Non-contrast MR lymphography of the lymphatic system of the liver NON-CONTRAST MR LYMPHOGRAPHY OF THE LYMPHATIC SYSTEM OF THE LIVER

International audienceThis review shows the images obtained with non-contrast MR lymphography in different pathologic conditions affecting the liver. Non-contrast MR lymphography is obtained with a free-breathing 3D high spatial resolution fast-recovery fast spin-echo sequence similar to that used for 3D MR cholangiopancreatography. The liver is the largest lymph-producing organ generating approximately half of the body's lymphatic fluid and is the most important part of the lymphatic system from a functional point of view. Therefore, understanding the anatomy, physiology, and physiopathology of the lymphatics of the liver is important. However, its anatomy and pathology are relatively unknown because of the absence of commonly used imaging techniques. We describe the anatomy, the physiology, and the pathophysiology of the lymphatic system of the liver and the possibility of identifying dilated lymphatic vessels in various liver diseases and conditions. Disruption of normal lymphatic structure and function is observed in various disease conditions. Liver lymph flow is directly correlated with portal venous pressure. Therefore, a dilatation of liver lymphatics is observed in portal hypertension as well as in increased pressure in hepatic veins. After liver transplantation, ligation of lymphatic vessels at the hilum reduces chylous ascites and results in lymphatic dilatation which is easily observed. In severe long-standing biliary stenosis, dilated lymphatic vessels are commonly demonstrated with non-contrast MR lymphography. In hepatocellular carcinoma, intrahepatic cholangiocarcinoma, and some metastases, lymphatic vessels are abundant in the immediate vicinity of the tumour. These various lymphatic abnormalities can be demonstrated with non-contrast MR lymphography.Key Points • Anatomy and pathology of the lymphatics of the liver are relatively unknown, partly because of lack of current imaging technique. • Non-contrast MR lymphography is obtained with a free-breathing 3D high spatial resolution fast spin-echo sequence similar to that used for 3D MR cholangiopancreatography. • Non-contrast MR lymphography may participate to the understanding of several abnormal liver conditions including portal hypertension, biliary diseases, and malignant hepatic tumours

Predictive criteria of response to endoscopic treatment for severe strictures in primary sclerosing cholangitis

International audienceBackground: The aim of this study was to identify predictive criteria of improvement after endoscopic treatment (ET) for severe strictures of extrahepatic bile ducts in patients with primary sclerosing cholangitis (PSC).Methods: PSC patients who had at least one ET for severe stricture were included. Features of magnetic resonance cholangiography (MRC), performed before ET, were evaluated according to a standard model of interpretation, and a radiologic qualitative score of probability of improvement after ET was built. Score 3 (likely) was given in case of severe common bile duct (CBD) stricture with marked dilatation without severe strictures of upstream ducts, Score 1 (unlikely) was given in case of severe multiple strictures of secondary ducts without biliary dilatation and Score 2 (undeterminate) was given to an intermediate pattern. The response to ET was assessed at 2 months (T2-response) from the last ET and at 12 months (T12-response) from inclusion.Results: Thirty-one patients were included. All had severe stricture (reduction ≥ 75% of the diameter) of CBD and 50% had severe stricture of right and/or left hepatic duct (LHD) at MRC before ET. According to the qualitative score, 16 patients had Score 3, 7 had Score 1 and 9 had Score 2. T12-response was obtained in 50% of patients. In univariate analysis, short LHD strictures, bilirubin, transaminases, pruritus and Score 3 were associated with T12-response. Increased bilirubin and transaminases were independent predictive factors of T12-response (HR 24, 95% CI: 3.4–170.4, P = 0.001 and 23.8, 95% CI: 3.4–169.4, P = 0.002, respectively).Conclusion: MRC, together with biochemical features, may contribute to identify the PSC patients who are likely to be improved after ET for severe strictures of extrahepatic bile ducts

Are Gadolinium-Enhanced MR Sequences Needed in Simultaneous 18 F-FDG-PET/MRI for Tumor Delineation in Head and Neck Cancer?

International audiencePET/MRI with 18F-FDG has demonstrated the advantages of simultaneous PET and MR imaging in head and neck cancer imaging, MRI allowing excellent soft-tissue contrast, while PET provides metabolic information. The aim of this study was to evaluate the added value of gadolinium contrast-enhanced sequences in the tumor delineation of head and neck cancers on 18F-FDG-PET/MR imaging