PRACTITIONER BRIEF INTRODUCTION

This article aims to give a brief introduction to radiology and the various techniques employed with particular reference to sport and exercise. A few basic rules and pitfalls of radiology will then be detailed. This article is by no means exhaustive but offers an overview of sports and exercise radiology.

By Dr Stephen Moore

COMMON RADIOLOGICAL INVESTIGATIONS Plain x-ray This is the most readily available investigation, and often provides the information necessary for diagnosis. The more x-rays that hit the photographic film, the blacker it develops. So dense parts of the body (such as bone) block many of the x-rays and show up as white. Hollow or air filled parts of the body (such as parts of the lung) show up as black. Soft tissues such as muscle and body organs show up as various shades of grey, depending on how dense they are. An x-ray may yield important information regarding fractures, dislocations, calcifi- cation and bony pathology.

Different views of the same area enable a fuller and clearer diagnosis to be made. The direction of the x-ray may be described as P-A or A-P, which means that the direction of the view is either posterior > anterior or anterior > posterior – this will give a slightly different resulting appearance. A lateral view is, as suggested, a ’side on’ view of the subject. In many cases, two ‘projections’ of the subject are taken, usually at right angle, firstly, many fractures are only visible in one plane, which exact plane is unknown to the radiographer until the images is taken and secondly, for assessment of alignment of fractures and spatial position of

foreign

bodies. Different views are relevant when looking at specific structures, for example a skyline view of the patella (with the knee in partial flexion) is particularly valuable in detection of patellar problems.

X-rays are useful in

establishing (or excluding) fractures and bony pathology (figures 1-3). Some commonly used terms regarding x-rays are described in Table 1.

www.sportex.net

Figure 2: The x-ray shows images of a distal radius and ulna, with a Colles fracture. The importance of x-raying the suspected site in two planes and at right angles to each other is vital, as the fracture may otherwise be missed.

RADIOLOGICAL

INVESTIGATIONS IN SPORT AND EXERCISE

Figure 3: A “skyline” view of the patello-femoral joint demonstrating lateral subluxation of

patella (the patella, on top, has shifted to the right)

Figure 1: An A-P x-ray showing a fracture of the medial and lateral malleoli of the ankle joint

Radioisotope bone scan A radioactive isotope (a substance deliberately modified and easily detectable – hence used as a tracer) called technecium is used for this scan. Technecium is a material which is particularly attractive for medical applications as the radiation it emits has the same wavelength as x-rays used for common medical diagnostic x-ray applications: this gives it adequate penetration while causing minimal damage. The technecium is injected into a peripheral vein and collects in areas where there is a lot of bone activity (eg. where bone cells are breaking down or being repaired). A bone scan is therefore used to detect areas of bone where there is cancer, infection or damage. These areas of activity are seen as ‘hot spots’ on the scan picture. Bone scans involve significant radiation exposure.

Radioisotope bone 15 the