Current trends in thoracic surgery

A novel computer modeling and simulation technique for bronchi motion tracking in human lungs under respiration

In this work, we proposed a novel computer modeling and simulation technique for motion tracking of lung bronchi (or tumors) under respiration using 9 cases of computed tomography (CT)-based patient-specific finite element (FE) models and Ogden's hyperelastic model. In the fabrication of patient-specific FE models for the respiratory system, various organs such as the mediastinum, diaphragm, and thorax that could affect the lung motions during breathing were considered. To describe the nonlinear material behavior of lung parenchyma, the comparative simulation for biaxial tension-compression of lung parenchyma was carried out using several hyperelastic models in ABAQUS, and then, Ogden's model was adopted as an optimal model. Based on the aforementioned FE models and Ogden's material model, the 9 cases of respiration simulation were carried out from exhalation to inhalation, and the motion of lung bronchi (or tumors) was tracked. In addition, the changes in lung volume, lung cross-sectional area on the axial plane during breathing were calculated. Finally, the simulation results were quantitatively compared to the inhalation/exhalation CT images of 9 subjects to validate the proposed technique. Through the simulation, it was confirmed that the average relative errors of simulation to clinical data regarding to the displacement of 258 landmarks in the lung bronchi branches of total subjects were 1.10%~2.67%. In addition, the average relative errors of those with respect to the lung cross-sectional area changes and the volume changes in the superior-inferior direction were 0.20%~5.00% and 1.29 ~ 9.23%, respectively. Hence, it was considered that the simulation results were coincided well with the clinical data. The novelty of the present study is as follows: (1) The framework from fabrication of the human respiratory system to validation of the bronchi motion tracking is provided step by step. (2) The comparative simulation study for nonlinear material behavior of lung parenchyma was carried out to describe the realistic lung motion. (3) Various organs surrounding the lung parenchyma and restricting its motion were considered in respiration simulation. (4) The simulation results such as landmark displacement, lung cross-sectional area/volume changes were quantitatively compared to the clinical data of 9 subjects.

What's new in minimally invasive thoracic surgery? Clinical application of augmented reality and learning opportunities in surgical simulation

Lung cancer represents the most lethal cancer worldwide. Surgery is the treatment of choice for early-stage non-small cell lung cancer, with an overall survival that can reach 90% at 5 years, but its detection is difficult to achieve due to the lack of symptoms. Screening programs are crucial to identify small cancer. Minimally invasive surgery has modified the therapeutical approach of these tumors, becoming the standard of care, with an important clinical yield in terms of reduction of postoperative pain and length of hospital stay. The aim of this mini-review is to explore and describe two important and innovative aspects in the context of "growing opportunities in minimally invasive thoracic surgery": the clinical application of augmented reality and its advantages for patient and surgeon, and the pedagogical issue through simulation-based training.

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.

Robotic resection of ectopic mediastinal parathyroid adenoma in multiple endocrine neoplasia 1

BACKGROUND

Hyperparathyroidism in patients with multiple endocrine neoplasia 1 is attributed to the excessive secretion of parathyroid hormone (PTH) from multiple parathyroid glands. This can be successfully treated through complete resection of the parathyroid glands; however, subsequent surgery is often required because of the presence of supernumerary or ectopic parathyroid glands. Therefore, identifying the locations of all functional glands is crucial for precise resection. Here, we report a case of ectopic mediastinal parathyroid adenoma that was successfully resected using robot-assisted thoracoscopic surgery.

