18F-fluorodeoxyglucose positron emission tomography/computed tomography in the evaluation of spinal giant cell tumors.

Objective: To investigate the value of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in the evaluation of spinal giant cell tumors (GCTs). Materials and methods: The PET/CT and clinical data of 16 patients with spinal GCTs were reviewed. The maximal standardized uptake value (SUVmax), longest diameter, and CT features of spinal GCTs were analyzed. The value of PET/CT and MRI in displaying the recurrent lesions was compared. PET Response Criteria in Solid Tumors were adopted to evaluate the response to radiotherapy. Results: Data from 7 males and 9 females (median age 32.5 years) were analyzed. Eight patients had primary GCTs with a median SUVmax of 11.91 and a median length of 4.42 cm. Eight patients had relapsed GCTs with a median SUVmax of 10.34 and a median length of 6.23 cm. There was no statistical difference between the SUVmax of primary and relapsed GCTs. The SUVmax did not correlate with length. In 8 relapsed patients, 4 lesions invaded the vertebral canal, but 2 of which were not displayed on MRI. Metal prostheses showed extremely low signal intensity on MRI, even in the 3 cases with increased intra-prosthetic 18F-FDG concentration. Five relapsed patients with subsequent radiotherapy had a repeat PET/CT. A complete, partial, and stable metabolic response was observed in 1, 3, and 1 patient, respectively. Conclusions: Both the primary and recurrent spinal GCTs avidly accumulate 18F-FDG. For recurrent GCTs, PET/CT may provide incremental value in the assessment of the vertebral canal and intra-prosthetic involvement and the response to radiotherapy. [ABSTRACT FROM AUTHOR]