Can radiographic morphometric parameters for the hip be assessed on MRI?

Area of Science:

• Orthopedic imaging
• Radiology
• Hip biomechanics

Background:

• Morphometric hip parameters from radiographs are crucial for diagnosing and treating hip disorders.
• Clinicians increasingly use MRI for hip measurements, but its comparability to radiography is unclear.

Purpose of the Study:

• To compare hip morphometric measurements, including lateral center-edge angle (LCE), Tönnis angle, extrusion index, and anterior center-edge angle (ACE), between MRI and radiography.
• To determine if MRI can reliably replace radiography for these key hip parameters.

Main Methods:

• Retrospective review of 103 hip imaging studies (46 femoroacetabular impingement, 57 hip dysplasia).
• Manual measurement of LCE, Tönnis angle, extrusion index, and ACE on both radiographs and MRI.
• Coronal, sagittal, and oblique sagittal reformats were reconstructed from 3D isotropic MRI sequences for comparison with radiographic gold standards.

Main Results:

• Good agreement was observed for LCE angle, Tönnis angle, and extrusion index between radiography and coronal MRI slices (mean differences ≤5° or ≤5% for extrusion index).
• Significant discrepancies were found for the anterior center-edge angle (ACE) between sagittal MRI slices and radiographs (differences ranging from 5° to 28°).

Conclusions:

• MRI can provide comparable measurements to radiography for LCE angle, Tönnis angle, and extrusion index.
• Radiographic anterior center-edge angle (ACE) measurements cannot be reliably estimated from MRI, indicating a limitation for this specific parameter.