CASE PRESENTATION

A 53-year-old woman underwent a total parathyroidectomy with autotransplantation for multiple endocrine neoplasia 1-associated primary hyperparathyroidism. The patient previously underwent laparoscopic distal pancreatectomy for a pancreatic neuroendocrine tumor. She also presented with a mediastinal tumor and nonfunctional pituitary adenoma that could be followed up. Blood tests before total parathyroidectomy showed high levels of intact PTH (183 pg/mL) and calcium (Ca; 10.3 mg/dL); however, postoperative blood tests still revealed high levels of intact PTH (103 pg/mL) and Ca (11.4 mg/dL). Computed tomography and magnetic resonance imaging revealed a 45-mm-sized mass in the right upper mediastinum as a well-defined solid and cystic lesion, whereas ^99mTc-methoxyisobutylisonitrile scintigraphy indicated a strong accumulation of tracers, suggesting an ectopic lesion in the mediastinum. Persistent hyperparathyroidism after total parathyroidectomy via neck incision was attributed to an ectopic parathyroid tumor in the mediastinum. Thus, we decided to resect the tumor using robot-assisted thoracoscopic surgery to perform the procedure gently and carefully. During surgery, a mediastinal tumor was identified as it was detected radiographically. Because it did not invade the surrounding tissues, it could be completely resected without injuring the capsule. The patient was discharged without complications. Postoperatively, Ca and intact PTH levels decreased back to normal. The final pathological diagnosis confirmed that the mass was an ectopic mediastinal parathyroid adenoma.

CONCLUSIONS

Minimally invasive surgical resection of a remnant ectopic lesion was successfully performed in a patient with multiple endocrine neoplasia 1 using robot-assisted thoracoscopic surgery.

Development of panorama vision ring for thoracoscopy

PURPOSE

Minimally invasive surgery (MIS) using a thoraco- or laparoscope is becoming a more common surgical technique. In MIS, a magnified view from a thoracoscope helps surgeons conduct precise operations. However, there is a risk of the visible area becoming narrow. To confirm that the operation field is safe, the surgeon will draw the thoracoscope back to check the marginal area of the target and insert it again many times during MIS. To reduce the surgeon's load, we aim to visualize the entire thoracic cavity using a newly developed device called "panorama vision ring" (PVR).

METHOD

The PVR is used instead of a wound retractor or a trocar. It is a ring-type socket with one big hole for the thoracoscope and four small holes for tiny cameras placed around the big hole. The views from the tiny cameras are fused into one wider view that visualizes the entire thoracic cavity. A surgeon can proceed with an operation by checking what exists outside of the thoracoscopic view. Also, she/he can check whether or not bleeding has occurred from the image of the entire cavity.

RESULTS

We evaluated the view-expansion ability of the PVR by using a three-dimensional full-scale thoracic model. The experimental results showed that the entire thoracic cavity could be visible in a panoramic view generated by the PVR. We also demonstrated pulmonary lobectomy in virtual MIS using the PVR. Surgeons could perform a pulmonary lobectomy while checking the entire cavity.

CONCLUSION

We developed the PVR, which uses tiny auxiliary cameras to create a panoramic view of the entire thoracic cavity during MIS. We aim to make MIS safer for patients and more comfortable for surgeons through the development of the PVR.

Computer-assisted image-based risk analysis and planning in lung surgery - a review

In this paper, we give an overview on current trends in computer-assisted image-based methods for risk analysis and planning in lung surgery and present our own developments with a focus on computed tomography (CT) based algorithms and applications. The methods combine heuristic, knowledge based image processing algorithms for segmentation, quantification and visualization based on CT images of the lung. Impact for lung surgery is discussed regarding risk assessment, quantitative assessment of resection strategies, and surgical guiding. In perspective, we discuss the role of deep-learning based AI methods for further improvements.

