If you have sacroiliac (SI) joint pain that has not subsided with first-line treatments, your doctor may suggest radiographic and imaging tests to investigate the cause of pain further and rule out serious medical conditions.
A broad variety of radiographic and imaging tests are available to help identify pain caused by SI joint dysfunction.
X-ray
X-rays may detect fractures or degenerative changes in the SI joint.
An x-ray is an imaging technique that uses electromagnetic radiation to provide a general overview of the spine. SI joint x-rays can help detect conditions affecting the joint, such as fractures and degenerative changes, including but not limited to joint space narrowing and bone spurs.
X-rays are often the first test used to diagnose SI joint dysfunction, as they are quick and easy to perform and help the physician determine if more detailed medical imaging, such as computed tomography (CT) or magnetic resonance imaging (MRI) scan, is needed.
CT scan
A CT scan helps identify joint erosion.
A CT scan is a radiological imaging technique that creates two-dimensional images of the body in horizontal and cross-sectional (sliced) planes. CT scans of the SI joint help visualize erosive changes in the joint and hardening and/or thickening of the bone (subchondral sclerosis).
It is important to note that a CT scan is generally not recommended for pregnant women and children under 10 due to potential tissue damage to the developing organs.
MRI scan
MRI can detect early inflammation and bone changes.
MRI is a highly sensitive and specific imaging technique that yields comprehensive images of the structure, function, and composition of tissues in the body., MRI scans of the SI joint can help detect early inflammation, erosive changes, arthritic changes, and soft-tissue problems. MRI scans can also rule out other sources of pain or serious medical conditions in the SI joint area.
Bone scan
A bone scan is a diagnostic test that uses nuclear imaging. This scan can help identify and track the severity of bone-related problems, including cancers, arthritis, infections, fractures, and unexplained bone pain.
Bone scans of the SI joint help identify stress fractures, inflammatory changes, infections, and tumors.
Diagnostic injection tests with ultrasound or fluoroscopy
SI joint blocks may be used to identify SI joint pain.
Diagnostic SI joint injections, also called SI joint blocks, use ultrasound or fluoroscopy (real-time x-ray imaging) to pinpoint pain originating from the SI joint. The test involves delivering a small amount of anesthetic and/or corticosteroid directly into the SI joint and monitoring the patient’s pain and other symptoms. Significant pain reduction (>75%) after the test typically confirms that the pain originates from the SI joint. Some researchers consider SI joint blocks as a gold standard test to identify SI joint pain, but in 20% to 50% of patients, these tests may yield false-positive results, which may lead to an inaccurate diagnosis.
Injections are minimally invasive and are usually considered a safe and low-risk procedure. However, as with any injection procedure, there is always a risk of side effects or potential complications, such as allergic reactions, nerve damage, bleeding, or infection, which must be discussed in detail with the physician before considering these tests.
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