Three-dimensional image in lung transplantation

Virtual-reality endoscopic navigation system in mediastinal natural orifice transluminal endoscopic surgery (with video)

The approaches to mediastinal surgery are open thoracic, thoracoscopic, and mediastinoscopy. However, using natural orifice transluminal endoscopic surgery (NOTES) would be minimally invasive if the mediastinum is reached via the esophagus. One disadvantage of NOTES was no information outside the wall. We focused on the electromagnetic tracking solution. The sensor position in the space created by the magnetic field generator can be determined. We performed a computed tomography (CT) of a pig before constructing the target mediastinal organs in 3D. The pig was placed in the magnetic field space, and the endoscope with the sensor was subsequently inserted orally and synchronized with the 3D image. By simultaneously viewing the actual and the virtual endoscopic image in 3D, the mediastinum can be visualized through the esophagus. We determined six points in advance in the 3D images, and the esophageal lumen closest to the esophagus from the points was marked with a clip under the endoscope. The CT scans showed that the mean error between the clip position and the closest point from the target point to the esophagus was 4.7 mm across three trials. We named this system the virtual-reality endoscopic navigation system (VENaS). VENaS can help determine the shortest distance to the point away from the esophagus and the 3D relation with the surrounding organs during esophageal endoscopy, and also displays gravity direction and an overhead view, thereby making it easy to approach areas with tumors or malformations in the mediastinum and increasing the realism of mediastinal NOTES.

Future directions for xenotransplantation in lungs

PURPOSE OF REVIEW

Advancements in preclinical xenotransplant studies have opened doors for clinical heart and kidney xenotransplantation. This review assesses recent progress in lung xenotransplantation research and its potential clinical implications.

RECENT FINDINGS

The efficacy of the humanized von Willebrand factor in reducing platelet sequestration in ex-vivo and in-vivo lung xenotransplant models was showcased. Combining human tissue factor pathway inhibitor and CD47 expression with selectin and integrin inhibition delayed neutrophil and platelet sequestration. Enhanced expression of human complement regulatory proteins and thrombomodulin in genetically engineered pig lungs improved graft survival by reducing platelet activation and modulating coagulation disruptions. Knocking out the CMAH gene decreased antibody-mediated inflammation and coagulation activation, enhancing compatibility for human transplantation. Furthermore, CMAH gene knockout in pigs attenuated sialoadhesin-dependent binding of human erythrocytes to porcine macrophages, mitigating erythrocyte sequestration and anemia. Meanwhile, in-vivo experiments demonstrated extended survival of xenografts for up to 31 days with multiple genetic modifications and comprehensive treatment strategies.

SUMMARY

Experiments have uncovered vital insights for successful xenotransplantation, driving further research into immunosuppressive therapy and genetically modified pigs. This will ultimately pave the way for clinical trials designed to improve outcomes for patients with end-stage lung disease.

Lung cancer after kidney transplantation: a 50-year experience at a single institution

PURPOSE

To investigate the clinical characteristics of lung cancer that develops after kidney transplantation.

METHODS

The clinical data of patients with lung cancer diagnosed after kidney transplantation were collected retrospectively. The medical records were extracted from our database. All patients underwent routine chest examination after kidney transplantation.

RESULTS

In total, 17 lung tumors were detected in 15 (0.6%) of 2593 patients who underwent kidney transplantation at our institution. Eleven lung tumors were completely resected from a collective 10 patients (surgical group). The remaining five patients did not receive surgical treatment (nonsurgical group). The surgical group underwent wedge resection (n = 5), segmentectomy (n = 1), lobectomy (n = 3), and bilobectomy (n = 1). The pathological stages were 0 (n = 1), IA1 (n = 2), IA2 (n = 4), IA3 (n = 2), and IB (n = 1). The surgical group had a significantly better prognosis than the nonsurgical group. There were no perioperative complications related to kidney transplantation in either group.

CONCLUSIONS

Routine chest examination would be useful for the early diagnosis and treatment of lung cancer after kidney transplantation. Moreover, surgical resection for early-stage lung cancer was associated with a better prognosis for kidney transplantation patients.

