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

Objective: Bone metastasis occurs frequently in nasopharyngeal carcinoma (NPC) patients. The aim of this study was to compare the clinical value of 18F-FDG PET/CT with that of 99mTc-MDP planar bone scintigraphy (PBS) for detecting bone metastasis in NPC patients.

Methods: Thirty-five histologically proven NPC patients were enrolled in this retrospective study. They underwent both 18F-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.

Results: 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).

Conclusions: PBS, as a conventional imaging, should be used as an important complement for detecting bone metastasis in NPC patients.