Istituto Nazionale di Fisica Nucleare (INFN), Genova, via Dodecaneso 33, I-16146, Italy.
Istituto Nazionale di Fisica Nucleare (INFN), Genova, via Dodecaneso 33, I-16146, Italy; Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy.
Neuroimage Clin. 2019;23:101846. doi: 10.1016/j.nicl.2019.101846. Epub 2019 May 4.
amyloid-PET reading has been classically implemented as a binary assessment, although the clinical experience has shown that the number of borderline cases is non negligible not only in epidemiological studies of asymptomatic subjects but also in naturalistic groups of symptomatic patients attending memory clinics. In this work we develop a model to compare and integrate visual reading with two independent semi-quantification methods in order to obtain a tracer-independent multi-parametric evaluation.
We retrospectively enrolled three cohorts of cognitively impaired patients submitted to F-florbetaben (53 subjects), F-flutemetamol (62 subjects), F-florbetapir (60 subjects) PET/CT respectively, in 6 European centres belonging to the EADC. The 175 scans were visually classified as positive/negative following approved criteria and further classified with a 5-step grading as negative, mild negative, borderline, mild positive, positive by 5 independent readers, blind to clinical data. Scan quality was also visually assessed and recorded. Semi-quantification was based on two quantifiers: the standardized uptake value (SUVr) and the ELBA method. We used a sigmoid model to relate the grading with the quantifiers. We measured the readers accord and inconsistencies in the visual assessment as well as the relationship between discrepancies on the grading and semi-quantifications.
It is possible to construct a map between different tracers and different quantification methods without resorting to ad-hoc acquired cases. We used a 5-level visual scale which, together with a mathematical model, delivered cut-offs and transition regions on tracers that are (largely) independent from the population. All fluorinated tracers appeared to have the same contrast and discrimination ability with respect to the negative-to-positive grading. We validated the integration of both visual reading and different quantifiers in a more robust framework thus bridging the gap between a binary and a user-independent continuous scale.
淀粉样蛋白-PET 阅读经典地实施为二进制评估，尽管临床经验表明，不仅在无症状受试者的流行病学研究中，而且在就诊于记忆诊所的有症状患者的自然群体中，边界病例的数量都不少。在这项工作中，我们开发了一种模型，以比较和整合视觉阅读与两种独立的半定量方法，以便获得与示踪剂无关的多参数评估。
我们回顾性地招募了三个认知障碍患者队列，他们分别接受了 F-氟比他滨（53 例）、F-氟甲基美金刚（62 例）和 F-氟比他滨（60 例） PET/CT，这三个队列分别来自于欧洲认知障碍疾病联盟（EADC）的 6 个欧洲中心。175 次扫描根据批准的标准进行了阳性/阴性的视觉分类，并由 5 位独立读者进行了 5 级评分（阴性、轻度阴性、边界、轻度阳性、阳性），读者对临床数据不知情。还对扫描质量进行了视觉评估和记录。半定量基于两种定量方法：标准化摄取值（SUVr）和 ELBA 方法。我们使用了一个 sigmoid 模型来将分级与定量相关联。我们测量了读者在视觉评估中的一致性和不一致性，以及分级和半定量之间的差异。
在不依赖于专门获得的病例的情况下，有可能在不同的示踪剂和不同的定量方法之间构建一个图谱。我们使用了一个 5 级的视觉量表，它与一个数学模型一起，在很大程度上独立于人群，为示踪剂提供了分级的截止值和过渡区域。所有氟代示踪剂在阴性到阳性分级方面似乎都具有相同的对比度和区分能力。我们在更稳健的框架中验证了视觉阅读和不同定量方法的整合，从而弥合了二进制和用户独立连续尺度之间的差距。
