Incidental discovery of multiple tracheal diverticula.

Tracheal diverticulum is observed in 1%-4% of the population, however, multiple tracheal diverticula are a rare occurrence. In this paper, we present a 75-year-old male, who was referred to a computed tomography-scan of the neck, chest, abdomen, and pelvis because of an unintended weight loss, fatigue, and a smoking history of 60 pack-years. A definitive cause for the symptoms was not found, however as an incidental finding, the patient was diagnosed with multiple tracheal diverticula along the back wall of trachea and left main bronchus. Despite the rare occurrence, it is important to recognize multiple tracheal diverticula in the diagnostic process, because of the possibility of either removing the diverticula or initiating prophylactic actions to prevent complications such as empyema and pneumomediastinum.

Pulmonary Nodule Detection in CT Images: False Positive Reduction Using Multi-View Convolutional Networks.

We propose a novel Computer-Aided Detection (CAD) system for pulmonary nodules using multi-view convolutional networks (ConvNets), for which discriminative features are automatically learnt from the training data. The network is fed with nodule candidates obtained by combining three candidate detectors specifically designed for solid, subsolid, and large nodules. For each candidate, a set of 2-D patches from differently oriented planes is extracted. The proposed architecture comprises multiple streams of 2-D ConvNets, for which the outputs are combined using a dedicated fusion method to get the final classification. Data augmentation and dropout are applied to avoid overfitting. On 888 scans of the publicly available LIDC-IDRI dataset, our method reaches high detection sensitivities of 85.4% and 90.1% at 1 and 4 false positives per scan, respectively. An additional evaluation on independent datasets from the ANODE09 challenge and DLCST is performed. We showed that the proposed multi-view ConvNets is highly suited to be used for false positive reduction of a CAD system.

Ground-Glass Opacity Lung Nodules in the Era of Lung Cancer CT Screening: Radiology, Pathology, and Clinical Management.

The advent of computed tomography screening for lung cancer will increase the incidence of ground-glass opacity (GGO) nodules detected and referred for diagnostic evaluation and management. GGO nodules remain a diagnostic challenge; therefore, a more systematic approach is necessary to ensure correct diagnosis and optimal management. Here we present the latest advances in the radiologic imaging and pathology of GGO nodules, demonstrating that radiologic features are increasingly predictive of the pathology of GGO nodules. We review the current guidelines from the Fleischner Society, the National Comprehensive Cancer Network, and the British Thoracic Society. In addition, we discuss the management and follow-up of GGO nodules in the light of experience from screening trials. Minimally invasive tissue biopsies and the marking of GGO nodules for surgery are new and rapidly developing fields that will yield improvements in both diagnosis and treatment. The standard-of-care surgical treatment of early lung cancer is still minimally invasive lobectomy with systematic lymph node dissection. However, recent research has shown that some GGO lesions may be treated with sublobar resections; these findings may expand the surgical treatment options available in the future.

Coronary artery calcification detected in lung cancer screening predicts cardiovascular death.

OBJECTIVES: It remains unknown whether non-electrocardiogram-gated coronary artery calcium (CAC) score in lung cancer screening provides incremental prognostic value. The aim of this study was to evaluate the prognostic value of CAC in the Danish Lung Cancer Screening Trial (DLCST), in addition to conducting a systematic review and meta-analysis including previously published studies regarding CAC in lung cancer screening. DESIGN: In DLCST, we measured Agatston CAC scores in 1,945 current and former smokers. Causes of death were extracted from the Danish National Death Registry. We used Cox proportional hazards model to determine hazard ratios (HRs) of CAC scores. A weighted fixed-effects model was used for the meta-analysis. RESULTS: Median follow-up in DLCST was 7.1 years, and 55% were men. Overall survival rates associated with CAC scores of 0, 1-400, and > 400 were 98%, 96%, and 92% (p < 0.001), respectively. Adjusted HR of cardiovascular death associated with CAC >400 was 3.8 (1.0-15) (p < 0.05). The meta-analysis included 28,045 asymptomatic participants. A high non-gated CAC score was associated with fatal or non-fatal cardiovascular events (p < 0.0001). CONCLUSION: Assessment of non-electrocardiogram-gated CAC in lung cancer screening programs is a robust prognostic measure of fatal or non-fatal cardiovascular events in current and former smokers independent of traditional cardiovascular risk factors.

Geodesic Atlas-Based Labeling of Anatomical Trees: Application and Evaluation on Airways Extracted From CT.

We present a fast and robust atlas-based algorithm for labeling airway trees, using geodesic distances in a geometric tree-space. Possible branch label configurations for an unlabeled airway tree are evaluated using distances to a training set of labeled airway trees. In tree-space, airway tree topology and geometry change continuously, giving a natural automatic handling of anatomical differences and noise. A hierarchical approach makes the algorithm efficient, assigning labels from the trachea and downwards. Only the airway centerline tree is used, which is relatively unaffected by pathology. The algorithm is evaluated on 80 segmented airway trees from 40 subjects at two time points, labeled by three medical experts each, testing accuracy, reproducibility and robustness in patients with chronic obstructive pulmonary disease (COPD). The accuracy of the algorithm is statistically similar to that of the experts and not significantly correlated with COPD severity. The reproducibility of the algorithm is significantly better than that of the experts, and negatively correlated with COPD severity. Evaluation of the algorithm on a longitudinal set of 8724 trees from a lung cancer screening trial shows that the algorithm can be used in large scale studies with high reproducibility, and that the negative correlation of reproducibility with COPD severity can be explained by missing branches, for instance due to segmentation problems in COPD patients. We conclude that the algorithm is robust to COPD severity given equally complete airway trees, and comparable in performance to that of experts in pulmonary medicine, emphasizing the suitability of the labeling algorithm for clinical use.

