Three-dimensional surface models of autopsied human brains constructed from multiple photographs by photogrammetry

Virtual three-dimensional (3D) surface models of autopsied human brain hemispheres were constructed by integrating multiple two-dimensional (2D) photographs. To avoid gravity-dependent deformity, formalin-fixed hemispheres were placed on non-refractile, transparent acrylic plates, which allowed us to take 2D photographs from various different angles. Photogrammetric calculations using software (ReCap Pro cloud service, Autodesk, San Rafael, CA, USA) allowed us calculate the 3D surface of each brain hemisphere. Virtual brain models could be moved and rotated freely to allow smooth, seamless views from different angles and different magnifications. When viewing rotating 3D models on 2D screens, 3D aspects of the models were enhanced using motion parallax. Comparison of different brains using this method allowed us to identify disease-specific patterns of macroscopic atrophy, that were not apparent in conventional 2D photographs. For example, we observed frontal lobe atrophy in a progressive supranuclear palsy brain, and even more subtle atrophy in the superior temporal gyrus in amyotrophic lateral sclerosis-frontotemporal lobar degeneration. Thus, our method facilities recognition of gyral atrophy. In addition, it provides a much more powerful and suitable way of visualizing the overall appearance of the brain as a three-dimensional structure. Comparison of normal and diseased brains will allow us to associate different macroscopic changes in the brain to clinical manifestations of various diseases.通过整合多张二维（2D）照片，我们构建了尸检人类大脑半球的虚拟三维（3D）表面模型。为避免重力诱导的变形，我们将福尔马林固定的大脑半球放置于无折射透明亚克力板上，从而能够从多种不同角度拍摄二维（2D）照片。借助美国加利福尼亚州圣拉斐尔市欧特克（Autodesk）公司的ReCap Pro云服务软件完成摄影测量计算，我们得以得到每个大脑半球的三维（3D）表面模型。该虚拟大脑模型可自由移动与旋转，支持从任意角度、不同放大倍率下获得流畅无缝的观察视角。当在二维（2D）屏幕上查看旋转的三维（3D）模型时，我们通过运动视差效果增强模型的三维视觉感知。采用该方法对比不同大脑样本，可识别出常规二维（2D）照片中难以显现的疾病特异性宏观萎缩模式。例如，我们在进行性核上性麻痹患者的大脑中观察到额叶萎缩，而在肌萎缩侧索硬化-额颞叶变性患者的大脑颞上回中发现了更为隐匿的萎缩。由此可见，本方法有助于识别脑回萎缩。此外，该方法还能以更高效且适配的方式，展现大脑作为三维结构的整体外观。对比正常与病变大脑，可帮助我们将大脑的不同宏观变化与各类疾病的临床表现建立关联。