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Improvements in monitoring and assessment of MRI-guided prostate cryoablation.

机译：MRI指导的前列腺冷冻消融监测和评估的改善。

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摘要

MRI-guided cryoablation is a promising minimally invasive therapy for localized prostate cancer. Monitoring of temperatures achieved during freezing is essential for successful cryosurgery. MRI potentially allows temperature mapping in frozen tissue, and can also provide assessment of treatment efficacy. The two aims of this work were to develop methods to improve imaging and quantitation of frozen tissue for temperature mapping with MRI, and to investigate the ability of MRI to characterize the extent of cryoinjury.;Imaging of frozen tissue requires ultrashort echo times, usually achieved with half RF pulses. However, these pulses are sensitive to gradient imperfections such as eddy currents that cause errors in the slice profile. The goal of this work was to develop RF pulses that were less sensitive to these distortions, thereby improving MR imaging of frozen tissue. Three RF pulses were developed that achieved an improved slice profile and were robust to eddy current errors. Experimental results demonstrate substantially better slice selectivity and T2* quantitation accuracy with these pulses.;MRI can also provide the ability to non-invasively assess tissue injury after cryoablation. The appearance of acute and chronic cryolesions was evaluated on MRI, correlated with freezing protocol and compared to histopathology. The influence of various freezing protocol parameters such as freeze area, duration, rate, and number of freeze cycles on lesion appearance was evaluated. This characterization of cryolesion appearance and evolution can potentially be used to assess tissue response after cryoablation.
机译：MRI引导的冷冻消融术是用于局部前列腺癌的一种有前途的微创疗法。监测冷冻过程中达到的温度对于成功的冷冻手术至关重要。 MRI可能允许在冷冻组织中进行温度定位，并且还可以提供治疗效果的评估。这项工作的两个目的是开发改进MRI成像温度的冷冻组织的成像和定量方法，并研究MRI表征冷冻损伤程度的能力。冷冻组织成像需要超短的回波时间，通常可以实现半个RF脉冲。但是，这些脉冲对梯度缺陷很敏感，例如涡流会导致切片轮廓出现错误。这项工作的目的是开发对这些失真不太敏感的RF脉冲，从而改善冷冻组织的MR成像。开发了三个RF脉冲，这些脉冲实现了改进的切片轮廓，并且对涡流误差具有鲁棒性。实验结果表明，在这些脉冲的作用下，切片的选择性和T2 *定量准确度大大提高。MRI还可以提供无创评估冷冻消融后组织损伤的能力。在MRI上评估了急，慢性冰冻眼的出现，与冷冻方案相关，并与组织病理学进行了比较。评估了各种冷冻方案参数，例如冷冻面积，持续时间，速率和冷冻周期数对病变外观的影响。冷冻消融外观和演变的这种表征可潜在地用于评估冷冻消融后的组织反应。

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  • 作者

    Josan, Sonal.;

  • 作者单位

    Stanford University.;

  • 授予单位 Stanford University.;
  • 学科 Engineering Biomedical.;Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 96 p.
  • 总页数 96
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物医学工程;无线电电子学、电信技术;
  • 关键词

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