Tc-Methylene Diphosphonate Planar Skull Bone Scan in Detecting Basal Skull Lesions in Nasopharyngeal Carcinoma

Received 10/2/2000; revised 11/17/2000; accepted 12/2/2000. For correspondence or reprints contact: Ming-Che Wu, M.D., Department of Nuclear Medicine, MacKay Memorial Hospital, 92, Section 2, Chung-San North Road, Taipei 10449, Taiwan. Tel: (886)2-25433535 ext. 3369, Fax: (886)2-25433535 ext. 2925, E-mail: [email protected] Background: The authors evaluated the performance of Tc-MDP planar skull bone scan in detecting basal skull lesions in patients with nasopharyngeal carcinoma, proposed a strategy for effective use of planar and SPECT skull bone scan in the imaging of NPC patients, and evaluated the influence of increased mastoid bone uptake on the interpretation of planar skull bone scans. Methods: One hundred and seventeen patients with nasopharyngeal carcinoma underwent whole body, bilateral planar skull, and skull SPECT bone scans. The findings for the skull base and mastoid bone on planar and SPECT images as interpreted by three nuclear medicine physicians from different hospitals were compared to reach a consensus. The SPECT consensus was then used as the final result for performance evaluation of the planar images. Results: The planar skull bone scan had a sensitivity of 78%, a specificity of 77%, an accuracy of 78%, a positive predictive value of 94%, and a negative predictive value of 45%. The consensus results and performance between the patients with and without mastoid lesions showed no significant statistical differences. Conclusion: We recommend NPC patients with negative or equivocal findings on planar skull bone scan undergo skull SPECT for further evaluation while those with positive findings may save the SPECT unless otherwise indicated. Increased uptake in mastoid bone does not adversely affect the reading of planar skull bone scan.