Development of a machine learning-based risk model for postoperative complications of lung cancer surgery.

PURPOSE: To develop a comorbidity risk score specifically for lung resection surgeries. METHODS: We reviewed the medical records of patients who underwent lung resections for lung cancer, and developed a risk model using data from 2014 to 2017 (training dataset), validated using data from 2018 to 2019 (validation dataset). Forty variables were analyzed, including 35 factors related to the patient's overall condition and five factors related to surgical techniques and tumor-related factors. The risk model for postoperative complications was developed using an elastic net regularized generalized linear model. The performance of the risk model was evaluated using receiver operating characteristic curves and compared with the Charlson Comorbidity Index (CCI). RESULTS: The rate of postoperative complications was 34.7% in the training dataset and 21.9% in the validation dataset. The final model consisted of 20 variables, including age, surgical-related factors, respiratory function tests, and comorbidities, such as chronic obstructive pulmonary disease, a history of ischemic heart disease, and 12 blood test results. The area under the curve (AUC) for the developed risk model was 0.734, whereas the AUC for the CCI was 0.521 in the validation dataset. CONCLUSIONS: The new machine learning model could predict postoperative complications with acceptable accuracy. CLINICAL REGISTRATION NUMBER: 2020-0375.

CHST4 Gene as a Potential Predictor of Clinical Outcome in Malignant Pleural Mesothelioma.

Malignant pleural mesothelioma (MPM) develops primarily from asbestos exposures and has a poor prognosis. In this study, The Cancer Genome Atlas was used to perform a comprehensive survival analysis, which identified the CHST4 gene as a potential predictor of favorable overall survival for patients with MPM. An enrichment analysis of favorable prognostic genes, including CHST4, showed immune-related ontological terms, whereas an analysis of unfavorable prognostic genes indicated cell-cycle-related terms. CHST4 mRNA expression in MPM was significantly correlated with Bindea immune-gene signatures. To validate the relationship between CHST4 expression and prognosis, we performed an immunohistochemical analysis of CHST4 protein expression in 23 surgical specimens from surgically treated patients with MPM who achieved macroscopic complete resection. The score calculated from the proportion and intensity staining was used to compare the intensity of CHST4 gene expression, which showed that CHST4 expression was stronger in patients with a better postoperative prognosis. The median overall postoperative survival was 107.8 months in the high-expression-score group and 38.0 months in the low-score group (p = 0.044, log-rank test). Survival after recurrence was also significantly improved by CHST4 expression. These results suggest that CHST4 is useful as a prognostic biomarker in MPM.

Impact of Pleural Thickness on Occurrence of Postoperative Complications in Patients with Malignant Pleural Mesothelioma.

OBJECTIVES: The rates of postoperative mortality and morbidity are high in patients with malignant pleural mesothelioma (MPM). Therefore, it is important to identify variables that increase the risk of postoperative complications. Pleural thickness has recently been identified as a prognostic indicator in patients with MPM. The aim of this study was to investigate clinical variables, including pleural thickness, that contribute to postoperative complications in patients with MPM. PATIENTS AND METHODS: A total of 47 patients who underwent surgical excision of MPM between 2005 and 2021 were enrolled in this study. Correlations between postoperative complications within 90 days of surgery and preoperative clinical factors were investigated. RESULTS: A total of 27 patients underwent extrapleural pneumonectomy (EPP), and the remaining 20 underwent pleurectomy/decortication (P/D). Macroscopic complete resections were obtained in all but three patients. Of the 47 patients, 23 (49%) experienced postoperative complications of grade 3 or worse. The major complication in patients with EPP was respiratory failure (n = 6), whereas the major complication in patients with P/D was prolonged air leakage (n = 7). Univariate logistic regression analysis found a correlation between postoperative complications and age, surgical side, and pleural thickness, while multivariate logistic regression analysis found surgical side (p = 0.04, 95% Cl 1.10-21.71, OR 4.90) and pleural thickness (p = 0.03, 95% Cl 1.21-23.00, OR 5.26) to significantly influence the occurrence of postoperative complications. CONCLUSIONS: Pleural thickness has a significant effect on the occurrence of postoperative complications. Patients with thick pleura on the right side are at greater risk of postoperative complications.

[Robot-assisted Extended Thymectomy via a Bilateral Approach for Patients with Myasthenia Gravis].

