Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK.
Department of Cardiovascular and Metabolic Health, University of East Anglia Norwich Medical School, Norwich, UK.
Open Heart. 2024 Mar 8;11(1):e002451. doi: 10.1136/openhrt-2023-002451.
The main objective of this study was to develop two-dimensional (2D) phase contrast (PC) methods to quantify the helicity and vorticity of blood flow in the aortic root.
This proof-of-concept study used four-dimensional (4D) flow cardiovascular MR (4D flow CMR) data of five healthy controls, five patients with heart failure with preserved ejection fraction and five patients with aortic stenosis (AS). A PC through-plane generated by 4D flow data was treated as a 2D PC plane and compared with the original 4D flow. Visual assessment of flow vectors was used to assess helicity and vorticity. We quantified flow displacement (FD), systolic flow reversal ratio (sFRR) and rotational angle (RA) using 2D PC.
For visual vortex flow presence near the inner curvature of the ascending aortic root on 4D flow CMR, sFRR demonstrated an area under the curve (AUC) of 0.955, p<0.001. A threshold of >8% for sFRR had a sensitivity of 82% and specificity of 100% for visual vortex presence. In addition, the average late systolic FD, a marker of flow eccentricity, also demonstrated an AUC of 0.909, p<0.001 for visual vortex flow. Manual systolic rotational flow angle change (ΔsRA) demonstrated excellent association with semiautomated ΔsRA (r=0.99, 95% CI 0.9907 to 0.999, p<0.001). In reproducibility testing, average systolic FD (FDsavg) showed a minimal bias at 1.28% with a high intraclass correlation coefficient (ICC=0.92). Similarly, sFRR had a minimal bias of 1.14% with an ICC of 0.96. ΔsRA demonstrated an acceptable bias of 5.72°-and an ICC of 0.99.
2D PC flow imaging can possibly quantify blood flow helicity (ΔRA) and vorticity (FRR). These imaging biomarkers of flow helicity and vorticity demonstrate high reproducibility for clinical adoption.
NCT05114785.
本研究的主要目的是开发二维（2D）相位对比（PC）方法，以量化主动脉根部血流的螺旋度和涡度。
这项概念验证研究使用了 5 名健康对照者、5 名射血分数保留的心力衰竭患者和 5 名主动脉瓣狭窄（AS）患者的 4D 血流心血管磁共振（4D 流 CMR）数据。通过 4D 流数据生成的平面 PC 被视为 2D PC 平面，并与原始 4D 流进行比较。使用 2D PC 评估血流矢量的视觉评估以评估螺旋度和涡度。我们使用 2D PC 量化了流量位移（FD）、收缩期流量反转比（sFRR）和旋转角（RA）。
对于 4D 流 CMR 上主动脉根部内曲附近的可见涡流流动，sFRR 的曲线下面积（AUC）为 0.955，p<0.001。sFRR>8%的阈值对视觉涡旋存在的敏感性为 82%，特异性为 100%。此外，标记流量偏心度的平均晚期收缩 FD 也表现出 AUC 为 0.909，p<0.001。手动收缩旋转流角度变化（ΔsRA）与半自动ΔsRA 表现出极好的相关性（r=0.99，95%CI 0.9907 至 0.999，p<0.001）。在重复性测试中，平均收缩 FD（FDsavg）的最小偏差为 1.28%，组内相关系数（ICC）为 0.92。同样，sFRR 的最小偏差为 1.14%，ICC 为 0.96。ΔsRA 的偏差可接受为 5.72°，ICC 为 0.99。
2D PC 血流成像可能能够量化血流螺旋度（ΔRA）和涡度（FRR）。这些血流螺旋度和涡度的成像生物标志物具有较高的临床可重复性。
NCT05114785。
