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Early-Stage Perfusion MRI Correlates Significantly With Femoral Head Deformity in Children Under 6 Years of Age With
Joonoh Lee1, Ahan Mistry2, Jessica Cao1
1University of Texas Southwestern Medical Center.
Insights
Perfusion MRI (pMRI) can predict Legg-Calvé-Perthes disease (LCPD) outcomes in children under 6. Early femoral head hypoperfusion on pMRI correlates with later deformity, aiding prognosis.
Area of Science:
- Pediatric Orthopedics
- Radiology
- Medical Imaging
Background:
- Legg-Calvé-Perthes disease (LCPD) onset before age 6 typically suggests good prognosis, yet some patients develop femoral head deformity.
- No reliable early prognosticator exists for LCPD in this age group.
- This study explores perfusion MRI (pMRI) for early outcome prediction in young LCPD patients.
Purpose of the Study:
- To investigate the correlation between early-stage perfusion MRI (pMRI) findings and radiographic outcomes in pediatric Legg-Calvé-Perthes disease (LCPD).
- To determine if early femoral head hypoperfusion on pMRI can predict long-term femoral head deformity (deformity index, epiphyseal index, sphericity deviation score).
Main Methods:
- Multicenter retrospective review of LCPD patients with disease onset before age 6.
- Inclusion criteria: pMRI at Waldenström stage I to IIa.
- Analysis of demographic, pMRI, and radiographic data (DI, EI, SDS) with statistical correlation and ROC analysis.
Main Results:
- Forty-one femoral heads (37 patients) analyzed; mean follow-up 4.1 years.
- Significant correlation found between increasing femoral head hypoperfusion and greater deformity (higher DI, lower EI, higher SDS).
- A 60% hypoperfusion threshold on pMRI predicted worse outcomes (higher DI, lower EI, higher SDS).
Conclusions:
- Early-stage femoral head hypoperfusion on pMRI significantly correlates with radiographic outcomes in LCPD patients under 6.
- A pMRI hypoperfusion threshold of 60% identifies hips at higher risk for deformity.
- pMRI shows potential as an early prognostic marker for LCPD, guiding treatment decisions.
Background:
In general, the onset of Legg-Calvé-Perthes disease (LCPD) before age 6 is thought to be associated with a good radiographic outcome. Many of these patients, however, still develop a poor outcome with ovoid-to-flat femoral head deformity. Currently, no early-stage prognosticator of outcome exists for patients younger than 6 years at onset. This study investigated whether perfusion MRI (pMRI) obtained in early stages of LCPD correlates with deformity index (DI), epiphyseal index (EI), and sphericity deviation score (SDS). We hypothesized that early-stage femoral head hypoperfusion would correlate significantly with these radiographic outcomes and serve as an early prognosticator.
Methods:
This multicenter study reviewed demographic, pMRI, and radiographic data from patients with LCPD who had disease onset before age 6. Inclusion criteria were pMRI at Waldenström stage I to IIa. DI and EI were evaluated at 2-year follow-up, and SDS at the healed stage. Statistical analyses included Pearson correlation and ROC analysis, with a threshold predictive of SDS >20.
Results:
Forty-one femoral heads (37 patients; mean age at onset 5.0±0.9 years) were analyzed with a mean follow-up of 4.1±1.3 years. Mean hypoperfusion was 49±28%. Mean DI was 0.38±0.18, EI was 0.26±0.10, and SDS was 18.2±12.9. Increasing hypoperfusion (%) correlated significantly with greater femoral head deformity, including higher DI ( r =0.76), lower EI ( r =-0.62), and higher SDS ( r =0.64) (all P <0.001). ROC analysis identified 62% hypoperfusion as optimal for predicting SDS >20 (AUC: 0.80; sensitivity 75%; specificity 87%). Using a 60% cutoff point, outcomes were worse above the threshold: DI (0.31±0.16 vs. 0.52±0.14, P =0.002), EI (0.30±0.09 vs. 0.19±0.07, P <0.001), and SDS (11.7±6.1 vs. 26.8±14.6, P =0.001).
Conclusions:
Early-stage femoral head hypoperfusion correlated significantly with radiographic outcomes at 2-year follow-up and at the healed stage in patients with LCPD onset before age 6. A pMRI hypoperfusion threshold of 60% identified femoral heads at a higher risk for femoral head deformity, supporting pMRI as a potential early prognostic marker.
Level Of Evidence:
Level III.
