Impact of computed tomography-positron emission tomography fusion in staging patients with thoracic malignancies

Background. Positron emission tomography (PET) has been demonstrated to improve staging in patients with thoracic malignancies. This study evaluates the ability of a new imaging technique to improve the spatial resolution and accuracy of PET. Methods. Patients with known or suspected malignancy (n = 21) who were referred for a dedicated PET scan were also evaluated with a new camera-based PET system, which uniquely allows simultaneous computed tomography (CT) and fusion of the camera-based PET images with the CT images. The dedicated PET scan was obtained 1 hour after intravenous injection of fluorodeoxyglucose. The camera-based PET imaging was fused with the CT images at approximately 2 hours after injection. The camera-based PET and CT-PET fusion images were read independently and blindly by 2 experienced observers and the presence and location of abnormalities was compared with dedicated PET scans. Results. Dedicated PET identified 18 sites in the chest as abnormal. The CT-PET fusion was superior to the camera-based PET alone, concordant with the dedicated PET in 16 of 21 patients compared with 13 of 21 by camera-based PET. The lesions missed by the camera-based PET were less than 1 cm in diameter. Fused CT-PET images provided superior anatomic localization and spatial resolution compared with dedicated PET and camera-based PET. Conclusions. CT-PET fusion images were more accurate than camera-based PET alone. CT-PET fusion improves the spatial resolution compared with dedicated PET and may improve the availability and efficacy of staging of patients with thoracic malignancies.