Non-invasive Estimation of the Arterial Input Function in PET Studies using Whole-Body Physiological Models

项目总结/摘要 正电子发射断层扫描（PET）是一种成像模式，可用于评估许多生理或病理检查。 病理过程通过使用各种特定的示踪剂。目前，最重要的临床 应用是在肿瘤学中使用示踪剂18F-FDG检测肿瘤和转移并评估治疗 反应PET可以是能够准确测量生理特性的完全定量成像模态 如葡萄糖代谢率、血流量或身体各部位的各种蛋白质分布。 然而，半定量指标，如标准摄取值（SUV）更常用于临床 设置，甚至一些研究设置。它们是使用完全定量方法的两个主要障碍 更频繁。第一个是需要动态扫描。第二是需要测量动脉 输入函数（AIF），以便应用动力学建模。这种AIF测量是侵入性的，复杂的， 特别是对于代谢的示踪剂。本研究的目的是开发新的方法来估计 当全身扫描时，直接从PET图像输入函数，包括代谢物校正 这通常是研究或临床应用所需要的。我们建议发展 描述体内分布、代谢和消除的全身生理模型（WBP模型） PET示踪剂和算法，以估计动脉输入功能，包括代谢校正，非 侵入性地使用这些WBP模型。我们将把这些新的方法应用于18F-FDG和各种其他 示踪剂，包括用于测量炎症的放射性示踪剂11 C-PBR 28，使用回顾性分析 现有数据和新获得的数据来测试和验证方法。对于18F-FDG，我们还将应用这些 WBP模型，用于改善临床实践中常规使用的静态全身扫描的量化， 提供针对输入函数中的可变性校正的SUV值，以及新的半定量指标， 葡萄糖代谢率比目前临床上使用的基于SUV的速率更准确。

Project Summary/Abstract Positron Emission Tomography (PET) is an imaging modality that can be used to asses many physiological or pathological process through the use of a variety of specific tracers. Currently, the most important clinical application is in oncology using the tracer 18F-FDG to detect tumors and metastases and assess treatment response. PET can be a fully quantitative imaging modality able to accurately measure a physiological property such as the glucose metabolic rate, blood flow, or various protein distribution in various part of the body. However, semi-quantitative indexes such as standard uptake values (SUV) are more routinely used in clinical settings, and even some research settings. They are two main obstacles to use the fully quantitative approach more frequently. The first one is the need for dynamic scans. The second is the need to measure the arterial input function (AIF) in order to apply kinetic modeling. This AIF measurement is invasive, and complex, especially for tracers that are metabolized. The goal of this study is to develop novel methods to estimate the input function directly from the PET images, including the metabolite correction, when a whole-body scan is performed, which is often already needed for the research or clinical application. We propose to develop whole-body physiological models (WBP models) to describe the in vivo distribution, metabolism and elimination of PET tracers and algorithms to estimate the arterial input function, including the metabolite-correction, non- invasively using these WBP models. We will apply these new methods to 18F-FDG and a variety of other tracers, including the radiotracer 11C-PBR28 used to measure inflammation, using retrospective analysis of existing data and newly acquired data to test and validate the methods. For 18F-FDG we will also apply these WBP models to improve the quantification of static whole-body scans routinely used in clinical practice by providing SUV values corrected for variability in the input function, and new semi-quantitative indexes of glucose metabolic rate more accurate that the SUV-based rates currently used clinically.