Advancement and Validation of Prostate Diffusion and Spectroscopic MRI

项目摘要/摘要 MR对肿瘤部位、体积和恶性程度的更可靠和准确的诊断估计将为前列腺癌的分期提供宝贵的服务，特别是在经直肠超声(TRUS)活检阴性的病例中。由于MR的无创性，它是一种很有前途的方法，可以用于主动监测(AS)患者的重复检查和治疗效果的监测。更详细的本地化对于新兴的靶向局部疗法也很有价值。目前的MR方法包括T2加权MRI、动态对比增强(DCE)MRI、弥散加权MRI(DWI)和3D-MR光谱成像(MRSI)，对于前列腺癌的分期非常有用，特别是如果联合使用的话。然而，这些方法中可能最敏感和最具体的方法，即DWI和MRSI，显示出几个不足之处，将通过本项目设想的技术发展来解决。此外，将探索一种新的基于分离组织中存在的快水和慢水扩散成分的对比，以改进前列腺癌的检测。其具体目标如下：1)通过将扫描持续时间缩短到临床可接受的时间，同时提高空间分辨率和消除由于截断伪影造成的频谱脂质污染的问题，来推进全腺体MRSI。2)提高前列腺DWI的空间分辨率和几何保真度，采用缩小视野和分段多次激发成像。3)对前列腺癌患者采用标准序列和新的MRSI和弥散成像序列进行MRI扫描。此外，为了实现扩散成分的分离，扩散成分有可能在细胞水平上对肿瘤生长相关组织畸变更敏感和特异，计划对在更大范围的扩散编码强度(b因子)上收集的DWI数据进行双指数分析。定量参数图将从MRSI、DWI和DCE MRI数据中生成。4)在临床指定的随访过程中获得MRI引导下的活检数据或全腺阶梯切片组织学，以验证改进的技术和新的对比剂能够更好地发现前列腺癌。术前参数图将与活检或组织学坐标系共同配准。显微镜图像上的单个活检核心和肿瘤轮廓的Gleason评分将与参数图上的结果进行比较。统计分析各参数及组合参数在区分肿瘤与正常组织中的作用。

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.