Real-time Ultrasonic Monitoring of Tumor Ablation

描述（由申请人提供）：对于化疗无效的肝肿瘤患者和不能手术的肝癌患者，微创治疗是必不可少的。射频（RF）和微波（MW）消融技术是间质性、局灶性的治疗方法，用于这些病例的频率越来越高。射频或微波探针放置的图像引导以及对处理体积的初步评估对于这些程序的成功至关重要。我们和其他人已经证明，基于超声的应变和模量成像有望准确描绘消融过程中的治疗体积。对表面结构的初步评估显示消融区域的图像对比度很高。我们的研究将开发和评估一种称为“电极位移弹性成像”（EDE）的新型应变成像方法，以监测微创消融治疗并划定坏死区域，而不考虑治疗深度。我们将首先使用传统曲线获取的回波数据来测试EDE的有效性

DESCRIPTION (provided by applicant): Minimally invasive treatments are essential for patients with liver tumors that do not respond to chemotherapy and for patients with inoperable liver cancers. Radiofrequency (RF) and microwave (MW) ablation techniques are interstitial, focal therapies that are being used with increasing frequency for these cases. Image guidance for placement of RF or MW probes and for initial assessments of treated volumes is essential for the success of these procedures. We and others have demonstrated that ultrasound based strain and modulus imaging are promising for accurately depicting the treated volumes in ablation procedures. Initial assessments for superficial structures demonstrate high image contrast of ablated regions. Our research will develop and evaluate a novel strain imaging method termed "electrode displacement elastography," or EDE, to monitor minimally invasive ablative treatments and delineate the zone of necrosis regardless of the depth of treatment. We will initially test the effectiveness of EDE using echo data acquired with conventional curvilinear and phased arrays. This will be done by imaging custom tissue-mimicking phantoms with Young's Modulus values equivalent to that of liver tissue to determine reliability of mapping out ablated and partially ablated regions for various EDE acquisition parameters. Finite element analysis (FEA) to model deformations induced by RF/microwave displacements will be performed to better understand these experimental results. We then will evaluate 2D EDE on human patients, acquiring data at typical imaging depths and for various liver states, i.e. cirrhotic liver for hepatocellular carcinoma (HCC) and softer livers with stiffer tumors for metastases. Comparisons between EDE strain and follow-up X-ray CT images will provide crucial information on the effectiveness of EDE strain images to delineate the zone of necrosis. We will then develop and test bi-plane and three-dimensional (3D) volumetric EDE strain and modulus imaging using a 2D matrix phased array transducer. Accuracy of ablation boundary delineation for different echo data acquisition conditions will be determined using tissue-mimicking phantoms. In-vivo studies will then be conducted to test bi-plane and 3D EDE for strain and modulus imaging both on a wood-chuck HCC model and a rabbit VX2 metastases model to evaluate depiction and delineation of cancers before and after ablation therapy. Comparisons of the strain and modulus images with histopathology using light microscopy of ablated tissue will be performed. Finally, a pilot study will be performed using percutaneous bi-plane and 3D EDE on human patients. Successful completion of these studies will pave the way for clinical trials using EDE for monitoring minimally invasive ablative therapies. Incidence of HCC has doubled in the last decade, with a mortality rate of 3-6 months without treatment. The clinical significance of accurate ultrasound-based guidance for ablation treatments will be high, both in terms of reducing patient morbidity and of lowering treatment costs.