Lung Volume Measurements Research Articles

RESPIRATORY FUNCTION IN NORMAL SINGLETON PREGNANCY, MULTIFETAL GESTATION AND POLYHYDRAMNIOS

Background : Study of respiratory functions of four groups of women: Nonpregnant, early pregnancy, singleton pregnancy at 36 weeks and twin/polyhydramnios at 36 weeks reveal that inspiratory capacity (IC), tidal volume (TV) and expiratory reserve volume (ERV) in different group pairing have statistically signicant difference. This is very important during the assessment of pregnant mother suffering from respiratory or cardiopulmonary disorder. Objectives :This study aims to observe the additional demands placed on the maternal respiratory system in cases of advanced normal pregnancy or over distended uterus, like multifetal gestation and polyhydramnios, and whether the average Indian woman is able to cope with these respiratory changes. Methods : Around 80 women were divided into four equal groups which included non-pregnant controls, normal early pregnancy (< 20 weeks), normal singleton pregnancy at 36 weeks and multifetal gestation/polyhydramnios, underwent spirometry for static lung volume measurement. The overall comparison was done by using the Kruskal-Wallis test whereas the individual comparison by Mann-Whitney test. Final statistical computing was performed with SPSS statistical package. Results : The groups were comparable on the basis of age, height and hemoglobin levels. Comparisons of various groups show statistically signicant difference in tidal volume, inspiratory capacity and expiratory reserve volume specially in advance pregnancy with control nonpregnant mothers without signicant adverse effect on respiratory system. Conclusions : Results of the study indicate that though there are signicant respiratory functional changes, healthy women, even having twin/polyhydramnios, can tolerate this well. But this knowledge is very important to assess and to formulate management of pregnant women with respiratory or cardiopulmonary compromise.

Reproducibility of 19 F-MR ventilation imaging in healthy volunteers.

PurposeTo assess the reproducibility of percentage ventilated lung volume (%VV) measurements in healthy volunteers acquired by fluorine (19F)‐MRI of inhaled perfluoropropane, implemented at two research sites.MethodsIn this prospective, ethically approved study, 40 healthy participants were recruited (May 2018‐June 2019) to one of two research sites. Participants underwent a single MRI scan session on a 3T scanner, involving periodic inhalation of a 79% perfluoropropane/21% oxygen gas mixture. Each gas inhalation session lasted about 30 seconds, consisting of three deep breaths of gas followed by a breath‐hold. Four 19F‐MR ventilation images were acquired per participant, each separated by approximately 6 minutes. The value of %VV was determined by registering separately acquired 1H images to ventilation images before semi‐automated image segmentation, performed independently by two observers. Reproducibility of %VV measurements was assessed by components of variance, intraclass correlation coefficients, coefficients of variation (CoV), and the Dice similarity coefficient.ResultsThe MRI scans were well tolerated throughout, with no adverse events. There was a high degree of consistency in %VV measurements for each participant (CoVobserver1 = 0.43%; CoVobserver2 = 0.63%), with overall precision of %VV measurements determined to be within ± 1.7% (95% confidence interval). Interobserver agreement in %VV measurements revealed a high mean Dice similarity coefficient (SD) of 0.97 (0.02), with only minor discrepancies between observers.ConclusionWe demonstrate good reproducibility of %VV measurements in a group of healthy participants using 19F‐MRI of inhaled perfluoropropane. Our methods have been successfully implemented across two different study sites, supporting the feasibility of performing larger multicenter clinical studies.

Bedside monitoring of lung volume available for gas exchange

BackgroundBedside measurement of lung volume may provide guidance in the personalised setting of respiratory support, especially in patients with the acute respiratory distress syndrome at risk of ventilator-induced lung injury. We propose here a novel operator-independent technique, enabled by a fibre optic oxygen sensor, to quantify the lung volume available for gas exchange. We hypothesised that the continuous measurement of arterial partial pressure of oxygen (PaO2) decline during a breath-holding manoeuvre could be used to estimate lung volume in a single-compartment physiological model of the respiratory system.MethodsThirteen pigs with a saline lavage lung injury model and six control pigs were studied under general anaesthesia during mechanical ventilation. Lung volumes were measured by simultaneous PaO2 rate of decline (VPaO2) and whole-lung computed tomography scan (VCT) during apnoea at different positive end-expiratory and end-inspiratory pressures.ResultsA total of 146 volume measurements was completed (range 134 to 1869 mL). A linear correlation between VCT and VPaO2 was found both in control (slope = 0.9, R2 = 0.88) and in saline-lavaged pigs (slope = 0.64, R2 = 0.70). The bias from Bland–Altman analysis for the agreement between the VCT and VPaO2 was − 84 mL (limits of agreement ± 301 mL) in control and + 2 mL (LoA ± 406 mL) in saline-lavaged pigs. The concordance for changes in lung volume, quantified with polar plot analysis, was − 4º (LoA ± 19°) in control and − 9° (LoA ± 33°) in saline-lavaged pigs.ConclusionBedside measurement of PaO2 rate of decline during apnoea is a potential approach for estimation of lung volume changes associated with different levels of airway pressure.

