P2.05-05 Availability of Four Dimensional Computed Tomography (4DCT) for Lung Cancer

Abstract

Four-dimensional computed tomography (4DCT) imaging is a new form of chest CT that can detect continuous movement of the airways and lungs under free breathing conditions. This method is likely to be used increasingly to evaluate pulmonary function or predict intraoperative adhesion or tumor invasion. A total of 31 cases that underwent 4DCT at the Kanagawa Cardiovascular Respiratory Center from October 2017 to February 2019 were reviewed. Dynamic ventilatory scans were performed using a 320-row multi detector CT (Aquilion ONE GENESIS, Canon Medical Systems, Otawara, Tochigi, Japan). The frame rate was 0.25sec/volume and the total estimated radiation exposure was 3.9 mSV. In surgical cases of lung cancer, the 4DCT findings were compared with the intraoperative assessment. We obtained 2 sets (upper lung region and lower region) of 4DCT covering the whole lung. These volume sets were connected and evaluated using imaging processing software. Intrathoracic adhesion and tumor invasion were defined by the differential movement between the tumor and adjacent structures, and laterality of the respiratory motion. There were 16 cases of non-neoplastic diseases, such as non-tuberculous mycobacteriosis, giant bulla and lung sequestration. The 15 neoplastic diseases included 2 solitary fibrous tumors and 13 lung cancers. Among them, 12 cases in the lung cancer group underwent surgical procedures and were able to be evaluated. The purposes of the preoperative 4DCT were as follows: evaluation of tumor invasion (n=8), reoperation cases (n=2), medical history of tuberculous mycobacteriosis (n=2) and suspicion of intrathoracic adhesion on chest X-ray (n=1). Adjacent structures were the descending aorta (n=2), pulmonary artery (n=1), subclavian artery (n=1) and chest wall (n=5). The surgical procedures included 10 lobectomies, 1 wedge resection and 1 open lung biopsy. The 4DCT findings were comparable with the intraoperative findings in eleven cases; intraoperative adhesions were noted at the same locations and there were no signs of direct tumor invasion to vital structures, as indicated by 4DCT. In only one case of suspected invasion of the subclavian artery, was unexpected adhesion to the upper mediastinum observed during surgery. As the motion of the apical region was restricted in all cases, we were not able to evaluate apical adhesion. The intraoperative findings supported those of 4DCT in 11/12cases. 4DCT of the whole lung was an useful and reliable tool for the preoperative assessment and determination of the surgical indication for lung cancers.