Measurement of a 2D electric dipole field using the acousto-electric effect
Measurement of a 2D electric dipole field using the acousto-electric effect
复制标题
利用声电效应测量二维电偶极子场
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
M. O’Donnell
中科院分区：
文献类型：
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作者：
R. Olafsson;R. Witte;M. O’Donnell
绘制心脏电流场的传统方法要么空间分辨率差（如ECG），要么耗时（如心内导管电极测绘）。我们提出了一种基于声电效应（AEE）和引线场理论的二维电流分布微创测绘方法。AEE是一种压力诱导的电导率调制，其中聚焦超声可以用作空间局部压力源。作为原理证明，我们通过一对电极注入28 mA，在0.9% NaCl溶液的薄浴中产生了二维偶极子场。一个7.5兆赫的传感器从下方聚焦在浴缸上。记录电极沿槽的边界以20°的步骤旋转。对于每个角度，换能器都以光栅扫描的方式扫过浴池。在每个点获得脉冲回波和AEE电压迹线。在后处理中，将AEE走线组合在一起，就像来自多电极圆形阵列一样。从AEE中估计出平面上各点的电流场方向和大小，并与仿真结果进行比较。利用粗纱单极电极独立绘制了势场图。该图与模拟场的相关系数为0.9957。电流源密度分析确定了电流源和电流汇的真实位置在1±2毫米以内。该方法可扩展到三维空间，在心脏电流场的高空间分辨率快速测绘中具有应用潜力。
Conventional methods for mapping cardiac current fields have either poor spatial resolution (e.g. ECG) or are time consuming (e.g., intra-cardiac catheter electrode mapping). We present a method based on the acousto-electric effect (AEE) and lead field theory for minimally-invasive mapping of 2D current distributions. The AEE is a pressure-induced conductivity modulation in which focused ultrasound can be used as a spatially-localized pressure source. As a proof of principle we generated a 2D dipole field in a thin bath of 0.9% NaCl solution by injecting 28 mA through a pair of electrodes. A 7.5 MHz transducer was focused on the bath from below. A recording electrode was rotated along the boundary of the bath in 20° steps. For each angle, the transducer was swept over the bath in a raster scan. A pulse-echo and an AEE voltage trace were acquired at each point. The AEE traces were combined in post-processing as if coming from a multi-electrode circular array. The direction and magnitude of the current field at each point in the plane was estimated from the AEE and compared to simulation. The potential field was independently mapped using a roving monopolar electrode. The correlation coefficient between this map and the simulated field was 0.9957. A current source density analysis located the current source and sink to within 1±2 mm of their true position. This method can be extended to 3 dimensions and has potential for use in rapid mapping of current fields in the heart with high spatial resolution.