Fast Field Echo Magnetic Resonance Imaging For Quantifying Acetabular Wall Coverage: A Validation Study With Computed...

Area of Science:

• Orthopedic imaging
• Hip dysplasia assessment
• Acetabular morphology evaluation

Background:

• Acetabular morphology in hip dysplasia is typically evaluated using computed tomography (CT) for bone and magnetic resonance imaging (MRI) for soft tissues.
• The agreement between CT and 3.0-T fast field echo (FFE) MRI for anterior and posterior acetabular sector angles (AASA, PASA) is not well-defined.

Purpose of the Study:

• To evaluate the correlation and agreement between CT and 3.0-T FFE MRI measurements of acetabular sector angles (ASAs) in hip dysplasia.
• To determine if T1-weighted FFE MRI can reliably replace CT for assessing acetabular coverage.

Main Methods:

• A cohort study involving 65 symptomatic dysplastic hips.
• Measurements of lateral center-edge angle (LCEA), acetabular wall indices (AWI, PWI), Tönnis angle, and pelvic signs were performed using both CT and 3.0-T MRI.
• Anterior and posterior acetabular sector angles (AASA, PASA) were obtained at equatorial, intermediate, and proximal levels for CT-MRI agreement assessment using Spearman rho (ρ).

Main Results:

• Intermediate AASA showed strong CT-MRI correlation (ρ = 0.807), while equatorial and proximal AASA correlations were moderate (ρ = 0.408, 0.398).
• All PASA measurements demonstrated good MRI-CT agreement (ρ ranging from 0.739 to 0.766).
• Acetabular wall index (AWI) correlated well with CT-derived anterior acetabular sector angles (AASAs) but weakly with MRI-derived AASAs (ρ ranging from 0.255 to 0.345).

Conclusions:

• T1-weighted FFE MRI cannot currently substitute CT for measuring acetabular coverage of the femoral head.
• While MRI-CT agreement was better posteriorly, anterior correlation was inaccurate, potentially leading to misinterpretation of AWI using MRI alone.
• CT is strongly recommended for assessing patients considered for hip joint preservation surgery, especially those with potential anterior wall defects.