Fractional exhaled nitric oxide could identify early spirometry change in clinically suspected asthma patients without airway obstruction

Fractional exhaled nitric oxide (FeNO) has been proposed as a non-invasive biomarker for allergic inflammation seen in asthma. The aim of this study was to assess the ability of FeNO to discriminate spirometry and lung volume measurements between those with and without airway obstruction among subjects with clinically suspected asthma. A retrospective study was conducted. Diagnostic evaluations including spirometry and FeNO testing (NO electrochemical equipment: NIOX VERO; Aerocrine AB, Solna, Sweden) were performed in all subjects. Airway obstruction was defined according to the Standardization of Spirometry of the American Thoracic Society (ATS)/European Respiratory Society (ERS), and 2014 recommendations of the Chinese National Guidelines of Pulmonary Function Test. It was used the Student t test for analysis of continuous variables and the χ2 test for analysis of discrete variables including FeNO levels and lung function metrics. Of the 138 subjects with clinically suspected asthma, airway obstruction was found in 61. There was no significant difference in the mean FeNO levels among subjects with or without airway obstruction ( p = 0.241) among un-selected subjects. Likewise, there was no difference in the FeNO levels between aged (>50 years) and younger subjects (⩽50 years) ( p = 0.804). A significant proportion of subjects had a normal FeNO level (<25 part per billion, ppb) in spite of having airway obstruction (39/138), 25 had an elevated FeNO level (⩾25 ppb) in spite of having no airway obstruction (25/138). Additionally, the airway-obstructed subjects with increased FeNO level had comparable spirometry to those with normal FeNO level ( p > 0.05). However, among subjects without airway obstruction, the forced expiratory volume in 1 s (FEV1)/predicted (pred), maximal expiratory flow at 25% of forced vital capacity (FVC) (MEF25%)/pred, maximal expiratory flow at 50% of FVC (MEF50%)/pred and maximum mid-expiratory flow (MMEF)/pred were significantly lower in the FeNO ⩾ 25 ppb group compared to those in the FeNO < 25 ppb group. These analyses indicated that increased FeNO levels could help to determinate early spirometry change within clinically suspected asthma subjects without airway obstruction. It is highlighted the importance of FeNO as a phenotype associated with an increased risk of airway obstruction in some subjects in this study.

A novel, automated, quantification of abnormal lung parenchyma in patients with COVID-19 infection: Initial description of feasibility and association with clinical outcome

ObjectiveGround-glass opacities are the most frequent radiologic features of COVID-19 patients. We aimed to determine the feasibility of automated lung volume measurements, including ground-glass volumes, on the CT of suspected COVID-19 patients. Our goal was to create an automated and quantitative measure of ground-glass opacities from lung CT images that could be used clinically for diagnosis, triage and research.DesignSingle centre, retrospective, observational study.MeasurementsDemographic data, respiratory support treatment (synthetised in the maximal respiratory severity score) and CT-images were collected. Volume of abnormal lung parenchyma was measured with conventional semi-automatic software and with a novel automated algorithm based on voxels X-Ray attenuation. We looked for the relationship between the automated and semi-automated evaluations. The association between the ground-glass opacities volume and the maximal respiratory severity score was assessed.Main resultsThirty-seven patients were included in the main outcome analysis. The mean duration of automated and semi-automated volume measurement process were 15 (2) and 93 (41) min, respectively (p = 8.05*10−8). The intraclass correlation coefficient between the semi-automated and automated measurement of ground-glass opacities and restricted normally aerated lung were both superior to 0.99. The association between the automated measured lung volume and the maximal clinical severity score was statistically significant for the restricted normally aerated (p = 0.0097, effect-size: −385 mL) volumes and for the ratio of ground-glass opacities/restricted normally aerated volumes (p = 0.027, effect-size: 3.3).ConclusionThe feasibility and preliminary validity of automated impaired lung volume measurements in a high-density COVID-19 cluster was confirmed by our results.

