.We prospectively enrolled 71 patients with hypervascular hepatic lesions to undergo dynamic magnetic resonance imaging (MRI) examination with RESOVIST. A total of 92 benign and malignant lesions, 44 of which histologically confirmed, were examined. Three blinded and independent readers visually assessed the arterial enhancement using a score from 0 (none) to 3 (maximum), the latter score comparable to that achievable by MultiHance administration.Out of the 92 hypervascular lesions, 41, 31, and 20 nodules were examined using the slow, fast, and both protocols, respectively. Relevant enhancement (scores 2-3) was found in 42% vs. 14.5% of cases for slow and fast protocols, respectively. Intraindividual comparison evaluation confirmed the better results obtained by slow than fast protocol (25% vs. 10%), with statistically relevant difference in distribution of scores (P=0.0004). The slow protocol showed values between 0 and 3 with an arithmetic mean of 1.1; the fast one, on the other hand, showed values between 0 and 2 with an arithmetic mean of 0.66.Slow infusion improves arterial enhancement after RESOVIST administration.

The purpose of this study was to compare three free-breathing T2-weighted MRI sequences in the evaluation of focal liver lesions.Forty-nine patients with 86 focal liver lesions (56 malignant, 30 benign) underwent liver MRI with free-breathing sequences: turbo spin-echo (TSE) with navigator-triggered prospective acquisition correction (PACE), respiration-triggered TSE, and HASTE with navigator-triggered PACE. The images were retrospectively reviewed by two independent observers. Diagnostic performance was evaluated with receiver operating characteristics and sensitivity. The images were assessed quantitatively by measurement of the liver signal-to-noise ratio (SNR) and the lesion-to-liver contrast-to-noise ratio (CNR).The PACE TSE sequence had better receiver operating characteristic curves for lesion detection and characterization than did the respiration-triggered TSE sequence, but the difference was not statistically significant (p0.05). The PACE TSE sequence had a significantly greater area under the curve for lesion detection (p0.01) and lesion characterization (p0.001) than did the PACE HASTE sequence. The composite sensitivity of the PACE TSE sequence for lesion detection was significantly higher than that of respiration-triggered TSE (p0.05) and PACE HASTE (p0.01). The mean signal-to-noise ratio for liver and the contrast-to-noise ratio for hepatic lesions were higher with the PACE HASTE than with the other sequences.The navigator-triggered PACE technique is a valid method for T2-weighted MRI of the liver and may replace conventional respiration-triggered techniques.

WEB This is a Web exclusive article. uvenile xanthogranuloma is a non–Langerhans cell form of histiocytosis most frequently diagnosed in young children, in 85% of cases before the patient is 1 year old. This condition predominantly presents as selfhealing cutaneous lesions. Systemic involvement worsens the prognosis, the mortality rate being as high as 6% [1]. Although the MRI appearance of juvenile xanthogranuloma in the brain [2] and musculoskeletal system [3] has been described, the MRI appearance of lesions in the liver and heart has not been described, to our knowledge. We report a case of juvenile xanthogranuloma with lesions in the liver and heart evaluated with MRI, CT, and sonography. We also review the imaging literature on this condition.

In dynamic liver MRI, reproducibility of the liver position is quite poor when making subtraction images. To improve this, moving directions and positions were analyzed to determine any recognizable pattern of liver motion.

Currently, acquisitions of dynamic liver MR image information have been obtained under voluntary expiration phase (VE) breath holding (BH). However, during subtraction processing of axial images, there is a problem with reproducibility of the liver position. Therefore, it is important for this study to improve the reproducibility of organ position.

Objective To assess the value of applying MultiVane to liver T2-weighted imaging (T2WI) compared with conventional T2WIs with emphasis on detection of focal liver lesions. Materials and Methods Seventy-eight patients (43 men and 35 women) with 86 hepatic lesions and 20 pancreatico-biliary diseases underwent MRI including T2WIs acquired using breath-hold (BH), respiratory-triggered (RT), and MultiVane technique at 3T. Two reviewers evaluated each T2WI with respect to artefacts, organ sharpness, and conspicuity of intrahepatic vessels, hilar duct, and main lesion using five-point scales, and made pairwise comparisons between T2WI sequences for these categories. Diagnostic accuracy (Az) and sensitivity for hepatic lesion detection were evaluated using alternative free-response receiver operating characteristic analysis. Results MultiVane T2WI was significantly better than BH-T2WI or RT-T2WI for organ sharpness and conspicuity of intrahepatic vessels and main lesion in both separate reviews and pairwise comparisons (p < 0.001). With regard to motion artefacts, MultiVane T2WI or BH-T2WI was better than RT-T2WI (p < 0.001). Conspicuity of hilar duct was better with BH-T2WI than with MultiVane T2WI (p = 0.030) or RT-T2WI (p < 0.001). For detection of 86 hepatic lesions, sensitivity (mean, 97.7%) of MultiVane T2WI was significantly higher than that of BH-T2WI (mean, 89.5%) (p = 0.008) or RT-T2WI (mean, 84.9%) (p = 0.001). Conclusion Applying the MultiVane technique to T2WI of the liver is a promising approach to improving image quality that results in increased detection of focal liver lesions compared with conventional T2WI.

The present paper provides a brief overview of the rationale behind magnetic resonance imaging (MRI) techniques, a description of the most common sequences used, and a general approach to performing liver MRI.

This is a report of a case with metastatic liver tumors in which a segmental hyperintense area was demonstrated by delayed liver MRI with manganese (II) N,N' -dipyridoxylethylenediamine-N,N'-diacetate-5,5'-bis(phosphate) (Mn-DPDP). No signal abnormality except for tumors was distinct either before or 30 min after administration of Mn-DPDP. The region with hyperintensity appeared 24 h after administration.

Infantile hepatic choriocarcinoma is a rare, highly malignant germ-cell tumour believed to result from a choriocarcinoma of the placenta that spreads to the child. Most infants present with a characteristic clinical picture of anaemia, hepatomegaly and precocious puberty. Imaging findings, including conventional MRI, may be non-specific. To improve the accuracy of diagnosis, we present the imaging findings of contrast-enhanced dynamic MRI in a 4.5-month-old boy with infantile hepatic choriocarcinoma.

We report on two patients who underwent magnetic resonance imaging (MRI) as part of the evaluation of focal liver lesions. Both lesions had completely different MRI appearances, showing characteristics of benign and malignant liver lesions. Neither patient had clinical signs of endocrine hyperactivity, and both underwent subsequent liver resection. Histology showed neuroendocrine liver tumors in both patients; and because no primary tumor could be identified after careful search, the diagnosis of primary neureoendocrine tumor of the liver was established. Our observations suggest that primary neuroendocrine tumors of the liver may have a wide spectrum of appearances on MRI.