Eur J Cardiothorac Surg 2008;34:875-877. doi:10.1016/j.ejcts.2008.07.014
Copyright © 2008, European Association for Cardio-thoracic Surgery. Published by Elsevier. All rights reserved.
Preoperative assessment of the pulmonary artery by three-dimensional computed tomography before video-assisted thoracic surgery lobectomy
Kenjiro Fukuhara*,
Akinori Akashi,
Shigeru Nakane,
Emiko Tomita
Department of General Thoracic Surgery, Takarazuka Municipal Hospital, 4-5-1 Kohama, Takarazuka, Hyogo 665-0827, Japan
Received 18 March 2008;
received in revised form 4 July 2008;
accepted 14 July 2008.
* Corresponding author. Tel.: +81 797 87 1161; fax: +81 797 87 1391. (Email: ks-fukuhara{at}orange.plala.or.jp).
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Abstract
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Objective: Our aim was to evaluate the efficacy of 3D imaging using multidetector row helical computed tomography (MDCT) in the preoperative assessment of the branching pattern of pulmonary artery (PA) before complete video-assisted thoracoscopic lobectomy (complete VATS lobectomy) for lung cancer. Methods: Forty-nine consecutive patients with clinical stage I lung cancer scheduled for complete VATS lobectomy were evaluated about branching pattern of PA on 16-channel MDCT. Intraoperative finding of the PA branching pattern were compared with the 3D-CT angiography images obtained using MDCT. Results: According to the intraoperative findings, 95.2% (139 of 146) of PA branches were precisely identified on preoperative 3D-CT angiography. All of the seven undetected branches were within 2 mm in diameter. There was not a case that needed conversion to open thoracotomy because of intraoperative bleeding. Conclusion: A 3D-CT angiography using MDCT clearly revealed individual anatomies of pulmonary artery and could play an important role in safely facilitating complete VATS lobectomy procedure. However, we were unable to detect several thin branches with this technique. So, more care should be taken to avoid bleeding from these small vessels.
Key Words: Lung cancer • 3D-CT angiography • VATS lobectomy • Complete VATS
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1. Introduction
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Lobectomy by video-assisted thoracic surgery (VATS lobectomy) is a well-established and widespread therapeutic method for treating small peripheral lung cancer [1,2]. We have applied complete video-assisted thoracoscopic lobectomy (complete VATS lobectomy) to clinical stage I primary lung cancer [3,4], but the branching pattern of pulmonary artery (PA) exhibits many variations and complete VATS lobectomy requires a more detailed understanding of local anatomy than does conventional open surgery. Therefore, preoperative identification of the branching pattern of PA will decrease the risk of unexpected bleeding at complete VATS lobectomy for lung cancer. With the recent development of multidetecter row helical computed tomography (MDCT), three-dimensional computed tomographic (3D-CT) angiography can easily and quickly be obtained and provide very useful visual information in various diseases [5]. In this study, we evaluated the efficacy of 3D imaging using MDCT in the preoperative assessment of the branching pattern of PA before complete VATS lobectomy for lung cancer.
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2. Methods
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From September 2005 to October 2007, 49 consecutive patients with clinical stage I lung cancer scheduled for complete VATS lobectomy were enrolled in this study. In our hospital, biphasic helical CT imaging is the standard examination for the staging of lung cancer. We obtained 16-channel MDCT images from these patients. The MDCT was performed on a scanner (Aquilion multi 16DAS TSX-101A, Toshiba Medical Systems, Tokyo, Japan) using a slice thickness of 1 mm reconstructed at 0.63 mm intervals with contrast material injection by a mechanical injector at a rate of 3 ml/s, for a total dose of 100 ml. The volume data obtained from the arterial phase were transferred to a workstation (Aquarius Net Station, Terarecon, USA), in which the data were converted to a 3D-CT angiography format using the volume-rendering technique. The 3D images were processed within 5–10 min after scanning. The additional cost for this investigation is almost zero because CT with injecting contrast medium is always taken in lung cancer cases in our institution for evaluation of lymph node enlargement. Before thoracotomy, lobar and segmental arteries branching directly from the main PA were identified meticulously by rotating the obtained 3D image on the display. All 3D-CT angiography images were prospectively evaluated by one radiologist and two surgeons in consensus because this method was considered to be better suited to this anatomical study due to the complexity of branching pattern of the number of anatomical variations. Intraoperative finding of the PA branching pattern were compared with the 3D-CT angiography images obtained using MDCT.
