FEASIBILITY OF OVERHAUSER-ENHANCED MR MAMMOGRAPHY

Overhauser 增强型 MR 乳房 X 光检查的可行性

• 批准号: 3432317
• 负责人: JAMES LEE
• 金额: $ 4.77万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 1994-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3432317
• 关键词: biomedical equipment development; breast neoplasm /cancer diagnosis; clinical biomedical equipment; magnetic resonance imaging; mammography; mass screening; nuclear magnetic resonance spectroscopy; technology /technique development

Breast cancer is the second leading cause of death in American women. For that reason the American Cancer Society recommends annual x-ray mammograms for women at risk. However, x-ray mammography has its drawbacks. The repeated x-ray dose may increase the risk of cancer, and x-ray mammography is notoriously non-specific, with five women sent to biopsy for every confirmed malignancy. Magnetic Resonance (MR) imaging has been extremely successful at detecting breast cancer when used with a contrast agent such as Gadolinium-DTPA. However, no one recommends that MR imaging be used in routine screening for breast cancer because it costs more than ten times as much as x-ray mammography. The long-range goal of this research is to develop a more economical method of MR imaging useful for breast cancer screening. This method will be cheaper because the magnet and imaging hardware will be tailored to the size of the breast rather than the whole body, and also because the static magnetic field will be about 100 times weaker than usual (i.e., 0.01 Tesla rather than 1.5 Tesla). The cost advantage of reducing the static field is that ordinary electromagnets can be used rather than expensive superconducting magnets. The disadvantage of low field strength is that MR signal is drastically reduced. The novelty of this system is that it will employ "Overhauser enhancement" to regain much of the signal lost by reducing the static field. Overhauser enhancement is made possible by the presence of unpaired electrons that are magnetically coupled to the nuclei contributing to the MR image. When the electrons are irradiated at their resonant frequency, the MR signal can be enhanced by up to 50 times, depending on the power with which the electrons are irradiated. The limitation of using Overhauser enhancement in people is that the absorbed power must be kept below prescribed safety levels. The absorbed power is proportional to the square of the resonant frequency. One way to reduce absorbed power while maintaining strong enhancement is to reduce the strength of the static magnetic field while the electrons are irradiated, and then return it to a higher value to acquire the MR image. The focus of this proposal is to experimentally determine the degree of field reduction that maximizes Overhauser enhancement while keeping the absorbed radio frequency power below human safety limits. This will determine the feasibility of using Overhauser enhanced imaging for breast cancer detection, and indicate the degree of field reduction that produces optimum results.

乳腺癌是美国女性死亡的第二大原因。为了 美国癌症协会建议年度X射线 有风险的女性乳房X线照片。但是，X射线乳房X线摄影具有 缺点。重复的X射线剂量可能会增加癌症的风险，并且 X射线乳房X线摄影是众所周知的非特异性，五名女性发送给 每种确认的恶性肿瘤的活检。磁共振（MR）成像 与 对比剂，例如gadolinium-DTPA。但是，没有人建议 MR成像可用于常规筛查乳腺癌，因为它 成本是X射线乳房X线摄影的十倍以上。 这项研究的远程目标是发展更经济的 MR成像的方法可用于乳腺癌筛查。此方法将 更便宜，因为磁铁和成像硬件将量身定制 乳房的大小，而不是整个身体，也是因为 静态磁场将比平常弱100倍（即 0.01特斯拉，而不是1.5特斯拉）。减少成本优势 静态场是可以使用普通电磁体而不是 昂贵的超导磁铁。低场强度的缺点 是MR信号大大降低。该系统的新颖性是 它将采用“超肝增强”来恢复大部分信号 通过减少静态场而丢失。 通过不配对的存在使大关增强成为可能 磁性耦合到核的电子 先生图像。当电子以谐振频率照射时， MR信号最多可增强50次，具体取决于功率 电子被照射。使用的限制 人们对人的高刺效增强是必须保留吸收的力量 低于规定的安全水平。吸收力与 谐振频率的正方形。减少吸收力的一种方法 保持强大的增强是降低静态的强度 电子时磁场被照射，然后将其返回到 获得MR图像的更高价值。 该建议的重点是实验确定 降低现场，可最大程度地提高大冲动器的增强，同时保持 在人体安全限制下吸收的射频功率。这会 确定使用超肝脏增强乳房成像的可行性 癌症检测，并指示降低的现场降低程度 产生最佳结果。

项目成果

Feasibility of overhauser-enhanced MR imaging with nitroxide free radicals.

氮氧自由基奥豪瑟增强磁共振成像的可行性。

• DOI: 10.1002/jmri.1880060147
• 发表时间: 1996
• 期刊: Journal of magnetic resonance imaging : JMRI
• 作者: Lee,JN