Predictors of conversion to thoracotomy during video-assisted thoracoscopic surgery lobectomy in lung cancer: additional predictive value of FDG-PET/CT in a tuberculosis endemic region

Abstract

Background: To evaluate the added clinical value of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) scans to chest CT imaging in predicting the conversion to thoracotomy during video-assisted thoracoscopic surgery (VATS) lobectomy in patients with lung cancer.

Methods: This is a retrospective study of 235 consecutive patients who underwent planned VATS lobectomy for primary lung cancer between 2011 and 2015. CT images were interpreted in terms of the presence and the attenuation of peribronchial lymph nodes (PLN) and peribronchial cuffs of soft (PCS) tissue, pleural calcification, and parenchymal calcified nodule. On FDG PET/CT images, anthracofibrotic lymph node was considered present when high FDG uptake (SUVmax >3.5) was observed on PET/CT images corresponded to PLN or PCS on chest CT.

Results: Among the 235 patients undergoing attempted VATS lobectomy, 55 (23.4%) underwent conversion to thoracotomy. Multivariate logistic regression analysis revealed that the attenuation of PLN or PCS on chest CT (OR, 2.57; 95% CI, 1.328-4.380, 0.005) was an only independent predictor of conversion. The ROC curve showed that combined FDG PET/CT and chest CT reading [areas under curve (AUC), 0.847 (95% CI, 0.795-0.891)] was significantly better than that of chest CT scans alone [AUC, 0.655 (95% CI, 0.50-0.751)] in predicting conversion (P=0.024).

Conclusions: The addition of FDG PET/CT scanning to chest CT imaging provides better performance for predicting conversion to thoracotomy during VATS lobectomy in lung cancer patients. Therefore, in lung cancer patients undergoing surgical resection, FDG PET/CT can provide additional reliable information in selecting the appropriate surgical approach for a lobectomy.

Keywords: Lung neoplasms; peribronchial lymph node (PLN); positron-emission tomography; thoracotomy; video-assisted thoracic surgery (VATS).

Figure 1

Receiver operating characteristic (ROC) curve for prediction of intraoperative conversion of VATS lobectomy based on chest CT alone [AUC, 0.655 (95% CI, 0.550–0.751); sensitivity, 91.30; specificity, 36.17; P value =0.003] and combined chest CT and FDG PET/CT [AUC, 0.847 (95% CI, 0.795–0.891); sensitivity, 80.00; specificity, 89.44; P value <0.001]. FDG, fluorodeoxyglucose; PET/CT, positron emission tomography/CT; AUC (95% CI), area under the curve (95% confidence interval).

Figure 2

A 75-year-old man who completed VATS lobectomy for squamous cell carcinoma. (A) Axial CT scan with contrast enhancement at the level of main bronchi shows a 1.5 cm mass in right upper lobe. (B-D) Axial scans obtained with (B) FDG PET/CT, (C) contrast-enhanced CT, and (D) unenhanced CT at the level of the bronchus intermedius show calcified lymph node (arrow in C,D) in right hilum, without significant FDG uptake. VATS, video-assisted thoracoscopic surgery; FDG, fluorodeoxyglucose; PET/CT, positron emission tomography/computed tomography.

Figure 3

A 76-year-old man who underwent conversion to thoracotomy during VATS lobectomy for squamous cell carcinoma due to peribronchial fibrosis. (A) Axial CT scan at the level of aortic arch shows a 1.0 cm persistent ground glass nodule in right upper lobe. (B-D) Axial scans obtained with (B) FDG PET/CT, (C) contrast-enhanced CT, and (D) unenhanced CT at the level of the main bronchi show lymph node with high attenuation (94 HU, arrow in C,D) in right hilum, with significant FDG uptake (SUVmax >3.5). VATS, video-assisted thoracoscopic surgery; FDG, fluorodeoxyglucose; PET/CT, positron emission tomography/computed tomography.