＜Editors' Choice＞ Elective nodal irradiation versus involved field radiotherapy for limited disease small cell lung cancer: a single-institution experience

Elective nodal irradiation (ENI) and involved field radiotherapy (IFRT) are definitive radiotherapeutic approaches used to treat patients with limited-disease small cell lung cancer (LD-SCLC). However, no solid consensus exists on their optimal target volume. The current study aimed to assess the clinical outcomes of patients with LD-SCLC who received definitive ENI or IFRT. A retrospective single-institution study of patients who received definitive radiotherapy between 2008 and 2020 was performed. All patients underwent whole-body positron emission tomography/computed tomography before three-dimensional conformal radiotherapy. Among the 37 patients analyzed, 22 and 15 received ENI and IFRT, respectively. The thoracic radiotherapy dose was mostly either 60 Gy in 30 fractions delivered in 2-Gy fractions once daily or 45 Gy in 30 fractions delivered in 1.5-Gy fractions twice daily. The median follow-up period was 21.4 months. A total of 12 patients (32%) experienced locoregional relapse: 10 within and 2 outside the irradiation fields. One patient in the IFRT group experienced isolated nodal failure. Differences in locoregional relapse-free, progression-free, and overall survival rates between ENI and IFRT were not significant. Overall, IFRT did not promote a significant increase in locoregional recurrence compared to ENI. Our findings suggested the utility of IFRT in standard clinical practice and support its use for patients with LD-SCLC.

Risk Assessment for Loss-of-Exercise Capacity After Lung Cancer Surgery: Current Advances in Surgery and Systemic Treatment

BACKGROUND

Considering advances in current post-recurrence treatment, we examined the prognostic significance of the number of risk factors for loss-of-exercise capacity (LEC) after lung cancer surgery, which were identified by our previous prospective observational study.

METHODS

Risk factors for LEC were defined as a short baseline 6-min walk distance (<400 m), older age (≥75 years), and low predicted postoperative diffusing capacity for carbon monoxide (<60%). Patients were classified as Risk 0/I/II/III according to the number of risk factors. The survival data were retrospectively analyzed.

RESULTS

Between 2014 and 2017, 564 patients (n = 307, 193, 57, 7; Risk 0/I/II/III) who underwent lung cancer surgery were included in the study. The number of risk factors was associated with smoking status, predicted postoperative forced expiratory volume in 1 s, histology, pathological stage, and adjuvant therapy. In a multivariate Cox regression analysis, compared to Risk 0, Risk I/II/III showed significant associations with overall survival (hazard ratios: 1.92, 3.35, 9.21; 95% confidence interval: 1.27-2.92, 2.01-5.58, 3.64-23.35; Risk I/II/III, respectively). In 141 patients with recurrence, molecular targeted therapies (MTTs) or immune checkpoint inhibitors (ICIs) were included in 58%, 47%, 32%, and 0% (Risk 0/I/II/III) during the course of treatment. In patients with MTT/ICI treatment, the estimated 1-year and 3-year post-recurrence survival rates were 88% and 58%, respectively.

CONCLUSIONS

Risk classification for LEC was associated with survival after lung cancer surgery, as well as post-recurrence treatment. The concept of physical performance-preserving surgery may contribute to improving the outcomes of current lung cancer treatment.

Improved visualization of virtual-assisted lung mapping by indocyanine green

Objectives

Virtual-assisted lung mapping (VAL-MAP) is a bronchoscopic marking method of dye application on the surface of the lungs before resecting nonpalpable nodules. However, in some cases, it can be difficult to identify the markings of VAL-MAP on computed tomography and intraoperative thoracoscopy. We developed and assessed the feasibility of indocyanine green VAL-MAP (ICG-VAL-MAP).

Methods

A historical control trial was conducted to investigate the effectiveness of ICG-VAL-MAP for marking visualization compared with that of VAL-MAP. In ICG-VAL-MAP, instead of indigo carmine, ICG and computed tomography contrast agents were used for dye marking, and near-infrared fluorescence endoscopy was employed to visualize the ICG markings. The other processes in VAL-MAP were carried out. The marking visibility was assessed in 3 grades of easy, faint, or not identifiable. We compared the visibility of the markings on computed tomography images and during thoracoscopic operations between VAL-MAP (567 markings in 147 cases) and ICG-VAL-MAP (142 markings in 63 cases).