Prenatal assessment of congenital diaphragmatic hernia at north american fetal therapy network centers: A continued plea for standardization.

Prenatal work-up for congenital diaphragmatic hernia (CDH) is important for risk stratification, standardization, counseling, and optimal therapeutic choice. To determine current practice patterns regarding prenatal CDH work-up, including prenatal ultrasound and magnetic resonance imaging (MRI) use, and to identify areas for standardization of such evaluation between fetal centers. A survey regarding prenatal CDH work-up was sent to each member center of the North American Fetal Therapy Network (NAFTNet) (n = 36). All responded. Sonographic measurement of lung-to-head ratio (LHR) was determined by all, 89% (32/36) of which routinely calculate observed-to-expected LHR. The method for measuring LHR varied: 58% (21/36) used a "trace" method, 25% (9/36) used "longest axis," and 17% (6/36) used an "antero-posterior" method. Fetal MRI was routinely used in 78% (28/36) of centers, but there was significant variability in fetal lung volume measurement. Whereas all generated a total fetal lung volume, the planes, methodology and references values varied significantly. All evaluated liver position, 71% (20/28) evaluated stomach position and 54% (15/28) quantified the degree of liver herniation. More consistency in workup was seen between centers offering fetal intervention. Prenatal CDH work-up and management differs considerably among North American fetal diagnostic centers, highlighting a need for its standardization.

Lung abnormalities do not influence aerobic capacity in school children born preterm.

Children born preterm have impaired lung function and altered lung structure. However, there are conflicting reports on how preterm birth impacts aerobic exercise capacity in childhood. We aimed to investigate how neonatal history and a diagnosis of bronchopulmonary dysplasia (BPD) impact the relationship between function and structure of the lung, and aerobic capacity in school-aged children born very preterm. Preterm children (≤ 32 w completed gestation) aged 9-12years with (n = 38) and without (n = 35) BPD, and term-born controls (n = 31), underwent spirometry, lung volume measurements, gas transfer capacity, a high-resolution computer tomography (CT) scan of the chest, and an incremental treadmill exercise test. Children born preterm with BPD had an elevated breathing frequency to tidal volume ratio compared to term controls (76% vs 63%, p = 0.002). The majority (88%) of preterm children had structural changes on CT scan. There were no differences in peak V̇O2 (47.1 vs 47.7mL/kg/min, p = 0.407) or oxygen uptake efficiency slope when corrected for body weight (67.6 vs 67.3, p = 0.5) between preterm children with BPD and term controls. There were no differences in any other exercise outcomes. The severity of structural lung disease was not associated with exercise outcomes in this preterm population. Children born preterm have impaired lung function, and a high prevalence of structural lung abnormalities. However, abnormal lung function and structure do not appear to impact on the aerobic exercise capacity of preterm children at school age.

PATIENT-SPECIFIC 3-D LUNG MODELING: THE FUTURE OF PRECISION LUNG CANCER SURGERY?

