Muscle imaging is inherently complex and presents unique morphological challenges and continuing integration of dynamic, physiological and functional capabilities as imaging technology progresses. In sports medicine, high-resolution ultrasound (US), which is now available not only in high-end equipments but also in portable machines, has proved to be an excellent tool to evaluate muscle strain and contusion injuries in athletes, providing good correlation with clinical findings. In the acute phase, US has nearly equal sensitivity to MR imaging to diagnose muscle strains, except in the first few hours after the injury, when fresh haemorrhage and oedema have similar echogenicity to normal muscle and strains may go unnoticed. Later in the process, US has been shown to be a useful tool in assessing the sequential stages of muscle repair. Local complications, such as vein thrombosis, irritation of adjacent neurovascular bundles, chronic haematoma and myositic ossificans can be demonstrated with this technique as well. However, US tends to underestimate the extent of injury and the abnormalities seen disappear more quickly when compared with MR imaging. At least in elite athletes, MR imaging seems, therefore, to play a more significant role in management of muscle injury, particularly when decisions regarding the time at which the patient can return to play are needed. By contrast, US is quicker, more accessible and cheaper than MR imaging. In most clinical settings, US should be regarded as the first-line imaging choice for assessing skeletal muscle injury. Learning Objectives: 1. To understand the mechanism of injury of muscles in athletes. Sports activity can affect tendons due to chronic overuse or acute injury. Both can result in complete tendon rupture. US is helpful not only in precise assessment of rupture severity and extent, but also in assessment of tendon degeneration, where rupture of individual collagen fibres stimulates a chronic cycle of reparative response caused due to repetitive microtrauma. In chronic tendinopathy histopathological changes, such as hypoxic, mucoid, calcifying, or lipoid degenerations are present. US enables differentiation of partial tears, tendinosis, tenosynovitis or paratendinosis because of active and passive dynamic examination possibilities and high-resolution capability when using high-frequency probes. US developments as power Doppler US, sonoelastography and contrast-enhanced US allow further new insights into tendinopathy. With the use of US, tendon changes can be Learning Objectives: 1. To appreciate the proposed mechanisms of pathogenesis of endometriosis and the relationship with the distribution of disease. 2. To be able to identify the most common imaging findings of endometriosis and to discuss the differential diagnosis.