Reconstructing 3d lung shape from a single 2d image during the deaeration deformation process using model-based data augmentation

Three-dimensional (3D) shape reconstruction is particularly important for computer assisted medical systems, especially in the case of lung surgeries, where large deaeration deformation occurs. Recently, 3D reconstruction methods based on machine learning techniques have achieved considerable success in computer vision. However, it is difficult to apply these approaches to the medical field, because the collection of a massive amount of clinic data for training is impractical. To solve this problem, this paper proposes a novel 3D shape reconstruction method that adopts both data augmentation techniques and convolutional neural networks. In the proposed method, a deformable statistical model of the 3D lungs is designed to augment various training data. As the experimental results demonstrate, even with a small database, the proposed method can realize 3D shape reconstruction for lungs during a deaeration deformation process from only one captured 2D image. Moreover, the proposed data augmentation technique can also be used in other fields where the training data are insufficient

Model-based registration for pneumothorax deformation analysis using intraoperative cone-beam CT images

[2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), 20-24 July 2020, Montreal, QC, Canada]Because the lung deforms during surgery because of pneumothorax, it is important to be able to track the location of a tumor. Deformation of the whole lung can be estimated using intraoperative cone-beam CT (CBCT) images. In this study, we used deformable mesh registration methods for paired CBCT images in the inflated and deflated states, and analyzed their deformation. We proposed a deformable mesh registration framework for deformations of partial organ shapes involving large deformation and rotation. Experimental results showed that the proposed methods reduced errors in point-to-point correspondence. As a result of registration using surgical clips placed on the lung surface during imaging, it was confirmed that an average error of 3.9 mm occurred in eight cases. The result of analysis showed that both tissue rotation and contraction had large effects on displacement

Deformation analysis of surface and bronchial structures in intraoperative pneumothorax using deformable mesh registration

The positions of nodules can change because of intraoperative lung deflation, and the modeling of pneumothorax-associated deformation remains a challenging issue for intraoperative tumor localization. In this study, we introduce spatial and geometric analysis methods for inflated/deflated lungs and discuss heterogeneity in pneumothorax-associated lung deformation. Contrast-enhanced CT images simulating intraoperative conditions were acquired from live Beagle dogs. The images contain the overall shape of the lungs, including all lobes and internal bronchial structures, and were analyzed to provide a statistical deformation model that could be used as prior knowledge to predict pneumothorax. To address the difficulties of mapping pneumothorax CT images with topological changes and CT intensity shifts, we designed deformable mesh registration techniques for mixed data structures including the lobe surfaces and the bronchial centerlines. Three global-to-local registration steps were performed under the constraint that the deformation was spatially continuous and smooth, while matching visible bronchial tree structures as much as possible. The developed framework achieved stable registration with a Hausdorff distance of less than 1 mm and a target registration error of less than 5 mm, and visualized deformation fields that demonstrate per-lobe contractions and rotations with high variability between subjects. The deformation analysis results show that the strain of lung parenchyma was 35% higher than that of bronchi, and that deformation in the deflated lung is heterogeneous

Kernel-based modeling of pneumothorax deformation using intraoperative cone-beam CT images

Event: SPIE Medical Imaging, 2021, Online OnlyIn this study, we introduce statistical modeling methods for pneumothorax deformation using paired cone-beam computed tomography (CT) images. We designed a deformable mesh registration framework for shape changes involving non-linear deformation and rotation of the lungs. The registered meshes with local correspondences are available for both surgical guidance in thoracoscopic surgery and building statistical deformation models with inter-patient variations. In addition, a kernel-based deformation learning framework is proposed to reconstruct intraoperative dfl ated states of the lung from the preoperative CT models. This paper reports the findings of pneumothorax deformation and evaluation results of the kernel-based deformation framework

Quantity and quality of antigravity muscles in patients undergoing living-donor lobar lung transplantation: 1-year longitudinal analysis using chest computed tomography images

Background: Skeletal muscle dysfunction is a common feature in patients with severe lung diseases. Although lung transplantation aims to save these patients, the surgical procedure and disuse may cause additional deterioration and prolonged functional disability. We investigated the postoperative course of antigravity muscle condition in terms of quantity and quality using chest computed tomography. Methods: 35 consecutive patients were investigated for 12 months after living-donor lobar lung transplantation (LDLLT). The erector spinae muscles (ESMs), which are antigravity muscles, were evaluated, and the cross-sectional area (ESMCSA) and mean attenuation (ESMCT) were analysed to determine the quantity and quality of ESMs. Functional capacity was evaluated by the 6-min walk distance (6MWD). Age-matched living donors with lower lobectomy were evaluated as controls. Results: Recipient and donor ESMCSA values temporarily decreased at 3 months and recovered by 12 months post-operatively. The ESMCSA of recipients, but not that of donors, surpassed baseline values by 12 months post-operatively. Increased ESMCSA (ratio to baseline ≥1) may occur at 12 months in patients with a high baseline ESMCT. Although the recipient ESMCT may continuously decrease for 12 months, the ESMCT is a major determinant, in addition to lung function, of the postoperative 6MWD at both 3 and 12 months. Conclusion: The quantity of ESMs may increase within 12 months after LDLLT in recipients with better muscle quality at baseline. The quality of ESMs is also important for physical performance; therefore, further approaches to prevent deterioration in muscle quality are required

