IEEE Trans Ultrason Ferroelectr Freq Control. 2020 Jan;67(1):25-36. doi: 10.1109/TUFFC.2019.2937733. Epub 2019 Sep 4.
High-resolution transcranial ultrasound imaging in humans has been a persistent challenge for ultrasound due to the imaging degradation effects from aberration and reverberation. These mechanisms depend strongly on skull morphology and have high variability across individuals. Here, we demonstrate the feasibility of human transcranial super-resolution imaging using a geometrical focusing approach to efficiently concentrate energy at the region of interest, and a phase correction focusing approach that takes the skull morphology into account. It is shown that using the proposed focused super-resolution method, we can image a 208- [Formula: see text] microtube behind a human skull phantom in both an out-of-plane and an in-plane configuration. Individual phase correction profiles for the temporal region of the human skull were calculated and subsequently applied to transmit-receive a custom focused super-resolution imaging sequence through a human skull phantom, targeting the 208- [Formula: see text] diameter microtube at 68.5 mm in depth and at 2.5 MHz. Microbubble contrast agents were diluted to a concentration of 1.6×10 bubbles/mL and perfused through the microtube. It is shown that by correcting for the skull aberration, the RF signal amplitude from the tube improved by a factor of 1.6 in the out-of-plane focused emission case. The lateral registration error of the tube's position, which in the uncorrected case was 990 [Formula: see text], was reduced to as low as 50 [Formula: see text] in the corrected case as measured in the B-mode images. Sensitivity in microbubble detection for the phase-corrected case increased by a factor of 1.48 in the out-of-plane imaging case, while, in the in-plane target case, it improved by a factor of 1.31 while achieving an axial registration correction from an initial 1885- [Formula: see text] error for the uncorrected emission, to a 284- [Formula: see text] error for the corrected counterpart. These findings suggest that super-resolution imaging may be used far more generally as a clinical imaging modality in the brain.
人类高分辨率经颅超声成像是超声领域的一个持续挑战，因为像差和混响会导致成像质量下降。这些机制强烈依赖于颅骨形态，并且在个体之间具有高度可变性。在这里，我们展示了使用几何聚焦方法在人体经颅超分辨率成像中的可行性，该方法可以有效地将能量集中在感兴趣的区域，以及一种相位校正聚焦方法，该方法考虑了颅骨形态。结果表明，使用所提出的聚焦超分辨率方法，我们可以在平面外和平面内配置下对人体颅骨模型后面的 208- [Formula: see text] 微管进行成像。为颅骨的颞区计算了单独的相位校正轮廓，随后将其应用于通过人体颅骨模型传输-接收定制的聚焦超分辨率成像序列，以在 68.5mm 深度和 2.5MHz 处靶向 208- [Formula: see text] 直径的微管。微泡造影剂被稀释至 1.6×10 个气泡/mL 的浓度，并通过微管灌注。结果表明，通过校正颅骨像差，在平面外聚焦发射的情况下，来自微管的 RF 信号幅度提高了 1.6 倍。在未校正的情况下，管的位置的横向注册误差为 990 [Formula: see text] ，在校正的情况下，其降低至低至 50 [Formula: see text] ，如 B 模式图像中所测量的。在平面外成像情况下，相位校正情况下的微泡检测灵敏度提高了 1.48 倍，而在平面内目标情况下，它提高了 1.31 倍，同时实现了轴向注册校正，从未校正发射的初始 1885- [Formula: see text] 误差到校正的 284- [Formula: see text] 误差。这些发现表明，超分辨率成像可以更广泛地用作大脑的临床成像方式。
