Background Quantifying the fibrotic and calcific composition of the aortic valve at CT angiography (CTA) can be useful for assessing disease severity and outcomes of patients with aortic stenosis (AS); however, it has not yet been validated against quantitative histologic findings. Purpose To compare quantification of aortic valve fibrotic and calcific tissue composition at CTA versus histologic examination. Materials and Methods This prospective study included patients who underwent CTA before either surgical aortic valve replacement for AS or orthotopic heart transplant (controls) at two centers between January 2022 and April 2023. At CTA, fibrotic and calcific tissue composition were quantified using automated Gaussian mixture modeling applied to the density of aortic valve tissue components, calculated as [(volume/total tissue volume) × 100]. For histologic evaluation, explanted valve cusps were stained with Movat pentachrome as well as hematoxylin and eosin. For each cusp, three 5-µm slices were obtained. Fibrotic and calcific tissue composition were quantified using a validated artificial intelligence tool and averaged across the aortic valve. Correlations were assessed using the Spearman rank correlation coefficient. Intermodality and interobserver variability were measured using the intraclass correlation coefficient (ICC) and Bland-Altman plots. Results Twenty-nine participants (mean age, 63 years ± 10 [SD]; 23 male) were evaluated: 19 with severe AS, five with moderate AS, and five controls. Fibrocalcific tissue composition strongly correlated with histologic findings (r = 0.92; P < .001). The agreement between CTA and histologic findings for fibrocalcific tissue quantification was excellent (ICC, 0.94; P = .001), with underestimation of fibrotic composition at CTA (bias, -4.9%; 95% limits of agreement [LoA]: -18.5%, 8.7%). Finally, there was excellent interobserver repeatability for fibrotic (ICC, 0.99) and calcific (ICC, 0.99) aortic valve tissue volume measurements, with no evidence of a difference in measurements between readers (bias, -0.04 cm3 [95% LoA: -0.27 cm3, 0.19 cm3] and 0.02 cm3 [95% LoA: -0.14 cm3, 0.19 cm3], respectively). Conclusion In a direct comparison, standardized quantitative aortic valve tissue characterization at CTA showed excellent concordance with histologic findings and demonstrated interobserver reproducibility. Clinical trial registration no. NCT06136689 Published under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Almeida in this issue.

中文翻译：

---

CTA 定量主动脉瓣纤维化和钙化组织：与组织学的前瞻性比较。


背景 在 CT 血管造影 (CTA) 中量化主动脉瓣的纤维化和钙化成分可有助于评估主动脉瓣狭窄 (AS) 患者的疾病严重程度和结果；然而，它尚未根据定量组织学结果得到验证。目的 比较 CTA 与组织学检查对主动脉瓣纤维化和钙化组织成分的定量。材料和方法 这项前瞻性研究包括 2022 年 1 月至 2023 年 4 月期间在两个中心进行主动脉瓣置换术或原位心脏移植（对照）之前接受 CTA 的患者。在 CTA 中，使用自动高斯混合法对纤维化和钙化组织成分进行量化模型应用于主动脉瓣组织成分的密度，计算公式为[(体积/总组织体积)×100]。为了进行组织学评估，用 Movat pentachrome 以及苏木精和伊红对移植的瓣膜尖端进行染色。对于每个尖点，获得三个 5 µm 切片。使用经过验证的人工智能工具对纤维化和钙化组织成分进行量化，并在主动脉瓣上进行平均。使用斯皮尔曼等级相关系数评估相关性。使用组内相关系数 (ICC) 和 Bland-Altman 图来测量多态性和观察者间变异性。结果 29 名参与者（平均年龄，63 岁±10 [SD]；23 名男性）接受了评估：19 名患有严重 AS，5 名患有中度 AS，5 名对照。纤维钙化组织成分与组织学结果密切相关（r = 0.92；P < .001）。 CTA 与纤维钙化组织定量的组织学结果之间的一致性非常好（ICC，0.94；P = .001），低估了 CTA 的纤维化成分（偏差，-4.9%；95% 一致限度 [LoA]：-18.5%、8.7%）。最后，纤维化（ICC，0.99）和钙化（ICC，0.99）主动脉瓣组织体积测量具有出色的观察者间重复性，没有证据表明读数器之间的测量存在差异（偏差，-0.04 cm3 [95% LoA：-0.27） cm3、0.19 cm3] 和 0.02 cm3 [95% LoA：-0.14 cm3、0.19 cm3]）。结论 在直接比较中，CTA 的标准化定量主动脉瓣组织表征显示出与组织学结果极好的一致性，并证明了观察者间的可重复性。临床试验注册号NCT06136689 根据 CC BY 4.0 许可证发布。本文提供了补充材料。另请参阅本期 Almeida 的社论。