Results

On the preoperative computed tomography images, ICG-VAL-MAP provided significantly better marking visualization than VAL-MAP (easy/faint/not identifiable = 142/0/0 vs 427/100/30; P < .0001). ICG-VAL-MAP provided significantly better intraoperative markings than VAL-MAP (easy/faint/not identifiable = 141/0/1, respectively, vs 475/50/42, respectively; P < .0001). Regarding complications, pneumothorax occurred in 8 (5.4%) cases of VAL-MAP and zero cases (0%) of ICG-VAL-MAP (P = .12); fever was observed in 7 (5.0%) cases of VAL-MAP and 2 (3.2%) cases of ICG-VAL-MAP (P = .72).

Conclusions

ICG-VAL-MAP provided significantly better visibility of markings than VAL-MAP. It might be useful in the resection of nonpalpable small lung lesions.

Comparison of Clinical Outcomes of Robot-Assisted, Video-Assisted, and Open Esophagectomy for Esophageal Cancer: A Systematic Review and Meta-analysis

IMPORTANCE

The utilization of robot-assisted minimally invasive esophagectomy (RAMIE) for esophageal cancer is increasing, despite limited data comparing RAMIE with other surgical approaches.

OBJECTIVE

To evaluate the literature for clinical outcomes of RAMIE compared with video-assisted minimally invasive esophagectomy (VAMIE) and open esophagectomy (OE).

DATA SOURCES

A systematic search of PubMed, Cochrane, Ovid Medline, and Embase databases from January 1, 2013, to May 6, 2020, was performed.

STUDY SELECTION

Studies that compared RAMIE with VAMIE and/or OE for cancer were included.

DATA EXTRACTION AND SYNTHESIS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guideline, data were extracted by independent reviewers. A random-effects meta-analysis of 9 propensity-matched studies was performed for the RAMIE vs VAMIE comparison only. A narrative synthesis of RAMIE vs VAMIE and OE was performed.

MAIN OUTCOMES AND MEASURES

The outcomes of interest were intraoperative outcomes (ie, estimated blood loss [EBL], operative time, lymph node [LN] harvest), short-term outcomes (anastomotic leak, recurrent laryngeal nerve [RLN] palsy, pulmonary and total complications, and 90-day mortality), and long-term oncologic outcomes.

RESULTS

Overall, 21 studies (2 randomized clinical trials, 11 propensity-matched studies, and 8 unmatched studies) with 9355 patients were included. A meta-analysis was performed with 9 propensity-matched studies comparing RAMIE with VAMIE. The random-effects pooled estimate found an adjusted risk difference (RD) of -0.06 (95% CI, -0.11 to -0.01) favoring fewer pulmonary complications with RAMIE. There was no evidence of differences between RAMIE and VAMIE in LN harvest (mean difference [MD], -1.1 LN; 95% CI, -2.45 to 0.25 LNs), anastomotic leak (RD, 0.0; 95% CI, -0.03 to 0.03), EBL (MD, -6.25 mL; 95% CI, -18.26 to 5.77 mL), RLN palsy (RD, 0.01; 95% CI, -0.08 to 0.10), total complications (RD, 0.05; 95% CI, -0.01 to 0.11), or 90-day mortality (RD, -0.01; 95% CI, -0.02 to 0.0). There was low certainty of evidence that RAMIE was associated with a longer disease-free survival compared with VAMIE. For OE comparisons (data not pooled), RAMIE was associated with a longer operative time, decreased EBL, and less pulmonary and total complications.

CONCLUSIONS AND RELEVANCE

In this study, RAMIE had similar outcomes as VAMIE but was associated with fewer pulmonary complications compared with VAMIE and OE. Studies on long-term functional and cancer outcomes are needed.

