Muscle and Nerve Imaging

This issue on muscle and nerve imaging relates to the theme of the European Society of Musculoskeletal Radiology (ESSR) meeting in Amsterdam (June 13–16, 2018). The ESSR promotes educational and research activities and is celebrating “25 years of excellence in musculoskeletal imaging.” This is a significant milestone for the society that has a growing number of members (∼ 1,800 at present) (www.essr.org).

Musculoskeletal radiology is a very innovative field of imaging, exploring new diseases, novel imaging techniques, and especially expanding clinical applications. Muscle and nerve is currently a hot topic, accelerated by new developments in both ultrasound (US) and magnetic resonance imaging (MRI) that offer highly detailed anatomical images of even the smallest nerves. Precise knowledge of nerve anatomy is consequently essential, in addition to knowing how to optimize imaging techniques and interpret pathology.

Imaging of muscle injuries is an important topic in sports, for professionals as well as amateurs of all ages. It is imperative to realize that patients of different ages have different types of injuries: bony avulsions, muscle tendon junction pathology or muscle tears. Clinicians rely on state-of-the-art imaging to treat their patients. However, differential diagnoses should always be considered including primary and secondary muscle diseases. This is especially critical because nonradiologists increasingly use US in their daily practice. When in doubt, they should not hesitate to consult radiologists to take advantage of their experience with a broad spectrum of pathology.

Loss of muscle quality, seen as muscle atrophy and fatty infiltration, can have multiple causes. It can be secondary to a muscle tear but also to neurologic disease or nerve entrapment. General muscle loss affects chronically ill patients but is also seen in the daily lives of the healthy elderly population. As populations continue to age worldwide, the impact of sarcopenia on public health will continue to grow; sarcopenia is an essential consideration on the agenda of vital aging. Radiologic imaging plays an important role both to diagnose muscle loss and also quantify it. The latter is a future application that may be of additional value in the management of muscle diseases and sarcopenia.

This issue presents 10 review articles on muscle and nerve anatomy including US and MRI techniques and both common and relatively rare pathology. The personal experience of the authors in addition to literature reviews will help readers put practical possibilities and limitations in perspective.

The first five articles focus on the muscles. The muscle-tendon-enthesis unit and accessory muscles are addressed separately. Primary and secondary involvement of muscles with differential diagnoses are described in the articles on myositis and fasciitis, patterns of muscle atrophy, and sarcopenia.

The remaining five articles focus on the nerves. US technique of the brachial plexus is introduced with its advantages and limitations. The technique of magnetic resonance neurography is explained systematically and will help readers get started. The use of US in imaging nerve entrapment is addressed in the elbow and wrists well as in the ankle and foot. In addition, the indications for US-guided treatment of peripheral nerve pathology, including tips and tricks, are highlighted in a separate article.

I trust readers will be challenged whether they are beginning or advancing their knowledge of the imaging of muscles and nerves. This information in this issue will guide clinicians in optimizing patient care.