SESSION TITLE: Fellows Lung Cancer Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: October 18-21, 2020 INTRODUCTION: Reconstruction software based on mathematical algorithms and machine learning are beginning to allow the processing of chest CT scans to generate highly specific 3D lung models. We describe our initial experience using this technology for simulation and planning of lung cancer resection. CASE PRESENTATION: DICOM data from patient CT scans was processed (IQQA-Lung, EDDA Technology, Princeton, NJ, USA) to generate 3D maps of patient's airways and vasculature as well as obtain information on lung volumes (cm3), tumor volume and volumes of individual lung lobes. Case 1: The model [Figure 1(A-G), Gif 1] generated demonstrated a 2.2 cm x 2.2 cm x 1.7 cm lesion in the left upper lobe (LUL). The lesion had a total volume of 3.39 cm3. Total lung volume (TLV), right lung volume (RLV) and left lung volume (LLV) were 4029.54 cm3, 2369.08 (58.79%) cm3 and 1660.46 (41.21%) cm3 respectively. LUL and left lower lobe (LLL) had volumes of 951.02 cm3 (57.27%) and 709.45 cm3 (42.73%) respectively. While the lesion appeared to be located in the lingular segment, our model showed that it crossed into the adjacent segments and a segmentectomy would have led to a close or positive margin. This was confirmed in the operating room. Case 2: The model [Figure 1(H-N), Gif 2] generated demonstrated a 2.6 cm x 2.3 cm x 1.3 cm lesion in the right lower lobe (RLL). The lesion had a total volume of 4.72 cm3. TLV, RLV and LLV were 2948.46 cm3, 1579.84 (53.58%) and 1368.62 (46.42%) cm3 respectively. Right upper lobe (RUL), right middle lobe (RML) and RLL had volumes of 738.09 cm3 (46.72%), 178.57 cm3 (11.3%) and 663.18 cm3 (41.98%) respectively. While the lesion appeared to be located in the superior segment, interplanar analysis showed that a segmentectomy would have led to a close or positive margin. This was confirmed intraoperatively. In addition, a small proximal pulmonary artery was identified preoperatively that informed on the need for extra vigilance during dissection of the PA. DISCUSSION: Highly accurate patient-specific lung models provide extensive detail on pulmonary vasculature and intersegmental planes, allowing for preoperative recognition of anatomic variations and guiding the extent of an ideal oncologic resection. The ability to get high-resolution images without the need for IV contrast is an added benefit. These models also provide an accurate measurement of postoperative residual lung volumes hence providing a surrogate marker for postoperative residual lung function and quality of life. These models also carry teaching value for residents and medical students. CONCLUSIONS: Highly accurate 3D lung models give detailed information on patient-specific anatomy as well as preoperative and postoperative lung volumes. These platforms should be utilized to obtain a better understanding of patient anatomy in order to make lung operations safer, more efficient and allow appropriate lung conservation surgery. Reference #1: Nakada, T., Akiba, T., Inagaki, T. and Morikawa, T., 2014. Thoracoscopic anatomical subsegmentectomy of the right S2b + S3 using a 3D printing model with rapid prototyping. Interact Cardiovasc Thorac Surg, 19(4), pp.696-698. Reference #2: Akiba T, Nakada T, Inagaki T. Three-Dimensional Pulmonary Model Using Rapid-Prototyping in Patient with Lung Cancer Requiring Segmentectomy. Annals of Thoracic and Cardiovascular Surgery. 2014;20(Supplement):490-492. DISCLOSURES: No relevant relationships by Mirza Zain Baig, source=Web Response No relevant relationships by Faiz Bhora, source=Web Response No relevant relationships by Zaid Muslim, source=Web Response

UTILITY OF NOVEL FLOW VOLUME LOOP INDEXES IN DIAGNOSING AIRFLOW OBSTRUCTION

SESSION TITLE: Obstructive Lung Disease Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: Spirometry testing has a relatively low sensitivity for diagnosing airflow obstruction in asthma. Furthermore, it is known that patients with airflow obstruction tend to demonstrate coving on their flow-volume loops. Quantitative measurements of coving-related indices may perhaps improve our ability to diagnose airflow obstruction in asthma. Our study sought to compare the performance of established spirometric indices of obstruction with novel indices derived from flow volume loops using ROC analysis. To our knowledge, this is the first study to employ asthmatic patients with age and gender matched controls to compare the global performance of criteria for airflow obstruction. METHODS: This is a retrospective case-control study. Controls were obtained from another IRB-approved study (REVORE). In this study, normal subjects were selected based on responses to an in-depth questionaire asking about symptoms of asthma. Those who reported no symptoms underwent formal pulmonary function testing, including spirometry with bronchodilator challenge. For our study, we selected participants who had normal spirometry, lung volumes and diffusion capacity to act as controls. We then selected age- and gender-matched patients from an IRB-approved cohort (LUVA) of patients with asthma. As part of the LUVA study, all subjects had spirometry, lung volume and diffusion capacity measurements. Flow-volume loops were analyzed for cases and controls using a free online graphing software package (GeoGebra). Several measurements of each flow-volume loops were taken, includingthe distance from the point of peak expiratory flow to the point along the expiratory curve at which coving was most pronounced (point of maximal deflection, or PMD). ROC and AUC analyses were performed in SPSS version 25 to compare (1) PMD in cases versus controls, (2) magnitude of deflection at PMD in cases versus controls (MOD), and (3) FEV1/FVC ratio in cases versus controls. The ROC and AUC of the new indices were compared to those of FEV1/FVC ratio. RESULTS: 13 controls were matched to 20 cases. The male to female ratio was 7:6. Mean age, height and weight were similar between groups. The AUC for PMD was 0.876 (95%CI 0.740-1.011). At a cutoff of 0.715, the sensitivity and specificity were 76.9% and 92.3%, respectively. The AUC for MOD was 0.858 (95%CI 0.682-0.984). At a cutoff of 2.735, the sensitivity and specificity were 84.6% and 76.9%, respectively. AUC for FEV1/FVC ratio was 0.870 (95%CI 0.711-1.029). At a cutoff of 0.738, the sensitivity and specificity were 76.9 and 100%, respectively. CONCLUSIONS: PMD was the best overall criteria for diagnosing obstruction in asthma. These findings need confirmation in a larger cohort of asthmatics matched for gender and age. CLINICAL IMPLICATIONS: These indices may have the potential to improve our ability to identify patients who may benefit from asthma therapies. DISCLOSURES: No relevant relationships by Eric Day, source=Web Response No relevant relationships by Evanpaul Gill, source=Web Response no disclosure on file for Sneha Gullapalli; No relevant relationships by Viraj Jain, source=Web Response No relevant relationships by Kara Schmidt, source=Web Response no disclosure submitted for Jose Vempilly

