Multidetector row ct

All CT images of the patients were taken with a multidetector-row CT (Siemens Medical Systems, Erlangen, Germany) in the Eye and ENT Hospital of Fudan University. Transverse scans throughout the orbits and nasal structures were acquired in the helical mode with a tube voltage of 120 kV and a current of 230 mA. The transverse scans were 0.75 mm thick and were converted to 3 mm thick CT sections of coronal planes. Then, we performed the lacrimal irrigation and injected the contrast agent ioversol into the nasolacrimal duct to obtain a CT-DCG. The CT-DCG was only performed in the PANDO group. The images were analyzed with a digital image workstation (Carestream CGRIS; Carestream Health, Rochester, NY, USA). All the CT measurements were performed by one of the authors (WW), who underwent radiological training for lacrimal and nasal CT structures. The methods of measurement used are outlined in subsequent sections of this article.

All CT images of the participants were completed with a multidetector-row CT (Siemens Healthineers, Erlangen, Germany) and analyzed by 1 researcher who was experienced and blinded to this study. The aorta was divided into 3 segments: the descending thoracic aorta stretching from the end of the frozen stent (S1), the abdominal aorta above the orifice of the renal artery (S2), and the abdominal aorta between the orifice of the renal artery and the iliac bifurcation (S3) (8 (link)). The false-lumen area was calculated by subtracting the true lumen area from the total aortic area (the outer surface of the aortic wall) (9 (link)). The FLAR was defined as the maximal value in each segment of the descending thoracic aorta and was calculated by dividing the false lumen area by the aortic area on the CT scan using the area measurement tool of the Neusoft PACS/RIS Version 5.5 Workstation (Neusoft Corp., Shenyang, China) (10 (link)). The postoperative to preoperative ratio of the FLAR was calculated by dividing the postoperative FLAR value by the preoperative FLAR value.