Is 18F-FDG PET/CT more reliable than 99mTc-MDP planar bone scintigraphy in detecting bone metastasis in nasopharyngeal carcinoma?

Bone metastasis occurs frequently in nasopharyngeal carcinoma (NPC) patients. The aim of this study was to compare the clinical value of F-18-FDG PET/CT with that of Tc-99m-MDP planar bone scintigraphy (PBS) for detecting bone metastasis in NPC patients. Thirty-five histologically proven NPC patients were enrolled in this retrospective study. They underwent both F-18-FDG PET/CT and PBS within 7 days in our department. In a lesion-based analysis, the skeletal system, excluding the head, was divided into four regions: the spine, the pelvis, the thorax, and the appendix. Bone metastasis was considered to be present by either biopsy or clinical follow-up for at least 6 months. PET/CT and PBS were compared by McNemar's paired-sample test. A total of 50 lesions were confirmed to be malignant (spine 27, thorax 11, pelvis 8 and appendix 4). Although PET/CT was found to be more sensitive on lesion level than PBS (sensitivity 70.0 versus 42.0 %; P = 0.044), there were still 14 metastatic (28.0 %) lesions that could be detected by PBS while negative in PET/CT imaging. In a patient-based analysis, fifteen (42.9 %) of 35 eligible patients were found to have bone metastasis. The sensitivity, specificity and accuracy of PET/CT was 60.0 % (9/15), 100 % (20/20) and 82.9 % (29/35); as for PBS, it was 66.7 % (10/15), 85.0 % (17/20) and 77.1 % (27/35), respectively. There was no statistical difference between PET/CT and PBS (P > 0.05). PBS, as a conventional imaging, should be used as an important complement for detecting bone metastasis in NPC patients.