Clinical utility of ¹⁸F-FDG PET/CT scan in primary bone tumour

Imaging plays an important role in the evaluation of primary bone tumors. Aim of this study was to evaluate the role of ¹⁸F-FDG PET/CT in staging, restaging, recurrence detection and changes in management of primary bone tumor patients. Material and Methods: Clinical records of patients with bone tumor, who had undergone ¹⁸F FDG PET/CT scan from April 2014 to August 2015, were reviewed retrospectively. Patients were also subjected to CT, MRI for characterization of lesion and to look for metastatic disease. The final diagnosis of primary bone tumor was confirmed by histopathological examination after biopsy or surgical excision of the lesion. ¹⁸F-FDG PET/CT scan was performed using standard protocol. PET scan finding were divided into four categories - site of primary bone tumor, other skeletal sites, lung lesion and regional lymphadenopathy. The lesion detected on PET scan was verified by tissue diagnosis after surgical excision and follow up PET scan, further imaging and follow-up. A total 33 diagnosed cases of primary bone tumor (19 male, 14 female; mean age 28 years, range 10-60 years) were analyzed retrospectively. Of the 33 patients, 12 were diagnosed to have osteosarcoma, 9 Ewing's sarcoma, 3 giant cell tumor, 8 chondrosarcoma and 1 enchondroma. PET/CT was used for initial staging in 7 patients, restaging/ response evalution in 7 patients, recurrence detection in 8 patients and surveillance in 11 patients. In staging of primary bone tumor, PET scan showed abnormal FDG uptake at primary site in all the 7 patients, lung lesions in 4 patients. Three of these 7 patients (42%) received additional therapy based on PET findings. In restaging/response evaluation, PET showed abnormal FDG uptake in other skeletal site in 2 patients, lung lesions in 3 patients. Two of the 7 (28%) patients in this category received additional chemotherapy and surgical excision in 1 patient (14%). Of the 8 patients evaluated for recurrence, PET scan was positive for recurrence in 2 patients (25%). PET scan show abnormal FDG uptake in other than primary skeletal site in 1 of the 11 patients studied for surveillance. Four patients (36%) received chemotherapy and surgical excision in 1 patient (10%). Our result show that whole body ¹⁸F- FDG PET/CT scans is very useful in detecting lesions at other site in addition to primary skeletal lesion and helps in deciding additional therapy based on PET scan findings. (author)