OptoSonics, Inc., 108 Straight Road, Oriental, North Carolina 28571, USA.
Med Phys. 2010 Nov;37(11):6096-100. doi: 10.1118/1.3497677.
The authors report a noninvasive technique and instrumentation for visualizing vasculature in the breast in three dimensions without using either ionizing radiation or exogenous contrast agents, such as iodine or gadolinium. Vasculature is visualized by virtue of its high hemoglobin content compared to surrounding breast parenchyma. The technique is compatible with dynamic contrast-enhanced studies.
Photoacoustic sonic waves were stimulated in the breast with a pulsed laser operating at 800 nm and a mean exposure of 20 mJ/pulse over an area of approximately 20 cm2. These waves were subsequently detected by a hemispherical array of piezoelectric transducers, the temporal signals from which were filtered and backprojected to form three-dimensional images with nearly uniform k-space sampling.
Three-dimensional vascular images of a human volunteer demonstrated a clear visualization of vascular anatomy with submillimeter spatial resolution to a maximum depth of 40 mm using a 24 s image acquisition protocol. Spatial resolution was nearly isotropic and approached 250 microm over a 64 x 64 x 50 mm field of view.
The authors have successfully visualized submillimeter breast vasculature to a depth of 40 mm using an illumination intensity that is 32 times less than the maximum permissible exposure according to the American National Standard for Safe Use of Lasers. Clearly, the authors can achieve greater penetration depth in the breast by increasing the intensity and the cross-sectional area of the illumination beam. Given the 24 s image acquisition time without contrast agent, dynamic, contrast-enhanced, photoacoustic breast imaging using optically absorbing contrast agents is conceivable in the future.
作者报告了一种非侵入性技术和仪器，可在不使用电离辐射或外源性对比剂（如碘或钆）的情况下，将乳房中的血管可视化三维。血管通过其与周围乳房实质相比的高血红蛋白含量而被可视化。该技术与动态对比增强研究兼容。
在乳房中用 800nm 脉冲激光以 20mJ/脉冲的平均暴露量激发光声声波，其面积约为 20cm2。这些波随后被半球形压电换能器阵列检测，其时间信号被过滤并反向投影，以形成具有几乎均匀 k 空间采样的三维图像。
使用 24 秒的图像采集协议，对一名志愿者的三维血管图像进行了演示，显示了血管解剖结构的清晰可视化，空间分辨率达到亚毫米级，最大深度为 40mm。空间分辨率几乎各向同性，在 64x64x50mm 的视场中接近 250 微米。
作者使用比美国国家激光安全使用标准允许的最大暴露量低 32 倍的光照强度成功地可视化了亚毫米级乳房血管，最大深度为 40mm。显然，通过增加强度和照明光束的横截面积，作者可以在乳房中实现更大的穿透深度。考虑到没有对比剂的 24 秒图像采集时间，使用光学吸收对比剂的动态、对比增强、光声乳腺成像在未来是可以想象的。
