Péntek Quentin, Hein Simon, Miernik Arkadiusz, Reiterer Alexander
Fraunhofer Institute for Physical Measurement Techniques, Heidenhofstraße 8, 79110 Freiburg, Germany, Phone: +49 761 8857-704.
Department of Urology and Division of Urotechnology, Medical Center, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany.
Biomed Tech (Berl). 2018 Jul 26;63(4):461-466. doi: 10.1515/bmt-2016-0185.
Bladder cancer is likely to recur after resection. For this reason, bladder cancer survivors often undergo follow-up cystoscopy for years after treatment to look for bladder cancer recurrence. 3D modeling of the bladder could provide more reliable cystoscopic documentation by giving an overall picture of the organ and tumor positions. However, 3D reconstruction of the urinary bladder based on endoscopic images is challenging. This is due to the small field of view of the endoscope, considerable image distortion, and occlusion by urea, blood or particles. In this paper, we will demonstrate a method for the conversion of uncalibrated, monocular, endoscopic videos of the bladder into a 3D model using structure-from-motion (SfM). First of all, frames are extracted from video sequences. Distortions are then corrected in a calibration procedure. Finally, the 3D reconstruction algorithm generates a sparse surface approximation of the bladder lining based on the corrected frames. This method was tested using an endoscopic video of a phantom that mimics the rich structure of the bladder. The reconstructed 3D model covered a large part of the object, with an average reprojection error of 1.15 pixels and a relative accuracy of 99.4%.
膀胱癌切除术后很可能复发。因此，膀胱癌幸存者在治疗后的数年里通常要接受后续膀胱镜检查，以查找膀胱癌复发情况。膀胱的三维建模可以通过呈现器官和肿瘤位置的全貌来提供更可靠的膀胱镜检查记录。然而，基于内镜图像对膀胱进行三维重建具有挑战性。这是由于内窥镜的视野小、图像有相当大的畸变，以及被尿素、血液或颗粒遮挡。在本文中，我们将演示一种使用运动恢复结构（SfM）将未校准的单目膀胱内镜视频转换为三维模型的方法。首先，从视频序列中提取帧。然后在校准过程中校正畸变。最后，三维重建算法根据校正后的帧生成膀胱内壁的稀疏表面近似。使用模拟膀胱丰富结构的假体的内镜视频对该方法进行了测试。重建的三维模型覆盖了该物体的大部分，平均重投影误差为1.15像素，相对精度为99.4%。
