**1. Introduction**

It might be strange to begin a chapter on diagnostics in the 21st century by highlighting doubts. Yet, the structure and physiology of muscles still escape our full understanding as the muscular system is a heterogeneous structure able to adapt to numerous functional demands, linked to physiological needs or pathologies. Indeed, the muscle is a complex mechanism, in which the phenotypical and morphological profile of the fibres varies between the double insertions and from surface to depth, and it adapts depending on stressors and stimuli which, independently of age, gender and physical activity, give rise to different responses within the same muscle. For these reasons the muscle appears to be a complex and not fully explored world.

This aspect is mainly concerned with physiopathology, and diagnostics nowadays has reached levels which perhaps were unimaginable 20 years ago. The development of electronic engi‐ neering has led to the construction of diagnostic machinery able to identify the finest details of the muscle. As history has proved, the continuous development of Ultrasound and MRI equipment, not to mention TAC, has changed the doctors' modus operandi over a period starting from the first musculoskeletal ultrasound image in 1972 by Leopold and McDonald to current 3D images, or from the first MRI image developed in the '70s to the current 3 Tesla MRI equipment.

The use of these devices in muscular injury diagnostics has acquired fundamental importance in Sports Medicine as regards diagnosis, prognosis and rehabilitation. The choice of using either Ultrasound or MRI is still subject to debate as it is influenced by several factors, such as type of injury, availability of the devices, the Radiologist's knowledge of Sport injuries, and the cost-benefit ratio, all of which the Sports Physician must evaluate carefully.

As the clinical cases shown prove, the difference in quality and accuracy of the images is well defined in favour of the MRI, but the decision still remains subject to a multifaceted vision.

© 2013 Manara et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
