📌 CT-Negative, MRI-Positive: The Cancellous Stress Fracture Pattern You Should Not Miss

https://youtube.com/shorts/WfY4j4MNEHQ

 

When the Cortex Is Intact but the Trabecula Collapses: Why Only MRI Reveals the True Injury

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Cancellous (trabecular) stress injuries of the femoral neck and femoral head often remain completely invisible on CT.
The cortex stays intact, the subchondral contour appears normal, and the subtle attenuation changes fall below CT’s detection threshold.

MRI, however, shows the full pathophysiology:

1. T1-weighted MRI

• Irregular, wavy, crumpled low-signal trabecular lines
  
  
• No cortical break, no subchondral crescent line
  
  

2. T2/STIR / PD-FS

• Prominent diffuse marrow edema
  
  
• Serpiginous dark microfracture lines within the edema
  
  
• No double-line sign and no collapse (distinguishes from AVN)
  
  

3. Mechanism
A single compression-dominant stress overload affecting the inferomedial femoral neck and the weight-bearing dome of the femoral head, producing a continuous-spectrum trabecular injury.

4. Why CT Fails

• Cortex intact → no structural cue
  
  
• Microtrabecular collapse below CT spatial resolution
  
  
• Marrow edema undetectable on CT
  
  
• Subtle density changes obscured by noise and beam hardening
  
  
• Articular surface remains morphologically normal
  
  

Conclusion
CT stays “normal,” but MRI reveals the biologic truth.
This pattern is a classic CT-occult, MRI-diagnostic cancellous stress fracture.

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#StressFracture, #FemoralNeck, #FemoralHead, #MRIImaging, #MSKRadiology, #BoneMarrowEdema, #OccultFracture, #Orthopaedics, #RadiologyEducation, #CTvsMRI, #Vibecase,

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