Should a hip MRI with or without contrast (Magnetic Resonance Imaging) be ordered after a fall?

Hip MRI After Fall: Contrast vs. No Contrast

MRI hip without IV contrast is the recommended imaging modality for evaluating suspected hip fractures after a fall with negative radiographs, with a highest appropriateness rating of 9/9 according to the American College of Radiology guidelines. 1, 2

Imaging Algorithm for Hip Injury After a Fall

1. Initial Imaging:

   • Standard radiographs (X-rays) of the hip should be the first imaging study 1, 2
   • Include anteroposterior (AP) view of the pelvis plus a lateral view of the affected hip

2. If Radiographs are Negative but Clinical Suspicion Remains High:

   • Proceed directly to MRI hip without IV contrast 1, 2
   • MRI without contrast has a sensitivity of 99% for detecting occult hip fractures 3

3. Alternative Options (if MRI is Contraindicated or Unavailable):

   • CT hip without IV contrast (rated 5/9 - may be appropriate) 1
   • Bone scan with SPECT (rated 6/9 - may be appropriate) 1

Why MRI Without Contrast is Preferred

• MRI without contrast receives the highest appropriateness rating (9/9) from the American College of Radiology for suspected hip fractures after negative radiographs 1, 2
• MRI with contrast is rated as "usually not appropriate" (1/9) for this indication 1
• Limited MRI protocols (coronal T1-weighted and STIR sequences) demonstrate 100% sensitivity for detecting occult hip fractures 3
• MRI can identify not only fractures but also soft tissue injuries, bone marrow edema, and other pathologies 2

Clinical Considerations

• Pain on axial loading of the limb and pre-fracture restricted mobility are both associated with higher likelihood of fracture, but these signs alone cannot rule out fracture 4
• Occult hip fractures are found in approximately 30-37% of patients with negative initial radiographs 5, 6
• Prompt diagnosis is critical as delayed treatment can lead to displacement, avascular necrosis, and increased morbidity and mortality
• Limited MRI protocols can be performed in under 5 minutes, making them time-efficient 3

Important Caveats

• CT may be considered if MRI is contraindicated (pacemakers, metal implants, claustrophobia) or unavailable 1, 6
• Approximately 26% of elderly patients have at least one contraindication to MRI 6
• While contrast-enhanced MRI may provide better visualization of soft tissue injuries, it offers no additional benefit for fracture detection in this setting 7
• For patients with total hip arthroplasty who sustain a fall, different imaging protocols apply - CT without contrast is recommended for acute injury evaluation 1

MRI without contrast remains the gold standard for detecting occult hip fractures after a fall when radiographs are negative, offering excellent diagnostic accuracy without the risks associated with IV contrast administration.