The influence of acquisition time on PET/CT imaging quality and lesion detectability

Objective: To explore the feasibility of shortening the acquisition time without influencing the image quality and detectability by analysing PET/CT imaging with different acquisition time. Methods: PET emission scan of 18 patients was performed in sequence of l min/bed, 2 min/bed, 3 min/bed after CT scan. Fifty-four images were totally obtained. Patients were grouped according to body weight: (1) 4.5-60 kg (n=7), (2) 61-7.5 kg (n=7), (3) 76-90 kg (n=4). Lesion detectability were co-analyzed by two experienced doctors; while image quality was judged separately by them. Results: One hundred and twenty-seven lesions were identified in 3 min/bed PET images (n=18); the smallest size was 3 mm. Only 3 were missed in 1 min/bed PET images, and all lesions were identified in the corresponding 2 min/bed PET images. All lesions from first group could be detected in the three kinds of acquisition time. Three lesions from second group were missed in the 1 min/bed PET images. Image quality of 1 and 2 min/bed differed significantly from the 3 min/bed (P<0.05) especially in high body weight patients; image quality of 1 min/bed was the worst. Conclusions: For patients with body weight less than 60 kg, 1-3 min/bed acquisition protocols show no difference both with lesion detectability and image quality, while in patients with body weight over 60 kg, 2-3 min/bed acquisition is suggested. For patients with serious and uncooperated conditions, 1 min/bed acquisition protocol can be selected if necessary. (authors)