The Relationship Between the Location of Uptake on Positron Emission Tomography/Computed Tomography and the Impingement Point by Computer Simulation in Femoroacetabular Impingement Syndrome With Cam Morphology.

Abstract

To clarify the concordance rate of the location of uptake on positron emission tomography/computed tomography (PET/CT) and the impingement point demonstrated in computer simulation in femoroacetabular impingement (FAI) syndrome with cam morphology. We included hip joints with FAI syndrome that underwent ¹⁸F-fluoride PET/CT. We also excluded hips with SUV_max <6. Each hip was evaluated for the region of the SUV_max point on PET/CT as well as the impingement point by computer simulation. We used ZedHip software (Lexi, Tokyo, Japan) for impingement simulation analysis based on CT data. Bony impingement is identified if there is a mesh in acetabular and femoral side contact in at least one unit. We investigated the rate of concordance between these 2 regions for each 10° flexion angle of the hip, ranging from 0° to 90°. Twenty-two hips of 22 patients were evaluated. The SUV_max region was most frequently distributed in the proximal middle region in 12 hips. In 18 of 22 hips (81.8%), the SUV_max region was concordant with the impingement region for at least one flexion angle. The concordance rates in 50° (P = .034), 60° (P = .007), 70° (P = .011), and 80° (P = .046) of flexion were significantly higher than in 90° of flexion. It was possible to visualize and clarify the detailed location of abnormal uptake in FAI syndrome patients with cam morphology by applying ¹⁸F-fluoride PET/CT. The concordance rates in 50°, 60°, 70°, and 80° of flexion were significantly higher than in 90° of flexion, which suggested that impingement may more frequently occur at less than 90° of flexion in FAI syndrome with cam morphology. Level III, cross-sectional diagnostic study.