advanced segmentation tools, every tissue may be highlighted or displayed in the background, thus providing additional information and helping to analyse liver anatomy. Virtual models can be ideally used in interventional procedures. Radiologists have to know the size and volume of the lesion to treat, as well as its precise location and relationship with the surrounding tissues. For a percutaneous approach such as radiofrequency ablation, the intervention can be planned and simulated by introducing, on screen, a "virtual" needle in the liver to reduce potential damage to the vessels and other organs when the "real" procedure will take place. These models may help not only interventional radiologists but also surgeons, who need to know the size and precise location of the lesion before operating on a patient. Laparoscopy is a typical example of how imaging can help to guide surgery. With this approach, the problem is that the field of view surgeons have is very limited because of the small size of the laparoscopic camera. A very good solution is to have a combination of both the live laparoscopic view and the preoperative or intraoperative processed images and models. Hepatic surgery requires detailed pre-operative evaluation of anatomical and structural analysis of each patient anatomical variation and topological distribution of anomalous structures and tumours. This includes a three-dimensional assessment of the liver segments based on vascular and biliary tree distribution. Furthermore, endoscopic and robotic surgeries rely on pre-operative planning and modelling of minimally invasive procedures that do not provide visual navigation that open surgery provides. Advanced image rendering and visualisation techniques are now available for surgeons to prepare their surgical interventions by extracting appropriate anatomical features from cross-section imaging techniques such as CT and MRI. These software programs that were initially expensive and only accessible to computer-savvy experts are becoming more widely accessible on personal computers and portable devices. Example of such software distributed for free under Open-Source licensing is the OsiriX software that allows 3D and 4D image manipulation and visualisation on standard personal computers. This software will be used to demonstrate the feasibility and practical usefulness of 3D rendering techniques for planning and modelling of surgical interventions. In addition to illustrating the different segmentation techniques, we will also review the different technical solutions available for accessing and manipulating three-dimensional images in the operating rooms. Different settings are applicable for different types of surgical interventions from endoscopic imaging to virtual reality rendering of images that can be used in the OR to the latest generation of "augmented-reality" techniques allowing real-time fusion of 3D rendered images with patient's physical anatomy. In the past decades x-ray fluoroscopy, ultrasound and endoscopic/laparoscopic imaging systems have been successfully used for intra-operative 2D and rarely 3D anatomical imaging. However, in the functional field only gamma probes were used as "1D" tools within surgical suites. In this presentation, the focus is on a novel imaging approach which allows the surgeon to acquire required functional 3D imaging information within the operating room with minimum interruption of the surgical workflow. We present the first success of this approach in terms of 3D intra-operative imaging using navigated low-energy gamma probes called freehand SPECT. We provide many examples of its successful deployment for different clinical applications based on diverse SPECT tracers. We will then discuss the possible application of similar technologies for intra-operative liver imaging. In this case, higher energy probes are needed as most liver tracers are PET tracers. We present the challenges that need to be overcome to finalise such solutions and discuss a few possible solutions. We will also demonstrate the possibility of then complementing such functional information with real-time 2D or 3D ultrasound imaging, and intra-operative 4D ultrasound-driven models of liver. In conjunction with advance As imaging modalities and computers have reached unmatched levels of precision, radiologists can now acquire very detailed information that they can use in 3D models within minutes after the examination, speeding up treatment planning. The co-called virtual imaging is proving to improve therapy outcome manifold, and its role might only increase in the future. This session will review all the progresses made from the detection and characterisation of liver disease to treatment planning. Knowing the latest advances in detecting and characterising liver disease has thus become mandatory to all radiologists, since an increasing number of molecular tools are currently being developed, and contrast media products targeting specific cells are multiplying. Biomarkers to assess liver functions or tumour activity/response have also become available. These spectacular computer science contributions to medicine will not require that the radiologist or the surgeon will eventually have to become computer experts themselves. The future will rather be based on a multidisciplinary integration which will allow surgery to be increasingly assisted by advanced imaging and computer technology. To develop virtual models of the liver that can serve as clinically useful imaging biomarkers, both the magnitude and the spatial distribution of the different objective measurements must be displayed. To be properly done, it is necessary to validate the relationship of the biomarkers with the reality of the organ and to check its technical and clinical usefulness. This process includes defining tests for the concepts and mechanisms; obtaining standardised and optimised anatomical, functional, and molecular images; analysing the data with computer models; displaying data appropriately; obtaining the appropriate statistic measures; and conducting tests on the principle, efficacy, and effectiveness. The development, standardisation, and optimisation of the different imaging acquisition protocols (for US, CT, MR and PET) and data analyses (physiological and biochemical computing, fusion of modalities, adequate measurements) will change some clinical research and patient care scenarios. In multimodality imaging, the need to combine morphofunctional and biological information can be approached