Investigations - 'Head to Toe'?

We have all been exposed to radiological investigations at some stage in our lives, whether it is an x-ray or CT scan or even an MRI. But what are these investigations looking at and will they have any adverse affects? Radiological investigations are routinely ordered by GP's, physiotherapists, chiropractors and the like. They are usually ordered to help diagnose particular problems or rule out any internal pathology. Are these investigations necessary? And if so, will they change the management of my condition? So often we are not given the information we need to make an informed decision about whether these investigations should be administered, so let’s have a look at what these investigations are and when they should be used.

Please note that the following investigations are discussed with musculoskeletal problems in mind. Many of the investigations below are also used for many other medical problems.

Plain Xray

An XRAY is a form of electromagnetic radiation. It can be used for many purposes. It is the most common diagnostic tool used by health professionals.

Features

• Readily available and often provides the necessary information for diagnosis rather than sophisticated expensive imaging techniques.
• Good for the following: Bony Abnormalities, Fractures, Dislocations, Dysplasia (abnormal formation), and Calcification.
• Positives
- Low Cost, Simple
- Physiotherapists may refer for XRAY without the need to see a GP. Only specific regions require GP referral check with your physiotherapist to see which X-Rays require a GP referral.
- Can usually get same day XRAY and reporting if required.
• Negatives
- Radiation exposure

Radioisotopic bone scan

Bone scans can be done to evaluate damage to the bones, detect cancer that has spread (metastasized) to the bones, and monitor conditions that can affect the bones (including infection and trauma). A bone scan can often detect a problem days to months earlier than a regular X-ray test. Bone scans are used as they detect changes in bone metabolism and are thus more sensitive to bone abnormalities.

The patient is injected a couple of hours before the scan with a liquid containing tracers. These little tracers, or markers, flow through the blood stream and are temporarily absorbed by bone they come into contact with. Usually, the markers distribute evenly throughout the bone. However, areas that absorb little or no amount of tracer appear as dark or "cold" spots, which may indicate a lack of blood supply to the bone (bone infarction) or the presence of certain types of cancer. Areas of rapid bone growth or repair absorb increased amounts of the tracer and show up as bright or "hot" spots in the pictures. Hot spots may indicate the presence of a tumor, a fracture, or an infection.

Features

• Highly sensitive but non-specific
• Used to detect areas of increased blood flow and bone turnover found in fractures and tumors
• Good for stress fractures, osteochondral lesions (bony joint surfaces)
• Requires GP referral
• Positives
– Highly sensitive
• Negatives
– non specific
– little information regarding soft tissues
– patient time (2 hours in between initial injection and scan)
– small radiation exposure

Computed Tomographic Scanning

A CT (computerized tomography) Scan is similar to an XRAY machine, but sends out several beams simultaneously on different angles to establish an image that can be read by a computer as slices through the body.

Features

• Cross sectional scanning of soft tissue, calcific deposits and bone
• Good for evaluation of spine, fractures in small bones and fractures in anatomically complex regions such as the ankle, foot or pelvis
• CT arthrography is performed after an injection of radio opaque contrast medium into joint or cavity, commonly shoulder or ankle.
• Requires GP referral
• Positives
– highly specific
• Negatives
– radiation exposure
– Possible claustrophobia

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) uses a strong magnetic field and radio waves to produce detailed pictures of the inside of your body.

Features

• Imaging of tendons, muscle and other soft tissues
• Good for Achilles, patellar and rotator cuff tendons, thigh and calf muscles
• Real time ultrasound during active movement (trans abdominals and shoulder impingement)
• Requires GP referral
• Positives
– painless, no radiation
• Negatives
– reliant on skill of operator

Other not so common investigations include

Neurological Investigations

Electromyography

• EMG studies muscle activity through surface electrodes or by needles inserted into the muscle.
• Measure response of muscle after an electrical stimulus

Nerve conduction studies

• Recognition and accurate localization of peripheral nerve pathology
• Good for demyelination, axonal damage, carpal tunnel

Muscle Assessment

Compartment pressure testing

• Intracompartmental pressures are measured at rest and during exercise
• Used in severe cases of shin pain and or posterior calf pain
• Can assist in determining the need for surgical interventions such as a fasciotomy to release the pressure.

Summary

It is important to remember that investigations form only part of the picture in relation to establishing an accurate diagnosis. It is also important to recognise the clinical tests used by your physiotherapist, GP or specialist to accurately determine the pathology that is presenting. Sometimes investigations can be misleading, so please discuss these with your health care practitioner. Below is some useful information regarding radiological investigations:

• Physiotherapist referral for X rays of Spinal, Hip and Pelvic regions will be mostly covered by medicare. Other areas will attract a lower rebate and cost the patient more. They may be best to obtain a referral from GP or specialist. Also of note is people over the age of 60 receive an even further discount.
• $250 for an MRI
• GP referral costings on average are:
- $50 – x ray
- $150 – CT Scan
- $90 – Ultrasound
- $150 – Bone Scan
- $250 – MRI
• Specialist referral for MRI receives full medical rebate.
• Multi Slice Ct Scanning is a relatively new technology which give excellent bony details and pictures. 3D images are not routinely generated for spinal pathologies as radiologist do not require these images for diagnosis. However they can be generated for no extra cost if requested and will allow for easier patient education and understanding.

If you have any concerns or questions regarding radiological investigations please speak to your health care practitioner.

Nb. Prices detailed here an estimate only. Please consult your nearest radiological investigation unit (MIA, Gribbles etc) or GP to obtain accurate prices.