A sacral MRI is a diagnostic imaging procedure that provides detailed pictures of the sacrum, a triangular bone at the base of the spine, and its surrounding soft tissues. This non-invasive test helps medical professionals identify various underlying issues affecting the lower back and pelvis.
What a Sacral MRI Is
A sacral MRI uses strong magnetic fields and radio waves to create detailed images of the inside of your body, without using radiation. The process involves the machine aligning protons, tiny particles within the body’s water molecules, using a powerful magnetic field. Short bursts of radio waves then temporarily knock these protons out of alignment.
As the radio waves are turned off, the protons realign, releasing signals detected by the MRI machine. A computer processes these signals to generate cross-sectional or 3D images of the sacrum and its adjacent structures. This allows for clear visualization of the sacrum, along with nearby nerves, ligaments, and muscles, providing a comprehensive view for diagnosis.
Why a Sacral MRI is Performed
Doctors often recommend a sacral MRI when patients experience persistent pain in the lower back or tailbone region that does not resolve with other treatments. Symptoms like sciatica, numbness, tingling, or weakness extending into the legs or feet can also prompt this scan, as these may indicate issues with the sacral nerves. Bowel or bladder dysfunction may also necessitate a sacral MRI.
The sacral MRI helps diagnose a range of conditions affecting the sacrum and surrounding areas. It can identify herniated discs or nerve compression impacting the sacral nerve roots, which often cause radiating pain. Fractures or other trauma to the sacrum are clearly visible, as are tumors, whether benign or malignant, within the bone or nearby soft tissues.
The scan is also effective at detecting infections like osteomyelitis or discitis. Inflammatory conditions such as sacroiliitis are frequently diagnosed using this imaging technique. Congenital abnormalities of the sacrum can also be identified.
Preparing for Your Sacral MRI
Before a sacral MRI, you will receive specific instructions from your healthcare provider. Removing all metal objects is important, including jewelry, watches, hairpins, and any clothing with metal zippers or buttons. Metal can interfere with the strong magnetic field of the MRI machine, distorting images or posing a safety risk.
Inform the technologist about any implanted medical devices, such as pacemakers, cochlear implants, artificial joints, or metal clips from previous surgeries. Some devices may be incompatible with MRI, while others require special precautions or adjustments to the scan protocol.
Contrast dye, gadolinium-based, may be used to enhance the visibility of certain tissues or abnormalities. If contrast is planned, inform the staff about any kidney issues or allergies, as these can affect the suitability or administration of the dye. Wearing loose, comfortable clothing is advised, and you may be asked to change into a hospital gown. If you experience claustrophobia, discuss this with your doctor beforehand, as options like open MRI machines or sedation may be available to help you relax. Unless contrast is administered orally or sedation is planned, food and drink restrictions are not required.
What to Expect During the Scan
During a sacral MRI, you will lie on a movable padded table that slides into the MRI machine, which is a large, tube-shaped scanner. Depending on the specific area being scanned, you may enter the machine either head first or feet first. Remain as still as possible throughout the procedure to ensure clear and accurate images are captured.
The MRI machine produces loud knocking, tapping, or banging noises during the scan. You will be provided with earplugs or headphones to help with this. The duration of a sacral MRI can vary, but it takes between 30 to 60 minutes.
You will be able to communicate with the technologist operating the scanner through an intercom system. They will be in a separate control room, observing you through a viewing window or on a monitor. If contrast dye is administered intravenously, you might feel a cool sensation at the injection site in your arm.
Understanding Your Results
After your sacral MRI scan is complete, the images are sent to a radiologist, a medical doctor trained to interpret diagnostic imaging. The radiologist meticulously examines the detailed pictures, looking for any abnormalities in the sacrum, sacroiliac joints, surrounding soft tissues, and nerve structures. They then compile a comprehensive report of their findings.
The radiologist’s report is sent to your referring doctor, who will discuss the results with you during a follow-up appointment. This discussion happens within a few days to a week or two, unless the findings require more urgent attention. Your doctor will explain what the images reveal and how these findings relate to your symptoms and overall health.
The MRI results serve as one piece of the diagnostic puzzle, providing objective information about the sacral region. Your doctor will consider these findings alongside your clinical symptoms, medical history, and potentially other diagnostic tests to form a complete diagnosis and develop an appropriate treatment plan. This integrated approach helps ensure the most accurate assessment and effective course of action for your condition.