Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, Illinois, USA.
Beckman Institute, University of Illinois Urbana-Champaign, Urbana, Illinois, USA.
Magn Reson Med. 2024 Aug;92(2):807-819. doi: 10.1002/mrm.30079. Epub 2024 Mar 12.
To develop and validate a noninvasive imaging technique for accurately assessing very slow CSF flow within shunt tubes in pediatric patients with hydrocephalus, aiming to identify obstructions that might impede CSF drainage.
A simulation of shunt flow enhancement of signal intensity (shunt-FENSI) signal is used to establish the relationship between signal change and flow rate. The quantification of flow enhancement of signal intensity data involves normalization, curve fitting, and calibration to match simulated data. Additionally, a phase sweep method is introduced to accommodate the impact of magnetic field inhomogeneity on the flow measurement. The method is tested in flow phantoms, healthy adults, intensive care unit patients with external ventricular drains (EVD), and shunt patients. EVDs enable shunt-flow measurements to be acquired with a ground truth measure of CSF drainage.
The flow-rate-to-signal simulation establishes signal-flow relationships and takes into account the T of draining fluid. The phase sweep method accurately accounts for phase accumulation due to frequency offsets at the shunt. Results in phantom and healthy human participants reveal reliable quantification of flow rates using controlled flows and agreement with the flow simulation. EVD patients display reliable measures of flow rates. Shunt patient results demonstrate feasibility of the method and consistent flow rates for functional shunts.
The results demonstrate the technique's applicability, accuracy, and potential for diagnosing and noninvasively monitoring hydrocephalus. Limitations of the current approach include a high sensitivity to motion and strict requirement of imaging slice prescription.
开发和验证一种非侵入性成像技术，以准确评估脑积水患儿分流管内非常缓慢的 CSF 流动，旨在识别可能阻碍 CSF 引流的阻塞。
使用分流增强信号强度（shunt-FENSI）信号模拟来建立信号变化与流速之间的关系。对信号强度数据的增强流量进行量化涉及标准化、曲线拟合和校准，以匹配模拟数据。此外，还引入了相位扫描方法来适应磁场不均匀性对流量测量的影响。该方法在流动体模、健康成年人、带有外部脑室引流管（EVD）的重症监护病房患者和分流患者中进行了测试。EVD 允许在 CSF 引流的真实测量值上获取分流流量测量值。
流速到信号的模拟建立了信号-流速关系，并考虑了引流液体的 T 值。相位扫描方法准确地考虑了由于分流处的频率偏移而导致的相位积累。在体模和健康人体参与者中的结果显示，使用受控流量进行可靠的流量定量，并与流量模拟一致。EVD 患者显示出可靠的流量测量值。分流患者的结果证明了该方法的可行性和功能性分流的一致流量。
结果表明该技术具有适用性、准确性和诊断及非侵入性监测脑积水的潜力。目前方法的局限性包括对运动的高度敏感性和对成像切片规定的严格要求。
