TY - JOUR T1 - Whole-body Parametric Imaging of FDG PET using uEXPLORER with Reduced Scan Time JF - Journal of Nuclear Medicine JO - J Nucl Med DO - 10.2967/jnumed.120.261651 SP - jnumed.120.261651 AU - Yaping Wu AU - Tao Feng AU - Yizhang Zhao AU - Tianyi Xu AU - Fangfang Fu AU - Zhun Huang AU - Nan Meng AU - Hongdi Li AU - Fengmin Shao AU - Meiyun Wang Y1 - 2021/08/01 UR - http://jnm.snmjournals.org/content/early/2021/08/19/jnumed.120.261651.abstract N2 - Parametric imaging of Ki (the net influx rate) in FDG PET has been shown to provide better quantification and improved specificity for cancer detection compared with SUV imaging. Current methods for generating parametric images usually requires a long dynamic scan time. With the recently developed uEXPLORER scanner, a dramatic increase of sensitivity has reduced the noise in dynamic imaging, making it more robust to employ a non-linear estimation method and flexible protocols. In this work, we explored 2 new possible protocols besides the standard 60-minute one for the possibility of reducing scan time for Ki imaging. Methods: In the proposed protocols, the first one is the conventional dynamic scans of a 60-minute scan time as the gold standard. The second scanning protocol includes two scan periods, 0-4 minutes, and 54-60 minutes post-injection. The third one consisted of a single scanning period from 50 minutes to 60 minutes post-injection. In the third protocol, a second injection was applied at t=56 minutes. The two new protocols were simulated from the 60-minute scans. A hybrid input function that combining the population-based input function and the image-derived input function (IDIF) was used. The results were also compared with the IDIF acquired from Protocol 1. A previously developed maximum likelihood approach was used for estimating the Ki images. A total of 7 cancer patients scanned using the uEXPLORER scanner were enrolled in this study. Lesions were identified from the patient data and the lesion Ki values were compared among different protocols. Results: The acquired hybrid input function was comparable in shape with the IDIF for each patient. The average area-under-curve difference was ~3%, suggesting good quantitative accuracy. The visual difference between the Ki images generated using IDIF and the hybrid input function was also minimal. The acquired Ki images using different protocols were visually comparable. The average Ki difference in the lesions was found to be 2.8%±2.1% for protocol 2 and 1%±2.2% for protocol 3. Conclusion: The results suggest that it is possible to acquire the Ki image using the nonlinear estimation approach with much-reduced scan time. Among the two new protocols, the protocol with dual injections shows the greatest promise in terms of practicality. ER -