Whole-body Patlak images can be obtained from an acquisition of first 6 min of dynamic imaging over the heart to obtain the arterial input function (IF), followed by multiple whole-body sweeps up to 60 min pi. The use of a population-averaged IF (PIF) could exclude the first dynamic scan and minimize whole-body sweeps to 30–60 min pi. Here, the effects of (incorrect) PIFs on the accuracy of the proposed Patlak method were assessed. In addition, the extent of mitigating these biases through rescaling of the PIF to image-derived IF values at 30–60 min pi was evaluated. Using a representative IF and rate constants from the literature, various tumour time-activity curves (TACs) were simulated. Variations included multiplication of the IF with a positive and negative gradual linear bias over 60 min of 5, 10, 15, 20, and 25% (generating TACs using an IF different from the PIF); use of rate constants (K1, k3, and both K1 and k2) multiplied by 2, 1.5, and 0.75; and addition of noise (μ = 0 and σ = 5, 10 and 15%). Subsequent Patlak analysis using the original IF (representing the PIF) was used to obtain the influx constant (Ki) for the differently simulated TACs. Next, the PIF was scaled towards the (simulated) IF value using the 30–60-min pi time interval, simulating scaling of the PIF to image-derived values. Influence of variabilities in IF and rate constants, and rescaling the PIF on bias in Ki was evaluated. Percentage bias in Ki observed using simulated modified IFs varied from − 16 to 16% depending on the simulated amplitude and direction of the IF modifications. Subsequent scaling of the PIF reduced these Ki biases in most cases (287 out of 290) to < 5%. Simulations suggest that scaling of a (possibly incorrect) PIF to IF values seen in whole-body dynamic imaging from 30 to 60 min pi can provide accurate Ki estimates. Consequently, dynamic Patlak imaging protocols may be performed for 30–60 min pi making whole-body Patlak imaging clinically feasible.

中文翻译：

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使用人口输入功能来减少扫描时间，全身进行Patlak ¹⁸ F-FDG PET成像

可以通过采集心脏的前6分钟动态成像来获得全身Patlak图像，以获得动脉输入功能（IF），然后进行多次全身扫描，直到pi 60分钟。使用人口平均IF（PIF）可能会排除首次动态扫描，并使全身扫描最小化至pi 30-30分钟。在这里，评估了（不正确）PIF对提出的Patlak方法准确性的影响。此外，还评估了在pi 30-60分钟时通过将PIF重新缩放为图像衍生的IF值来缓解这些偏差的程度。使用代表性的IF和文献中的速率常数，模拟了各种肿瘤时间活性曲线（TAC）。变化包括IF乘以60、5、10、15、20，和25％（使用不同于PIF的IF生成TAC）；使用速率常数（K1，k3以及K1和k2）乘以2、1.5和0.75；加上噪声（μ= 0和σ= 5、10和15％）。随后使用原始IF（代表PIF）进行Patlak分析，以获取不同模拟的TAC的流入常数（Ki）。接下来，使用30-60分钟pi的时间间隔将PIF缩放到（模拟的）IF值，从而将PIF缩放到图像衍生的值。评估了IF和速率常数的变化以及重新调整PIF对Ki偏差的影响。使用模拟修改的IF观察到的Ki的百分比偏差在− 16至16％之间变化，具体取决于IF修改的模拟幅度和方向。随后对PIF进行缩放，在大多数情况下（290个中的287个）将这些Ki偏差降低为< 5％。模拟表明，从pi的30到60分钟的全身动态成像中看到的（可能不正确）PIF到IF值的缩放可以提供准确的Ki估计。因此，可以在pi进行30-60分钟的动态Patlak成像方案，使全身Patlak成像在临床上可行。