Patel V, Hoffmann K R, Ionita C N, Keleshis C, Bednarek D R, Rudin S
Med Phys. 2008 Oct;35(10):4757-64. doi: 10.1118/1.2989989.
Rotational angiography (RA) gantries are used routinely to acquire sequences of projection images of patients from which 3D renderings of vascular structures are generated using Feldkamp cone-beam reconstruction algorithms. However, these systems have limited resolution (<4 lp/mm). Micro-computed tomography (micro-CT) systems have better resolution (>10 lp/mm) but to date have relied either on rotating object imaging or small bore geometry for small animal imaging, and thus are not used for clinical imaging. The authors report here the development and use of a 3D rotational micro-angiography (RMA) system created by mounting a micro-angiographic fluoroscope (MAF) [35 microm pixel, resolution >10 microp/mm, field of view (FOV)=3.6 cm] on a standard clinical FPD-based RA gantry (Infinix, Model RTP12303J-G9E, Toshiba Medical Systems Corp., Tustin, CA). RA image sequences are obtained using the MAF and reconstructed. To eliminate artifacts due to image truncation, lower-dose (compared to MAF acquisition) full-FOV (FFOV) FPD RA sequences (194 microm pixel, FOV=20 cm) were also obtained to complete the missing data. The RA gantry was calibrated using a helical bead phantom. To ensure high-quality high-resolution reconstruction, the high-resolution images from the MAF were aligned spatially with the lower-dose FPD images, and the pixel values in the FPD image data were scaled to match those of the MAF. Images of a rabbit with a coronary stent placed in an artery in the Circle of Willis were obtained and reconstructed. The MAF images appear well aligned with the FPD images (average correlation coefficient before and after alignment: 0.65 and 0.97, respectively) Greater details without any visible truncation artifacts are seen in 3D RMA (MAF-FPD) images than in those of the FPD alone. The FWHM of line profiles of stent struts (100 microm diameter) are approximately 192+/-21 and 313+/-38 microm for the 3D RMA and FPD data, respectively. In addition, for the dual-acquisition 3D RMA, FFOV FPD data need not be of the highest quality, and thus may be acquired at lower dose compared to a standard FPD acquisition. These results indicate that this system could provide the basis for high resolution images of regions of interest in patients with a reduction in the integral dose compared to the standard FPD approach.
旋转血管造影（RA）机架通常用于获取患者的投影图像序列，利用费尔德坎普锥形束重建算法从中生成血管结构的三维渲染图。然而，这些系统的分辨率有限（<4线对/毫米）。微型计算机断层扫描（micro-CT）系统具有更好的分辨率（>10线对/毫米），但迄今为止，其要么依赖旋转物体成像，要么采用小孔径几何结构用于小动物成像，因此未用于临床成像。作者在此报告一种三维旋转微血管造影（RMA）系统的开发与应用，该系统是通过将一台微血管造影荧光镜（MAF）[35微米像素，分辨率>10微米/毫米，视野（FOV）=3.6厘米]安装在基于平板探测器（FPD）的标准临床RA机架（Infinix，型号RTP12303J-G9E，东芝医疗系统公司，加利福尼亚州图斯廷）上创建而成。使用MAF获取RA图像序列并进行重建。为消除因图像截断导致的伪影，还获取了低剂量（与MAF采集相比）全视野（FFOV）FPD RA序列（194微米像素，FOV=20厘米）以补充缺失数据。使用螺旋珠模体对RA机架进行校准。为确保高质量的高分辨率重建，将MAF的高分辨率图像与低剂量FPD图像进行空间对齐，并对FPD图像数据中的像素值进行缩放以匹配MAF的像素值。获取并重建了一只在 Willis 环动脉中植入冠状动脉支架的兔子的图像。MAF图像与FPD图像显示出良好的对齐（对齐前后的平均相关系数分别为0.65和0.97）。与单独的FPD图像相比，在三维RMA（MAF-FPD）图像中可以看到更多细节且无任何可见的截断伪影。对于三维RMA，支架支柱（直径100微米）线轮廓的半高宽分别约为192±21微米和313±38微米（分别对应三维RMA和FPD数据）。此外，对于双采集三维RMA，FFOV FPD数据无需具有最高质量，因此与标准FPD采集相比，可以在更低剂量下获取。这些结果表明，与标准FPD方法相比，该系统可为患者感兴趣区域的高分辨率图像提供基础，同时降低总体剂量。