Extended thymectomy is a procedure to remove the thymus gland and surrounding adipose tissue, while the traditional approach via a median sternotomy, minimally invasive approaches such as video-assisted thoracoscopic surgery (VATS) and robot-assisted thoracoscopic surgery (RATS) have been adopted. This report described the technique of bilateral approach for extended thymectomy in patients with myasthenia gravis (MG) by robot-assisted thoracoscopic surgery, and also showed the perioperative outcomes and postoperative exacerbation rates of 11 patients. In most patients, score of MG symptom were reduced and levels of anti-acetylcholine receptor antibodies declined postoperatively. In a small number of cases, the safety and efficacy of a RATS bilateral approach for extended thymectomy were confirmed.

Pleural Invasion Depth of Disseminated Nodules in Patients with Stage IVa or Recurrent Thymoma: Assessment, Curative Impact, and Surgical Outcomes.

BACKGROUND: Thymoma patients with pleural dissemination are difficult to manage, and their treatment strategy remains undefined. This study aimed to investigate the clinicopathologic features of these patients, focusing on the association between the depth of pleural invasion and prognosis. METHODS: Between 2003 and 2019, the study identified 120 disseminated lesions in 20 thymoma patients. Seven patients had de novo stage IVa thymoma and 13 were recurrent cases. Extrapleural pneumonectomy was performed for 8 patients and debulking surgery for 12 patients. Invasion depth of pleural tumors was classified into two groups: when the disseminated tumors invaded the pleura beneath the elastic layer, the tumor was diagnosed as Da, and when the disseminated tumors invaded the pleura beyond the elastic layer, the tumor was diagnosed as Db. RESULTS: Of 120 nodules, 31 (26%), found in eight patients with recurrent malignancies, were classified as Db. The pathologic status of the surgical margin (PSM) was positive in eight patients, seven of whom had Db nodules. The 5-year overall survival (OS) rate was 100% in the Da group and 75% in the Db group (P = 0.02). The 5-year progression-free survival (PFS) rate was 66.7% in the Da group and 25% in the Db group (P = 0.02). Cox univariate analysis showed that PFS was significantly influenced by the depth of invasion (P = 0.04) and PSM (P = 0.03). CONCLUSION: Depth of pleural invasion may influence survival outcomes for thymoma patients with pleural dissemination. The patients in this study with Da-disseminated nodules had an increased probability of a longer OS and PFS and tended to achieve negative PSM compared with the patients with Db.

Diagnostic utility of metabolic parameters on FDG PET/CT for lymph node metastasis in patients with cN2 non-small cell lung cancer.

BACKGROUND: The aim of this study was to assess the diagnostic utility of metabolic parameters on fluorine-18-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET)/computed tomography (CT) for predicting lymph node (LN) metastasis in patients with cN2 non-small cell lung cancer (NSCLC). METHODS: We retrospectively reviewed patients who underwent surgery for cN2 NSCLC between 2007 and 2020. Those who had clinically diagnosed positive hilar and mediastinal LNs by routine CT and PET/CT imaging were investigated. To measure the metabolic parameters of LNs, the data according to maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and LN-to-primary tumor ratio of SUVmax (LPR) were examined. The diagnosis of each retrieved LN was confirmed based on histopathological examination of surgical tissue specimens. Receiver operating characteristics (ROC) curves with area under the curve (AUC) calculations and multivariate analysis by logistic regression were performed. RESULTS: Forty-five patients with 84 clinically diagnosed positive hilar or mediastinal LNs were enrolled in the present study. Of the 84 LNs, 63 LNs were pathologically proven as positive (75%). The SUVmax, MTV, TLG, and LPR of LN metastasis were significantly higher than those of benign nodes. In the ROC analysis, the AUC value of LPR [AUC, 0.776; 95% confidence interval (CI), 0.640-0.913] was higher than that of LN SUVmax (AUC, 0.753; 95% CI, 0.626-0.880) or LN TLG3.5 (AUC, 0.746; 95% CI, 0.607-0.885). Using the optimal LPR cutoff value of 0.47, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 84.1, 66.7, 88.3, 58.3, and 79.8%, respectively. Multivariate analysis by logistic regression showed that LPR was an independent predictor for LN metastasis (odds ratio, 6.45; 95% CI, 1.785-23.301; P = 0.004). In the subgroup analysis of adenocarcinoma patients (n = 18; 32 LNs), TLG3.5 was a better predictor (AUC, 0.816; 95% CI, 0.639-0.985) than LPR (AUC, 0.792; 95% CI, 0.599-0.986) or LN SUVmax (AUC, 0.792; 95% CI, 0.625-0.959). CONCLUSIONS: Our findings suggest that LPR on FDG-PET is a useful predictor for LN metastasis in patients with cN2 NSCLC. TLG can be a good predictor for LN metastasis in patients with adenocarcinoma.

