From the MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Rd, London W12 0HS, England (T.J.W.D., M.Q., A.d.M., P.J.O., P.F.T., S.A.C., D.P.O.); National Heart and Lung Institute (T.J.W.D., J.S.R.G., S.A.C.), and Division of Experimental Medicine, Department of Medicine (G.M.J.W., J.W., M.R.W.), Imperial College London, London, England; National Heart Centre Singapore, Singapore, and Duke-NUS Graduate Medical School, Singapore (J.C., S.A.C.); and Department of Cardiology, National Pulmonary Hypertension Service, Imperial College Healthcare NHS Trust, London, England (L.S.G.E.H., J.S.R.G.).
Radiology. 2018 Aug;288(2):386-395. doi: 10.1148/radiol.2018172821. Epub 2018 Jun 5.
Purpose To measure right ventricular (RV) trabecular complexity by its fractal dimension (FD) in healthy subjects and patients with pulmonary hypertension (PH) and to assess its relationship with hemodynamic and functional parameters and future cardiovascular events. Materials and Methods This retrospective study used data acquired from May 2004 to October 2013 in 256 patients with newly diagnosed PH who underwent cardiac MRI, right-sided heart catheterization, and 6-minute walk distance testing, with median follow-up of 4.0 years. A total of 256 healthy control subjects underwent cardiac MRI only. Biventricular FD, volumes, and function were assessed on short-axis cine images. Reproducibility was assessed with the intraclass correlation coefficient, correlation between variables was assessed with the Pearson correlation test, and mortality prediction was compared by using uni- and multivariable Cox regression analyses. Results RV FD reproducibility had an intraclass correlation coefficient of 0.97 (95% confidence interval [CI]: 0.96, 0.98). RV FD was higher in patients with PH (median, 1.310; interquartile range [IQR], 1.281-1.341) than in healthy subjects (median, 1.264; IQR, 1.242-1.295; P < .001), with the greatest difference near the apex. RV FD was associated with pulmonary vascular resistance (r = 0.30, P < .001). At univariable Cox regression analysis, RV FD was a significant predictor of death (hazard ratio [HR], 1.256; 95% CI: 1.011, 1.560; P = .04); however, at multivariable analysis, RV FD did not enable prediction of survival independently of conventional parameters of RV remodeling (HR, 1.179; 95% CI: 0.871, 1.596; P = .29). Conclusion Fractal analysis of RV trabecular complexity is a highly reproducible measure of remodeling in patients with PH that is associated with afterload, although the gain in survival prediction over traditional markers is not significant. Published under a CC BY 4.0 license. Online supplemental material is available for this article.
通过分形维数（FD）测量健康受试者和肺动脉高压（PH）患者的右心室（RV）小梁复杂性，并评估其与血流动力学和功能参数以及未来心血管事件的关系。
本回顾性研究使用了 2004 年 5 月至 2013 年 10 月期间在 256 名新诊断为 PH 的患者中获得的数据，这些患者接受了心脏 MRI、右侧心导管检查和 6 分钟步行距离测试，中位随访时间为 4.0 年。共有 256 名健康对照仅接受了心脏 MRI。在短轴电影图像上评估双心室 FD、容量和功能。使用组内相关系数评估可重复性，使用 Pearson 相关检验评估变量之间的相关性，并通过单变量和多变量 Cox 回归分析比较死亡率预测。
RV FD 的可重复性具有 0.97（95%置信区间[CI]：0.96，0.98）的组内相关系数。PH 患者的 RV FD 较高（中位数，1.310；四分位距[IQR]，1.281-1.341），高于健康受试者（中位数，1.264；IQR，1.242-1.295；P<0.001），最大差异在心室顶部附近。RV FD 与肺血管阻力相关（r = 0.30，P<0.001）。在单变量 Cox 回归分析中，RV FD 是死亡的显著预测因子（危险比[HR]，1.256；95%CI：1.011，1.560；P = 0.04）；然而，在多变量分析中，RV FD 不能独立于 RV 重塑的常规参数预测生存（HR，1.179；95%CI：0.871，1.596；P = 0.29）。
RV 小梁复杂性的分形分析是 PH 患者重构的一种高度可重复的测量方法，与后负荷相关，尽管在传统标志物的基础上，生存预测的收益并不显著。在 CC BY 4.0 许可下发布。本文提供了在线补充材料。
