General Principles
- •
Imaging in sports medicine plays an increasingly important role in the diagnosis of injury and in decision making regarding return to play.
- •
Increasingly sophisticated imaging modalities allow for the precise diagnosis of various patterns of injury but also present the care provider with a bewildering range of tests.
- •
Continued participation of older athletes in sporting activities also presents a challenge as degenerative findings become intermingled with sports-related injuries detected by imaging studies.
Indications for Imaging
- •
The approach to imaging in sports medicine mirrors the philosophy applied in clinical medicine as a whole. Imaging should primarily be pursued only when it is likely to alter the management of the patient and when the benefits outweigh the risks. The cost and availability of imaging studies are also important factors to consider ( Box 63.1 ).
Box 63.1
Indications for Medical Imaging in Sports Medicine
- •
Imaging likely to change clinical management
- •
When diagnosis is established but extent of injury and associated injuries must be defined
- •
When conservative management has failed
- •
When atypical or systemic symptoms are present that cast doubt on a common diagnosis
- •
When additional information is needed for surgical planning
- •
- •
It is important to consider the risks of exposure to ionizing radiation, particularly in young or pregnant patients. In addition, discomfort, expense, and inconvenience of imaging to the patient are valid concerns.
Imaging Techniques
- •
Musculoskeletal imaging techniques used in sports medicine provide an excellent depiction of anatomic structures and often facilitate a precise diagnostic accuracy. Imaging modalities differ in their mode of image generation and in terms of cost and radiation exposure.
- •
Radiographs (plain radiographs) create two-dimensional images of anatomy and typically serve as the first-line imaging study. Computed tomography (CT) also uses ionizing radiation to create cross-sectional images. Nuclear medicine examinations (including bone scintigraphy) detect gamma rays emitted from a radiopharmaceutical administered to the patient. Each of these modalities requires exposure of the patient to ionizing radiation.
- •
Magnetic resonance imaging (MRI) does not use ionizing radiation but is contraindicated for certain patients with metallic implanted medical devices. Ultrasound is generally safe, although tissue heating may be a concern.
- •
The use of the modern picture archiving and communication system (PACS) software allows diagnostic images to be stored and shared widely, which has greatly increased the portability of imaging information.
- •
The judicious use of ionizing radiation is critical in protecting the safety of sporting patients, particularly the young who face greater theoretical lifetime risks from exposure to ionizing radiation. Some common examinations and typical dose levels are listed in Table 63.1 .
TABLE 63.1
COMMON EXAMINATIONS AND TYPICAL DOSE LEVELS
Examination
Average Effective Dose (mSv)
Chest (Posteroanterior and Lateral)
0.05
Extremity Radiograph
0.005
Abdomen, Hip or Pelvis Radiograph
0.7
Thoracic or Lumbar Spine Radiographs
1.25
CT Thoracic or Lumbar Spine
6
CT Abdomen/Pelvis
8–14
Bone scan
6.3
- •
The diagnosis and management of injuries in sports medicine greatly relies on accurate history and physical examination findings as well as an understanding of the mechanism of injury. Communicating this information at the time of an imaging request allows the radiologist to interpret studies in the appropriate clinical context and provide the most accurate report.
- •
A close working relationship among sports medicine providers, radiologic technologists, and diagnostic radiologists helps foster an efficient system and ensure that appropriate care is delivered to the patient.
Radiographs
- •
Radiographs (plain radiographs) use ionizing radiation and provide excellent depiction of bony anatomy with very high spatial resolution. The PACS software allows radiographic images to be windowed and leveled, which reveals additional detail in the soft tissues.
- •
Advantages: The benefits of radiographic evaluation are the high spatial resolution and high sensitivity in detecting subtle fractures or dislocations. Radiographs are widely available, and a multitude of standardized views have been developed to evaluate each bone and joint.
- •
Disadvantages: Radiographs generate images through the use of ionizing radiation, and thus, care must be exercised in their use, particularly in young athletes. However, the overall dose is small, particularly when imaging extremities (see Table 63.1 ). Dose is more substantial when imaging the hip, pelvis, or spine because these structures are deeper in the patient and require a greater radiographic exposure to penetrate surrounding soft tissues and to provide images of diagnostic quality.
- •
While the spatial resolution is high, soft tissue contrast is limited; thus, radiographs are less useful in assessment of soft tissue injuries. However, in several cases, the exclusion of a bony component to an injury is sufficient to direct appropriate management.
- •
Common indications: When an imaging study is required in the evaluation of an injured athlete, radiographs are almost always the starting point. Even if no fracture or dislocation is present, other features such as a joint effusion may direct the provider to suspect an occult intra-articular injury.
- •
Fractures are well depicted by radiographs, and at least two orthogonal views are required to depict any displacement or angulation that may be present. When the patient requires additional imaging with another modality such as MRI, the radiographs still play an important role in depicting the bony anatomy and may improve the accuracy of MRI interpretation.
- •
Certain diagnoses such as an anterior shoulder dislocation may be obvious by clinical examination, but radiographs confirm the diagnosis and are critical for demonstrating significant fractures that may accompany the dislocation ( Fig. 63.1A ).
