Usefulness of Bone SPECT/CT for Predicting Avascular Necrosis of the Femoral Head in Children with Slipped Capital Femoral Epiphysis or Femoral Neck Fracture

Objective: This study aimed to investigate the usefulness of bone single-positron emission tomography/computed tomography (SPECT/CT) of the hip in predicting the later occurrence of avascular necrosis (AVN) after slipped capital femoral epiphysis (SCFE) or femoral neck fracture in pediatric patients. The quantitative parameters of SPECT/CT useful in predicting AVN were identified. Materials and Methods: Twenty-one (male:female, 10:11) consecutive patients aged < 18 years (mean age +/- standard deviation [SD], 11.0 +/- 2.7 years) who underwent surgery for SCFE or femoral neck fracture and postoperative bone SPECT/CT were included. The maximum standardized uptake value (SUV), mean SUV, and minimum SUV of the femoral head were measured. The ratios of the maximum SUV, mean SUV, and minimum SUV of the affected femoral head to the contralateral side were determined. Patients were followed up for > 1 year after the surgery. The SPECT/CT parameters were compared between patients who developed AVN and those who did not. The accuracy of SPECT/CT parameters for predicting AVN was assessed. Results: Six patients developed AVN. There was a significant difference in the ratio of the mean SUV among patients who developed AVN (mean +/- SD, 0.8 +/- 0.3) and those who did not (1.1 +/- 0.2, p = 0.018). However, there were no significant differences in the ratios of the maximum and minimum SUV between the groups (allp = 0.205). For the maximum, mean, and minimum SUVs, no significant differences were observed between the groups (p = 0.519, 0.733, and 0.470, respectively). The cutoff mean SUV ratio of 0.87 yielded a 66.7% sensitivity and 93.2% specificity for predicting AVN. Conclusion: Quantitative bone SPECT/CT is useful for evaluating femoral head viability in pediatric patients with SCFE or femoral neck fractures. Clinicians should consider the high possibility of later AVN development in patients with a decreased mean SUV ratio.