Thoracoscopic Wedge Resection for Low-Grade Fibromyxoid Sarcoma (Evans Tumor) with Massive Calcification and Originating from the Lung: A Rare Case in an Unexpected Location.

We encountered a rare case of low-grade fibromyxoid sarcoma, which is generally known as Evans tumor, with massive calcification originating from the lung. The patient was a 22-year-old man with Duchenne muscular dystrophy who was referred for a detailed investigation of an intrathoracic tumor with massive calcification. Although our preoperative diagnosis was a solitary fibrous tumor originating from the mediastinum or diaphragm, intraoperative thoracoscopy revealed the tumor arising from the left lower lobe without adhesion to the other organs. Considering his medical history, we aimed to preserve lung function and chose wedge resection, which completely removed the tumor. Based on the pathological findings, the tumor was diagnosed as low-grade fibromyxoid sarcoma with massive calcification originating from the lung. Although extremely rare, this tumor should be considered as a differential diagnosis for a solitary lung mass with massive calcification in young adults.

Clinical application of resection process map as a novel surgical guide in thoracic surgery.

Resection Process Map (RPM) is a surgical simulation system that uses preoperative three-dimensional computed tomography. Unlike the usual static simulation, this system provides surgeons an individualized dynamic deformation of the lung parenchyma and vessels. RPM was first introduced in 2020. Although the intraoperative usefulness of this system has been evaluated experimentally, there have been no reports on its clinical use. Herein, we presented in detail the first experience on RPM during robot-assisted anatomical lung resection in the real clinical setting.

Complete visualization using indocyanine green in thoracic surgery for pulmonary sequestration.

Preoperative three-dimensional computed tomography (CT) facilitates accurate identification of aberrant systemic arteries in thoracic surgery for pulmonary sequestration (PS). Furthermore, the boundary between normal and sequestrated lungs can be visualized using the spread of fluorescent indocyanine green (ICG) when performing surgery for PS. This study aimed to determine how to completely visualize anatomical variations, safely treat aberrant arteries, remove only sequestrated lungs, and perform minimally invasive surgery for PS. Seventeen patients underwent lung resection for intralobar PS at our institution between 2009 and 2022. We retrospectively reviewed the surgical outcomes and intraoperative images using ICG to assess the efficacy and feasibility of near-infrared fluorescence imaging. Since 2019, intraoperative near-infrared fluorescence imaging with ICG has been used in six patients, including four females and two males (median age, 56 years), to visualize the boundary between normal and sequestrated lungs. Aberrant arteries were identified using preoperative three-dimensional CT, and the boundary between sequestrated and normal lungs could be clearly delineated intraoperatively using ICG in all cases. The median operative time was 145 min (range, 88-167 min), and the median blood loss was 5 mL (range, 1-191 mL). The overlay mode using near-infrared thoracoscopy, which merges visible light images with fluorescent images, was safer and more useful than conventional thoracoscopy for delineating boundaries with electrocautery. No intraoperative or postoperative complications occurred. The median postoperative hospital stay was 5 days (range, 3-7 days). Intraoperative identification of the boundary between normal and sequestrated lungs using ICG was simple and feasible. We suggested that this technique was effective for lesion resection and normal lung preservation during surgery for intralobar PS.

New method for delineation of the intersegmental line in a deflated lung.

