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Clinical issue: Cystic liver lesions incorporate a broad heterogeneous group of mostly benign but also malignant abnormalities. The radiological aim is the non-invasive diagnosis with the use of different imaging modalities to determine the type of lesion.Standard radiological methods: The common generally asymptomatic incidental findings of cystic lesions on ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) must be classified on the basis of specific imaging features. Such a differentiation is essential because the clinical consequences and the appropriate therapy can vary depending on the underlying pathology. Due to the morphological overlap of many cystic lesions, conventional radiological methods are often insufficient.Methodical innovations: The huge advances in cross-sectional imaging (multidetector CT, MRI with special sequences and different contrast agents and MR cholangiopancreatography) in combination with the clinical history usually enable a non-invasive diagnosis. Pathognomonic morphological and hemodynamic lesion features, as well as a knowledge of the pathomechanisms, help to differentiate this broad spectrum of entities.Achievements: In this article the different entities of cystic liver lesions, together with the appropriate diagnostic method for detection and distinction and including their strengths and limitations, are demonstrated.Practical recommendations: A well-founded knowledge about the development of various cystic liver lesions and the suitable choice of imaging method facilitate a non-invasive diagnosis.

Die fokale nodulare Hyperplasie (FNH) und das hepatozellulare Adenom (HCA) sind Leberlasionen hepatozellularen Ursprungs. Die FNH ist eine sehr haufige, das HCA eine sehr seltene Leberlasion. Die Unterscheidung zwischen einem HCA und einer atypischen FNH kann eine grose Herausforderung darstellen, da beide Entitaten vorwiegend bei Patientinnen mittleren Alters vorkommen. Die konventionellen Bildgebungsmodalitaten beinhalten die Sonographie (US), die Computertomographie (CT) und die Magnetresonanztomographie (MRT). Die Unterscheidung zwischen der FNH und dem HCA ist klinisch von groser Relevanz, da fur FNH keine Behandlung notwendig ist, wohingegen HCA ublicherweise aufgrund des Risikos einer Ruptur, Blutung oder einer malignen Entartung ein individuelles Management erfordern. Die genannten radiologischen Verfahren ermoglichen meistens eine genaue und sichere Diagnose einer typischen FNH. Liegen jedoch atypische Zeichen einer FNH vor, v. a. in Kombination mit der Anamnese einer malignen Grunderkrankung, sind diese Bildgebungsmodalitaten fur eine exakte Diagnosestellung unzureichend. Im Falle atypischer FNH ist der Einsatz der modernen MRT-Technik mit hepatobiliarem Kontrastmittel gegeben, die einerseits fur die Differenzierung der FNH von Metastasen eine hohe Sensitivitat und Spezifitat zeigt und andererseits 90 % der Adenomsubtypen gegenuber einer FNH zu unterscheiden vermag. In diesem Artikel werden die histopathologischen und radiologischen Merkmale beider Entitaten erlautert sowie die zur Differenzierung und Diagnose hilfreichen Bildgebungsmodalitaten inklusive der Vor- und Nachteile erklart. Die Differenzierung von FNH und HCA, die neue Klassifikation der HCA nach den phano- und genotypischen Eigenschaften, und die Korrelation mit den typischen MR-Merkmalen sowie dem unterschiedlichen Anfarbeverhaltensmuster werden aufgezeigt. Schlieslich werden die individuellen Behandlungsstrategien der HCA-Subtypen diskutiert.

Das Fach Radiologie hat in der Medizin eine Sonderstellung erlangt. Eine exakte Diagnose ist entscheidend, um rasch und effizient behandeln zu konnen. Dies wirkt sich direkt auf den einzelnen Patienten aus, was mit einer Verkurzung der Zeit bis zur Diagnosestellung, dem Vermeiden unnotiger invasiver Methoden oder teuren zeitaufwendigen Verlaufskontrollen einhergeht. Die MRT stellt aufgrund ihrer kontinuierlichen Entwicklungen der letzten Jahre ein Musterbeispiel dar, v. a. bei der Diagnostik der verschiedenen Lebererkrankungen. In diesem Artikel erlautern wir den direkten Zusammenhang zwischen neueren technischen Entwicklungen im Bereich der MRT wie 3,0 T, diffusionsgewichteten Sequenzen, Perfusions-MRT, Spektroskopie, Texturanalyse sowie MR-Elastographie und dem Stellen einer sicheren, nichtinvasiven Diagnose der fokalen und diffusen Leberveranderungen.

Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) are liver lesions of hepatocellular origin. The FNH is a commonly occurring hepatic lesion whereas HCA is very rare. Non-invasive differentiation between HCA subtypes and atypical FNH may pose a diagnostic challenge as both entities predominantly occur in middle-aged female patients.The conventional imaging modalities include ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI). Distinguishing FNH from HCA is of great importance clinically as FNH is considered to be a benign lesion and needs no further management. In contrast HCA is considered to be a borderline tumor due to the risk of hemorrhage, growth and even malignant transformation and requires individualized management.The above mentioned radiological procedures usually enable an accurate and certain diagnosis of a typical FNH to be achieved. In cases of atypical FNH, particularly in patients with a clinical history of malignancy, these imaging modalities are insufficient to establish a clear diagnosis. In this scenario, the use of modern hepatobiliary contrast-enhanced MRI will enable a differentiation between FNH and metastasis with a high sensitivity and specificity. Furthermore, it allows a differentiation of FNH from 90 % of adenoma subtypes.This article describes the histopathological and radiological features of these lesions and explains the advantages and limitations of various imaging modalities used for the diagnosis and differentiation of these entities.The new classification of HCAs according to phenotype and genotype and their imaging features, as well as different enhancement patterns, are described. The correlation between HCA subtypes and their individual management are also discussed.

Cystic liver lesions incorporate a broad heterogeneous group of mostly benign but also malignant abnormalities. The radiological aim is the non-invasive diagnosis with the use of different imaging modalities to determine the type of lesion.The common generally asymptomatic incidental findings of cystic lesions on ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) must be classified on the basis of specific imaging features. Such a differentiation is essential because the clinical consequences and the appropriate therapy can vary depending on the underlying pathology. Due to the morphological overlap of many cystic lesions, conventional radiological methods are often insufficient.The huge advances in cross-sectional imaging (multidetector CT, MRI with special sequences and different contrast agents and MR cholangiopancreatography) in combination with the clinical history usually enable a non-invasive diagnosis. Pathognomonic morphological and hemodynamic lesion features, as well as a knowledge of the pathomechanisms, help to differentiate this broad spectrum of entities.In this article the different entities of cystic liver lesions, together with the appropriate diagnostic method for detection and distinction and including their strengths and limitations, are demonstrated.A well-founded knowledge about the development of various cystic liver lesions and the suitable choice of imaging method facilitate a non-invasive diagnosis.

Radiology has gained an exceptional position in medicine because a correct diagnosis is the most crucial issue in determining an accurate and personalized therapeutic strategy. This has a direct influence not only on the individual patient but also on the socio-economic aspects of healthcare services in terms of shortening the time interval to establish a diagnosis and to avoid risk-associated invasive diagnostic methods or long-term, cost-intensive follow-up. Magnetic resonance imaging (MRI) is an excellent example of this which due to continuous technological developments and emerging techniques allows a non-invasive diagnosis of the different hepatic diseases. In this article, we illustrate the direct correlation between the recent technical advances in MRI, such as 3.0 T, diffusion-weighted imaging, perfusion imaging, spectroscopy, texture analysis and MR elastography and obtaining a confident non-invasive diagnosis of focal and diffuse liver diseases.