Lumbar scanner: All about this imaging (Procedure)

Article reviewed and approved by Dr. Ibtissama Boukas, physician specializing in family medicine 

To better understand the causes of back pain, it is not uncommon for the doctor to prescribe an imaging test such as a lumbar scan to his doctor.

What is the lumbar scan, and when is it prescribed? How does the actual exam take place? How to interpret the results?

This popular article explains everything you need to know about the lumbar CT scan.

Definition

The lumbar scan is a test ofmedical imagery non-invasive that uses X-rays to produce horizontal, or axial (called slices) images of the lumbar region.

Specifically, the lumbar scan will show detailed images of the lower back. This includes the vertebrae, muscles, intervertebral discs, fat and organs.

This examination is more detailed than a standard X-ray. Indeed, the X-ray beam moves around the body during the lumbar scan, allowing to obtain several views of the lumbar region.

The lumbar scan can be performed with or without contrast. Contrast refers to a substance taken by mouth, injected intravenously, or administered rectally. It allows you to see the organ or tissue under study more clearly.

Indication for CT scan of the lumbar spine

If you have a back problem, the doctor may refer you for a lumbar scan.

On the other hand, it should be understood that this examination is not prescribed in first intention. Indeed, the results ofmedical imaging are not systematically related to symptoms. This means that we can observe insignificant findings that would not necessarily explain your low back pain.

The objective of the lumbar scan is to clarify the diagnostic when the clinical examination or the treatments used are inconclusive. Here are some reasons why it will be relevant to use a lumbar scan:

• After a trauma, to determine the presence of vertebral fracture
• If the pain is accompanied by fever (possible infection)
• If a birth defect of the spine (such as spina bifida)
• To identify a cyst
• If you want to know more about the symptoms of sciatica (to diagnose a herniated disc)
• To see the integrity of vertebrae lumbar (osteoarthritis)
• To guide a lumbar infiltration
• To guide a lumbar surgery
• If we want to eliminate a serious harm like a cancer
• If x-rays or clinical examination are inconclusive

In general, the risks associated with a lumbar CT scan are few. For one thing, the level of irradiation is considered safe for adults. However, repeated scans are not recommended. Similarly, pregnant women should not have a CT scan during the first 6 months of pregnancy.

The administration of contrast material can sometimes cause symptoms, especially when administered intravenously. These usually don't last long:

• Hot flashes
• Headaches
• Metallic taste in the mouth
• Nausea and vomiting

The lumbar scanner must be differentiated from other types of medical imaging. Moreover, some tests are more precise than the scanner, and are sometimes prescribed to better understand the lumbar region.

Indeed, MRI makes it possible to observe the soft tissues in addition to the vertebrae, and allows the precise diagnosis of a herniated disc and its consequences on the nerve roots and the spinal cord.

How is a lumbar scan performed?

Before having a lumbar scan, you should tell your doctor if you suffer from one of the following conditions:

• Diabetes: Because fasting is required for at least 3 hours before procedures involving contrast material, blood sugar levels may drop and cause symptoms.
• Pregnancy: To determine if it is permissible to expose the fetus to irradiation.
• Allergies: This would be a problem if you are allergic to the contrast product used (barium).
• Kidney problems: The contrast medium could damage the kidneys in some cases.
• Claustrophobia: Since you have to enter a narrow cylindrical device, you may develop anxiety. Painkillers are sometimes prescribed in these cases.
• Metal implant: If you had surgery where a piece of metal was put in, this may affect the results.

The lumbar scan could be preceded by a contrast injection to optimize the results by highlighting your blood vessels, organs, etc. You will also be asked to remove any jewelry.

During the exam, a technician will usually ask you to lie on your back, although some procedures require the patient to be on their stomach. Although the positions may be uncomfortable, it is important to minimize movement so as not to distort the results.

If necessary, straps and pillows can be used to maintain a fixed position and optimize the quality of the images obtained. You may also be asked to hold your breath for short periods of time.

The technician will be in an adjoining room to minimize irradiation. It will communicate through a microphone when you are in the scanner. He can obviously stop the examination at any time if necessary.

The lumbar scan takes on average 10-15 minutes, but some exams take up to 45 minutes.

After the session, the doctor may continue the examination with imaging tests (such as MRI), blood tests, or other. Otherwise, you will be kept for a short time to monitor your reaction, especially if a contrast product has been used. Although these situations are rare, it is possible to observe certain reactions such as:

• Itching
• Swelling
• Skin rash
• Difficulty breathing
• Redness at the injection site

If all goes well after the exam, you will eventually be given a follow-up appointment for the doctor to disclose the results of the lumbar scan to you.

Note: Nursing mothers should wait 24 hours after contrast injection before resuming breastfeeding.

Note: If you are taking Metformin for your diabetes, it is recommended to wait 48 hours after a contrast injection before continuing the medication.

How much does a lumbar spine scan cost?

The price of the lumbar scanner will depend on the center. In general, it varies between 25 and 70 euros.

The refund by the Social Security is 70% in France. If you benefit from mutual insurance, it is possible that it covers the rest of the amount to be paid. In Quebec, costs are covered when they are prescribed in the public domain.

How to read a lumbar scan?

The reading of the lumbar scanner as such is complex, and should be carried out by a specialist doctor (such as a radiologist).

However, the scanner (which usually comes in CD form) also comes with a written report. It is in this report that you will find the terms relating to your condition.

As mentioned previously, the results of the lumbar scan should not be systematically attributed to your symptoms. Indeed, several asymptomatic people have however presented abnormalities on the CT scan in the context ofscientific studies.

It is therefore necessary to link the results of the lumbar scan with the clinical examination carried out by the healthcare professional, as well as the other tests carried out if necessary.

Conclusion

The lumbar scan is prescribed by the doctor to clarify the diagnosis and explain the cause of back pain, especially when the x-ray or clinical examination is inconclusive.

It uses x-rays to produce detailed images of the lower back. If necessary, a contrast product can be used to better visualize the structures at the lumbar level.

The exam is relatively short, and you will be guided by a technician through the process. The results will then be explained by your doctor during the follow-up appointment.

Good recovery !