Hip MRI Recognition Pattern

Systematic approach to interpreting hip MRI with anatomical landmarks, common pathologies, and protocol optimization

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1. MRI Protocol

A. Standard Sequences

• • T1-weighted:
  - Anatomical detail
  - Bone marrow evaluation
  - Slice thickness: 3-4mm
• • T2-weighted fat-sat:
  - Fluid-sensitive
  - Labral tears, edema
  - STIR alternative
• • PD-weighted:
  - Cartilage assessment
  - Intermediate TE

B. Specialized Sequences

• • DESS/3D SPGR:
  - High-resolution cartilage imaging
  - Labral evaluation
• • MR Arthrography:
  - Intra-articular contrast
  - Distends joint capsule

2. Anatomical Evaluation

A. Key Structures

Structure

Normal Appearance

Pathology Clues

Labrum

Triangular, low T1/T2 signal

Increased signal, detachment

Cartilage

2-3mm thickness, smooth

Focal defects, delamination

Ligamentum teres

Hypointense, 30-35mm length

Thickening, partial tears

B. Imaging Planes

• • Axial:
  - Anterior/posterior joint capsule
  - Iliopsoas tendon
• • Coronal:
  - Superior labrum
  - Weight-bearing cartilage
• • Sagittal oblique:
  - Anterior/inferior labrum
  - Femoroacetabular impingement

3. Labral Pathology

A. Labral Tears

Type

Location

MRI Signs

Anterior

1-3 o'clock position

Most common in FAI

Superior

10-2 o'clock position

Dysplasia association

Degenerative

Diffuse

Adjacent cartilage loss

B. Paralabral Cysts

• • Features:
  - T2 hyperintense
  - Often multiloculated
  - Associated with labral tear

4. Femoroacetabular Impingement

A. Cam Morphology

• • Features:
  - Alpha angle >55°
  - Femoral head-neck offset <8mm
  - Anterolateral bump

B. Pincer Morphology

• • Features:
  - Crossover sign
  - Lateral center edge angle >40°
  - Protrusio acetabuli

5. Bone Marrow Patterns

A. Stress Injuries

Grade

MRI Features

I

STIR hyperintensity only

II

T1 hypointensity + STIR+

III

Partial cortical involvement

IV

Fracture line visible

B. AVN Staging

• • Early:
  - T1: geographic subchondral hypointensity
  - T2: double line sign
• • Late:
  - Subchondral collapse
  - Secondary OA changes

6. Reporting Template

• 1. Technique: Sequences, contrast use
• 2. Labrum:
  - Tear location/extent
  - Paralabral cysts
• 3. Cartilage:
  - Outerbridge grading
  - Delamination
• 4. Bone:
  - Marrow edema pattern
  - FAI morphology
• 5. Soft tissues:
  - Iliopsoas bursitis
  - Tendon pathology

Always correlate with patient history and physical exam. For FAI assessment, measure alpha angles on radial sequences. In young athletes, evaluate for subtle labral tears and early cartilage damage. For AVN, specify percentage of femoral head involvement. Document incidental findings (ganglion cysts, synovial disorders) with appropriate follow-up recommendations.

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