Gadolinium-based contrast agents (GBCAs) have helped to improve the role of magnetic resonance imaging (MRI) for the diagnosis and treatment of diseases. There are currently nine different commercially available gadolinium-based contrast agents (GBCAs) that can be used for body MRI cases, and which are classifiable according to their structures (cyclic or linear) or biodistribution (extracellular-space agents, target/specific-agents, and blood-pool agents). The aim of this review is to illustrate the commercially available MRI contrast agents, their effect on imaging, and adverse reaction on the body, with the goal to lead to their proper selection in different clinical contexts. When we have to choose between the different GBCAs, we have to consider several factors: (1) safety and clinical impact; (2) biodistribution and diagnostic application; (3) higher relaxivity and better lesion detection; (4) higher stability and lower tissue deposit; (5) gadolinium dose/concentration and lower volume injection; (6) pulse sequences and protocol optimization; (7) higher contrast-to-noise ratio at 3.0 T than at 1.5 T. Knowing the patient\'s clinical information, the relevant GBCAs properties and their effect on body MRI sequences are the key features to perform efficient and high-quality MRI examination.

In the future, the application of quantitative imaging and computational analysis will reduce the burden on radiologists. We herein report 8 pilot cases both with and without intrahepatic biliary stricture (IHBS) diseases which have been analyzed with the novel analytical system MRCP+ (Perspectum Ltd., Oxford, UK). The colored and well-visualized 3D models of the entire biliary trees could be obtained in all 8 cases. Three representative cases did not show dilated regions in the intrahepatic bile ducts. Cases diagnosed as a pancreatico-biliary maljunction showed slightly increased dilated visualization in the extrahepatic duct. Except in a case with severe stenosis resulting from hepatolithiasis, the number of visualized intrahepatic bile ducts tended to be decreased and the volume of biliary tree and the total length of stricture and dilatation were also decreased. However, the number of IHBS or dilatation was unchanged. The number of strictures obtained by MRCP+ and the subjective counts of stenosis from a radiologist was not found to be correlated. In a case of severe stenosis at the left lateral bile duct, the number of intrahepatic biliary dilatations was increased. The latest computerized 3D modeling technology was found to be useful in visualizing the alteration of intraluminal diameter of the entire biliary trees at a glance, which can provide the automatic diagnosis of IHBS diseases at an earlier phase.

Primary sclerosing cholangitis (PSC) is a rare and chronic cholestatic liver disease of unknown cause commonly associated with inflammatory bowel disease (IBD) and characterized by progressive obliterative fibro-inflammation of the biliary tree. Although the natural course is highly variable, PSC is often progressive, leading to biliary cirrhosis and its complications. In addition, PSC is a condition harbouring broad neoplastic potential with increased susceptibility for the development of both biliary and colon cancer. As in other chronic liver diseases, non-invasive methods play a major role in the diagnosis and monitoring of PSC. MR cholangiography is the key exam for the diagnosis and has replaced diagnostic endoscopic retrograde cholangiopancreatography (ERCP). A strict and standardised protocol for carrying out MR cholangiography is recommended. Liver stiffness measured by FibroScan® correlates with the degree of liver fibrosis, has a prognostic value and should be repeated during follow-up. Invasive methods still play an important role, especially ERCP which is indicated for therapeutic purposes or for endo-biliary sample collection in suspected cholangiocarcinoma (following discussion in a multidisciplinary team meeting) and total colonoscopy which is recommended at the initial diagnosis of any PSC and annually in patients with IBD.

Biliary hamartomas (BHs) are rare malformative cystic/cystic-like lesions of the liver affecting the biliary tree, named after Hanns von Meyenburg who described them for the first time and still known with this eponym to this day. They usually lack clinical symptoms, and abnormalities in liver function tests are unusual; thus, it is typically an incidental finding of liver imaging. Despite being benign lesions, BHs can pose clinical challenges; the first one is differential diagnosis with other more relevant pathological conditions. Therefore, knowledge of MR imaging findings of BHs is helpful for a prompt and correct diagnosis, avoiding unnecessary invasive procedures and/or an excessive number of radiological investigations. This pictorial review is aimed to depict the most typical MR imaging features of multiple biliary hamartomas (von Meyenburg Complex), in order to familiarize the diagnosis and facilitate the differentiation from other hepato-biliary cystic diseases.

