From the Guidelines
The order for an MRI to diagnose sacral or iliac or sacroiliac joint insufficiency fractures should specify the location as including the sacrum and pelvis, with a dedicated protocol that includes T1-weighted sequences and STIR or T2-weighted fat-suppressed sequences. When ordering an MRI for suspected insufficiency fractures, it is crucial to include the sacrum and pelvis in the imaging protocol, as stress fractures of the sacrum can be the source of radiated hip/groin pain 1.
The choice of MRI protocol is essential for accurate diagnosis, and a dedicated protocol should include T1-weighted sequences to show fracture lines as dark lines, and STIR or T2-weighted fat-suppressed sequences to show bone marrow edema as bright signal. This approach helps to differentiate sacral or pelvic insufficiency fractures from metastases and other conditions that may present with similar symptoms.
Some key points to consider when ordering an MRI for suspected insufficiency fractures include:
- Including the sacrum and pelvis in the imaging protocol
- Using a dedicated MRI protocol with T1-weighted sequences and STIR or T2-weighted fat-suppressed sequences
- Considering the use of in-phase and out-of-phase MRI sequences to differentiate benign stress fractures from pathologic fractures 1
- Being aware that bone scintigraphy may lack specificity and that supplemental imaging with MRI or CT may be necessary for conclusive diagnosis or to avoid false positives 1.
By following this approach, clinicians can ensure accurate diagnosis and effective management of sacral or iliac or sacroiliac joint insufficiency fractures, which is critical for improving patient outcomes and reducing morbidity and mortality.
From the Research
Imaging Protocol for Diagnosing Sacral or Iliac or Sacroiliac Joint Insufficiency Fractures
When ordering an MRI for a sacral or iliac or sacroiliac joint insufficiency fracture, the following locations should be specified:
- The sacrum
- The ilium
- The sacroiliac joint
- The lumbar spine
Recommended MRI Sequences
The order should specify the following MRI sequences:
- Coronal fat-suppressed T2-weighted image
- Coronal STIR (short tau inversion recovery) sequence
- T1-weighted MRI
- T2-weighted MRI
- Contrast-enhanced T1-weighted MRI
Key Considerations
When diagnosing sacral or iliac or sacroiliac joint insufficiency fractures, consider the following:
- The presence of additional pelvic fractures in characteristic locations can help confirm the diagnosis 2
- Diffusion-weighted MRI can help differentiate sacral insufficiency fractures from metastases of the sacrum 3
- MRI is more sensitive than CT or X-ray for detecting sacral insufficiency fractures 4, 5
- A detailed history and clinical findings are crucial for diagnosis and treatment 6
Location-Specific Considerations
When imaging the sacrum, consider the following:
- Sacral insufficiency fractures can be difficult to diagnose on plain radiographs 4, 5
- MRI is useful for evaluating the complexity of the fracture pattern 4, 5 When imaging the ilium, consider the following:
- Iliac insufficiency fractures are rare and may be mistaken for metastatic disease 2
- CT and MRI can help diagnose iliac insufficiency fractures 2 When imaging the sacroiliac joint, consider the following:
- Sacroiliitis and sacral insufficiency fracture can coexist 6
- MRI can help diagnose sacroiliitis and sacral insufficiency fracture 6