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3. Results
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In all 49 patients examined, PA branches were clearly identified with MDCT (Figs. 1– 4
). Central type of lingular artery was also clearly detected (Fig. 3).
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Fig. 1. Three-dimensional computed tomography pulmonary angiography image of the right pulmonary artery. This case was performed right upper lobectomy. All of PA branches were detected.
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Fig. 2. Three-dimensional computed tomography pulmonary angiography image of the right pulmonary artery. This case was performed right upper lobectomy. One of posterior ascending artery was not detected.
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Fig. 3. Three-dimensional computed tomography pulmonary angiography image of the left pulmonary artery. This case was performed left upper lobectomy. The lingular artery that branched off the anterior artery was detected.
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Fig. 4. Three-dimensional computed tomography pulmonary angiography image of the left pulmonary artery. This case was performed left upper lobectomy. One lingular artery was not detected.
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Right and left complete VATS lobectomy was performed in 28 and 21 patients, respectively. According to the intraoperative findings, 95.2% (139 of 146) of PA branches were precisely identified on preoperative 3D CT angiography (Table 1
). Undetected PA branches were superior segmental artery in four right surgeries (Fig. 2) and apical artery, lingular artery (Fig. 4), and superior segmental artery in left surgeries. All seven missed branches were less than 2 mm in actual diameter.
All 49 cases underwent successful complete VATS lobectomy without massive bleeding on the basis of the 3D CT angiography. All seven missed branches were ligated and separated during complete VATS lobectomy.
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4. Discussion
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Lobectomy by video-assisted thoracic surgery for primary lung cancer is widely performed due to technical improvements and technological advancements [1,2]. However, the techniques of VATS lobectomy vary greatly among institutions. As Yim et al. [6] noted, VATS lobectomy actually covers a wide spectrum of operative techniques and a broad range of methods, including not only pure endoscopic surgery, but also minithoracotomy, in which the thoracoscope serves only as a light source. We have applied pure endoscopic lobectomy (complete VATS lobectomy) to clinical stage I lung cancer patients [3,4]. Because complete VATS uses purely endoscopic techniques with 100% monitor vision without rib-spreading minithoracotomy, it is difficult to obtain an image of the entire lesion and we cannot manipulate lesions directly. Therefore, knowledge of the branching pattern of pulmonary artery is essential for preoperative planning of complete VATS lobectomy; we have introduced MDCT into the preoperative inspection.
The development of MDCT has advanced clinical CT scanning. Currently, the 3D displays of anatomic structures have become feasible for the determination of surgical methods and preoperative planning in liver and gastric surgeries [7,8]. However, there have been few reports on the use of 3D displays for the endoscopic surgical treatment of lung cancer.
In our study, 3D-CT angiography using MDCT clearly showed the anatomy of PA; this approach proved to be useful to preoperatively assess individual vascular variation. This technique made it possible to have safe and rapid manipulation of the origins of PA branches and lymph node dissection without incurring injury to the involved PA.
3D-CT imaging has various advantages. First, 3D-CT angiography is a minimally invasive vascular imaging method that is less expensive than conventional diagnostic angiography. Second, 3D-CT imaging can be visualized interactively from any viewpoint [9]. We can obtain favorable 3D images in any direction needed by the operating crews. However, we could not detect several thin branches with this technique. This may be a limitation of resolution of MDCT. Successful complete VATS lobectomies were performed without massive bleeding even in these cases. However, generally, the difficulty happens when the small branches are unexpectedly encountered and rupture. The vascular anatomy of the lung and its many common variations should be well known to anyone who performs VATS lobectomies. The identification rate with our technique is not a satisfactory result, but from the surgeon's mental point of view this preoperative information sets the surgeon's mind at ease during lung resection. More care should be taken to avoid bleeding from these small vessels during complete VATS lobectomy. With more technical developments in hardware and software, this problem might be solved in the near future (e.g. using 64-channel MDCT).
In conclusion, 3D-CT angiography using MDCT gave a clear visualization of PA. This technique was found to be useful for the safe performance of VATS lobectomy for the treatment of patients with lung cancer.
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References
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Abstract
1. Introduction
