Frasconi Paolo, Baracchi Daniele, Giusti Betti, Kura Ada, Spaziani Gaia, Cherubini Antonella, Favilli Silvia, Di Lenarda Andrea, Pepe Guglielmina, Nistri Stefano
Department of Information Engineering, University of Florence, 50139 Florence, Italy.
Department of Experimental and Clinical Medicine, University of Florence, 50139 Florence, Italy.
Diagnostics (Basel). 2021 Feb 2;11(2):220. doi: 10.3390/diagnostics11020220.
To develop a tool for assessing normalcy of the thoracic aorta (TA) by echocardiography, based on either a linear regression model (Z-score), or a machine learning technique, namely one-class support vector machine (OC-SVM) (Q-score). TA diameters were measured in 1112 prospectively enrolled healthy subjects, aging 5 to 89 years. Considering sex, age and body surface area we developed two calculators based on the traditional Z-score and the novel Q-score. The calculators were compared in 198 adults with TA > 40 mm, and in 466 patients affected by either Marfan syndrome or bicuspid aortic valve (BAV). Q-score attained a better Area Under the Curve (0.989; 95% CI 0.984-0.993, sensitivity = 97.5%, specificity = 95.4%) than Z-score (0.955; 95% CI 0.942-0.967, sensitivity = 81.3%, specificity = 93.3%; < 0.0001) in patients with TA > 40 mm. The prevalence of TA dilatation in Marfan and BAV patients was higher as Z-score > 2 than as Q-score < 4% (73.4% vs. 50.09%, < 0.00001). Q-score is a novel tool for assessing TA normalcy based on a model requiring less assumptions about the distribution of the relevant variables. Notably, diameters do not need to depend linearly on anthropometric measurements. Additionally, Q-score can capture the joint distribution of these variables with all four diameters simultaneously, thus accounting for the overall aortic shape. This approach results in a lower rate of predicted TA abnormalcy in patients at risk of TA aneurysm. Further prognostic studies will be necessary for assessing the relative effectiveness of Q-score versus Z-score.
基于线性回归模型（Z评分）或机器学习技术，即单类支持向量机（OC-SVM）（Q评分），开发一种通过超声心动图评估胸主动脉（TA）正常情况的工具。对1112名年龄在5至89岁之间的前瞻性纳入的健康受试者测量TA直径。考虑性别、年龄和体表面积，我们基于传统Z评分和新型Q评分开发了两种计算器。在198名TA>40mm的成年人以及466名患有马凡综合征或二叶式主动脉瓣（BAV）的患者中对这两种计算器进行比较。在TA>40mm的患者中，Q评分获得了比Z评分更好的曲线下面积（0.989；95%CI 0.984-0.993，敏感性=97.5%，特异性=95.4%）（0.955；95%CI 0.942-0.967，敏感性=81.3%，特异性=93.3%；P<0.0001）。当Z评分>2时，马凡综合征和BAV患者中TA扩张的患病率高于Q评分<4%时（73.4%对50.09%，P<0.00001）。Q评分是一种基于对相关变量分布假设较少的模型评估TA正常情况的新型工具。值得注意的是，直径无需线性依赖人体测量指标。此外，Q评分可以同时捕获所有四个直径的这些变量的联合分布，从而考虑主动脉的整体形状。这种方法导致TA动脉瘤风险患者中预测TA异常的发生率较低。需要进一步的预后研究来评估Q评分与Z评分的相对有效性。
