CHIMERE UR 7516, Jules Verne University of Picardy, Amiens, 80000, France.
Medical Image Processing Department, Amiens Picardy University Medical Center, Amiens, 80000, France.
Fluids Barriers CNS. 2024 Mar 7;21(1):25. doi: 10.1186/s12987-024-00520-0.
Understanding of the cerebrospinal fluid (CSF) circulation is essential for physiological studies and clinical diagnosis. Real-time phase contrast sequences (RT-PC) can quantify beat-to-beat CSF flow signals. However, the detailed effects of free-breathing on CSF parameters are not fully understood. This study aims to validate RT-PC's accuracy by comparing it with the conventional phase-contrast sequence (CINE-PC) and quantify the effect of free-breathing on CSF parameters at the intracranial and extracranial levels using a time-domain multiparametric analysis method.
Thirty-six healthy participants underwent MRI in a 3T scanner for CSF oscillations quantification at the cervical spine (C2-C3) and Sylvian aqueduct, using CINE-PC and RT-PC. CINE-PC uses 32 velocity maps to represent dynamic CSF flow over an average cardiac cycle, while RT-PC continuously quantifies CSF flow over 45-seconds. Free-breathing signals were recorded from 25 participants. RT-PC signal was segmented into independent cardiac cycle flow curves (Q) and reconstructed into an averaged Q. To assess RT-PC's accuracy, parameters such as segmented area, flow amplitude, and stroke volume (SV) of the reconstructed Q from RT-PC were compared with those derived from the averaged Q generated by CINE-PC. The breathing signal was used to categorize the Q into expiratory or inspiratory phases, enabling the reconstruction of two Q for inspiration and expiration. The breathing effects on various CSF parameters can be quantified by comparing these two reconstructed Qt.
RT-PC overestimated CSF area (82.7% at aqueduct, 11.5% at C2-C3) compared to CINE-PC. Stroke volumes for CINE-PC were 615 mm³ (aqueduct) and 43 mm³ (spinal), and 581 mm³ (aqueduct) and 46 mm³ (spinal) for RT-PC. During thoracic pressure increase, spinal CSF net flow, flow amplitude, SV, and cardiac period increased by 6.3%, 6.8%, 14%, and 6%, respectively. Breathing effects on net flow showed a significant phase difference compared to the other parameters. Aqueduct-CSF flows were more affected by breathing than spinal-CSF.
RT-PC accurately quantifies CSF oscillations in real-time and eliminates the need for cardiac synchronization, enabling the quantification of the cardiac and breathing components of CSF flow. This study quantifies the impact of free-breathing on CSF parameters, offering valuable physiological references for understanding the effects of breathing on CSF dynamics.
理解脑脊液（CSF）循环对于生理研究和临床诊断至关重要。实时相位对比序列（RT-PC）可定量检测逐搏 CSF 流动信号。然而，自由呼吸对 CSF 参数的详细影响尚未完全了解。本研究旨在通过与传统相位对比序列（CINE-PC）进行比较来验证 RT-PC 的准确性，并使用时域多参数分析方法定量评估颅内和颅外 CSF 参数受自由呼吸的影响。
36 名健康参与者在 3T 扫描仪上进行 MRI 检查，以使用 CINE-PC 和 RT-PC 测量颈段（C2-C3）和 Sylvian 导水管的 CSF 震荡。CINE-PC 使用 32 个速度图来表示平均心动周期内的动态 CSF 流动，而 RT-PC 则连续 45 秒定量 CSF 流动。记录了 25 名参与者的自由呼吸信号。将 RT-PC 信号分割成独立的心动周期流量曲线（Q），并将其重建为平均 Q。为了评估 RT-PC 的准确性，将 RT-PC 重建 Q 的分割面积、流量幅度和每搏输出量（SV）等参数与 CINE-PC 生成的平均 Q 衍生的参数进行了比较。使用呼吸信号将 Q 分类为呼气或吸气相，从而可以重建吸气和呼气的两个 Q。通过比较这两个重建的 Qt，可以定量评估各种 CSF 参数的呼吸影响。
与 CINE-PC 相比，RT-PC 高估了 CSF 面积（导水管为 82.7%，C2-C3 为 11.5%）。CINE-PC 的每搏输出量为 615mm³（导水管）和 43mm³（颈段），RT-PC 的每搏输出量为 581mm³（导水管）和 46mm³（颈段）。在胸内压升高时，脊髓 CSF 净流量、流量幅度、SV 和心动周期分别增加了 6.3%、6.8%、14%和 6%。与其他参数相比，呼吸对净流量的影响具有明显的相位差。导水管 CSF 流量受呼吸影响大于脊髓 CSF 流量。
RT-PC 可实时准确地定量 CSF 震荡，无需心脏同步，可量化 CSF 流动的心脏和呼吸成分。本研究定量评估了自由呼吸对 CSF 参数的影响，为理解呼吸对 CSF 动力学的影响提供了有价值的生理参考。
