Using Cine-Averaged CT With the Shallow Breathing Pattern to Reduce Respiration-Induced Artifacts for Thoracic Cavity PET/CT Scans.

Abstract

<b>OBJECTIVE.</b> PET/CT provides a fusion of both anatomic and functional information. However, because of the temporal difference of both modalities and respiratory motion of lungs, misregistration of lesions is frequently observed on thoracic PET/CT scans. The effect of cine-averaged CT (CACT) acquisition incorporated with the shallow breathing pattern of patients on the improvement of registration and quantification of lesions was investigated. <b>MATERIALS AND METHODS.</b> Thirty patients with cancer who underwent routine PET/CT followed by CACT of the thoracic region were enrolled. The misalignment between PET/helical CT (HCT) and PET/CACT was calculated. In addition, the PET data were attenuation-corrected by HCT and CACT images, and the maximum standardized uptake value (SUV_max) was evaluated. <b>RESULTS.</b> All lesions in the PET/HCT images showed misalignment larger than 5 mm, whereas only 33% of lesions in the PET/CACT images showed misalignment larger than 5 mm. The mean values of the maximum misalignment of the lesions in PET/HCT and PET/CACT images were 14.10 ± 6.26 mm and 5.92 ± 4.31 mm, respectively. Seven percent of the lesions had an increase in SUV_max of more than 20%, and 47% showed a slight increase in SUV_max of less than 5% after applying CACT. The mean percentage difference between the SUV_max of CACT and that of HCT was 12%. <b>CONCLUSION.</b> Using the CACT technique and the shallow breathing pattern effectively reduces misregistration of lesions and recovers the underestimated SUV_max. The CACT method can be applied in clinical practice of thoracic PET/CT for better cancer management.