[Lung cancer screening with low dose CT requires careful consideration].

Results from the American National Lung Screening Trial (NLST) show a significant reduction in lung cancer and all-cause mortality in a high risk population screened with annual low-dose CT. Handling of pulmonary nodules, false positive tests, overdiagnosis, psychosocial consequences and cost-efficiency etc. are all aspects that require careful consideration. This paper gives an overview of the current knowledge on these issues. Before a recommendation can be made, we need an overall evaluation of both the benefits and harms in CT screening for lung cancer.

[Lung cancer screening with low-dose CT - Danish and international results].

Lung cancer is the cancer type that causes the largest number of deaths in Denmark. With advances in medical imaging and widespread use of computed tomography (CT), it is possible to detect even small abnormalities in lung tissue. This has led to a great interest in lung cancer screening with low-dose CT and launching of randomised screening trials worldwide. This paper gives an overview of the current lung cancer screening trials in Denmark and internationally and focuses on main lung cancer findings and mortality results.

Emphysema progression is visually detectable in low-dose CT in continuous but not in former smokers.

OBJECTIVES: To evaluate interobserver agreement and time-trend in chest CT assessment of emphysema, airways, and interstitial abnormalities in a lung cancer screening cohort. METHODS: Visual assessment of baseline and fifth-year examination of 1990 participants was performed independently by two observers. Results were standardised by means of an electronic score sheet; kappa and time-trend analyses were performed. RESULTS: Interobserver agreement was substantial in early emphysema diagnosis; highly significant (p < 0.001) time-trends in both emphysema presence and grading were found (higher prevalence and grade of emphysema in late CT examinations). Significant progression in emphysema was seen in continuous smokers, but not in former smokers. Agreement on centrilobular emphysema subtype was substantial; agreement on paraseptal subtype, moderate. Agreement on panlobular and mixed subtypes was only fair. Agreement was fair regarding airway analysis. Interstitial abnormalities were infrequent in the cohort, and agreement on these was fair to moderate. A highly significant time-trend was found regarding interstitial abnormalities, which were more frequent in late examinations. CONCLUSIONS: Visual scoring of chest CT is able to characterise the presence, pattern, and progression of early emphysema. Continuous smokers progress; former smokers do not. KEY POINTS: • Substantial interobserver consistency in determining early-stage emphysema in low-dose CT. • Longitudinal analyses show clear time-trends for emphysema presence and grading. • For continuous smokers, progression of emphysema was seen in all lung zones. • For former smokers, progression of emphysema was undetectable by visual assessment. • Onset and progression of interstitial abnormalities are visually detectable.

Optimal surface segmentation using flow lines to quantify airway abnormalities in chronic obstructive pulmonary disease.

This paper introduces a graph construction method for multi-dimensional and multi-surface segmentation problems. Such problems can be solved by searching for the optimal separating surfaces given the space of graph columns defined by an initial coarse surface. Conventional straight graph columns are not well suited for surfaces with high curvature, we therefore propose to derive columns from properly generated, non-intersecting flow lines. This guarantees solutions that do not self-intersect. The method is applied to segment human airway walls in computed tomography images in three-dimensions. Phantom measurements show that the inner and outer radii are estimated with sub-voxel accuracy. Two-dimensional manually annotated cross-sectional images were used to compare the results with those of another recently published graph based method. The proposed approach had an average overlap of 89.3±5.8%, and was on average within 0.096±0.097mm of the manually annotated surfaces, which is significantly better than what the previously published approach achieved. A medical expert visually evaluated 499 randomly extracted cross-sectional images from 499 scans and preferred the proposed approach in 68.5%, the alternative approach in 11.2%, and in 20.3% no method was favoured. Airway abnormality measurements obtained with the method on 490 scan pairs from a lung cancer screening trial correlate significantly with lung function and are reproducible; repeat scan R(2) of measures of the airway lumen diameter and wall area percentage in the airways from generation 0 (trachea) to 5 range from 0.96 to 0.73.

[Tracheomalacia as a cause of chronic cough]. / Trakeomalaci som årsag til kronisk hoste.

Tracheomalacia is a rare condition involving increased flaccidity of the tracheal cartilage, widening of the posterior membranous wall and a reduced airway calibre. This combination can cause a tracheal collapse, expiratory flow obstruction and decreased clearance of secretions. We present a case of a 70-year-old woman with severe coughing symptoms and obvious tracheomalacia diagnosed with a high resolution computed tomography in the expiratory phase. On a computed tomography, tracheomalacia has an easily recognizable pattern, which is only visible during expiration. Tracheomalacia is probably an underdiagnosed condition.