[Modern diagnostics of cystic liver lesions and hemangiomas]. / Moderne Diagnostik zystischer Leberläsionen und Hämangiome.

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.

[Focal nodular hyperplasia and hepatocellular adenoma]. / Fokale noduläre Hyperplasie und hepatozelluläres Adenom.

CLINICAL ISSUE: 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. STANDARD RADIOLOGICAL METHODS: 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. METHODOLOGICAL INNOVATIONS: 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. ACHIEVEMENTS: 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. PRACTICAL RECOMMENDATIONS: 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.

[Detection of lung nodules. New opportunities in chest radiography]. / Detektion pulmonaler Rundherde. Neue Möglichkeiten der Thoraxradiographie.

BACKGROUND: Chest radiography still represents the most commonly performed X-ray examination because it is readily available, requires low radiation doses and is relatively inexpensive. However, as previously published, many initially undetected lung nodules are retrospectively visible in chest radiographs. STANDARD RADIOLOGICAL METHODS: The great improvements in detector technology with the increasing dose efficiency and improved contrast resolution provide a better image quality and reduced dose needs. METHODICAL INNOVATIONS: The dual energy acquisition technique and advanced image processing methods (e.g. digital bone subtraction and temporal subtraction) reduce the anatomical background noise by reduction of overlapping structures in chest radiography. Computer-aided detection (CAD) schemes increase the awareness of radiologists for suspicious areas. RESULTS: The advanced image processing methods show clear improvements for the detection of pulmonary lung nodules in chest radiography and strengthen the role of this method in comparison to 3D acquisition techniques, such as computed tomography (CT). ASSESSMENT: Many of these methods will probably be integrated into standard clinical treatment in the near future. Digital software solutions offer advantages as they can be easily incorporated into radiology departments and are often more affordable as compared to hardware solutions.

[Dose reduction and adequate image quality in digital radiography: a contradiction?]. / Dosisreduktion und adäquate Bildqualität in der digitalen Radiographie: ein Widerspruch?

CLINICAL/METHODICAL ISSUE: Dose reduction and adequate image quality in digital radiography - a contradiction? STANDARD RADIOLOGICAL METHODS: Digital radiography has already replaced traditional screen-film systems. METHODICAL INNOVATIONS: Substantial improvements in both dose efficiency and spatial resolution demonstrate the rapid developments in digital radiography. PERFORMANCE: Needle-detector systems have shown up to a 50% dose reduction compared to traditional screen-film systems. There is also a dose reduction capability of up to 50% comparing direct radiography (DR) systems to computed radiography (CR) systems for chest X-rays. However, despite the most recent achievements of CR technology, the dose efficiency of DR systems (caesium iodide flat-panel detector) is unparalleled. ACHIEVEMENTS: The progress in detector technology has contributed to dose reduction and improved image quality, while saving time and providing a higher examination rate. PRACTICAL RECOMMENDATIONS: The use of dose indicators and longitudinal dose control are important to avoid substantial accidental dose increase. The dose applied to patients should fall markedly below the defined diagnostic reference levels within the European Union. Regular quality control, as well as continuous education and training of medical and technical personnel, contribute to ensure that the ALARA (as low as reasonably achievable) principle is consistently followed.