Brown Katherine, Hoyt Kenneth
Annu Int Conf IEEE Eng Med Biol Soc. 2020 Jul;2020:2121-2124. doi: 10.1109/EMBC44109.2020.9176087.
Super-resolution ultrasound imaging (SR-US) has enabled a tenfold improvement in resolution of the microvasculature with clinical application in many disease processes such as cancer, diabetes and cardiovascular disease. Plane wave ultrasound (US) platforms in turn are capable of the very high frame rates needed to track microbubble (MB) contrast agents used in SR-US. Both B-mode US imaging and contrast enhanced US imaging (CEUS) have been effectively used in SR-US, with B-mode US having higher signal-to-noise ratio (SNR) and CEUS providing higher contrast-to-tissue ratio (CTR). Lengthy imaging time needed for SR-US to allow perfusion and MB detection is an impediment to clinical adoption. Both SNR and CTR improvements can enhance SR-US imaging by enhancing the detection of MBs thus reducing imaging time. This study simultaneously evaluated nonlinear contrast pulse sequences (CPS) employing different amplitude modulation (AM) and pulse inversion (PI) nonlinear CEUS imaging techniques as well as combinations of the two, (AMPI) with B-mode US imaging. The objective was to improve the detection rate of MB during SR-US. Imaging was performed in vitro and in vivo in the rat hind limb using a Vantage 256 research scanner (Verasonics Inc.). Comparisons of four CPS compositions with B-mode US imaging was made based on the number of MB detected and localized in SR-US images. The use of a PI nonlinear CEUS imaging strategy improved SR-US imaging by increasing the number of MB detected in a sequence of frames by an average of 28.3% and up to 52.6% over a B-mode US imaging strategy, which would decrease imaging time accordingly.
超分辨率超声成像（SR-US）已使微血管分辨率提高了十倍，并在癌症、糖尿病和心血管疾病等多种疾病过程中得到临床应用。平面波超声（US）平台则能够提供超分辨率超声中用于追踪微泡（MB）造影剂所需的非常高的帧率。B 模式超声成像和对比增强超声成像（CEUS）都已有效地应用于超分辨率超声中，B 模式超声具有更高的信噪比（SNR），而 CEUS 提供更高的对比组织比（CTR）。超分辨率超声为实现灌注和微泡检测所需的冗长成像时间是其临床应用的一个障碍。信噪比和对比组织比的提高都可以通过增强微泡的检测来改善超分辨率超声成像，从而减少成像时间。本研究同时评估了采用不同幅度调制（AM）和脉冲反转（PI）非线性 CEUS 成像技术的非线性对比脉冲序列（CPS），以及两者的组合（AMPI）与 B 模式超声成像。目的是提高超分辨率超声期间微泡的检测率。使用 Vantage 256 研究扫描仪（Verasonics 公司）在大鼠后肢进行体外和体内成像。基于在超分辨率超声图像中检测和定位的微泡数量，对四种 CPS 组成与 B 模式超声成像进行了比较。使用 PI 非线性 CEUS 成像策略可改善超分辨率超声成像，与 B 模式超声成像策略相比，在一系列帧中检测到的微泡数量平均增加 28.3%，最多增加 52.6%，这将相应地减少成像时间。
