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E2195. Adult Non-Traumatic Hip Imaging: Radiographic Techniques and Metrics - A Resident Primer
Authors
  1. Arezu Monawer; University of Washington
  2. Hoiwan Cheung; University of Washington
  3. Alireza Abadi; University of Washington
  4. Majid Chalian; University of Washington
Background
Radiographs remain the most basic and critical imaging method for initial assessment of hip and pelvic pathologies. High quality radiographs are accessible, cost effective, and offer high diagnostic yield for specific pathologies. An appropriate understanding of image acquisition technique and common radiographic metrics can help the radiologist identify common non-traumatic hip pathologies.

Educational Goals / Teaching Points
• Review different radiographic imaging views of the hip (pelvis not included) • Familiarize with clinical importance of each imaging view • Review anatomic landmarks and various measurements and their clinical significance when assessing for Cam-type femoral-acetabular impingement (FAI), Pincer-type FAI, and developmental dysplasia of the hip (DDH)

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
A. Background B. Normal anatomy C. Hip radiographic views (quality control, acquisition technique, advantages and disadvantages to each view) a. AP view b. Lateral Views i. Frog-leg lateral ii. Cross-table lateral iii. Dunn 45º and 90º iv. False profile D. Radiographic Metrics (required views, anatomic landmarks, measurement techniques) a. Cam-type FAI i. Alpha angle ii. Femoral head-neck offset and ratio b. Pincer-type FAI i. Acetabular version ii. Acetabular depth 1. Lateral center-edge angle of Wiberg 2. Anterior center-edge angle 3. Acetabular depth ratio (acetabular quotient) 4. Femoral head extrusion index iii. Acetabular inclination 1. Tonnis angle (sourcil inclination) 2. Sharp angle (global inclination) c. DDH i. Acetabular depth ii. Acetabular inclination iii. Delta Angle iv. Head-neck shaft angle E. Case-based review

Conclusion
Hip dysplasia and impingement syndromes could have devastating outcomes if not diagnosed and treated at earlier stages of the disease. Radiography is the initial imaging modality of choice for screening such pathologies. Familiarity of radiology residents to different non-traumatic pathologies of the hip and various imaging metrics for their analysis is important for early diagnosis and decision-making. Information extracting from radiographs significantly impacts the interpretation of more advanced imaging such as CT and MRI.