Potential Application of Bone Scintigraphy in Nasopharyngeal Carcinoma With Skull Base and Adjacent Bony Involvement

Abstract

Background: Bone scintigraphy has an established role to evaluate skeletal metastasis by detecting lesions earlier compared with radiographic changes. Skull base and adjacent bony involvement could possibly be evaluated using bone scintigraphy and might influence nasopharyngeal carcinoma (NPC) treatment planning. Skull base lesions in NPC are also associated with concomitant skeletal metastases. Aim: To determine clinical characteristics of NPC patients with skull base lesions and adjacent bony involvement who underwent bone scintigraphy and their scan findings. Methods: Bone scintigraphy performed for 87 NPC patients between June 2014 and February 2018. Whole-body imaging acquired at 3 hours after 99mTc methylene diphosphonate (MDP) injection. Clinical information and scintigraphic findings were compiled. Patients with prior evidence and/or bone scintigraphic features of skull base lesions or adjacent bony involvement were included (n = 46). Synchronous malignancy or ongoing bone infection cases were excluded. Results: 17 patients had prior evidence of skull base or adjacent bony involvement that were all subsequently positive on bone scintigraphy. We detected another 29 patients with MDP-avid skull base or adjacent bony involvement. Average age of entire cohort was 51 years. Approximately 78% were males. Majority were ethnic Chinese (48%). Most patients (57%) had stage 4 diseases prior to bone scintigraphy with 9 patients demonstrating distant metastasis mainly to lungs and bones. Only 28 patients were receiving ongoing treatment. Overall, 18 patients (39%) showed concomitant MDP-avid skeletal metastases on whole-body imaging. Patients whom already had existing documented distant metastasis were significantly associated with concomitant MDP-avid skeletal metastases ( P < 0.05), while other parameters including gender, age, ethnicity, disease staging and treatment status showed no significant correlation. Conclusion: Bone scintigraphy could potentially be used to assess skull base and adjacent bony involvement besides concomitant skeletal metastasis among our cohort of NPC patients.