Beneficial effects of extracorporeal membrane oxygenation over cardiopulmonary bypass in living-donor lobar lung transplantation

Background

Extracorporeal membrane oxygenation (ECMO) has been frequently used instead of cardiopulmonary bypass (CPB) as extracorporeal circulatory support during cadaveric lung transplantation. This study compared the outcomes of intraoperative CPB or ECMO in living-donor lobar lung transplantation (LDLLT).

Methods

CPB and ECMO were performed in 23 and 53 patients, respectively, who underwent initial bilateral LDLLT in our institution from 2008 to 2019. We retrospectively compared the short- and long-term outcomes between the 2 groups.

Results

Patient background, graft size-matching data, operation time, extracorporeal circulation time, and bleeding amount were not significantly different in the 2 groups. However, the CPB group required more transfusion than the ECMO group (6,860 vs 3,840 ml, respectively; p = 0.002). The rate of increase in body weight through LDLLT was 7.4% and 4.9% in CPB and ECMO groups, respectively (p = 0.040), and primary graft dysfunction scores were significantly worse in the CPB group. Postoperative ECMO support was required in 4 cases, and hospital death occurred in 1 patient exclusively in the CPB group. Chronic lung allograft dysfunction (CLAD) was diagnosed in 43.5% and 17.0% of patients in the CPB and ECMO groups, respectively (p = 0.021), and the 5-year CLAD-free survival was 55.8% and 72.7% of patients, respectively (p = 0.013).

Conclusions

Intraoperative ECMO reduced primary graft dysfunction, possibly due to the lower requirement for intraoperative transfusion and less intraoperative weight gain causing systemic edema. The beneficial effect of ECMO in the early phase may result in less CLAD development in the long-term follow-up after LDLLT.

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.

Potential Role of Computed Tomography Volumetry in Size Matching in Lung Transplantation

BACKGROUND

Accumulated knowledge on the outcomes related to size mismatch in lung transplantation derives from predicted total lung capacity equations rather than individualized measurements of donors and recipients. The increasing availability of computed tomography (CT) makes it possible to measure the lung volumes of donors and recipients before transplantation. We hypothesize that CT-derived lung volumes predict a need for surgical graft reduction and primary graft dysfunction.

METHODS

Donors from the local organ procurement organization and recipients from our hospital from 2012 to 2018 were included if their CT exams were available. The CT lung volumes and plethysmography total lung capacity were measured and compared with predicted total lung capacity using Bland Altman methods. We used logistic regression to predict the need for surgical graft reduction and ordinal logistic regression to stratify the risk for primary graft dysfunction.

RESULTS

A total of 315 transplant candidates with 575 CT scans and 379 donors with 379 CT scans were included. The CT lung volumes closely approximated plethysmography lung volumes and differed from the predicted total lung capacity in transplant candidates. In donors, CT lung volumes systematically underestimated predicted total lung capacity. Ninety-four donors and recipients were matched and transplanted locally. Larger donor and smaller recipient lung volumes estimated by CT predicted a need for surgical graft reduction and were associated with higher primary graft dysfunction grade.

CONCLUSION

The CT lung volumes predicted the need for surgical graft reduction and primary graft dysfunction grade. Adding CT-derived lung volumes to the donor-recipient matching process may improve recipients' outcomes.

Living-donor Segmental Lung Transplantation for Pediatric Patients

OBJECTIVE

The preset study evaluated the outcome of living-donor segmental lung transplantation for pediatric patients.

METHODS

Between August 2009 and May 2021, we performed living-donor segmental lung transplantation in 6 critically ill pediatric patients, including 1 patient on a ventilator alone and another patient on a ventilator and extracorporeal membrane oxygenation (ECMO). There were 4 male and 2 female patients, with a median age of 7 years (range, 4-15 years) and a median height of 112.7 cm (range, 95-125.2 cm). The diagnoses included complications of allogeneic hematopoietic stem cell transplantation (n = 4) and pulmonary fibrosis (n = 2). All patients received bilateral lung transplantation under cardiopulmonary bypass. A basal segment and a lower lobe were implanted in 3 patients, and a basal segment and an S6 segment were implanted in the other 3 patients. In 2 patients, the right S6 segmental graft was horizontally rotated 180° and implanted as the left lung.

