Reliable Human-Model Observers for Emission Tomography

描述（由申请人提供）：我们的总体目标是开发数值观测器，用于发射断层扫描中可靠的技术评估。正电子发射断层扫描 (PET) 和单光子发射断层扫描 (SPECT) 是多种癌症成像的主要临床方法。然而，早期检测通常提供了癌症存活的最佳机会，而这些成像方式对小肿瘤的诊断效用有限。基于任务的系统发展评估可以促进早期识别有前途的新技术，以提高这些模式的诊断能力。然而，人类观察者的评估对于发展用途来说通常是不切实际的。此外，旨在预测人类表现的可用数学模型（或数值观察者）——我们称之为人类模型观察者——存在很大的局限性，包括对可以考虑的诊断任务类型的限制。部分由于这些限制，现有的人体模型观察者经常需要在成像过程发生任何变化时重新验证。我们的观察者开发方法建立在任务等效的概念之上，即数值观察者的任务尽可能接近地反映所需的临床任务。在这笔资助中，我们提出了一种新颖的观察者框架，该框架受到放射科医生视觉搜索（VS）过程描述的影响，其中图像的初始全局扫描识别值得仔细检查的候选位置。我们将使用 VS 范式来研究以下假设：任务等价 i) 可以产生可靠地推广到广泛诊断任务的人类观察者模型，ii) 对于确保真正相关的基于任务的评估是必要的。我们将通过神经内分泌肿瘤 (NET) 的氟 18 脱氧葡萄糖 (FDG) 全身 PET 和 SPECT In-111 成像观察研究来检验这些假设。用于发展研究的最先进的模型观察者应该能够执行检测定位任务，并且我们的观察者研究将使用 Jackknife FROC (JAFROC) 方法进行分析。这项工作的具体目标是：1）确定 FDG-PET 图像切片的哪些特征吸引了人类观察者的最初注意力； 2）开发VS数值观测器，用于FDG-PET中的肿瘤检测定位任务； 3) 在以混合 PET 图像为特色的 JAFROC 检测定位研究中针对人类测试 VS 观察者； 4) 研究 VS 观察器对 SPECT 和 3D 检测定位任务的泛化； 5) 比较从 VS 和现有数值观测器获得的肿瘤 SPECT 的系统优化。该应用是针对 In-111 NET 成像的平行孔准直器设计的优化。 公共健康相关性：正电子发射断层扫描（PET）和单光子发射断层扫描（SPECT）的功能成像在癌症诊断和治疗中发挥着重要作用。尽管如此，早期检测为许多癌症的生存提供了最佳机会，并且提高这些方法对小肿瘤的诊断能力仍然是主要的研究重点。这项工作的重点是开发评估方法，以协助早期识别技术进步，从而提高 PET 和 SPECT 的诊断效用。

DESCRIPTION (provided by applicant): Our overall objective is to develop numerical observers for dependable technology evaluations in emission tomography. Positron emission tomography (PET) and single-photon emission tomography (SPECT) are the primary clinical modalities for imaging many types of cancer. However, early de- tection often presents the best chances of surviving cancer whereas these imaging modalities have limited diagnostic utility for small tumors. Systematic task-based developmental assessments could facilitate early identification of promising new technology for improving the diagnostic capabilities of these modalities. Yet, assessments with human observers are generally impractical for developmental use. Moreover, available mathematical models (or numerical observers) intended to predict human performance-what we refer to as human-model observers-present significant limits, including con- straints on the types of diagnostic tasks that can be considered. Partly because of these constraints, existing human-model observers frequently require revalidation given any change to the imaging pro- cess. Our approach to observer development is founded on the concept of task equivalence, whereby the task for the numerical observer mirrors the desired clinical task as closely as possible. In this grant, we propose a novel observer framework that is influenced by descriptions of radiologists' visual-search (VS) processes, in which an initial global scan of an image identifies candidate locations deserving closer inspection. We shall use the VS paradigm to investigate the hypotheses that task equivalence i) can lead to a human-observer model that reliably generalizes to a wide range of diagnostic tasks, and ii) is necessary to ensure truly relevant task-based evaluations. We shall test these hypotheses through observer studies with fluorine-18 deoxyglucose (FDG) whole-body PET and SPECT In-111 imaging of neuroendocrine tumors (NETs). A state-of-the-art model observer for developmental stud- ies should be capable of detection-localization tasks, and our observer studies will be analyzed with jackknife FROC (JAFROC) methodology. The specific aims of this work are to: 1) determine what features of FDG-PET image slices attract initial human-observer attention; 2) develop a VS numerical observer for tumor detection-localization tasks in FDG-PET; 3) test the VS observer against humans in a JAFROC detection-localization study featuring hybrid PET images; 4) investigate generalizations of the VS observer to SPECT and 3D detection-localization tasks; and 5) compare system optimiza- tions for oncologic SPECT obtained from the VS and existing numerical observers. The application is optimization of a parallel-hole collimator design for In-111 NET imaging. PUBLIC HEALTH RELEVANCE: Functional imaging with positron emission tomography (PET) and single-photon emission tomog- raphy (SPECT) has a significant role in cancer diagnosis and management. Still, early detection offers the best chances for surviving many cancers and refining the diagnostic capabilities of these modali- ties for small tumors continues to be a major research focus. This work is focused on the development of assessment methods for assisting in the early identification of technological advances that could improve the diagnostic utility of PET and SPECT.