Developing Virtual Colonoscopy for Cancer Screening

描述（由申请人提供）：结直肠癌是美国第三大最常见的诊断癌症，也是癌症死亡的第二大原因。它通常是在晚期被诊断出来的，在病人出现症状之后，这解释了它的高死亡率。由于大多数结肠癌是由息肉在5至15年的恶变期内引起的，因此一直提倡筛查计划来检测小息肉。不幸的是，大多数人都没有遵循这个建议。该项目的健康相关性是通过开发一种方便，几乎无风险的检测小息肉的方法来显着增加愿意参加筛查计划的人数。计算机断层扫描结肠成像（CTC）或基于CT的虚拟结肠镜检查（VC）已显示出与金标准光学结肠镜检查（OC）相当的性能，可通过微创方式检测8 mm及以上的息肉。作为一种筛查工具，目前的CTC必须被更大的人群所接受，对较小的息肉具有更高的检测能力。最近CTC被医疗保险覆盖范围所接受的拒绝记录了这些需求，例如减少CT辐射，检测较小的息肉，减轻肠道准备（BP）压力，最大限度地减少读者变化，提高效率等。将CTC发展为一种安全、准确、成本效益高、侵入性最小、压力最小的筛查方式。为了推进CTC实现长期目标，本项目更新的具体目标是：（1）开发和评价自适应统计重建算法，以尽可能低的mAs水平获得当前腹部CT图像质量，以最大限度地降低X射线暴露风险。该算法不仅考虑X射线量子统计和能谱，而且考虑系统背景噪声，因为该噪声在低mAs水平下起着明显的作用。(2)开发和评价一种部分容积（PV）统计分割算法，并校正粪便标记不均匀性，以改善电子结肠清洗（ECC）。这一改进将导致更小息肉的检测，CT辐射减少一半，并通过接近无导管CTC来减轻患者对BP的压力。(3)开发和评估一种ECC自适应、基于纹理的特征提取算法，以改善计算机辅助息肉检测（CADpolyp），从而提高CTC的成本效益。人们希望，对较小息肉具有更高检测能力的改进性能和更大人群的可接受性（通过更少的辐射和压力）将使CTC向被医疗保险覆盖范围接受的筛查模式发展。低mAs的统计重建将有助于其他CT应用。具有不均匀性校正的PV图像分割将有益于其他虚拟内窥镜应用，例如提取血管壁用于虚拟血管造影中的斑块分析和膀胱壁用于虚拟膀胱造影中的生长的早期检测。 公共卫生相关性：该提案旨在通过使用（1）尽可能低的低剂量CT扫描，（2）压力较小的肠道准备（BP），例如，最小的轻泻药和/或无泻药BP，和（3）用于息肉检测的计算机辅助检测（CAD）和三维（3D）内窥镜视图的集成。

DESCRIPTION (provided by applicant): Colorectal carcinoma is the third most commonly diagnosed cancer and the second leading cause of death from cancer in the United States. Often it is diagnosed at an advanced stage, after the patient has developed symptoms, explaining its high mortality rate. Since most colon cancers arise from polyps over a 5 to 15 year period of malignant transformation, screening programs to detect small polyps have been advocated. Unfortunately most people do not follow this recommendation. The health relatedness of this project is to dramatically increase the number of people willing to participate in screening programs by developing a convenient, nearly risk-free method of detecting small polyps. Computed tomography colonography (CTC) or CT-based virtual colonoscopy (VC) has shown a comparable performance to the gold-standard optical colonoscopy (OC) for detecting polyps of 8mm and larger by a less invasive manner. To be a screening tool, current CTC has to be advanced for acceptance by a larger population with higher detection capability on smaller polyps. These needs are documented by the recent refusal of CTC being accepted by Medicare coverage, such as reducing CT radiation, detecting smaller polyps, relieving bowel preparation (BP) stress, minimizing reader variation, improving efficiency, etc. We have made good progress in technical advancement toward the broad, long-term objective of this project, i.e., developing CTC as a safe, accurate, cost-effective, minimal-invasive, least-stressful screening modality. To advance CTC toward the long-term objective, the specific aims of this project renewal are: (1) To develop and evaluate an adaptive statistical reconstruction algorithm to obtain the current abdominal CT image quality at as low mAs level as achievable to minimize the risk of X-ray exposure. The algorithm will consider not only the X-ray quanta statistics and energy spectrum, but also the system background noise because this noise plays a noticeable role at low mAs level. (2) To develop and evaluate a partial-volume (PV) statistical segmentation algorithm with correction of fecal tagging inhomogeneity to improve electronic colon cleansing (ECC). The improvement will lead to the detection of smaller polyps, reduction of CT radiation by a half, and relief of patient stress on BP by approaching toward cathartic-free CTC. (3) To develop and evaluate an ECC-adaptive, texture-based, feature-extraction algorithm to improve computer-aided polyp detection (CADpolyp) toward enhancement of CTC cost-effectiveness. It is hoped that an improved performance with higher detection capability on smaller polyps and more acceptable by a large population (via less radiation and stress) would advance CTC toward a screening modality with acceptance by Medicare coverage. The low-mAs statistical reconstruction would be helpful to other CT applications. The PV image segmentation with correction of inhomogeneity would be beneficial to other virtual endoscopy applications, such as extracting blood vessel wall for plaque analysis in virtual angiography and bladder wall for early detection of growth in virtual cystography. PUBLIC HEALTH RELEVANCE: This proposal aims to develop computed tomography colonography (CTC) or CT-based virtual colonoscopy (VC) toward a screening modality by using (1) as low as achievable low-dose CT scan, (2) less-stressful bowel preparation (BP), e.g., minimal laxative and/or cathartic-free BP, and (3) integration of computer-aided detection (CAD) and three-dimensional (3D) endoscopic views for polyp detection.