Background: Preoperative three-dimensional (3D) computed tomography (CT) images have been widely used as surgical guides in lung surgery; however, the lungs tend to be deflated during surgery. Discrepancies between the preoperatively constructed 3D image and the intraoperative view of the deflated lungs often require preoperative and/or intraoperative marking methods for sublobar pulmonary resection. We have developed a lung deflation simulation algorithm in which 3D CT images of the deflated lungs can be predicted only based on the preoperative CT taken in an inflated phase of respiration. Using this system, we conducted a preliminary study to retrospectively compare the intersegmental line predicted by our lung deflation simulation algorithm with the intersegmental line delineated by the intravenous administration of indocyanine green. Methods: Sixteen patients who underwent unilateral segmentectomy between January 1, 2020, and June 30, 2022, were included in the study. The identified intersegmental lines were confirmed intraoperatively using indocyanine green. These actual intersegmental lines were compared with those delineated on 3D images using the lung deflation simulation algorithm. Results: Of the 16 patients who underwent pulmonary segmentectomy, the consistency of these intersegmental lines was in complete agreement in twelve patients, partial agreement in three patients, and disagreement in one patient. The concordance rate of the intersegmental lines was 75%. Conclusions: The lung deflation simulation algorithm provides a new surgical guide in addition to the currently utilized ones. Continuous innovation might lead to a less invasive surgical technique for delineating the intersegmental line.

Video-assisted thoracoscopic surgery for pleuroperitoneal communication.

Here we report the cases of five patients on continuous ambulatory peritoneal dialysis (CAPD) who developed hydrothorax because of pleuroperitoneal communication. Preoperative computed tomography (CT) peritoneography revealed penetrated sites on the diaphragm in all patients. All patients underwent video-assisted thoracoscopic surgery (VATS), and a dialysate containing indigo carmine was injected intraperitoneally through a CAPD catheter to confirm the fistula. In all patients, a thinned bleb was found at the center of the diaphragmatic tendon consistent with that noted on preoperative CT peritoneography. The bleb was resected using a surgical stapler in four patients, and the pleuroperitoneal communication did not recur. However, in one patient, the bleb was only covered with reinforcement agents and the hydrothorax recurred after CAPD. This study demonstrates that VATS treatment for pleuroperitoneal communication is safe and effective but that lesion resection would be more useful for preventing hydrothorax recurrence in patients undergoing CAPD.

Setting a quality indicator for actual surgery time relative to scheduled surgery time in the context of increasing robotic-assisted thoracic surgery cases.

OBJECTIVE: This study aimed to demonstrate to the involved departments the goal of increasing the number of robotic-assisted thoracic surgery (RATS) cases/surgeons and acceptable surgery times. METHODS: This retrospective study included 1572 patients who underwent thoracic surgery from fiscal year (FY) 2018 to FY 2021. The factors evaluated included the number of surgery cases and actual and scheduled surgery times. RESULTS: The total number of RATS and total surgery cases increased after the quality indicator (QI) setting (n = 363, 360, 417, and 432 in FY 2018, 2019, 2020, and 2021, respectively). In FY 2020, 93.3% of the QI target was achieved, while in FY 2021, 88% was achieved. The number of RATS lobectomy/segmentectomy increased as the FY progressed (n = 31, 47, 58, and 116 in FY 2018, 2019, 2020, and 2021, respectively). The mean surgical time by RATS starters decreased in FY 2020 and 2021 (171.4 min.; 74 cases; seven RATS starters) compared with those in FY 2018 and 2019 (198.0 min.; 57 cases; six RATS starters) (P = 0.002). CONCLUSIONS: The goal of increasing the number of surgery cases and RATS cases/surgeons within the given framework was achieved by setting the QI.

Lingular-segment torsion after extended left-upper division segmentectomy by video-assisted thoracic surgery with indocyanine green fluorescence imaging.

Lingular-segment torsion after left-upper division segmentectomy (LUDS) is a rare complication, and the cause remains unclear. Here we report the case of a patient who developed lingular-segment torsion after LUDS for multiple lung metastases of breast cancer. One lung nodule was located in the S1 + 2 segment and another between the upper lobe and S6 on an incomplete interlobar fissure. The lung metastases were resected by extended LUDS using video-assisted thoracic surgery with indocyanine green fluorescence imaging. The staple line on the lingular segment was vertically tilted against the interlobar line because of the atypical defect of the fluorescence plane and nodule position. Chest X-ray and contrast-enhanced computed tomography indicated ischemia and torsion of the lingular segment on the second postoperative day, and completion of lingular segmentectomy was performed. This case showed the vertical intersegment staple line during LUDS was one of the important causes of postoperative torsion of the lingular segment.

Immunosuppressive treatment for myasthenia gravis crises improve the taste disorder in patients with thymoma: two case reports.

