In patients with collagen vascular disorders, e.g. scleroderma, GGO secondary to pulmonary involvement needs to be differentiated from drug-induced lung disease. This refresher course will put GGO in the context of outpatients versus inpatients, the acuity of clinical symptoms, e.g. fever, cough and dyspnoea, signs of massive systemic inflammation, and the clinical situation such as inhalational history, pneumotoxic drug administration, immunocompromisation, or bone marrow-suppression. This lecture will introduce the neuroradiological findings of the three commonest phakomatoses referred for neuroimaging in paediatric practice, namely Sturge-Weber syndrome, Tuberous sclerosis complex and Neurofibromatosis type 1. I will present the findings on the background of the suspected pathogenesis of the conditions with the aim of making the imaging findings understandable. Appropriate imaging protocols will be discussed for each of the conditions. Ground-glass opacity (GGO) is characterised on HRCT by the presence of a hazy increase in lung opacity that does not cause obscuration of underlying bronchial and vascular margins. Although a very common finding, it also constitutes a very nonspecific term since it can be seen in a variety of different intraalveolar and interstitial processes with different histology including inflammatory, infectious and neoplastic diseases that have a common physiologic mechanism: partial displacement of air. Ground-glass opacity may even be seen in normal processes such as poor ventilation in dependant lung areas and in expiration. Moreover, GGO can represent either an ongoing, active and potentially treatable disease or an irreversible process. In order to interprete correctly this highly nonspecific but very significant finding it is crucial to attempt to further classify the different large main entities in which this radiological finding appears. Are there specific radiological and HRCT findings that can help us differentiate GGO in autoimmune-inflammatory conditions from infectious and neoplastic processes? Are there associated findings other than GGO -such as nodules, reticulation or focal disease and distribution of findings that can narrow the differential diagnosis? Systematic evaluation of GGO and associated findings as well as integration with clinical information (acute, subacute or chronic symptoms) is essential in defining GGO subtypes in order to improve radiological diagnosis. Radiologists who regularly review high-resolution CT (HRCT) should be aware of the range of patterns and, more importantly, their potential pathological meaning. A pattern of ground-glass opacification is one of the more common HRCT findings but, to the unwary, its interpretation can be problematic. An important underlying principle is that a ground-glass pattern may be caused by any process -physiological or pathological -which partially displaces air. Physiological (i.e. non-diseaserelated) ground-glass opacification is perhaps most commonly seen in subjects who, for whatever reason (e.g. breathlessness, obesity), are unable maintain or achieve a satisfactory inspiratory effort during scanning. A generally increased lung density (in contrast to adults) is also a feature in infants and young children simply because there are fewer alveoli in the developing lung. Finally, it is worth noting The number of 7T magnetic resonance (MR) scanners is growing rapidly, and 7T has proved beneficial for MR imaging and spectroscopy. 7T provides the principal advantages of higher image signal-to-noise ratio, changes in T1, T2 and T2* contrast and increased blood oxygenation level-dependent (BOLD) contrast for use in functional MRI. These gains can be exploited to improve the spatial resolution and/or temporal resolution of anatomical and functional images. Changes in contrast can be exploited to enhance depiction of pathology such as lesions in multiple sclerosis, and neurodegenerative conditions such as Alzheimer's and Parkinson's disease. Whilst for MR spectroscopy, 7T provides the advantage of increased spectral resolution. 7T has opened up novel contrast mechanisms including susceptibility-weighted imaging (SWI) which provides information on the local variation in magnetic susceptibility highlighting differences in iron concentration and myelin. Ultra-high field provides increased longitudinal relaxation times, providing increased signal changes for Arterial Spin Labelling (ASL). This presentation will discuss the advantages of 7T and the applications which benefit from 7T over lower field MR. The limitations of 7T in the clinical setting will be discussed, including the issue of specific absorption rate (SAR), and B1 and B0 inhomogeneity. Technical developments to overcome these limitations and enable the wider clinical use of 7T MR will be discussed. Over the recent years the clinical MRI field strengths have gradually been increased to 3 Tesla; however, whole body MRI systems with higher fields of up to 9.4 Tesla have become available in experimental settings. Compared with clinical field strengths, MRI at very high magnetic fields has several advantages but also some unique challenges. With increasing field strength the signal-to-noise ratio increases, which can be used to either increase the spatial resolution in the images, or to acquire the images more rapidly. Unfortunately, the energy deposited in the human body via the RF excitation scales quadratically with the field strength. Thus, the specific absorption rate (SAR) is a critical factor in all rapid imaging protocols and requires the design of RF pulses with low SAR, (e.g. VERSE pulses). Inhomogeneities of the RF field which are induced by standing wave phenomena have to be compensated and make the design of efficient spin echo pulse sequences very difficult. At higher field also the field inhomogeneities become larger and stronger imaging gradients are required to overcome the susceptibility-induced image distortion. Stronger gradient systems are difficult to manufacture, and the usable gradient slew rate is limited by peripheral nerve stimulation thresholds. Furthermore, stronger and faster gradients become very loud at high fields, and special measures for sound protection are required. Despite these limitations, high field MRI offers image with very high resolution, it provides unique contrasts, a better spectral separation of the resonance lines and high signal for non-proton applications. MRI has become a vital tool for clinical diagnosis and research. A major current trend is the introduction of more powerful static magnetic fields, in particular human research magnets > 3 T. Advantages of higher magnetic fields include higher SNR and unique tissue contrasts due to enhanced sensitivity to tissue susceptibility differences. As field strength increases, the frequency of the RF fields used for tissue excitation increases linearly according to the Larmor relation, leading to correspondingly shorter wavelengths inside the tissue. Interference and penetration effects make it quite difficult to achieve RF excitation uniformity, particularly in body applications when a large cross-section is imaged, and lead to subjectdependent signal dropouts according to body habitus. The inherent advantages of higher magnetic fields can thus often not be leveraged to realise expected imaging benefits. Preliminary research indicates that these effects can be addressed by use of parallel transmission strategies such as RF shimming and Transmit SENSE: in RF shimming a multi-element transmit coil array is driven with amplitude and phase weightings optimised for a particular body region; Transmit SENSE is a further generalisation in which different RF pulse waveforms are applied to each element. These novel excitation strategies result in alterations of the RF energy distribution in the tissue, making new demands on the prediction and monitoring of SAR and concomitant tissue heating. Once these challenges are mastered, it Most biliary intervention is performed endoscopically but endoscopy may fail and the antegrade placement of a catheter into the bowel assists endoscopic access. Previously, the primary management of malignant bile duct obstruction was with the endoscopic placement of 10 F plastic stents. When ERCP failed, PTC using a 7 F catheter allowed the placement of an endoscopic 10 F stent but kept complications low because of the avoidance of a 10 F trans-hepatic track. Now, with the advent of 6 Fr trans-hepatic delivery systems for 10 mm diameter metal stents this combined procedure has fallen into disuse. Endoscopic access for the management of stones can fail, most commonly because of a peri-ampullary diverticulum.