Lumbar Spine Imaging Techniques Summary

Overview of Vertebral Anatomy and Imaging Techniques

  • Importance of memorizing vertebral anatomy (e.g., Scotty dog representation).
  • Superior and inferior articular processes form zygapophyseal joints, ask about leg and ear representation.

Lumbar Vertebrae Identification

  • L1 to L5 lumbar vertebrae differentiate in appearance, particularly in imaging.
  • Patient rotation: 50 degrees for L1-L2, 45 degrees for L3-L5 to visualize zygapophyseal joints clearly.
  • Referenced on page 339 of the textbook.

Imaging Techniques and Considerations

  • Oblique Views:

    • Anterior obliques better visualize upside of joints; posterior obliques visualize downside.
    • Note differences in common practices; most use posterior obliques.

  • Landmarks:

    • Lower costal margin correlates with L2-L3; iliac crest coincides with L4-L5.

Central Ray Positioning

  • AP Lumbar Spine:

    • Centering guidelines: typically 2 fingers above the iliac crest, adjust for specific views.
    • Variations in collimation based on desired visibility of thoracic and sacral regions.

  • Oblique Views:

    • Direct CR at L3, 2 inches medial to upside for zygapophyseal joints.
    • Perform 50-degree rotation for L1-L2, 45 degrees for others.

Lateral Positioning

  • Lateral Lumbar View:

    • Assess for fractures and spondylolisthesis; correct angling necessary for patient demographics.

  • Spot View:

    • Specific for L4-L5 and L5-S1; center at 1.5 inches below the crest 2 inches posterior to ASIS.

Special Views

  • AP Axial View:

    • Assessing L5-S1 and SI joints; CR angles: 30 degrees for males, 35 degrees for females.

  • Lateral Spinal Fusion Series (Flexion/Extension):

    • Evaluates mobility at fusion sites, typically performed erect with wider collimation.

Evaluation Criteria for Imaging

  • Positioning errors: rotation can misalign spinous processes and intervertebral foramina visibility.
  • Pedicle visibility indicates patient positioning: medially viewed indicates over-rotation, laterally indicates under-rotation.