The Impact of Acquisition Time on Image Quality in Whole-Body 18F-FDG PET/CT for Cancer Staging

Abstract

UNLABELLED: Our objective was to evaluate the impact of acquisition time on image quality, lesion detection rate, standardized uptake values, and lesion volume for (18)F-FDG PET in cancer patients. METHODS: Over 7 mo, 33 cancer patients were included in this study. In these patients, 63 lesions were independently evaluated by 2 nuclear medicine specialists (experienced and beginner). Two consecutive whole-body (18)F-FDG PET/CT scans using a 3-min and 1.5-min acquisition time per bed position were obtained for each patient. Lesions were visually identified, and their locations were compared. The lesion volumes and standardized uptake values of the primary tumor, lymph nodes, and metastases were determined and compared. Image quality was scored using a 5-range Likert-type scale. For all parameters, interobserver agreement was assessed. RESULTS: All relevant lesions could be identified at both acquisition times. Image quality was slightly adversely affected by an acquisition time of 1.5 min but was excellent or good in 85% of the scans. In a patient with increased blood sugar levels, the image quality was rated moderate at 3 min and poor at 1.5 min. The quality of lesion visualization was excellent regardless of the acquisition time. Lesion volume and maximum standardized uptake value on PET images showed an excellent correlation between the 2 acquisition times (Pearson correlation coefficient, 0.99 and 0.97, respectively). Interobserver agreement was excellent (κ > 0.83). CONCLUSION: Although image quality is slightly poorer, reducing the acquisition time to 1.5 min per bed position seems to be clinically feasible without decreasing the lesion detection rate even for less experienced observers.