Department of Neurology, Clinical Neuroscience Center, University Hospital Zurich, Zurich, Switzerland; Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, University College London, London, UK; MRI Unit, Chalfont Centre for Epilepsy, UK.
Institute of Nuclear Medicine, University College London, London, UK.
Neuroimage. 2021 Aug 15;237:118194. doi: 10.1016/j.neuroimage.2021.118194. Epub 2021 May 21.
Blood-based kinetic analysis of PET data relies on an accurate estimate of the arterial plasma input function (PIF). An alternative to invasive measurements from arterial sampling is an image-derived input function (IDIF). However, an IDIF provides the whole blood radioactivity concentration, rather than the required free tracer radioactivity concentration in plasma. To estimate the tracer PIF, we corrected an IDIF from the carotid artery with estimates of plasma parent fraction (PF) and plasma-to-whole blood (PWB) ratio obtained from five venous samples. We compared the combined IDIF+venous approach to gold standard data from arterial sampling in 10 healthy volunteers undergoing [F]GE-179 brain PET imaging of the NMDA receptor. Arterial and venous PF and PWB ratio estimates determined from 7 patients with traumatic brain injury (TBI) were also compared to assess the potential effect of medication. There was high agreement between areas under the curves of the estimates of PF (r = 0.99, p<0.001), PWB ratio (r = 0.93, p<0.001), and the PIF (r = 0.92, p<0.001) as well as total distribution volume (V) in 11 regions across the brain (r = 0.95, p<0.001). IDIF+venous V had a mean bias of -1.7% and a comparable regional coefficient of variation (arterial: 21.3 ± 2.5%, IDIF+venous: 21.5 ± 2.0%). Simplification of the IDIF+venous method to use only one venous sample provided less accurate V estimates (mean bias 9.9%; r = 0.71, p<0.001). A version of the method that avoids the need for blood sampling by combining the IDIF with population-based PF and PWB ratio estimates systematically underestimated V (mean bias -20.9%), and produced V estimates with a poor correlation to those obtained using arterial data (r = 0.45, p<0.001). Arterial and venous blood data from 7 TBI patients showed high correlations for PF (r = 0.92, p = 0.003) and PWB ratio (r = 0.93, p = 0.003). In conclusion, the IDIF+venous method with five venous samples provides a viable alternative to arterial sampling for quantification of [F]GE-179 V.
基于血液的 PET 数据动力学分析依赖于对动脉血浆输入函数 (PIF) 的准确估计。一种替代从动脉采样的侵入性测量的方法是图像衍生的输入函数 (IDIF)。然而，IDIF 提供的是全血放射性浓度，而不是所需的血浆中游离示踪剂放射性浓度。为了估计示踪剂 PIF，我们使用来自颈动脉的 IDIF 校正了来自五个静脉样本的血浆母体分数 (PF) 和血浆与全血 (PWB) 比的估计值。我们将联合 IDIF+静脉方法与 10 名接受 NMDA 受体 [F]GE-179 脑 PET 成像的健康志愿者的动脉采样的金标准数据进行了比较。还比较了来自 7 名创伤性脑损伤 (TBI) 患者的动脉和静脉 PF 和 PWB 比估计值，以评估药物的潜在影响。在大脑的 11 个区域，PF 的曲线下面积的估计值之间具有高度一致性（r = 0.99，p <0.001）、PWB 比（r = 0.93，p <0.001）和 PIF（r = 0.92，p <0.001）以及总分布容积（V）（r = 0.95，p <0.001）。IDIF+静脉 V 的平均偏差为 -1.7%，具有类似的区域变异系数（动脉：21.3 ± 2.5%，IDIF+静脉：21.5 ± 2.0%）。简化 IDIF+静脉方法仅使用一个静脉样本提供了不太准确的 V 估计值（平均偏差 9.9%；r = 0.71，p <0.001）。一种通过将 IDIF 与基于人群的 PF 和 PWB 比估计值相结合来避免采血需求的方法系统地低估了 V（平均偏差 -20.9%），并产生了与使用动脉数据获得的 V 估计值相关性较差的 V 估计值（r = 0.45，p <0.001）。来自 7 名 TBI 患者的动脉和静脉血液数据高度相关 PF（r = 0.92，p = 0.003）和 PWB 比（r = 0.93，p = 0.003）。总之，使用五个静脉样本的 IDIF+静脉方法为 [F]GE-179 V 的定量提供了一种可行的动脉采样替代方法。