by either acquiring images at different times (asynchronous) and fusing them through digital image manipulation techniques or simultaneously acquiring or computing images (synchronous) and merging them automatically. MR diffusion-weighted, MR and US contrast-enhanced pharmacokinetic imaging, cellular imaging, chemical quantitative imaging and PET tracers will be co-registered and merged to further increase molecular and functional imaging as a relevant medical discipline in hepatology. Multimodality imaging models will be displayed as parametric or multiparametric graphs of the liver reality associated with the DICOM Structured Reporting initiative as the standardisation of structured data and clinical observations in the liver imaging environment. Osmolality, iconicity and viscosity are important physicochemical factors which influence the safety of these agents. Gd-CM are either linear or macrocyclic and available as ionic or non-ionic preparations. The stability of the Gd-CA is an important safety feature of these agents particularly in patients with reduced renal function. The macrocyclic agents have high kinetic stability, whereas the non-ionic linear preparations have low kinetic and thermodynamic stability. Contrast media adverse effects can be divided into acute and delayed reactions. Acute reactions are allergic like and usually develop within one hour of CM administration. Delayed reactions develop after an hour and within a week of CM administration. Acute reduction in renal function referred to as contrast-induced nephropathy (CIN) may develop after contrast administration in patients with pre-existing risk factors. Patients with advanced reduction in renal function may develop the complication of nephrogenic systemic fibrosis (NSF) after administration of low-stability Gd-CM. In this session contrast-induced nephropathy and nephrogenic systemic fibrosis will be discussed. Measures to reduce the incidence these adverse effects will also be presented. Session Objectives: 1. To provide an understanding of the bio-distribution of extra cellular water soluble contrast agents after intravenous administration. 2. To highlight the physico-chemical properties that influence the safety of iodinebased and gadolinium-based contrast agents. 3. To provide a summary of the different adverse effects that might occur with the use of contrast agents including an approach to minimising the risk of these adverse events. The pharmacokinetics of iodinated contrast media are quite simple. They distribute evenly in the extravascular space and are excreted by glomerular filtration. No metabolisation occurs. The pathophysiology of CIN is complex and not well understood. Basically, a misbalance between vasodilatation and vasoconstriction takes place inside the kidney after intra arterial or intravenous CM administration. Furthermore, increased oxygen demand of tubular cells due to increased reabsorbtion of sodium and water is a second mechanism, leading to transient medullar ischaemia. The third mechanism is the increased production of reactive oxygen species (ROS) due to the developed ischaemia. ROS lead to more cellular injury and increased misbalance between vasodilatative and vasoconstrictive mediators. Identifying the patient at risk is the first step in prevention. Knowledge of the patient's medical record and a recent basic kidney function are mandatory. High-risk patients should receive prevention. Two major topics in CIN prevention are the questions whether iso-osmolar CM cause significantly less CIN than low-osmolar CM and whether hydration schedules with NaHCO3 give significantly less CIN than hydration schedules with NaCl 0.9%. The radiologist has three roles in the evaluation of pulmonary infection: 1) detection and description; 2) differential diagnosis; and 3) evaluation of complications. We will approach these through unknown cases and audience participation. Detection and description: In everyday practice, if the chest X-ray is negative, it is assumed, clinically, that the patient has no pneumonia. Unfortunately, this is not the case for immunocompromised patients, such as AIDS patients, bone marrow patients, etc. If there is strong clinical suspicion of pneumonia, a CT is often revealing when the chest X-ray was negative. Descriptors of pneumonia patterns are often confusing, because some descriptors are clinical, some are pathological, and many are based on early X-ray descriptions. These confusing, and often conflicting terminology issues will be addressed. Differential diagnosis: Imaging is not a substitute for microbiology. However, certain patterns are characteristic of certain types of infection and are often helpful in the initial clinical management of patients until cultures are available. The imaging appearance, combined with basic clinical information (white blood count, fever, and duration of illness) can often lead to the correct or narrowed differential diagnosis. Complications: The majority of pneumonias show imaging and clinical improvement within several days and complete resolution within four to six weeks. Deviation from this pattern suggests a complication, such as abscess, empyema, resistant organisms, a structural problem in the lung, or noninfectious diagnosis. These complications and the role of CT will be emphasised. Non-pulmonary infections may involve mediastinum, heart and vessels, chest wall and pleura. This course will focus on mediastinal, pleural and chest wall disease. Acute mediastinitis is a potentially life-threatening condition that is rare but requires prompt diagnosis and treatment. Spontaneous or iatrogenic esophageal rupture is the by far most common cause. Other causes include post-surgical mediastinitis and extension of infection from adjacent spaces (neck, pharynx, pleura or retroperitoneum). This course uses typical cases to discuss important differential diagnoses and the sensitivity and specificity of various radiologic findings for diagnosis of acute mediastinitis. The distinction between a parapneumonic pleural effusion and an empyema based on radiologic findings may be impossible. Features will be discussed hat suggest a "complicated" course that may requires interventional or even surgical treatment. Features that differentiate empyema from lung abscess at CT will be presented. An empyema necessitatis describes a chronic empyema that attempts to decompress through the chest wall. Underlying infectious agents include tuberculosis, actinomyces, staphylococcus and various types of fungi. It