Evaluation of predictive factors related to the presence or absence of supplemental oxygen therapy and comparison of physical functions after video-assisted thoracic surgery

We performed a retrospective study of 102 individuals to evaluate predictive factors for needing supplemental oxygen therapy following video-assisted thoracic surgery (VATS) and to compare patients' physical functions before and after surgery. Prior to surgery, we evaluated quadriceps torque, 6-minute walk distance (6MWD), timed up and go test, and grip strength. During the 6MWD, patients' oxygen saturation was recorded every minute. Quadriceps torque and 6MWD were evaluated again following surgery. The indication for supplemental oxygen therapy was determined based on desaturation (<85%) during the 6MWD in room air. A total of 14 patients needed oxygen therapy at discharge (group A), while 88 patients did not need oxygen therapy (group B). In group A, the postoperative 6MWD was repeated with supplemental oxygen. Compared with the same parameters in group B, in group A the percentage diffusing capacity for carbon monoxide was significantly lower (p=0.011), while a history of smoking (p=0.016), exercise-induced hypoxemia (EIH, p<0.001), chronic obstructive pulmonary disease (p<0.001), and interstitial pneumonia (p=0.008) were significantly higher. Logistic regression analysis showed that EIH was an independent risk factor for requiring supplemental oxygen therapy following surgery (odds ratio: 46.2, 95% CI: 9-237.1; p<0.001). In group A, patients' minimum oxygen saturation was significantly improved by oxygen administration (83.4±3.4 vs. 87.7±3.3, p=0.002), but there was no difference in walking distance (359.5±64.2 vs. 353.6±41.6, p=0.482). Our data indicate that patients should be preoperatively evaluated to predict postoperative hypoxemia and that this evaluation could complement the prediction of postoperative need for oxygen therapy.

Ischemia-Reperfusion Injury in Lung Transplantation

Lung transplantation has been established worldwide as the last treatment for end-stage respiratory failure. However, ischemia–reperfusion injury (IRI) inevitably occurs after lung transplantation. The most severe form of IRI leads to primary graft failure, which is an important cause of morbidity and mortality after lung transplantation. IRI may also induce rejection, which is the main cause of mortality in recipients. Despite advances in donor management and graft preservation, most donor grafts are still unsuitable for transplantation. Although the pulmonary endothelium is the primary target site of IRI, the pathophysiology of lung IRI remains incompletely understood. It is essential to understand the mechanism of pulmonary IRI to improve the outcomes of lung transplantation. Therefore, we reviewed the state-of-the-art in the management of pulmonary IRI after lung transplantation. Recently, the ex vivo lung perfusion (EVLP) system has been clinically introduced worldwide. Various promising therapeutic strategies for the protection of the endothelium against IRI, including EVLP, inhalation therapy with therapeutic gases and substances, fibrinolytic treatment, and mesenchymal stromal cell therapy, are awaiting clinical application. We herein review the latest advances in the field of pulmonary IRI in lung transplantation.

Differential impacts of postoperative complications on patients' survival in completely resected non-small-cell lung cancer

OBJECTIVE

The aim of this study was to investigate the effects of inflammatory respiratory complications on long-term survival in patients with resected non-small cell lung cancer. We defined inflammatory respiratory complications to include the following six conditions: pneumonia, empyema, bronchial fistula, respiratory dysfunction, acute interstitial pneumonia, and atelectasis.

METHODS

Part of the National Clinical Database was linked to our prospective database from 2014 to 2017. Linkage was achieved for 866 patients. The Kaplan-Meier method was used to evaluate the overall, relapse-free, and cancer-related survival. The Cox proportional hazard model was used to analyze the impact of each complication.

RESULTS

Of the 736 patients included in the study, 149 had complications. The 5-year overall and cancer-specific survival rates were significantly lower in patients with inflammatory respiratory complications. The Cox proportional hazard model showed that the inflammatory respiratory complications had a significant impact on overall survival (hazard ratio 2.48, 95% confidence interval 1.41-4.38) but not air leak (hazard ratio 1.38, 95% confidence interval 0.70-2.70).

CONCLUSIONS

Our study shows the differential impact of each complication on the survival of patients with non-small cell lung cancer. The presence of inflammatory respiratory complications was the only predictor of poor overall survival.