Purpose

Functional positron emission tomography (fPET) with [¹⁸F]FDG allows quantification of stimulation-induced changes in glucose metabolism independent of neurovascular coupling. However, the gold standard for quantification requires invasive arterial blood sampling, limiting its widespread use. Here, we introduce a novel fPET method without the need for an input function.

Methods

We validated the approach using two datasets (DS). For DS1, 52 volunteers (23.2 ± 3.3 years, 24 females) performed Tetris® during a [¹⁸F]FDG fPET scan (bolus + constant infusion). For DS2, 18 participants (24.2 ± 4.3 years, 8 females) performed an eyes-open/finger tapping task (constant infusion). Task-specific changes in metabolism were assessed with the general linear model (GLM) and cerebral metabolic rate of glucose (CMRGlu) was quantified with the Patlak plot as reference. We then estimated simplified outcome parameters, including GLM beta values and percent signal change (%SC), and compared them, region and whole-brain-wise.

Results

We observed higher agreement with the reference for DS1 than DS2. Both DS resulted in strong correlations between regional task-specific beta estimates and CMRGlu (r = 0.763…0.912). %SC of beta values exhibited strong agreement with %SC of CMRGlu (r = 0.909…0.999). Average activation maps showed a high spatial similarity between CMRGlu and beta estimates (Dice = 0.870…0.979) as well as %SC (Dice = 0.932…0.997), respectively.

Conclusion

The non-invasive method reliably estimates task-specific changes in glucose metabolism without blood sampling. This streamlines fPET, albeit with the trade-off of being unable to quantify baseline metabolism. The simplification enhances its applicability in research and clinical settings.

中文翻译：

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使用功能性 PET 对脑葡萄糖代谢的刺激特异性变化进行无创评估

目的

^{使用 [ 18} F]FDG的功能性正电子发射断层扫描 (fPET)可以量化刺激引起的葡萄糖代谢变化，而与神经血管耦合无关。然而，定量的黄金标准需要侵入性动脉血采样，限制了其广泛使用。在这里，我们介绍一种新颖的 fPET 方法，无需输入函数。

方法

我们使用两个数据集 (DS) 验证了该方法。对于 DS1，52 名志愿者（23.2 ± 3.3 岁，24 名女性）在 [ ¹⁸ F]FDG fPET 扫描（推注 + 持续输注）期间执行了 Tetris®。对于 DS2，18 名参与者（24.2 ± 4.3 岁，8 名女性）执行了睁眼/手指敲击任务（持续输液）。使用一般线性模型 (GLM) 评估特定任务的代谢变化，并使用 Patlak 图作为参考来量化大脑葡萄糖代谢率 (CMRGlu)。然后，我们估计了简化的结果参数，包括 GLM beta 值和信号变化百分比 (%SC)，并在区域和全脑方面对它们进行了比较。

结果

我们观察到 DS1 与参考文献的一致性高于 DS2。两种 DS 都导致区域特定任务 beta 估计与 CMRGlu 之间存在很强的相关性（r  = 0.763…0.912）。beta 值的 %SC 与 CMRGlu 的 %SC 表现出高度一致（r  = 0.909…0.999）。平均激活图显示 CMRGlu 和 beta 估计值 (Dice = 0.870…0.979) 以及 %SC (Dice = 0.932…0.997) 之间分别具有高度空间相似性。

结论

这种非侵入性方法可以可靠地估计任务特定的葡萄糖代谢变化，无需抽血。这简化了 fPET，尽管代价是无法量化基线代谢。这种简化增强了其在研究和临床环境中的适用性。