近期，中国医师协会胸外科医师分会副会长、四川大学华西医院副院长刘伦旭教授团队在专注于肺癌转化研究的国际专刊《Translational Lung Cancer Research》上（影响因子4.806），发表题为“Discovery of lung surface intersegmental landmarks by three-dimensional reconstruction and morphological measurement”（基于智能三维重建和形态学测量对肺表面段间标志点的发现）的临床研究论文，系统阐述了通过智能三维全量化重建技术确定有效的肺表面段间标志点对解剖性肺段切除术的意义。
肺表面各肺段间缺乏解剖性标志点，使段间平面的辨认成为精准解剖性肺段切除术最大的挑战之一。为了确定肺表面段间标志点，刘伦旭教授团队采用EDDA科技公司IQQA精准手术规划平台重建肺段的立体模型，并利用形态学测量技术沿肺表面解剖标志线测量每个肺段的长度。该研究共收集华西医院胸外科619例患者CT扫描的原始数据，并将其导入IQQA平台，根据二维薄层CT中支气管树的走形建立三维肺段模型，通过重建段间静脉、结合段间静脉的走形来保证肺段模型边界的准确性。然后通过3D测量工具测量各段间标志点间的距离，并进一步计算各段间标志点距离的比值。排除解剖结构不完全及再次手术等情况，由上述数据中成功地重建了500例（男性241例，女性259例）解剖结构完整的立体肺段模型用于研究，沿肺表面解剖标志线测量了各肺段的段间标志点间的距离，并进一步计算了各段间标志点之间的长度比例。
虽然在不同个体中各段的肺表面段间点之间的距离存在差异，但是各段间点之间距离的比例在人群中是相对恒定的，并不随性别、年龄、身高、体重而变化。由此得出结论，肺表面各段间点之间的距离比例保持相对恒定，这种恒定的比例的发现将无形的段间平面可视化、量化，有助于指导外科医生在解剖性肺段切除术中，以一种相对简单、安全的方式识别段间平面。此项研究对开展胸腔镜下解剖性肺段切除术提供了强有力的理论支撑，而IQQA平台使这样的全量化大数据研究和科学分析成为可能。
We downloaded the CT scan data from Picture Archiving and Communication Systems (PACS) in the form of Digital Imaging and Communications in Medicine (DICOM), and then imported the data into a 3D reconstruction system (IQQA-Lung, EDDA Technology, Princeton, NJ, USA) to generate patients’ 3D segmental models. This system recognized the lung and automatically reconstructed a rough 3D model of the trachea-bronchi system. Minor misrecognitions and deficiencies in distal bronchi imaging were reconciled and replenished manually. Based on the 3D model of bronchial tree, the system could define the intersegmental planes interactively, and then build the segmental models. Meanwhile, since the intersegmental veins travel along the intersegmental planes, we also reconstructed the pulmonary veins in each 3D segmental model, and combined this with the pathways of intersegmental veins to ensure the accuracy of the segmental models (Figure S1).
Figure S1 3D model of pulmonary vein. (A) 3D morphology of the pulmonary vein; (B) lateral view of the LUL after hiding S3. LUL, left upper lobe.
Figure 1 The anatomic landmarks of the lung surface. (A) The posterior view of the lung; (B) the lateral view of the lung; (C) the inferior view of the lung; (D) the medial view of the lung.
Identification of the route of each segment on the lung surface along the lobe’s anatomic landmark lines
To identify the route of each segment on the lung surface, we firstly marked the intersegmental points between the adjacent segments along the lobe’s anatomic boundary lines on 3D segment models.
The anatomic landmarks of the lobe and intersegmental points on the lung surface of the left upper lobe (LUL) are shown in Figure 2A.
Figure 2 The anatomic landmarks and intersegmental marks of the left lung.
The anatomic landmarks of lobe and intersegmental points on the lung surface of the left lower lobe (LLL) are shown in Figure 2B,C,D,E,F.
The anatomic landmarks of the lobe and intersegmental points on the lung surface of the right upper lobe (RUL) are shown in Figure 3A.
Figure 3 The anatomic landmarks and intersegmental marks of the RLL.
The anatomic landmarks of the lobe and intersegmental points on the lung surface of the right lower lobe (RLL) are shown in Figure 3B,C,D,E,F.
The connecting line between two adjacent intersegmental points or between an intersegmental point and a lobe anatomic landmark was the route of each segment on the lung surface.
On the 3D segment models, we used the measurement tools in IQQA-Lung system to measure the length of each segment on the lung surface (Figures S2,S3). For instance, on the segment model of LUL, we measured the distance between a and d along the anterior margin of the left lung; thus the length of S1+2 on the anterior margin of left lung could be identified (Figure S2A).
Figure S2 Diagrammatic measurements of each distance between the intersegmental marks on the surface of the left lung on 3D lung segment models.
Figure S3 Diagrammatic measurements of each distance between the intersegmental marks on the surface of the right lung on 3D lung segment models.
A total of 619 patients were enrolled in this study, 500 of whom (241 male and 259 female) had been successfully reconstructed with complete 3D segmental models. Seventy-two patients were excluded for pulmonary fissure dysplasia which could lead to segmentation failure or inaccuracy; 17 patients were excluded for infectious lesion or atelectasis which prohibits identification of bronchi; 22 patients were excluded for a history of pulmonary surgery; 8 patients were excluded for the low-quality original scanned images. The average age was 54.3±12.4 years (range: 20–88 years), and there was no significant difference between males and females (P=0.624). The average height was 161.1±7.5 cm (range: 138–181 cm). The average weight was 59.6±10.0 kg (range: 39–95 kg). Baseline characteristics of patients are summarized in Table 1.
The average length of each segment on lung surface is shown in Table 2.
Moreover, in order to reveal the spatial relationship among the segments and investigate the landmarks of intersegmental planes on the lung surface intuitively, we calculated the proportions of the lengths between adjacent segments along the lobe anatomic landmark lines (Table 3).
Figure S4 The lateral view of left lung, which shows the intersegmental landmark of S1+2 based on our data.
We discovered that proportion between lengths of adjacent segments on lung surface stayed constant. The constant proportion reflected and uncovered the lung surface intersegmental landmarks, which could navigate surgeons to identify intersegmental planes during anatomic segmentectomy in an easy and safe way without any cost.
