Department of Medical Imaging, Gold Coast University Hospital, Southport, QLD 4215, Australia.
School of Biomedical Sciences, Queensland University of Technology (QUT), Brisbane, QLD 4006, Australia; Translational Research Institute, Woolloongabba, QLD 4102, Australia.
Magn Reson Imaging. 2022 Oct;92:212-223. doi: 10.1016/j.mri.2022.07.004. Epub 2022 Jul 16.
Mammographic Density (MD) is the degree of radio-opacity of the breast in an X-ray mammogram. It is determined by the Fibroglandular: Adipose tissue ratio. MD has major implications in breast cancer risk and breast cancer chemoprevention. This study aimed to investigate the feasibility of accurate, low-cost quantification of MD in vivo without ionising radiation. We used single-sided portable nuclear magnetic resonance ("Portable NMR") due to its low cost and the absence of radiation-related safety concerns. Fifteen (N = 15) healthy female volunteers were selected for the study and underwent an imaging routine consisting of 2D X-ray mammography, quantitative breast 3T MRI (Dixon and T-based 3D compositional breast imaging), and 1D compositional depth profiling of the right breast using Portable NMR. For each participant, all the measurements were made within 3-4 h of each other. MRI-determined tissue water content was used as the MD-equivalent quantity. Portable NMR depth profiles of tissue water were compared with the equivalent depth profiles reconstructed from Dixon and T-based MR images, which were used as the MD-equivalent reference standard. The agreement between the depth profiles acquired using Portable NMR and the reconstructed reference-standard profiles was variable but overall encouraging. The agreement was somewhat inferior to that seen in breast tissue explant measurements conducted in vitro, where quantitative micro-CT was used as the reference standard. The lower agreement in vivo can be attributed to an uncertainty in the positioning of the Portable NMR sensor on the breast surface and breast compression in Portable NMR measurements. The degree of agreement between Portable NMR and quantitative MRI is encouraging. While the results call for further development of quantitative Portable NMR, they demonstrate the in-principle feasibility of Portable NMR-based quantitative compositional imaging in vivo and show promise for the development of safe and low-cost protocols for quantification of MD suitable for clinical applications.
乳腺密度（MD）是 X 射线乳房摄影中乳房的射线不透明度程度。它由纤维腺体：脂肪组织比例决定。MD 对乳腺癌风险和乳腺癌化学预防有重大影响。本研究旨在探索在体内进行准确、低成本、无电离辐射的 MD 定量的可行性。我们使用单边便携式磁共振（“便携式 NMR”），因为它成本低且不存在与辐射相关的安全问题。选择了 15 名（N=15）健康女性志愿者进行研究，并进行了成像常规，包括二维 X 射线乳房摄影、定量乳房 3T MRI（Dixon 和基于 T 的三维组成性乳房成像）以及使用便携式 NMR 对右乳房进行一维组成性深度剖析。对于每个参与者，所有测量都是在彼此的 3-4 小时内完成的。MRI 确定的组织水含量被用作 MD 等效量。将组织水的便携式 NMR 深度分布与从 Dixon 和基于 T 的 MR 图像重建的等效深度分布进行比较，后者用作 MD 等效参考标准。使用便携式 NMR 获得的深度分布与重建的参考标准分布之间的一致性是可变的，但总体上令人鼓舞。与在体外进行的乳房组织外植体测量中看到的一致性相比，其一致性稍差，其中定量微 CT 被用作参考标准。体内一致性较低的原因可能是由于在乳房表面放置便携式 NMR 传感器的位置和便携式 NMR 测量中的乳房压缩存在不确定性。便携式 NMR 与定量 MRI 之间的一致性令人鼓舞。虽然结果需要进一步开发定量便携式 NMR，但它们证明了基于便携式 NMR 的体内定量组成成像的原理可行性，并为开发适合临床应用的安全、低成本 MD 定量协议提供了希望。
