CT scan: lumbar spine

Alternative Names: CT scan of the lower back

A CT (Computerised Tomography) scan of the lower back is carried out to investigate problems associated with the lower spine, spinal cord, and nerve roots in the spinal cord — problems such as low back pain, weakness in the legs, and injuries to the spine. It helps doctors to diagnose e.g. disc herniation (discs that stick out between the bones of the spine and press on the nerve roots), fractured vertebrae, tumours, and arthritis. A CT scanner is a tunnel-like machine in which you lie while it takes X-rays that are turned into detailed images by a computer. A special dye, which contains iodine, may be injected into a vein in your arm to enhance the images; some people are allergic to this dye.

What is it?
Computerised Tomography (CT) is an imaging technique that uses X-ray beams, which are analysed by a computer to produce detailed images.

A CT scan of the lumbar spine (lower back) scans the lower spine, spinal cord, and nerve roots (nerves as they leave the spinal cord). It is done in a radiology facility and takes less than an hour to perform.

Why is it done?
A CT scan of the lower spine is done when investigating problems such as:

• Low back pain
• Weakness in the legs
• Spinal injuries

It is used when considering diagnoses such as:

• Disc herniation (where an intervetrebral disc protrudes and puts pressure on the nerve roots)
• Fractured vertebrae (from an injury or osteoporosis)
• Tumours (of bone, most commonly secondary spread from tumours elsewhere)
• Arthritis (joint pain and swelling involving the joints between the vertebrae)

What happens?

Before – how to prepare
You will need to sign a consent form but no other special preparations are needed. Any jewellery, or other metal objects, should be removed.

During – how the test is done
You will need to lie within the CT scanner – you lie on a couch with the tunnel-like scanner around you. It is essential that you lie very still while the machine takes a sequence of images, moving fractionally each time. The machine may be quite noisy, and some people feel a little claustrophobic inside the “tunnel” but there is no pain or discomfort involved at all.

A special dye, called contrast media, may be injected into a vein in your arm, to enhance the images.

After the test
The initial results should be available within an hour or so but detailed analysis and interpretation of the images may take longer.

Risks and Compilations
The radiation involved in taking X-rays may, potentially, be harmful, but most experts do not consider this to be a significant problem.

Some people are allergic to the dye/contrast media, which usually contains iodine.

Short Description
A CT (Computerised Tomography) scan of the lower back is carried out to investigate problems associated with the lower spine, spinal cord, and nerve roots in the spinal cord — problems such as low back pain, weakness in the legs, and injuries to the spine.

Keywords
CT scan of the lower back, lumbar scan, CT scan of the spine, back scan, CAT scan, cat scan