Development of a registration framework to validate MRI with histology for prostate focal therapy
Development of a registration framework to validate MRI with histology for prostate focal therapy
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DOI：
10.1118/1.4935343
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发表时间：
2015-12-01
期刊：
影响因子：
3.8
通讯作者：
Haworth, A.
中科院分区：
文献类型：
--
作者：
Reynolds, H. M.;Williams, S.;Haworth, A.
目的：病灶治疗已被提出作为前列腺癌全腺体治疗的替代方法，旨在减少治疗副作用。作者最近验证了一种放射生物学模型，该模型考虑了肿瘤位置和肿瘤特征，包括肿瘤细胞密度、Gleason评分和缺氧，以规划局灶治疗的最佳剂量分布。作者提出，该模型可以使用多参数MRI（mpMRI）进行通知，并在本研究中提出了一个配准框架，用于映射前列腺mpMRI和组织学数据，其中组织学将提供有关肿瘤位置和生物学的“地面实况”数据。作者的目的是应用这个框架，以不断增长的数据库，以开发一个前列腺生物图谱，这将使MRI为基础的规划前列腺局灶性治疗treatment.Methods：6例患者预定常规根治性前列腺切除术被用于这个概念验证研究。每例患者在手术前接受mpMRI扫描，之后将切除的前列腺标本用福尔马林固定并固定在定制设计的切片盒中的琼脂糖凝胶中。获取切片盒中样本的T2加权MRI，之后切割5 mm的前列腺切片，并对组织学切片进行显微切片。使用许多图像处理和配准步骤将组织学图像与离体MRI配准，并将可变形图像配准（REDD）应用于3D T2w图像，以对齐体内和离体MRI数据。骰子系数度量和相应的特征点，从两个独立的注释者被选中，以评估的revisionaccuracy.Results：从所有六名患者的图像注册，提供组织学和体内MRI在体外MRI的参考框架为每个病人。结果表明，与包含MRI上可见特征的前列腺的初始手动对准相比，其体内和体外3D T2w MRI配准的方法提高了准确性。体内MRI和组织学之间的平均估计不确定度为3.3 mm，其中包括应用MRI后体内和离体MRI之间的平均误差3.1 mm。体内和体外MRI之间的前列腺轮廓的平均骰子系数从0.83增加到0.93后，patient.Conclusions：作者已经开发了一个注册框架，通过实施一些处理步骤和体外MRI的前列腺标本的前列腺组织学映射在体内的MRI数据。对前列腺的验证具有挑战性，特别是在具有很少或大部分线性而非球形特征的前列腺中。目前正在完善其MR成像协议，以提高数据质量，这可能会提高配准精度。将在此框架内注册其他mpMRI序列，以量化前列腺肿瘤位置和生物学。(C)2015年美国医学物理学家协会。
Purpose: Focal therapy has been proposed as an alternative method to whole-gland treatment for prostate cancer when aiming to reduce treatment side effects. The authors recently validated a radiobiological model which takes into account tumor location and tumor characteristics including tumor cell density, Gleason score, and hypoxia in order to plan optimal dose distributions for focal therapy. The authors propose that this model can be informed using multiparametric MRI (mpMRI) and in this study present a registration framework developed to map prostate mpMRI and histology data, where histology will provide the "ground truth" data regarding tumor location and biology. The authors aim to apply this framework to a growing database to develop a prostate biological atlas which will enable MRI based planning for prostate focal therapy treatment.Methods: Six patients scheduled for routine radical prostatectomy were used in this proof-of-concept study. Each patient underwent mpMRI scanning prior to surgery, after which the excised prostate specimen was formalin fixed and mounted in agarose gel in a custom designed sectioning box. T2-weighted MRI of the specimen in the sectioning box was acquired, after which 5 mm sections of the prostate were cut and histology sections were microtomed. A number of image processing and registration steps were used to register histology images with ex vivo MRI and deformable image registration (DIR) was applied to 3D T2w images to align the in vivo and ex vivo MRI data. Dice coefficient metrics and corresponding feature points from two independent annotators were selected in order to assess the DIR accuracy.Results: Images from all six patients were registered, providing histology and in vivo MRI in the ex vivo MRI frame of reference for each patient. Results demonstrated that their DIR methodology to register in vivo and ex vivo 3D T2w MRI improved accuracy in comparison with an initial manual alignment for prostates containing features which were readily visible on MRI. The average estimated uncertainty between in vivo MRI and histology was 3.3 mm, which included an average error of 3.1 mm between in vivo and ex vivo MRI after applying DIR. The mean dice coefficient for the prostate contour between in vivo and ex vivo MRI increased from 0.83 before DIR to 0.93 after DIR.Conclusions: The authors have developed a registration framework for mapping in vivo MRI data of the prostate with histology by implementing a number of processing steps and ex vivo MRI of the prostate specimen. Validation of DIR was challenging, particularly in prostates with few or mostly linear rather than spherical shaped features. Refinement of their MR imaging protocols to improve the data quality is currently underway which may improve registration accuracy. Additional mpMRI sequences will be registered within this framework to quantify prostate tumor location and biology. (C) 2015 American Association of Physicists in Medicine.