Introduction
Neck pain and back pain are one of the commonest musculoskeletal problems seen by general practitioners and specialist orthopaedic surgeons alike.
The doctor usually would have a good idea of the location and likely cause of the spinal problem after taking careful clinical history and performing directed physical examination. The doctor may then order imaging tests to confirm the findings, before deciding on the appropriate treatment plan for the patient.
X-rays
X-rays are the first-line imaging study in the investigation of spinal problems. X-rays are widely available, cost-effective, and can be performed fairly easily and quickly.
Abnormalities of spinal alignment are well shown on X-rays, such as abnormal step between the vertebral levels (spondylolisthesis) and abnormal curvature (scoliosis) (Figure 1). X-rays are also used to detect fracture after an injury or accident.
Figure 1. There is scoliosis of the spine which is curved to the left side. X-rays are useful for evaluating the severity of scoliosis, and repeat X-rays can be performed to monitor for any worsening. If there is any underlying inborn deformity of the spine that is causing scoliosis, it can be seen on X-ray as well.
X-rays are useful to screen for spinal degeneration, which may manifest as bone spur formation in the vertebral bodies, hypertrophy (enlargement) of the facet joints, and disc space narrowing (Figure 2). However, as X-rays can only show the bony part of the spine, soft tissue structures such as the intervertebral discs, muscles around the spine, spinal cord and spinal nerves cannot be directly evaluated by X-rays alone.
Figure 2. Picture A is an X-ray of a relatively normal lumbar spine in a young patient. Picture B shows degenerative changes including disc space narrowing (1) and facet joint hypertrophy (2). Disc space narrowing usually indicates underlying disc problem, although it does not reliably predict the severity. There may still be significant disc degeneration if the disc space is normal. MRI is still the most reliable test to evaluate discs.
MRI scan
MRI (Magnetic Resonance Imaging) is an advanced scan that uses magnetic field and radio waves, and it does not emit any harmful radiation at all. MRI allows detailed analysis of both bone and soft tissue structures of the spine, and therefore it plays an increasingly important role in the evaluation of the spinal conditions for the past 2-3 decades.
MRI is not a necessary test for all spinal problems, but if there are persistent symptoms after initial treatment or if there are symptoms that may suggest significant underlying problem, a doctor may then decide to order it.
MRI is useful for evaluating all aspects of degeneration in the joints and discs of the spine. It can detect compression of the spinal cord or spinal nerves due to bone spurs or disc prolapse (Figure 3).
Figure 3. MRI shows that the L4-L5 disc is degenerate, and it is protruding into the spinal canal and pressing on the spinal nerves.
Very occasionally, uncommon but important conditions such as spinal infections, tumours and spinal cord abnormalities are uncovered by MRI, which might otherwise be missed by X-rays alone (Figure 4).
Figure 4. The patient had significant back pain for a period of time, which turned out to be due to spinal infection rather than disc degeneration on MRI.
CT scan
CT (Computed Tomography) is an advanced scan that uses X-rays to produce fine cross-sectional images, allowing the radiologist and surgeon to study the bony anatomy in great detail.
CT scan of the spine is less commonly performed compared to MRI but there are some situations that may require it, which include urgent evaluation of complex spinal fractures after acute serious trauma (eg. road traffic accident), evaluation of the post-surgical spine with metal implants to assess for healing and integrity of the implants (Figure 5), and to precisely guide some spinal procedures.
Figure 5. The presence of metal implants in the spine can significantly affect MR images but this is less so for CT scan. Because CT scan can show fine bony details well, it is useful to assess for bone healing and to detect any break or loosening of metal implants.
CONTRIBUTED BY DR LEE CHIN HWEE, CONSULTANT RADIOLOGIST