18F‐NaF PET/CT IMAGING IN FIBROUS DYSPLASIA OF BONE

Abstract

Fibrous dysplasia (FD) is a mosaic skeletal disorder resulting in fractures, deformity, and functional impairment. Clinical evaluation has been limited by a lack of surrogate endpoints capable of quantitating disease activity. The purpose of this study was to investigate the utility of 18F‐NaF PET/CT imaging in quantifying disease activity in patients with FD. Fifteen consecutively evaluated subjects underwent whole‐body 18F‐NaF PET/CT scans, and FD burden was assessed by quantifying FD‐related 18F‐NaF activity. 18F‐NaF PET/CT parameters obtained included (i) SUVmax (standardized uptake value [SUV] of the FD lesion with the highest uptake); (ii) SUVmean (average SUV of all 18F‐NaF–positive FD lesions); (iii) total volume of all 18F‐NaF–positive FD lesions (TV); and (iv) total FD lesion activity determined as the product of TV multiplied by SUVmean (TA =\u2009 TV ×\u2009 SUVmean) (TA). Skeletal outcomes, functional outcomes, and bone turnover markers were correlated with 18F‐NaF PET/CT parameters. TV and TA of extracranial FD lesions correlated strongly with skeletal outcomes including fractures and surgeries (p values ≤\u20090.003). Subjects with impaired ambulation and scoliosis had significantly higher TV and TA values (P <\u20090.05), obtained from extracranial and spinal lesions, respectively. Craniofacial surgeries correlated with TV and TA of skull FD lesions (P <\u20090.001). Bone turnover markers, including alkaline phosphatase, N‐telopeptides, and osteocalcin, were strongly correlated with TV and TA (P <\u20090.05) extracted from FD lesions in the entire skeleton. No associations were identified with SUVmax or SUVmean. Bone pain and age did not correlate with 18F‐NaF PET/CT parameters. FD burden evaluated by 18F‐NaF‐PET/CT facilitates accurate assessment of FD activity, and correlates quantitatively with clinically‐relevant skeletal outcomes. © 2019 American Society for Bone and Mineral Research.