Imaging Semiology: Ultrasound and MRI in the Assessment of Muscle Injury

Abstract

Competitive athletes are at a high risk for acute and repetitive muscle injury. Although the clinical examination remains the core of any patient evaluation, radiology plays an increasingly important role in the initial assessment and follow-up of muscle injury. Muscle injuries are responsible for a large proportion of time lost to competition. Appropriate management decisions, return to training and competition, and prediction of injury recurrence may all be influenced by appropriate imaging. Magnetic resonance imaging (MRI) has been applied to muscle injuries for more than a decade and has evolved into a valuable tool for the routine evaluation of traumatic muscle injuries in athletes. Ultrasound remains a popular alternative modality for the assessment of acute muscle injury and has some definite advantages over MRI: lower cost and greater availability, short imaging time, no contraindications (e.g. pacemakers), capability for dynamic imaging and comparison with the contralateral side. However, user dependence and lower sensitivity tend to outweigh some of these advantages. This chapter will outline the semiology of muscle injuries, that is describe different types and signs of musculotendinous injuries including musculotendinous strain, muscle contusion and avulsion injury. The focus of this chapter is on clinically applicable techniques of standard MRI and ultrasound.