Development of a combined ARFI/SWEI ultrasound elasticity imaging system for targeted prostate biopsy guidance

摘要 前列腺癌是美国男性中最常见的癌症，早期发现对 有效的治疗或管理。在前列腺癌的初步筛查后，根据升高的 前列腺特异性抗原(PSA)水平或可疑的直肠指诊，是目前临床护理的标准 诊断是经直肠超声(TRUS)引导的活检，其中10到12个系统采样的核心是 接受了检查。由于TRUS手术是由传统的B型超声成像指导的，在 前列腺癌通常不具有独特的外观，活组织检查核心从 在整个腺体中预先确定的位置网格，并且不是专门针对癌症可疑的 地区。因此，当第一次活组织检查未能发现癌症时，通常需要重复活组织检查。近期 研究已经证明了替代成像方式的能力，例如多参数磁共振成像(MpMRI) 或超声造影(CEUS)，为有针对性的前列腺活检提供影像指导。这些 然而，技术也有缺点，包括将mpMRI卷与Real-MRI注册存在挑战。 在活检过程中进行时间B型超声成像，或需要将微泡造影剂注射到 患者的血管系统用于CEUS成像。这项提议的目标是开发一种低成本的、可用于临床的3D 超声弹性成像系统用于指导具有临床意义的靶向活检 前列腺疾病。先前的研究表明，前列腺癌比周围的癌症更僵硬。 因此，可以使用基于超声波声辐射力的技术对其进行成像。建议数 系统将同时采集两种弹性成像模式：声辐射力脉冲(ARFI)成像 和剪切波弹性成像(SWI)，以便创建高分辨率的定量刚度图 前列腺。我假设使用联合3D ARFI/Swei前列腺体积来指导对 与目前的经直肠手术相比，前列腺癌将导致诊断敏感性和分期准确性的提高 超声检查的标准活组织检查。在这项拟议的工作中，我将开发高级ARFI/SWEI重建 方法为了考察声辐射力激励的次数和强度之间的权衡， 换能器加热，并重建图像质量。特别是，我将使用专门的有限元模拟 工具来比较不同的超声成像序列并在最先进的设备上实现这些序列 商用超声波扫描仪。为了在体外环境中评估这些序列，我将获得 在定制的组织模拟前列腺解剖模型中结合了ARFI/SWEI数据。从这里开始，我将评估 3D ARFI/SWEI成像系统在临床环境中的性能，通过使用该系统获得靶向 可疑前列腺癌患者的活检芯数及超声诊断准确性的比较 具有标准护理程序的目标系统。

ABSTRACT Prostate cancer is the most common cancer among men in the United States, and early detection is crucial for effective treatment or management. Following an initial screening for prostate cancer based on elevated prostate-specific antigen (PSA) levels or suspicious digital rectal exam, the current clinical standard of care for diagnosis is a transrectal ultrasound (TRUS)-guided biopsy, in which 10 to 12 systematically sampled cores are taken and examined. Because the TRUS procedure is guided by conventional B-mode ultrasound imaging, in which prostate cancer does not typically have a unique appearance, the biopsy cores are sampled from a predetermined grid of locations throughout the gland, and are not specifically targeted to cancer-suspicious regions. As a result, there is often a need for repeat biopsies when the first biopsy fails to detect cancer. Recent studies have demonstrated the ability of alternative imaging modalities, such as multiparametric MRI (mpMRI) or contrast-enhanced ultrasound (CEUS), to provide imaging guidance for a targeted prostate biopsy. These techniques have drawbacks, however, including challenges with registering the mpMRI volume with the real- time B-mode ultrasound image during the biopsy, or the need to inject microbubble contrast agents into the patient’s vasculature for CEUS imaging. The goal of this proposal is to develop a low-cost, clinic-ready 3D ultrasound elasticity imaging system to guide a targeted biopsy that is specific for clinically significant disease in the prostate. Previous work has demonstrated that prostate cancer is stiffer than the surrounding healthy tissue and can thus be imaged using ultrasonic acoustic radiation force-based techniques. The proposed system will simultaneously acquire two elasticity imaging modes: acoustic radiation force impulse (ARFI) imaging and shear wave elasticity imaging (SWEI), in order to create high-resolution, quantitative stiffness maps of the prostate. I hypothesize that using combined 3D ARFI/SWEI prostate volumes to guide a targeted biopsy for prostate cancer will result in improved diagnostic sensitivity and staging accuracy compared to current transrectal ultrasound standard-of-care biopsy. In this proposed work, I will develop advanced ARFI/SWEI reconstruction methods in order to examine the tradeoff between the number and intensity of acoustic radiation force excitations, transducer heating, and reconstructed image quality. In particular, I will use specialized finite-element simulation tools to compare different ultrasonic imaging sequences and implement these sequences on a state-of-the-art commercial ultrasound scanner. In order to evaluate these sequences in an in vitro setting, I will acquire combined ARFI/SWEI data in custom tissue-mimicking prostate anatomy phantoms. From here, I will assess the performance of the 3D ARFI/SWEI imaging system in a clinical setting, by using the system to obtain targeted biopsy cores in patients with suspected prostate cancer and comparing the diagnostic accuracy of the ultrasound targeting system with standard-of-care procedures.