Methods to shorten [¹⁸F]FDG Patlak PET imaging procedures ranging from 65–90 to 20–30 min after injection, using a population-averaged input function (PIF) scaled to patient-specific image-derived input function (IDIF) values, were recently evaluated. The aim of the present study was to explore the feasibility of ultrashort 10-min [¹⁸F]FDG Patlak imaging at 55–65 min after injection using a PIF combined with direct Patlak reconstructions to provide reliable quantitative accuracy of lung tumor uptake, compared with a full-duration 65-min acquisition using an IDIF. Methods: Patients underwent a 65-min dynamic PET acquisition on a long-axial-field-of-view (LAFOV) Biograph Vision Quadra PET/CT scanner. Subsequently, direct Patlak reconstructions and image-based (with reconstructed dynamic images) Patlak analyses were performed using both the IDIF (time to relative kinetic equilibrium between blood and tissue concentration (t*) = 30 min) and a scaled PIF at 30–60 min after injection. Next, direct Patlak reconstructions were performed on the system console using only the last 10 min of the acquisition, that is, from 55 to 65 min after injection, and a scaled PIF using maximum crystal ring difference settings of both 85 and 322. Tumor lesion and healthy-tissue uptake was quantified and compared between the differently obtained parametric images to assess quantitative accuracy. Results: Good agreement was obtained between direct- and image-based Patlak analyses using the IDIF (t* = 30 min) and scaled PIF at 30–60 min after injection, performed using the different approaches, with no more than 8.8% deviation in tumor influx rate value (K_i) (mean difference ranging from −0.0022 to 0.0018 mL/[min × g]). When direct Patlak reconstruction was performed on the system console, excellent agreement was found between the use of a scaled PIF at 30–60 min after injection versus 55–65 min after injection, with 2.4% deviation in tumor K_i (median difference, −0.0018 mL/[min × g]; range, −0.0047 to 0.0036 mL/[min × g]). For different maximum crystal ring difference settings using the scan time interval of 55–65 min after injection, only a 0.5% difference (median difference, 0.0000 mL/[min × g]; range, −0.0004 to 0.0013 mL/[min × g]) in tumor K_i was found. Conclusion: Ultrashort whole-body [¹⁸F]FDG Patlak imaging is feasible on an LAFOV Biograph Vision Quadra PET/CT system without loss of quantitative accuracy to assess lung tumor uptake compared with a full-duration 65-min acquisition. The ultrashort 10-min direct Patlak reconstruction with PIF allows for its implementation in clinical practice.

最近评估了使用缩放到患者特异性图像衍生输入函数 （IDIF） 值的群体平均输入函数 （PIF） 缩短注射后 65-90 至 20-30 分钟的 [¹⁸F]FDG Patlak PET 成像程序的方法。本研究的目的是探索注射后 55-65 分钟超短 10 分钟 [¹⁸F]FDG Patlak 成像的可行性，使用 PIF 结合直接 Patlak 重建，以提供可靠的肺肿瘤摄取定量准确性，与使用 IDIF 的全持续时间 65 分钟采集相比。方法：患者在长轴视野 （LAFOV） Biograph Vision Quadra PET/CT 扫描仪上进行了 65 分钟的动态 PET 采集。随后，在注射后 30-60 分钟，使用 IDIF（血液和组织浓度之间达到相对动力学平衡的时间 （t*） = 30 分钟）和缩放的 PIF 进行直接 Patlak 重建和基于图像（使用重建的动态图像）Patlak 分析。接下来，仅使用采集的最后 10 分钟，即注射后 55 到 65 分钟，在系统控制台上执行直接 Patlak 重建，并使用 85 和 322 的最大晶环差设置进行缩放的 PIF。量化肿瘤病变和健康组织摄取，并在不同获得的参数图像之间进行比较，以评估定量准确性。结果：使用 IDIF （t* = 30 min） 进行直接和基于图像的 Patlak 分析，并在注射后 30-60 min 进行缩放的 PIF 之间获得了良好的一致性，使用不同的方法进行，肿瘤内流率值 （K_i） 偏差不超过 8.8%（平均差异范围为 -0.0022 至 0.0018 mL/[min × g]）。 当在系统控制台上进行直接 Patlak 重建时，发现注射后 30-60 分钟与注射后 55-65 分钟使用缩放的 PIF 之间有极好的一致性，肿瘤 K_i 偏差为 2.4%（中位数差异，-0.0018 mL/[min × g];范围，-0.0047 至 0.0036 mL/[min × g]）。对于使用注射后 55-65 分钟扫描时间间隔的不同最大晶环差设置，在肿瘤 K_i 中仅发现 0.5% 的差异（中位数差异，0.0000 mL/[min × g];范围，-0.0004 至 0.0013 mL/[min × g]）。结论：超短全身 [¹⁸F]FDG Patlak 成像在 LAFOV Biograph Vision Quadra PET/CT 系统上是可行的，与全时 65 分钟的采集相比，在不损失定量准确性的情况下评估肺肿瘤摄取。使用 PIF 的超短 10 分钟直接 Patlak 重建允许在临床实践中实施。