Radiologic Imaging Techniques

Abstract

Accurate diagnosis with the use of radiological imaging is often required if clinical findings in sports injuries are nonspecific. The preferred imaging modality is multifactorial. Often an optimal imaging pathway is not available. This chapter reviews the general imaging strategies that can be employed to diagnose and grade sports injuries. Radiographs in two orthogonal perpendicular projections are generally the first and often the only imaging needed for the evaluation of fractures. In case of clinical suspicion of radiographic occult fracture, MRI is the method of choice. The presence of radiopaque foreign bodies, intra-articular bone fragments, or advanced degenerative joint changes and the results after fixation can be assessed with radiographs.

Major advantages of US are its high spatial resolution for superficial structures, low cost, availability at short notice, ease of examination, short examination times, and lack of radiation exposure. Since approximately 30 % of sports injuries deal with muscle and tendon injuries, ultrasound (US) plays a major role in primary diagnosis of sports traumatology. US palpation, active and passive dynamic US study, and color-power Doppler imaging may be very helpful to the correct diagnosis. In patients with tendinosis, angiogenesis in the tendon may be correlated with clinical symptoms and discriminates early from advanced stages of tendinopathy. Furthermore, US provides image guidance for interventional procedures. For better evaluating deeply located structures, other (cross-sectional) imaging modalities may be required. Other disadvantage of ultrasound includes operator dependency.

CT imaging, by virtue of its excellent multiplanar capability and submillimeter spatial resolution, is a valuable imaging tool for the evaluation of all kinds of sports injuries. It has proved to be an effective method for documenting bone injuries particularly in complex bony structures such as the wrist and pelvis and may often show post-traumatic changes not shown by radiography. It may be helpful for the assessment of comminuted fractures, improving visualization of the fracture’s extent and location, shape and position of the fracture fragments, and the condition of articular surfaces. New iterative CT reconstruction algorithms and cone beam computerized tomography (CBCT) techniques are developed to reduce radiation dose with similar or even increased image quality.

The major advantage of CT arthrography (CTA) is the assessment of the cartilage lesions continuous with the articular surface of the cartilage. Limitations of CTA include its invasiveness, possible allergic reaction, use of ionizing radiation, and poor extra-articular soft tissue contrast resolution.

Magnetic resonance imaging is the most complete radiological imaging technique with accurate evaluation of musculoskeletal soft tissue, bone, and joint structures. Its major indication in sports injury is internal derangement of joints, occult bone fractures, stress reaction and fracture of bone, and deeply located muscle and tendon tears. Acute, subacute, and active chronic lesions are demonstrated with high conspicuity due to their increased water content that produces a “light bulb effect” on fat-suppressed sequences with long repetition time (TR); this sequence has become the cornerstone of musculoskeletal imaging.

Equipment and techniques for MRI vary widely; it is generally accepted that high-field-strength magnets provide the highest quality images.

Major indications for MR arthrography (MRA) are labral lesions of the shoulder and hip joint, TFC and intrinsic ligament lesions of the wrist, and grade III osteochondral lesion of the talus.