OBJECTIVE: To compare the quality of images obtained by T1-weighted hepatobiliary MR cholangiography using Gd-EOB-DTPA with 1-mm isovoxel acquisition and compressed sensing (T1-MRCCS) or parallel imaging (T1-MRCPI) for assessment of biliary tree anatomy.
METHODS: We prospectively reviewed T1-MRCCS, T1-MRCPI, and respiratory-triggered 3D T2-weighted MR cholangiography (T2-MRC) images in 58 patients. Two radiologists independently assessed the three sets of images and scored the biliary tree visualization and overall image quality in all cases using a 5-point Likert scale. The resulting scores were compared among T1-MRCCS, T1-MRCPI, and T2-MRC images using a Friedman test followed by a Scheffe test. The inter-reader agreement in scoring was assessed using κ statistics.
RESULTS: The image quality scores for the gallbladder on both T1-MRCCS and T1-MRCPI were significantly lower than those on T2-MRC (p < 0.01) for both readers. Meanwhile, the image quality scores for the right and left hepatic ducts and the anterior and posterior branches of the right hepatic duct on both T1-MRCCS and T1-MRCPI were significantly higher than those on T2-MRC (p < 0.05) for both readers. For Reader 2, the overall image quality scores on T1-MRCCS and T1-MRCPI were both significantly higher than those on T2-MRC (p < 0.05). There were no significant differences between the image quality scores on T1-MRCCS and T1-MRCPI for visualization of each bile duct (p < 0.05).
CONCLUSIONS: There may be no significant difference in quality between T1-MRCCS images and T1-MRCPI images for assessment of biliary tree anatomy, and both types of images may be better than T2-MRC images, although clinical indication is limited compared with T2-MRC.

OBJECTIVE: To assess whether contrast-enhanced T1-weighted MR Cholangiography may provide additional information in the evaluation of biliary complications in orthotopic liver transplant recipients.
METHODS: Eighty liver transplant patients with suspicion of biliary adverse events underwent MR imaging at 1.5 T scanner. After acquisition of axial T1-/T2-weighted images and conventional T2-weighted MR Cholangiography (image set 1), 3D gradient-echo T1-weighted fat-suppressed LAVA (Liver Acquisition with Volume Acceleration) sequences were obtained about 30 min after intravenous infusion of mangafodipir trisodium (Mn-DPDP,Teslascan(®)) (image set 2). The diagnostic value of mangafodipir trisodium-enhanced MR Cholangiography in the detection of biliary complications was tested by separate analysis results of image set 1 alone and image set 1 and 2 together. MRI results were correlated with direct cholangiography in 46 patients, surgery in 14 and/or clinical-radiological follow-up in the remaining 20 cases.
RESULTS: The level of confidence in the assessment of biliary adverse events was significantly increased by the administration of mangafodipir trisodium (p < 0.05). Particularly, contrast-enhanced T1-weighted LAVA sequences tended to out-perform conventional T2-weighted MR Cholangiography in the delineation of anastomotic and non-anastomotic biliary strictures and in the diagnosis of biliary leak.
CONCLUSIONS: Contrast-enhanced T1-weighted MR Cholangiography may improve the level of diagnostic confidence provided by conventional T2-weighted MR Cholangiography in the evaluation of biliary complications after orthotopic liver transplantation.