RESULTS

Among the 9 segmental grafts implanted, 7 functioned well after reperfusion. Two rotated S6 segmental grafts became congestive, with 1 requiring graft extraction and the other venous repair, which was successful. There was 1 hospital death (14 days) due to sepsis and 1 late death (9 years) due to leukoencephalopathy. The remaining 4 patients are currently alive at 9 months, 10 months, 1.3 years, and 1.9 years.

CONCLUSIONS

Living-donor segmental lung transplantation was a technically difficult but feasible procedure with acceptable outcomes for small pediatric patients with chest cavities that were too small for adult lower lobe implantation.

Radiologic evaluation of compensatory lung growth using computed tomography by comparison with histological data from a large animal model

Non-invasive analysis using computed tomography (CT) data may be a promising candidate to evaluate neo-alveolarization in adult lungs following lung resection. This study evaluates and compares the validity of CT analysis with histologic morphometry for compensatory lung growth in a large animal model. We calculated the radiologic tissue volume and the radiologic lung weight from CT data taken at 1, 3, and 6 months post-surgery on 15 male beagle dogs that had a right thoractotomy, bilobectomy, or pneumonectomy (n = 5 in each group). Results were analyzed using one-way ANOVA and were subsequently compared to histologic findings of tissue samples at 6 months post-surgery using Pearson's correlation. An increase in radiologic tissue volume and radiologic lung weight was identified, which was positively correlated with histologic lung parenchymal amounts (correlation coefficient = 0.955 and 0.934, respectively, p < 0.001). Histology of lung specimens at 6 months post-surgery revealed an increase in the tissue amount in both Bilobectomy and Peumonectomy groups, which was consistent with compensatory lung growth. Radiologic tissue volume and radiologic lung weight reflected compensatory lung growth following lung resection. Radiologic assessment using CT data can be a promising clinical modality to evaluate postoperative lung growth.

Living-donor lobar lung transplantation

Living-donor lobar lung transplantation (LDLLT) has become an important life-saving option for patients with severe respiratory disorders, since it was developed by a group in the University of Southern California in 1993 and introduced in Japan in 1998 in order to address the current severe shortage of brain-dead donor organs. Although LDLLT candidates were basically limited to critically ill patients who would require hospitalization, the long-term use of steroids, and/or mechanical respiratory support prior to transplantation, LDLLT provided good post-transplant outcomes, comparable to brain-dead donor lung transplantation in the early and late phases. In Kyoto University, the 5- and 10-year survival rates after LDLLT were reported to be 79.0% and 64.6%, respectively. LDLLT should be performed under appropriate circumstances, considering the inherent risk to the living donor. In our transplant program, all living donors returned to their previous social lives without any major complications, and living-donor surgery was associated with a morbidity rate of <15%. Both functional and anatomical size matching were preoperatively performed between the living-donor lobar grafts and recipients. Precise size matching before surgery could provide a favorable pulmonary function and exercise capacity after LDLLT. Various transplant procedures have recently been developed in LDLLT in order to deal with the issue of graft size mismatching in recipients, and favorable post-transplant outcomes have been observed. Native upper lobe-sparing and/or right-to-left inverted transplantation have been performed for undersized grafts, while single-lobe transplantation has been employed with or without contralateral pneumonectomy and/or delayed chest closure for oversized grafts.

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.

Single-lobe transplantation with contralateral pneumonectomy: Long-term survival

We report two cases of long-term survival after single living-donor lobar lung transplantation with contralateral pneumonectomy. An 8-year-old female with pulmonary graft-versus-host disease after cord-blood transplantation underwent single living-donor lobar lung transplantation with simultaneous contralateral pneumonectomy due to an oversized graft. She has been performing daily life activities for ≥11 years with limited physical development. A 41-year-old female with short stature underwent single living-donor lobar lung transplantation due to pulmonary graft-versus-host disease after peripheral blood stem cell transplantation. Contralateral pneumonectomy was required 7 years following living-donor lobar lung transplantation due to pneumonia in the native lung. Eleven years after living-donor lobar lung transplantation, she is able to perform daily life activities.

