Sacroiliac imaging is a set of medical tests used to get a detailed view of the bones and tissues around the sacroiliac (SI) joint, which connects the spine to the hips. This imaging is particularly useful for evaluating lower back or pelvic pain, helping to rule out issues like fractures, tumors, or other structural abnormalities that could impact treatment decisions.

To properly evaluate the SI joint, a three-test imaging set is commonly ordered:

A CT scan without contrast of the SI joint to assess bone structure and rule out fractures. A lumbar MRI to rule out lower back issues that may contribute to symptoms. Hip X-rays to ensure that hip pathology is not the underlying cause of pain. While imaging plays a role in identifying red flags, it is important to understand that it is a poor indicator of SI-mediated pain. Whether the scan shows osteoarthritis or not, it does not necessarily correlate with pain generation in the SI joint. Many patients with SI dysfunction have normal imaging, and conversely, arthritis seen on imaging does not confirm the SI joint as the source of pain. The diagnosis of SI joint dysfunction is primarily based on clinical evaluation and diagnostic injections, rather than imaging alone.

Preparation for imaging may include fasting for a few hours if contrast is required and informing the doctor of any allergies, pregnancy, or implanted medical devices that could affect the test. Patients who experience claustrophobia should mention this beforehand, as MRI scans require lying inside a tunnel-like machine for a period of time.

While imaging helps rule out serious conditions, a thorough clinical evaluation remains the key to diagnosing SI joint dysfunction and determining the best course of treatment.