An MRI of the sacrum shows detailed images of sacral bones, sacroiliac joints, surrounding soft tissues and nerve roots. It detects fractures, bone marrow changes (edema, infection, metastases), tumors, inflammatory or degenerative sacroiliitis, abscesses and post‑operative changes. MRI best identifies soft‑tissue pathology and nerve compression causing radicular pain, helping guide diagnosis and treatment planning.

An MRI of the sacrum typically takes about 20 to 40 minutes, though it can range from 15 up to 60 minutes depending on the complexity, need for contrast injection, and sequences required. Preparation and positioning add extra time; if contrast (gadolinium) is used expect an additional 10–15 minutes. You’ll lie still throughout to ensure clear images.

Costs vary widely by country and facility. In India a non-contrast lumbosacral MRI typically ranges ₹2,000–₹10,000; in the UK private scans cost about £200–£800 while NHS scans are covered; in the U.S. prices commonly run $400–$3,000+ (higher for hospital billing or contrast-enhanced studies). Additional fees apply for contrast, radiologist report, or urgent appointments.

For sacrum evaluation, CT provides the best bony detail and is preferred for suspected sacral fractures or complex pelvic trauma. MRI is superior for marrow lesions, occult fractures, infection, tumor, or neural/soft‑tissue assessment. Plain radiographs are a limited initial test; bone scintigraphy can detect occult fractures or metastases when CT/MRI are inconclusive.

MRI can detect many causes of sacral nerve injury — it visualizes the spinal canal, nerve roots, discs, tumors, inflammation, and compression of the sacral plexus. However, MRI shows structural and inflammatory changes, not microscopic or purely functional nerve damage. Electrophysiological tests (EMG/nerve conduction) and clinical evaluation are often needed to confirm nerve fiber injury or dysfunction.

Special sacral/sacroiliac tests commonly include FABER (Patrick) test, Gaenslen’s test, thigh‑thrust (posterior shear), distraction and compression (iliac compression) tests, sacral thrust (anterior sacral springing), Yeoman’s test, Gillet’s (stork) test for SI mobility, and the Fortin finger sign for SI region pain localization. These provocation, mobility, and palpation tests help identify sacral/SI dysfunction.