has to be differentiated from other mostly neoplastic diseases that tend to cross fascial planes such as lymphoma or Pancoast tumor. Currently, up to 50% of all MRI examinations worldwide are performed using contrast agents, either an extracellular agent or an organ-specific agent. The extracellular MRI contrast agents are chelates that contain the paramagnetic ion gadolinium which strongly affects the relaxation properties of water protons, leading to changes in tissue contrast. Gd-DTPA was the first extracellular agent to be introduced in clinical practice. Since the introduction of Gd-DTPA in 1988, various gadolinium chelates with different chemical properties became available for clinical use. For many years, it was believed that gadolinium-based contrast agents (GBCA) were nearly a 100% safe which led to a liberal and off label use of these agents. The condition that came to be known as nephrogenic systemic fibrosis (NSF) was first identified in 1997, but reported in the peer-reviewed literature in 2000. Since then, NSF has been the subject of a wide-ranging multidisciplinary medical investigation that has proven an indisputable link to renal disease and a compelling association with the increasing use of GBCA in the renally impaired. NSF is a severely disabling complication of renal disease with some features that overlap with those of other conditions. Accurate diagnosis of NSF requires careful clinicopathological correlation. US-and European authorities have confirmed the categorisation of GBCAs in three risk categories in view of NSF. The number of new NSF cases has been dramatically reduced since the introduction of these risk categories. In this talk also an update of NSF reports will be given. Both ultrasound (US) and magnetic resonance imaging (MRI) are recognised as generally safe imaging modalities and thus appropriate for use in the diagnostics of pregnant females and foetuses. However, to some extent both techniques may carry some risks when used during pregnancy which every radiologist must be aware of. Ultrasound may induce adverse effects by either thermal or non-thermal means. The risk of inducing thermal effects is greater in the second and third trimesters, when foetal bone is intercepted by the ultrasound beam. Non-thermal mechanisms include acoustic cavitation, radiation force and acoustic streaming and may be more significant in early gestation, when the relatively loosely tethered embryonic tissues are exposed to an ultrasound beam in a liquid path. The likelihood of producing cavitation-type non-thermal effects is enhanced by the presence in the sound field of gas-encapsulated echo-contrast media. There is no scientific evidence in humans to suggest that the risk to the foetus from a routine MRI imaging examination is significantly increased during pregnancy. The radiofrequency radiation pulses used in MRI imaging although nonionizing, result in energy deposition and can potentially lead to tissue heating. However, the use of single-shot echo train spin-echo sequences is commonplace in foetal imaging and unlikely to result in significant temperature changes. Another potential risk of MRI to the foetus is connected to intravenous application of gadolinium-based contrast agents, which are not recommended during pregnancy. Yet, available evidence suggests it is unlikely that these compounds have an adverse effect on the developing foetus. Patients suffering polytrauma require to be handled with a special approach and attitude of the medical personnel from the on-site primary care through the emergency room, diagnostic and life support measures to the operation theatre and the intensive care unit, because of the complexity and the life-threatening nature of the multiple injuries causing unique clinical consequences. The survival of these patients is greatly dependent on the duration of time elapsing between the injury and the start of definitive therapy. The role of imaging diagnostics is, on the one hand, essential to explore the lesions of key importance and, on the other hand, is limited by time constraint and urgency. A clear understanding of the task and an ability to work under pressure are required of the imaging diagnostic team. Suffering polytrauma in pregnancy is a very uncommon situation, which typically may occur as a result of motor vehicle accident or interpersonal (usually domestic) violence. In these cases, the absolute priority is the preservation of the life of the mother; therefore, the usual concerns regarding the use of ionising radiation and contrast media are of less importance. At the same time, the radiologist has to be aware of the special risks caused by potential injuries and their consequences on the pregnant uterus, placenta and foetus. The altered anatomical situation may also hinder the proper imaging evaluation of the situation. Pregnancy is a specific time during which special care must be taken of a mother and foetus whenever diagnostic imaging is necessary. Ultrasonography (US) and magnetic resonance imaging (MRI) are the safest imaging methods as they do not involve ionising radiation. They are not completely adverse effect free, i.e. both can cause tissue heating, which is potentially harmful to the foetus. Nevertheless, they should be considered as the methods of choice when maternal problems require diagnostic imaging, both preferentially without the use of contrast media. There are however clinical problems which cannot be solved without the use of ionising radiation. Two main clinical settings will be discussed during this session: polytrauma and pulmonary embolism (PE), both requiring computed tomography (CT) in most cases. In cases of polytrauma, saving the mother's life is a priority, and radiation protection of the foetus is a secondary problem. When CT angiography is performed to confirm or rule out PE, the protocols are optimised as far as the radiation dose and contrast medium volume are concerned (i.e. 100 or even 80 kV instead of 140 kV). The use of CT is considered to be quite safe in terms of foetus safety if the examination covers the region of the head, neck and thorax of the mother. However even with the use of CT in the region of the abdomen and pelvis, the threshold of 100 mGy is rarely exceeded. Session Objectives: 1. To become familiar with the risk of using radiological modalities in pregnant woman. 2. To consolidate knowledge of the pros and cons of the different imaging techniques. 3 . To learn about the indications requiring the use of imaging in pregnancy.