Background: Taste disorders in patients with thymoma accompanied by myasthenia gravis (MG) is rare. Case Description: The first case was a male in his 50s who underwent surgery for Masaoka stage III type B3 thymoma. He experienced a loss of taste before surgery, which showed no improvement after surgery. Due to a MG crisis 44 days after surgery, the patient underwent intensive treatment with mechanical ventilation, steroid pulse therapy, and intravenous immunoglobulin (IVIG) therapy. The patient recovered taste when he started oral food intake after the treatment for the MG crisis (about 3 months after surgery). Despite the recovery of taste after steroid pulse therapy and IVIG therapy, taste disorder gradually worsened about 1 year and 9 months after surgery, resulting in an almost complete loss of sweet taste 2 years after surgery. The second case was a male in his 60s who underwent surgery for Masaoka stage II type B1 thymoma. He experienced loss of taste before surgery, which showed no improvement after surgery. Five years and two months after surgery, the patient was diagnosed with a MG crisis and underwent steroid pulse therapy. Along with improvements in MG symptoms, taste disorders gradually improved. After 6 years and 10 months of surgery, the patient is still alive without MG symptoms (only pyridostigmine, 180 mg/body/day), taste disorder, and thymoma recurrence. Conclusions: The autoimmune mechanism may contribute to taste disorders in patients with thymoma, which can be recovered by immunosuppressive treatment in our cases.

Real-world evidence of safety and influence for lung cancer surgery under COVID-19 pandemic in Japan.

Background: The COVID-19 pandemic has affected the clinical practice of lung cancer surgery in Japan, but few studies have revealed the real situation of surgical practice for lung cancer in this country. This latest information will help us to decide the future direction of lung cancer surgery under pandemic circumstances. Methods: We collected data from patients with primary lung cancer who underwent thoracic surgery between 2018 and 2021. To investigate the impact of the COVID-19 pandemic on lung cancer surgery, we compared between 2018-2019 (prepandemic group) and 2020-2021 (pandemic group) in the respect of patient characteristics, pathological findings, and short-term outcome after lung cancer resection by Mann-Whitney and Fisher's exact tests. Moreover, the monthly number of surgeries for lung cancer in our institution during 2020-2021 was compared with the number of newly diagnosed COVID-19 patients in Japan by Spearman correlation analysis. Results: From 2018 through 2021, 936 patients with primary lung cancer underwent surgical intervention in our institute and were included in this study. The number of surgeries did not decrease in the pandemic group (n=443) compared with that in the prepandemic group (n=493). Tumor and invasive size in stage I which was measured by pathologist were significantly larger in the pandemic group than in the prepandemic group (tumor size: P=0.031, invasive size: P<0.001). In terms of postoperative short-term outcome, the median hospital stay was 6 days, 30-day mortality was 2, and morbidity was around 20% in both groups. Only one patient suffered from COVID-19 infection 5 months after right upper lobectomy. An increased ratio of newly diagnosed COVID-19 cases in Japan was negatively correlated with the number of surgeries for lung cancer in our institution in the next month (r=-0.393, P=0.007), although there was no correlation in the present or the month after next. Conclusions: Even during the COVID-19 pandemic period, lung cancer surgery could be performed safely and in a sustainable manner. However, pathological findings of lung cancer tended to be progressive in early-stage lung cancer.

Influencing Factors on Intersegmental Identification Adequacy in Segmentectomy with Intraoperative Indocyanine Green (ICG) Intravenous Administration.

Accurate identification of the intersegmental plane is essential in segmentectomy, and Indocyanine Green (ICG) assists in visualizing lung segments. Various factors, including patient-related, intraoperative, and technical issues, can influence boundary delineation. This study aims to assess the rate of unsuccessful intersegmental identification and identify the contributing factors. We analyzed cases of lung segmentectomy from April 2020 to March 2023, where intraoperative ICG was intravenously administered during robot-assisted or video-assisted thoracoscopic surgery. Cases where fluorescence extended beyond expected boundaries within 30 s were classified as the "unclear boundary group". This group was then compared to the "clear boundary group". The study encompassed 111 cases, 104 (94%) of which were classified under the "clear boundary group" and 7 (6%) under the "unclear boundary group". The "unclear boundary group" had a significantly lower DLCO (15.7 vs. 11.8, p = 0.03) and DLCO/VA (4.3 vs. 3.0, p = 0.01) compared to the "clear boundary group". All cases in the "unclear boundary group" underwent lower lobe segmentectomy. ICG administration effectively outlines pulmonary segments. Challenges in segment demarcation may occur in cases with low DLCO and DLCO/VA values, particularly during lower lobe segmentectomy.

