Subharmonic-aided pressure estimation (SHAPE) estimates hydrostatic pressure using the inverse relationship with subharmonic amplitude variations of ultrasound contrast agents (UCAs). We studied the impact of varying incident acoustic outputs (IAO), UCA concentration, and hematocrit on SHAPE. A Logiq 9 scanner with a 4C curvilinear probe (GE, Milwaukee, Wisconsin) was used with Sonazoid (GE Healthcare, Oslo, Norway) transmitting at 2.5 MHz and receiving at 1.25 MHz. An improved IAO selection algorithm provided improved correlations (r from −0.85 to −0.95 vs. −0.39 to −0.98). There was no significant change in SHAPE gradient as the pressure increased from 10 to 40 mmHg and hematocrit concentration was tripled from 1.8 to 4.5 mL/L (Δ0.00-0.01 dB, p = 0.18), and as UCA concentration was increased from 0.2 to 1.2 mL/L (Δ0.02-0.05 dB, p = 0.75). The results for the correlation between the SHAPE gradient and hematocrit values for patients (N = 100) in an ongoing clinical trial were also calculated showing a poor correlation value of 0.14. Overall, the SHAPE gradient is independent of hematocrit and UCA concentration. An improved algorithm for IAO selection will make SHAPE more accurate.

中文翻译：

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影响次谐波辅助压力估计 (SHAPE) 的因素

次谐波辅助压力估计 (SHAPE) 使用与超声造影剂 (UCA) 的次谐波幅度变化的反比关系来估计静水压力。我们研究了不同的入射声输出 (IAO)、UCA 浓度和血细胞比容对 SHAPE 的影响。带有 4C 曲线探头（GE，Milwaukee，Wisconsin）的 Logiq 9 扫描仪与 Sonazoid（GE Healthcare，Oslo，Norway）一起使用，发射频率为 2.5 MHz，接收频率为 1.25 MHz。改进的 IAO 选择算法提供了改进的相关性（r 从 -0.85 到 -0.95 对比 -0.39 到 -0.98）。SHAPE 梯度没有显着变化，因为压力从 10 毫米汞柱增加到 40 毫米汞柱，血细胞比容浓度从 1.8 到 4.5 毫升/升（Δ0.00-0.01 分贝，p = 0.18）增加三倍，并且随着 UCA 浓度从 0.2 增加至 1.2 mL/L（Δ0.02-0.05 dB，p = 0.75）。还计算了正在进行的临床试验中患者 (N = 100) 的 SHAPE 梯度和血细胞比容值之间的相关性，结果显示相关性较差，为 0.14。总的来说，SHAPE 梯度与血细胞比容和 UCA 浓度无关。IAO 选择的改进算法将使 SHAPE 更准确。