The importance of central airway dilatation in patients with bronchiolitis obliterans

Background: Bronchiolitis obliterans (BO) is a clinical syndrome characterised by progressive small airway obstruction, causing significant morbidity and mortality. Central airway dilatation is one of its radiological characteristics, but little is known about the clinical and pathological associations between airway dilatation and BO. Methods: This retrospective study consecutively included patients who underwent lung transplantation due to BO at Kyoto University Hospital from 2009 to 2019. Demographic and histopathological findings of the resected lungs were compared between patients with and without airway dilatation measured by chest computed tomography (CT) at registration for lung transplantation. Results: Of a total of 38 included patients (median age, 30 years), 34 (89%) had a history of hematopoietic stem-cell transplantation, and 22 (58%) had airway dilatation based on CT. Patients with airway dilatation had a higher frequency of Pseudomonas aeruginosa isolation with greater residual volume than those without airway dilatation. Quantitative CT analysis revealed an increase in lung volume to predictive total lung capacity and a percentage of low attenuation volume <-950 HU at inspiration in association with the extent of airway dilatation. Airway dilatation on CT was associated with an increased number of bronchioles with concentric narrowing of the lumen and thickening of the subepithelium of the walls on histology. Conclusions: In patients with BO, airway dilatation may reflect increased residual volume or air trapping and pathological extent of obstructive bronchioles, accompanied by a risk of Pseudomonas aeruginosa isolation. More attention should be paid to the development of airway dilatation in the management of BO

Patient-reported dyspnea and health predict waitlist mortality in patients waiting for lung transplantation in Japan

Background: Waitlist mortality due to donor shortage for lung transplantation is a serious problem worldwide. Currently, the selection of recipients in Japan is mainly based on the registration order. Hence, scientific evidence for risk stratification regarding waitlist mortality is urgently needed. We hypothesized that patient-reported dyspnea and health would predict mortality in patients waitlisted for lung transplantation. Methods: We analyzed factors related to waitlist mortality using data of 203 patients who were registered as candidates for lung transplantation from deceased donors. Dyspnea was evaluated using the modified Medical Research Council (mMRC) dyspnea scale, and the health status was determined with St. George's Respiratory Questionnaire (SGRQ). Results: Among 197 patients who met the inclusion criteria, the main underlying disease was interstitial lung disease (99 patients). During the median follow-up period of 572 days, 72 patients died and 96 received lung transplantation (69 from deceased donors). Univariable competing risk analyses revealed that both mMRC dyspnea and SGRQ Total score were significantly associated with waitlist mortality (p = 0.003 and p < 0.001, respectively) as well as age, interstitial lung disease, arterial partial pressure of carbon dioxide, and forced vital capacity. Multivariable competing risk analyses revealed that the mMRC and SGRQ score were associated with waitlist mortality in addition to age and interstitial lung disease. Conclusions: Both mMRC dyspnea and SGRQ score were significantly associated with waitlist mortality, in addition to other clinical variables such as patients' background, underlying disease, and pulmonary function. Patient-reported dyspnea and health may be measured through multi-dimensional analysis (including subjective perceptions) and for risk stratification regarding waitlist mortality

Dual approach for large mediastinal tumors in the thoracic outlet: transmanubrial osteomuscular sparing approach and video-assisted thoracoscopic surgery

Background: Selecting the proper surgical approach for mediastinal tumors in the thoracic outlet is difficult. Video-assisted thoracoscopic surgery is ideal because of the less invasiveness; however, it is often difficult to resect tumors only by video-assisted thoracoscopic surgery due to the poor visualization of the cranial side of tumors. We report two successfully treated cases by using a dual approach consisting of the transmanubrial osteomuscular sparing technique and video-assisted thoracoscopic surgery for aiming both the less invasiveness and the good visualization of the cranial side of tumors. Case presentatnions: We present two resected cases of the mediastinal tumor in the thoracic outlet. The first case was a 28-year-old woman and the second case was a 37-year-old man. They had a mediastinal tumor in the thoracic outlet which was detected on the roentgenogram. A definitive preoperative diagnosis was unavailable. The surgical resection was started with video-assisted thoracoscopic surgery in the both cases. After the dissection of the caudal side of the tumor, the dissection of the cranial side was judged to be difficult and risky because the tumor was located adjacent to major vessels and the good visualization of this side couldn’t be acquired. Therefore, the transmanubrial approach was sequentially performed and complete resection was safely achieved. Postoperatively, although transient Horner syndrome appeared in both cases, they recovered from this syndrome and were discharged. The final diagnosis was schwannoma for both cases. Neither of the cases had any functional restriction of the upper extremity. Conclusions: This dual approach for mediastinal tumors in the thoracic outlet is useful in terms of safety and lower invasiveness