Three-dimensional simulation, surgical navigation and thoracoscopic lung resection
A 78-year-old man with a history of pulmonary tuberculosis and gastric cancer was found to have a small solitary pulmonary nodule in the left upper lobe 4 months ago in chest computed tomography (CT) done for postoperative follow-up for gastric cancer (Fig. A). Routine laboratory study results, including the tumor markers carcinoembryonic antigen, sialyl Lewis X-1, and squamous cell carcinoma antigen, were within normal limits. He was preoperatively staged as N0 by positron emission tomography, high-resolution CT (HRCT) of the chest and abdomen, and the magnetic resonance imaging of brain. He was also examined by thin-sliced chest CT scan. Based on thin-sliced plain chest CT scan, based on the data of which a virtual 3-D pulmonary model was designed for him on a personal computer (PC) before operation. Patient-specific 3-D pulmonary model was created by the following methods. Homemade software, called CTTRY (Tokyo Women's Medical University, Tokyo, Japan), was used []. By using 120 of 1-mm thin-sliced CT scan images of the tumor and the hilum in digital imaging and communications in medicine format, CTTRY allowed us to mark pulmonary arteries, veins, bronchi and tumor in the thin-sliced CT scan images. CTTRY attempted to reconstruct an anatomical model with the help of anatomically correct images (Fig. B). After feeding the reconstructed model images into a PC, the pulmonary arteries, veins and bronchi of patient were traced and marked by an experienced thoracic surgeon for the anatomic structure on the images. The location and thickness of the bronchi and pulmonary vascular were rendered as various-sized cylinders. Then, based on the resulting numerical data, a 3-D image, which was converted by the surface-rendering technique, was reconstructed using software (Metasequoia, ) (Fig. C). When his virtual 3-D pulmonary model was reconstructed by CTTRY, the tumor was found to be involved in two subsegments [horizontal subsegment of apicoposterior segment (S1 + 2c) and posterior subsegment of anterior segment (S3a)] (Fig. E). Further, the data of the reconstructed 3-D images by Metasequoia were converted with Autodesk® 3ds Max® 2012 (Autodesk, San Rafael, CA, USA) (Fig. D). Finally, image software, REMO Exporter® (3D Incorporated, Kanagawa, Japan), which reproduced Autodesk data with real-time computer graphics (CG), was able to indicate with a stereoscopic vision display by 3-DCG data. On a PC, reconstructed 3-D pulmonary images were provided side by side and were output to a monitor. Surgeons were able to watch the 3-DCG of the reconstructed 3-D pulmonary model with a 3-D liquid-crystal (LC) monitor by REMO Viewer® (3D Incorporated). The reconstructed 3-D images on a 3-D LC monitor were able to be manipulated by virtual surgical procedures such as reshaping, cutting and moving (Fig. E). The simulation result was able to allow the subsegmentectomy of S1 + 2c and S3a to be performed with a sufficient surgical margin. A 3-D digital vision system (Shinko Optical, Tokyo, Japan) was used for 3-D thoracoscopic performance. This system included a 11-mm, 30° stereo digital scope and a 3-D data-processing unit. Wearing glasses, thoracoscopic procedures were performed by the surgeons and by means of intraoperative navigation, the patient's actual reconstructed 3-D pulmonary model was able to be watched with 3-D LC displays (Fig. ). Complete VATS bi-subsegmentectomy was selected in preoperative simulation and was performed with intraoperative assessment of lymph nodes; hilar node dissection with mediastinal lymph node sampling was done using conventional thoracoscopic instruments (Fig. A and B). Final histologic examination revealed T1aN0M0 pulmonary adenocarcinoma. The patient's postoperative course was uneventful.