Orthotopic liver transplantation is the treatment of choice in adult patients with endstage liver disease. Survival of both graft and patient has progressively improved over time due to improvements in surgical and medical treatment. However, post-transplant complications still have a significant impact on morbidity and mortality associated with transplant surgery. The most common adverse events of the graft include vascular (arterial and venous stenosis and thrombosis), biliary (leakage, strictures, stones) and parenchymal complications (hepatitis virus C infection, HCC recurrence, liver abscesses). The diagnosis of these adverse events is often challenging because of the low specificity of clinical and biologic findings. Different diagnostic algorithms have been proposed for the detection of graft complications and, in this setting, radiological evaluation plays a key role in differential diagnosis of graft complications and the exclusion of other adverse events. Ultrasound examination is established the first-line method of identifying adverse events in liver transplant recipients but a normal or a technically unsatisfactory study cannot exclude the presence of biliary, vascular and/or parenchymal complications. In these circumstances, before planning any treatment, multi-detector CT and/or MR imaging and MR cholangiography should be performed for the evaluation of vascular structures, biliary system, liver parenchyma and fluid collections. The aim of this review is to illustrate the role and state-of-the-art of non-invasive cross-sectional imaging techniques in the diagnosis and management of complications which primarily affect the graft in patients after liver transplantation.

BACKGROUND: Detailed knowledge of the biliary anatomy is essential to avoid complications in living donor liver transplantation. The aim of this study was to determine the optimal dosage of Gd-EOB-DTPA for contrast-enhanced magnetic resonance cholangiography (ce-MRC) with reference to contrast-enhanced CT cholangiography (ce-CTC).
METHODS: 30 potential living liver donors (PLLD) underwent both ce-CTC and ce-MRC. Ten candidates each received single, double or half-dose Gd-EOB-DTPA. Ce-MRC images with and without inversion recovery pulses (T1w±IR) were acquired 20-30min after intravenous contrast injection. Image data was quantitatively and qualitatively reviewed by two radiologists based on a on a 5-point scale. Data sets were compared using a Mann-Whitney-U-test or Wilcoxon-rank-sum-test. Kappa values were also calculated.
RESULTS: All image series provided sufficient diagnostic information both showing normal biliary anatomy and variant bile ducts. Ce-CTC showed statistically significant better results compared to all ce-MRC data sets. T1w MRC with single dose Gd-EOB-DTPA proved to be superior to half and double dose in subjective and objective evaluation without a statistically significant difference.
CONCLUSIONS: Ce-MRC is at any dosage inferior to ce-CTC. As far as preoperative planning of bile duct surgery is focused on the central biliary anatomy, ce-MRC can replace harmful ce-CTC strategies, anyway. Best results were seen with single dose GD-EOB-DTPA on T1w MRC+IR.

The aim of this study was to evaluate utility of gadoxetic acid disodium (Gd-EOB-DTPA)-enhanced magnetic resonance cholangiography (MRC) for the detection of biliary complications after living donor liver transplantation (LDLT). A total of 18 patients with suspected biliary complications underwent MRC. T2-weighted MRC and contrast-enhanced MRC (CE-MRC) were used to identify the biliary complications. MRC included routine breath-hold T2-weighted MRC using half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences and Gd-EOB-DTPA-enhanced MRC T1-weighted volumetric interpolated breath-hold examination (VIBE) sequences. Before confirming the biliary complications, one observer reviewed the MRC images and the CE-MRC images separately. The verification procedures and MRC findings were compared, and the sensitivity, specificity, and accuracy of both techniques were calculated for the identification of biliary complications. The observer found six of seven biliary complications using CE-MRC. The sensitivity was 85.7% and the accuracy was 94.4%. Using MRC alone, sensitivity was 57.1% and accuracy was 55.5%. The accuracy of Gd-EOB-DTPA-enhanced MRC was superior to MRC in locating biliary leaks (p < 0.05). The usage of Gd-EOB-DTPA-enhanced MRC yields information that complements the MRC findings that improve the identification of biliary complications. We recommend the use of MRC in addition to Gd-EOB-DTPA-enhanced MRC to increase the preoperative accuracy when assessing the biliary complications after LDLT.

OBJECTIVE: 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.
CONCLUSIONS: The opacification of the gallbladder lumen follows a distinctive anti-dependent distribution.