Comparing 18-fluoro-2-deoxyglucose positron emission tomography with a combination of technetium 99m tetrofosmin single photon emission computed tomography and computed tomography to detect recurrent or persistent nasopharyngeal carcinomas after radiotherapy

BACKGROUND, The diagnostic accuracy of combined computed tomography (CT) an d technetium 99m tetrofosmin (Tc-TF) single photon emission computed tomogr aphy (SPECT) of head and neck to differentiate recurrent or residual nasoph aryngeal carcinomas (NPCs) from benign lesions after radiotherapy was evalu ated and compared with positron emission tomography (PET) with 18-fluoro-2- deoxyglucose (FDG). METHODS. Four months after radiotherapy, 36 patients with NPC underwent Tc- TF SPECT and CT of head and neck to differentiate recurrent or residual NPC from benign lesions. Histopathologic examinations were performed on nasoph aryngeal biopsies of all 36 patients. RESULTS. Based on the biopsy results, the sensitivity, specificity, and acc uracy of Tc-TF SPECT were 64%, 96%, and 86%, respectively, for differentiat ion of recurrent or persistent NPC from benign lesions. For CT and FDG-PET, the sensitivity, specificity, and accuracy were 73%, 88%, and 83% and 100% , 96%, 97%, respectively. For the 27 patients with NPC whose Tc-TF SPECT an d CT results were congruent, the combination of Tc-TF SPECT and CT had the same sensitivity, specificity, and accuracy (100%, 96%, and 96%) as FDG-PET . For the nine patients with NPC with incongruent Tc-TF SPECT and CT result s, FDG-PET correctly differentiated two benign lesions from seven recurrent /residual NPCs. CONCLUSIONS, Although, FDG-PET is the best tool for detecting recurrent or residual NPC, combined congruent Tc-TF SPECT and CT results achieved the sa me accuracy as FDG-PET. Therefore, we concluded that FDG-PET could be consi dered only when Tc-TF SPECT and CT give incongruent results. (C) 2001 Ameri can Cancer Society.