Applicability of color-coded computed tomography images in lung volume reduction surgery planning

Lung Volume Reduction Surgery in Patients with Homogeneous Emphysema

Randomized controlled trials have demonstrated that lung volume reduction surgery (LVRS) improves exercise capacity, lung function, and quality of life in patients with heterogenous emphysema on computed tomographic and perfusion scan. However, most patients have a nonheterogenous type of destruction. These patients, summarized under "homogeneous emphysema," may also benefit from LVRS as long they are severely hyperinflated, and adequate function is remaining with a diffusing capacity of the lungs for carbon monoxide greater than 20% and no pulmonary hypertension. Surgical mortality is low when patients are well selected.

Quantitative Evaluation of COVID-19 Pneumonia Lung Extension by Specific Software and Correlation with Patient Clinical Outcome

Lung infection named as COVID-19 is an infectious disease caused by the most recently discovered coronavirus 2 (SARS-CoV-2). CT (computed tomography) has been shown to have good sensitivity in comparison with RT-PCR, particularly in early stages. However, CT findings appear to not always be related to a certain clinical severity. The aim of this study is to evaluate a correlation between the percentage of lung parenchyma volume involved with COVID-19 infection (compared to the total lung volume) at baseline diagnosis and correlated to the patient's clinical course (need for ventilator assistance and or death). All patients with suspected COVID-19 lung disease referred to our imaging department for Chest CT from 24 February to 6 April 2020were included in the study. Specific CT features were assessed including the amount of high attenuation areas (HAA) related to lung infection. HAA, defined as the percentage of lung parenchyma above a predefined threshold of -650 (HAA%, HAA/total lung volume), was automatically calculated using a dedicated segmentation software. Lung volumes and CT findings were correlated with patient's clinical course. Logistic regressions were performed to assess the predictive value of clinical, inflammatory and CT parameters for the defined outcome. In the overall population we found an average infected lung volume of 31.4 ± 26.3% while in the subgroup of patients who needed ventilator assistance and who died as well as the patients who died without receiving ventilator assistance the volume of infected lung was significantly higher 41.4 ± 28.5 and 72.7 ± 36.2 (p < 0.001). In logistic regression analysis best predictors for ventilation and death were the presence of air bronchogram (p = 0.006), crazy paving (p = 0.007), peripheral distribution (p < 0.001), age (p = 0.002), fever at admission (p = 0.007), dyspnea (p = 0.002) and cardiovascular comorbidities (p < 0.001). In multivariable analysis, quantitative CT parameters and features added incremental predictive value beyond a model with only clinical parameters (area under the curve, 0.78 vs. 0.74, p = 0.02). Our study demonstrates that quantitative evaluation of lung volume involved by COVID-19 pneumonia helps to predict patient's clinical course.

Advances in imaging for lung emphysema

Lung emphysema represents a major public health burden and still accounts for five percent of all deaths worldwide. Hence, it is essential to further understand this disease in order to develop effective diagnostic and therapeutic strategies. Lung emphysema is an irreversible enlargement of the airways distal to the terminal bronchi (i.e., the alveoli) due to the destruction of the alveolar walls. The two most important causes of emphysema are (I) smoking and (II) α1-antitrypsin-deficiency. In the former lung emphysema is predominant in the upper lung parts, the latter is characterized by a predominance in the basal areas of the lungs. Since quantification and evaluation of the distribution of lung emphysema is crucial in treatment planning, imaging plays a central role. Imaging modalities in lung emphysema are manifold: computed tomography (CT) imaging is nowadays the gold standard. However, emerging imaging techniques like dynamic or functional magnetic resonance imaging (MRI), scintigraphy and lately also the implementation of radiomics and artificial intelligence are more and more diffused in the evaluation, diagnosis and quantification of lung emphysema. The aim of this review is to shortly present the different subtypes of lung emphysema, to give an overview on prediction and risk assessment in emphysematous disease and to discuss not only the traditional, but also the new imaging techniques for diagnosis, quantification and evaluation of lung emphysema.

Identification of target zones for lung volume reduction surgery using three-dimensional computed tomography rendering

Background

The key issues for performing lung volume reduction surgery (LVRS) is the identification of the target zones. Recently introduced three-dimensional computed tomography rendering methods are used to identify the morphological distribution and its severity of lung emphysema by densitometry. We demonstrate a new software for emphysema imaging and show the pre- and post-operative results in patients undergoing LVRS planned based on this new technology.

Methods

A real-time three-dimensional image analysis software system was used pre- and 3 months post-operatively in five patients with heterogeneous emphysema and a single patient with homogeneous morphology scheduled for LVRS. Focus was on low attenuation areas with <950 HU, distribution on both lungs and the value of the three-dimensional images for planning surgery. Functional outcome was assessed by pulmonary function tests after 3 months.

Results

Five patients underwent bilateral LVRS and one patient had unilateral LVRS. All patients showed a median increase in forced expiratory volume in 1 s of 70% (range 30–120%), compared with baseline values. Hyperinflation (expressed as residual volume/total lung capacity ratio) was reduced by 30% (range 5–32%). In the patients with heterogeneous emphysema, the pre- and post-operative computed tomography scans and the densitometries showed a decrease in low attenuation areas by 23% (right side) and by 17% (left side), respectively.

Conclusion

We demonstrate three-dimensional computed tomography-rendered images for planning personalised remodelling of hyperinflated lungs using LVRS. This user-friendly software has the potential to assist surgeons and interventional pulmonologists to select patients and to visualise target areas in LVRS procedures.

New, user-friendly software with 3D CT-rendered images can be used for planning personalised remodelling of hyperinflated lungs using LVRShttps://bit.ly/3fbICn2