Clinical usefulness of fused PET/CT compared with PET alone or CT alone in nasopharyngeal carcinoma patients

Abstract

The diagnostic accuracy of fused positron emission tomography/computed tomography (PET/CT) was compared with CT alone and PET alone in the staging and re-staging of nasopharyngeal carcinoma (NPC) patients.

Patients and methods: Eighty-six fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG) PET/CT studies were retrospectively performed in 70 patients with NPC, 20 patients for primary tumor staging and 50 patients for re-staging after treatment. Each lesion was analyzed visually and assigned a score on a 5-point scale. Each study was interpreted in 3 ways: PET images were evaluated in the absence of CT data, CT images in the absence of PET data and fused PET/CT images. The results of these images were correlated with histological findings, as well as long-term radiological and clinical follow-up (the shortest follow-up period after imaging was 6 months). PET, CT and PET/CT accuracy were compared by a McNemar test.

Results: Fused PET/CT correctly characterized the tumor-node-metastasis system stage in 82 out of 86 studies (95.4%; 95% CI: 90.9% to 99.9%). PET alone and CT alone were found to be accurate in 71 out of 86 studies (82.6%; 95% CI: 74.5% to 90.6%) and 63 out of 86 studies (73.3%; 95% CI: 63.9% to 82.6%), respectively. Furthermore, the differences between PET/CT and either PET alone or CT alone were statistically significant (p<0.05). Overall, the study-based analysis of PET/CT for staging NPC demonstrated 48 true-positive, 2 false-negative, 34 true-negative and 2 false-positive studies. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of FDG-PET/CT studies for staging NPC were 96%, 94.4%, 95.4%, 96% and 94.4%, respectively.

Conclusion: PET/CT is more accurate than PET alone or CT alone for the depiction of NPC. Fused PET/CT is a valuable imaging tool in patients for staging diagnosis of NPC.