Advancement and Validation of Prostate Diffusion and Spectroscopic MRI

项目总结/摘要 更可靠和准确的诊断估计肿瘤的位置，体积和恶性程度的MR将提供一个宝贵的服务，对分期前列腺癌，特别是在阴性的经直肠超声（TRUS）活检的情况下。MR由于其无创性，是一种很有前途的方法，可用于主动监测（AS）患者的重复检查和监测治疗效果。更详细的定位对于新兴的靶向局部治疗也是有价值的。 目前收集的MR方法，包括T2加权MRI，动态对比增强（DCE）MRI，扩散加权MRI（DWI）和3D-MR光谱成像（MRSI）似乎是非常有用的前列腺癌分期，特别是如果联合使用。然而，这些方法中潜在的最敏感和最具体的方法，即DWI和MRSI，表现出一些缺陷，这将通过本项目的技术发展来解决。此外，一种新的对比度的基础上分离的快速和缓慢的水扩散成分存在于组织中，将探索改善前列腺癌的检测。具体目标如下：1）通过将扫描持续时间减少到临床可接受的时间，同时提高空间分辨率并消除由于截断伪影导致的光谱的脂质污染问题，来推进全腺体MRSI。2)通过缩小视野和分段多次激发成像提高前列腺DWI的空间分辨率和几何保真度。3)使用标准序列和新的MRSI和扩散成像序列对前列腺癌患者进行MRI扫描。此外，为了实现扩散成分的分离，其具有在细胞水平上对肿瘤生长相关组织畸变更敏感和特异的潜力，计划采用在更宽范围的扩散编码强度（b因子）上收集的DWI数据的双指数分析。将根据MRSI、DWI和DCE MRI数据生成定量参数图。4)在有临床指征的随访过程中获得MRI引导活检数据或全腺体阶梯切片组织学，以验证改进的技术和新型造影剂能够上级地检测前列腺癌。 术前参数图将与活检或组织学坐标系共配准。将显微镜图像上的单个活检芯和肿瘤轮廓的Gleason评分与参数图上的结果进行比较。将对每个参数和组合参数区分肿瘤与正常组织的效用进行统计分析。

Project Summary/Abstract More reliable and accurate diagnostic estimation of tumor locations, volumes, and malignancy grade with MR would provide an invaluable service towards staging prostate cancer, particularly in cases with negative transrectal ultrasound (TRUS) biopsy. MR, due to the non-invasive nature, is a promising method for repeated exams in patients under active surveillance (AS) and for monitoring treatment effects. More detailed localization is also valuable for emerging targeted local therapies. The current collection of MR methods, which includes T2-weighted MRI, dynamic contrast-enhanced (DCE) MRI, diffusion-weighted MRI (DWI) and 3D-MR spectroscopic imaging (MRSI) appears to be very useful for staging of prostate cancer, particularly if used in combination. However, the potentially most sensitive and specific of these methods, namely DWI and MRSI, exhibit several deficiencies, which will be addressed by the technical developments contemplated for this project. Moreover, a novel contrast based on the separation of the fast and slow water diffusion components present in tissues, will be explored for improved detection of prostate cancer. The specific aims are as follows: 1) To advance whole-gland MRSI by reducing scan duration to a clinically acceptable time, while improving spatial resolution and eliminating the problem of lipid contamination of spectra due to truncation artifacts. 2) To advance spatial resolution and geometric fidelity of prostate DWI with reduced field-of-view and segmented multi-shot imaging. 3) To perform MRI scans in prostate cancer patients with standard sequences and new MRSI and diffusion imaging sequences. Moreover, to attain a separation of diffusion components, which have the potential to be more sensitive and specific to tumor growth related tissue aberrations at the cellular level, it is planned to employ biexponential analysis of DWI data collected over a wider range of diffusion encoding strength (b-factor). Quantitative parameter maps will be generated from MRSI, DWI, and DCE MRI data. 4) To obtain MRI-guided biopsy data or whole-gland step section histology during clinically indicated follow-up procedures in order to validate that the improved techniques and the novel contrast permit superior detection of prostate cancer. Pre-procedural parameter maps will be co-registered to the biopsy or histology coordinate system. Gleason scores of individual biopsy cores and tumor outlines on microscopy images will be compared with findings on parameter maps. The utility of each parameter and combined parameters to differentiate tumor from normal tissue will be analyzed statistically.