Prognostic impact of highly solid component in early-stage solid lung adenocarcinoma.

Background: Based on computed tomography (CT) findings of lung cancer, solid nodules have a much worse prognosis than subsolid nodules, even if the nodules are subcentimeter in size. There is, however, no systematic method for determining the prognosis of solid tumors on CT. This study aimed to discover the prognostic factor of early-stage solid lung adenocarcinoma using three-dimensional CT volumetry. Methods: Patients with pathological stage I solid lung adenocarcinoma who underwent complete resection between 2007 and 2012 were selected in this retrospective study. Clinicopathological data and preoperative multidetector CT findings, such as tumor size on the two-dimensional axial image, three-dimensional tumor volume between -600 and 199 HU, and three-dimensional solid volume between 0 and 199 HU, which corresponded to highly solid components, were compared between recurrence and non-recurrence. Furthermore, these radiological values were compared to pathological invasive volume (PIV). Results: During this time, 709 patients had their lung cancer completely removed. From this cohort, 90 patients with pathological stage I solid lung adenocarcinoma were selected. In addition, recurrence was found in 26 patients (28.9%). Although two-dimensional axial image, serum carcinoembryonic antigen (CEA) level, and SUVmax on 18F fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) did not differ statistically between recurrent and non-recurrent patients, three-dimensional tumor and solid tumor volume did. Multivariate analysis indicated that three-dimensional solid tumor volume [hazard ratio: 2.440; 95% confidence interval (CI): 1.110-5.361, P=0.026] and epidermal growth factor receptor (EGFR) mutation (hazard ratio: 4.307; 95% CI: 1.328-13.977, P=0.015) were significantly associated with disease-free survival (DFS). When three-dimensional tumor and solid tumor volume were compared to PIV, three-dimensional solid tumor volume (3,091 mm3 on average) showed a highly similar value with PIV (2,930 mm3 on average), whereas three-dimensional tumor volume (6,175 mm3 on average) was significantly larger than PIV (P<0.001). Conclusions: In patients with early-stage solid lung adenocarcinoma, the measurement of three-dimensional solid tumor volume, which is correlated with PIV, accurately predicted the postoperative outcome.

Postoperative empyema complicated with descending necrotizing fasciitis: a case report.

BACKGROUND: Empyema is a serious complication of lung surgery. CASE PRESENTATION: We report a case of Streptococcus anginosus empyema complicated by descending necrotizing fasciitis after surgery. Ten days after the initial surgery, the patient presented with arrhythmia and hypotension with septic shock. Pleural fluid analysis led to the diagnosis of empyema, and surgical debridement (second surgery) was performed. One week after the emergency surgery, a palpable pink erythematous skin change was observed on the ipsilateral iliac crest. Hence, the second emergency surgery (third surgery) was performed to debride the subcutaneous and intramuscular abscesses. CONCLUSIONS: The possibility of descending abscess and necrotizing fasciitis should be considered when Streptococcus anginosus is detected.

A novel system applying artificial intelligence in the identification of air leak sites.

Objective: Prolonged air leak is the most common complication of thoracic surgery. Intraoperative leak site detection is the first step in decreasing the risk of leak-related postoperative complications. Methods: We retrospectively reviewed the surgical videos of patients who underwent lung resection at our institution. In the training phase, deep learning-based air leak detection software was developed using leak-positive endoscopic images. In the testing phase, a different data set was used to evaluate our proposed application for each predicted box. Results: A total of 110 originally captured and labeled images obtained from 70 surgeries were preprocessed for the training data set. The testing data set contained 64 leak-positive and 45 leak-negative sites. The testing data set was obtained from 93 operations, including 58 patients in whom an air leak was present and 35 patients in whom an air leak was absent. In the testing phase, our software detected leak sites with a sensitivity and specificity of 81.3% and 68.9%, respectively. Conclusions: We have successfully developed a deep learning-based leak site detection application, which can be used in deflated lungs. Although the current version is still a prototype with a limited training data set, it is a novel concept of leak detection based entirely on visual information.