Current trends in thoracic surgery

Thoracic surgery has evolved drastically in recent years. Although thoracic surgeons mainly deal with tumorous lesion in the lungs, mediastinum, and pleura, they also perform lung transplantation surgery in patients with end-stage lung disease. Herein, we introduce various major current topics in thoracic surgery. Minimally invasive surgical procedures include robot-assisted thoracic surgery and uniportal video-assisted thoracic surgery. Novel techniques for sublobar resection include virtual-assisted lung mapping, image-guided video-assisted thoracic surgery, and segmentectomy using indocyanine green. Three-dimensional (3D) computed tomography (CT) simulation consists of surgeon-friendly 3D-CT image analysis systems and new-generation, dynamic 3D-CT imaging systems. Updates in cadaveric lung transplantation include use of marginal donors, including donation after circulatory death, and ex vivo lung perfusion for such donors. Topics in living donor lobar lung transplantation include size matching, donor issues, and new surgical techniques. During routine clinical practice, thoracic surgeons encounter various pivotal topics related to thoracic surgery, which are described in this report.

Pediatric lung transplantation: Results of volume reduction in smaller children

Pediatric LTX is challenged by the scarcity of suitable donor organs. To alleviate the problem of size matching, volume reduction of the donor is a possible option. Previous reports address mostly older teenagers, and data about younger patients are lacking. The purpose of this study was to investigate whether trimming had influence on the morbidity and mortality in slightly younger recipients, operated in a single center. Between 2015 and 2018, 20 patients were transplanted at the GOSH London. The mean age was 11.5 (±4.6) years. Nine patients underwent volume reduction prior to transplantation (T group). The other patients received classical bilateral LTX (NT group). Ischemia times were longer in the T group, but this difference was not statistically significant. We observed no 30-day mortality. Hospital survival in the T group was 78% vs 90% in the NT group. After almost 3 years, mortality in the T group was 22% vs 28% in the NT group. None of these differences was statistically significant. The mean duration of MV, intensive care stay, and hospital stay were 11.5, 19.9, and 44.8 days, respectively. Results were equal in terms of morbidity, defined as respiratory and neurological complications or the need for ECMO. Results show that volume reduction prior to LTX is a feasible option, even in smaller children. While awaiting long-term results, accepting larger donor organs could be a strategy to further reduce waiting list time and subsequently lower the mortality on the waiting list.

Unilateral Chronic Lung Allograft Dysfunction Assessed by Biphasic Computed Tomographic Volumetry in Bilateral Living-donor Lobar Lung Transplantation

Background

Early diagnosis of unilateral chronic lung allograft dysfunction (CLAD) is difficult because the unaffected contralateral lung functions as a reservoir in bilateral living-donor lobar lung transplantation (LDLLT). We previously reported the usefulness of ¹³³Xe ventilation scintigraphy for detection of unilateral change, but the supply of ¹³³Xe has been stopped globally. The present study aimed to examine the usefulness of inspiratory and expiratory computed tomography (I/E CT) volumetry for detection of unilateral change in CLAD patients.

Methods

This was a retrospective single-center, observational study using prospectively collected data. A total of 58 patients who underwent bilateral LDLLT from August 2008 to February 2017 were analyzed. Respiratory function tests, I/E CT were prospectively conducted. ΔLung volume was defined as the value obtained by subtracting expiratory lung volume from inspiratory lung volume.

Results

Fourteen (24%) cases were clinically diagnosed with CLAD, of which 10 (71%) were diagnosed as unilateral CLAD. ΔLung volume of bilateral lungs strongly correlated with forced vital capacity (r = 0.92, P < 0.01) and forced expiratory volume in 1 second (r = 0.80, P < 0.01). Regardless the phenotypes (bronchiolitis obliterans syndrome or restrictive allograft syndrome) of CLAD, Δlung volume onset/baseline significantly decreased compared with that in the non-CLAD group. Among the 10 unilateral CLAD patients, 3 with clinically suspected unilateral rejection yet did not show a 20% decline in forced expiratory volume in 1 second. In 2 of these, Δlung volume of unilateral lungs on the rejection side decreased by 20% or more.

Conclusions

Our findings suggest that I/E CT volumetry may be useful for assessment and early diagnosis of unilateral CLAD after bilateral LDLLT.