PRACTITIONER BRIEF

Ultrasound scans is particularly useful in imaging the soft tissues about the knee, muscle injury, bone healing and foreign bodies.

Figure 9: PET scan showing a brain tumor

Positron emission tomography (PET) scan Primarily used to detect diseases of the brain and heart. A short-lived iso- tope is incorporated

into a substance used by the body such as glucose which is absorbed by the tumor of interest. PET scans are often viewed along side CT scans, which can be performed on the same equipment without moving the patient. This allows a tumour detected by the PET scan to be viewed next to the rest of the patient’s anatomy detected by the CT scan. Useful in oncology and cardiolo- gy but in supplementing information obtained from a CT scan (figure 9).

IN SUMMARY A variety of radiological methods are used in order to aid management of injuries. Each has their own strengths and limita- tions. While x-ray is still the most common of these, other techniques are becoming increasingly valuable, in particular ultra- sound. Although scans provide valuable information, they must be used thought- fully and interpreted with care, many an injury has been missed, overlooked or incorrectly interpreted by failing to follow one of the basic rules outlined.

THE AUTHOR

Dr Stephen Moore DRCOG MBChB MRCGP MSc (Sports Medicine) FFEMS is a GP with an interest in sports medicine. He is the sports physician for the Sheffield United Football Academy.

KEY POINTS

■ X-rays are useful for assessing factures and bony pathologies

■ Radioisotope bone scans are useful in the detection of stress fractures and osteochondral lesions but do involve significant radiation

■ CT scans give clear pictures of soft tissue including muscles and allows cross sectional imaging. Good where bony injury is suspected and more detailed than x-rays so good in eval-

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uation of the spine or fractures of small bones or anatomically complex areas like the ankle, foot and pelvis.

■ MRI scans are less accurate in defining bone detail than CT scans but better at detection of subtle soft tissue changes and particularly spinal disc pathology, evaluating soft tissue masses and bone marrow tumours.

■ Ultrasound scans are good for visualis- ing large tendons, haematomas and cal-

cification. Used in real time ultrasound can also be used to guide joint injections. They are particular- ly good for imaging soft tissues around the knee along with muscle injury and bone healing.

■ PET scans are primarily used to detect disease of the brain and heart and may be used alongside CAT scans.

TEN USEFUL RULES OF RADIOLOGY

Therapists often get frustrated when they refer a patient to A&E expecting that they will be given an x-ray or one of the other forms of investigation, only to find when they return to the clinic that it hasn’t been done. Doctors work (or should do) under the following rules.

1. Treat the patient, not the radiograph. The diagnosis of certain injuries (for example scaphoid fracture) is dependent upon the clinical findings. In such cases the radiograph does not provide the diagnosis but excludes other abnormalities. Even if no radiological abnormality is found the appropriate treatment based on the clinical findings should be started

2. Take a history and examine the patient before requesting a radiograph. For exam- ple, in a head injury case with diminished level of consciousness - consider a cervical spine injury/x-ray

3. Request a radiograph only when necessary. For example, for patients with fractured ribs, a chest radiograph is appropriate only to detect abnormalities to the underlying soft tissues. Oblique rib views requested solely to determine if and where a rib is fractured are not appropriate because they will not necessarily show the fractured rib. Providing that there is no underlying injury, even if a fractured rib is identified the management of the patient will not be altered.

4. Never look at a radiograph without seeing the patient, and never see the patient without the looking at the radiograph. Correlating the radiological findings with the clinical examination helps to reduce the chances of missing an abnormality.

5. Look at every radiograph, the whole radiograph, and the radiograph as a whole. Studying radiographs close up, in a well lit, noisy room with many distractions, increases the chances of missing abnormalities.

6. Re-examine the patient when there is an incongruity between the radiograph and the expected findings. If this occurs then check to confirm that no mistakes have been made. Special views or investigations may be needed to identify the injury.

7. The rule of twos: two views - because of its alignment, a fracture may be visible in only one view; two joints - because of the risk of associated dislocation or sub- luxation when a fracture is suspected, the radiograph must include the joint at either end of the long bones; two occasions - the natural course of certain conditions makes it necessary for radiographs to be repeated at a later date; two sides - abnormalities can be detected more easily if you compare the normal and injured side; two radiographs - certain fractures, such as the neck of the talus, may benefit from being compared to a normal radiograph.

8. Take radiographs before and after a procedure. This can confirm reduction in fracture or relocation of a dislocated joint.

9. If a radiograph does not look quite right ask and listen, there is probably something wrong. If unsure, always seek further advice and also remember to listen to the radiographer. Never be afraid to refer for further advice.

10. Ensure you are protected by fail safe mechanisms. Check the name and the date on the scan. Is it the correct patient? Safety backup also includes an effective reporting service; all radiographs must be reviewed by a radiologist.

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