What is the role of MRI in diagnosing ischial bursitis?

MRI in Diagnosing Ischial Bursitis

MRI is highly recommended for diagnosing ischial bursitis after initial radiographs and should include fluid-sensitive sequences (STIR or T2-weighted fat-saturated) for optimal visualization of soft tissue inflammation and fluid collections. 1

Diagnostic Imaging Algorithm for Ischial Bursitis

1. Initial Radiographs

   • Start with plain radiographs to rule out bony pathology
   • Look for osseous abnormalities at the ischial tuberosity
   • Evaluate for fractures, erosions, or enthesopathic bone formation

2. MRI Evaluation

   • Perform MRI when clinical suspicion for ischial bursitis exists despite normal radiographs
   • Essential sequences:
     • Fluid-sensitive sequences (STIR or T2-weighted fat-saturated)
     • T1-weighted images for anatomical detail
   • IV contrast is generally not required for routine evaluation 1

3. Key MRI Findings in Ischial Bursitis

   • Fluid collection adjacent to ischial tuberosity
   • Bursal wall thickening
   • Surrounding soft tissue edema
   • Possible adjacent muscle edema

Clinical Correlation with MRI Findings

• MRI has excellent sensitivity for detecting soft tissue inflammation and fluid collections characteristic of ischial bursitis 1
• MRI can help differentiate ischial bursitis from other conditions that may present with similar symptoms:
  • Hamstring tendinopathy
  • Ischiofemoral impingement
  • Sciatic nerve pathology
  • Inferior cluneal neuralgia 2

Treatment Considerations Based on MRI Findings

• MRI findings can guide treatment decisions:

  • Mild cases: Conservative management with rest, NSAIDs, and physical therapy
  • Moderate to severe cases: Image-guided injections may be indicated
  • Refractory cases: Surgical intervention may be necessary

• Image-guided injections (particularly fluoroscopically guided) have shown superior efficacy (86.25% pain relief) compared to landmark-based injections (55% pain relief) 3

Special Considerations

• Patients with underlying inflammatory diseases may require more aggressive intervention as they have poorer response to conservative treatment (66.7% non-response rate vs. 10.3% in those without inflammatory disease) 4

• MRI should be specifically requested to evaluate for ischial bursitis, as standard protocols may need modification to properly visualize the affected area 5

• When interpreting MRI results, consider that some findings may be present in asymptomatic individuals, making clinical correlation essential

MRI plays a crucial role in confirming the diagnosis of ischial bursitis, guiding appropriate treatment, and ruling out other pathologies that may present with similar symptoms.