Low back pain or what is commonly known as ” sciatica ” or “lumbago” can have many causes and is often due to more than one. Some of the most common causes are decompensation, overload or insufficiency of the back muscles, herniated disc, degenerative disc disease, poor alignment of the spine including scoliosis, osteoporotic compression fractures, trauma, infection.
To determine the cause of the problem, doctors would recommend MRI for back pain as the first step in the diagnosis. So, what imaging tests should you do for low back pain or sciatica? Today we explain the differences between the 3 imaging tests most requested by spine surgeons, which are radiography, resonance and CT:
X – rays give an idea of the shape of the spine. They are the best imaging test to assess spinal alignment and deformities. It should be the first exam used to evaluate the spine. They are most useful when they are performed under load, that is, with the patient standing, but sometimes we perform them in flexion (forward), in extension (backward), lying face up (supine position) or face down (prone position) to check the stability of the spine.
Radiology is not painful but X-ray irradiation is harmful, so its use should be limited to cases where it is really justified. The RCGP points out that an X-ray of the lumbar spine carries 150 times more radiation than a chest X-ray.
Magnetic Resonance, it is excellent for the study of soft tissues. Detects disc herniation, canal stenosis, nerve or spinal cord injuries, tumors and fractures. The MRI does not expose the patient to any type of dangerous radiation, nor is it painful. It does, however, require the patient to be still for about 15 minutes in a small space, so it can be unpleasant for those who are anxious or prone to claustrophobia.
However, there are studies that have shown that magnetic resonance imaging (MRI) is not as reliable as it was considered in the diagnosis of back ailments: the same image was interpreted differently by different doctors, or even by the same doctor at different times.
Other studies have shown that on a lumbar MRI, up to 30% of healthy and pain-free people show herniated discs, and 70% protrusions, and from approximately 40 years of age practically all healthy subjects show signs of bone and disc degeneration.
In the cervical spine, the findings are similar: 87.6% of healthy patients without pain have disc protrusions; already at the age of 20, they are present in 73.3% of men and 78% of women, and the frequency, size and number of protrusions increase with age.
It has not been shown that there are differences in cervical findings between patients with neck pain and asymptomatic people, so the clinical significance of the images and their diagnostic utility have not been demonstrated. MRI should be performed in cases where it has been shown to be reliable, thus avoiding misdiagnosis,
Computed Tomography or scanner is very useful to analyze the alignment of the spine and to study the bone, especially when the patient has had a spinal cord injury. The scanner allows you to see the bone better than the MRI. It is the best test to evaluate how bone is forming (arthrodesis) after spinal surgery.
The scan is not painful but it is not harmless either; exposes the patient to considerable irradiation, equivalent to that of several X-rays at the same time.
What imaging tests should you do for low back pain or sciatica? We cannot forget that the first and most important sources of information to find out the causes of back pain are the patient’s clinical history and physical examination. Imaging tests will only have value if their results correspond to those of the physical examination.