Telemonitoring Techniques for Lung Volume Measurement: Accuracy, Artifacts and Effort.

Telemonitoring becomes more important in pulmonary research. It can be used to decrease the pressure on the health care system, to lower the costs of health care and to increase quality of life of patients. Previous studies show contradictory results regarding the effectiveness of telemonitoring. According to multiple researchers, inefficiency can be a result of poor study design, low data quality and usability issues. To counteract these issues, this review proves for an in-depth explanation of four (potential) telemonitoring systems in terms of work principle, accuracy, disturbing factors and usability. The evaluated systems are portable spirometry/breath-by-breath analyzers, respiratory inductance and magnetic plethysmography and electrical impedance tomography. These insights can be used to select the optimal technique for a specific purpose in future studies.

Longitudinal lung function measurements in single lung transplant recipients with chronic lung allograft dysfunction

Phenotyping chronic lung allograft dysfunction (CLAD) in single lung transplant (SLTX) recipients is challenging. The aim of this study was to assess the diagnostic and prognostic value of longitudinal lung function tests in SLTX recipients with CLAD. A total of 295 SLTX recipients were analyzed and stratified according to native lung physiology. In addition to spirometry, measurements of static lung volumes and lung capacities were used to phenotype patients and to assess their prognostic value. Outcome was survival after CLAD onset. Patients with insufficient clinical information were excluded (n = 71). Of 224 lung transplant recipients, 105 (46.9%) developed CLAD. Time to CLAD onset (hazard ratio [HR]: 0.82, 95% CI: 0.74-0.90; p < 0.001), severity of CLAD at onset (HR: 0.97, 95% CI: 0.94-0.99; p = 0.009), and progression after onset of CLAD (HR: 1.03, 95% CI: 1.00-1.05; p = 0.023) were associated with outcome. Phenotypes at onset were bronchiolitis obliterans syndrome (BOS) (59.1%), restrictive allograft syndrome (RAS) (12.4%), mixed phenotype (6.7%), and undefined phenotype (21.9%). Survival estimates differed significantly between phenotypes (p = 0.004), with RAS and mixed phenotype being associated with the worst survival, followed by BOS and undefined phenotype. Finally, a higher hazard for mortality was noticed for RAS (HR: 2.34, 95% CI: 0.99-5.52; p = 0.054) and mixed phenotype (HR: 3.30, 95% CI: 1.20-9.11; p = 0.021) while controlling for time to CLAD onset and severity of CLAD at onset. Phenotyping CLAD in SLTX remains challenging with a high number of patients with an undefined phenotype despite comprehensive lung function testing. However, phenotyping is of prognostic value. Furthermore, early, severe, and progressive CLADs are associated with worse survival.

P0663RELATIONSHIP BETWEEN ENDOTHELIAL LESION AND PULMONARY DYSFUNCTION AMONG HEMODIALYTIC CHRONIC KIDNEY DISEASE PATIENTS WITH AND WITHOUT DIABETES MELLITUS

Abstract Background and Aims Patients with Chronic Kidney Disease (CKD) on dialysis and Diabetes Mellitus type 2 (DM2) may develop dysfunction in several systems, including the respiratory system. The aim of this study is to investigate if there is a relationship between endothelial lesion and pulmonary dysfunction in patients with CKD in hemodialysis with and without DM2. Method This is a cross-sectional study, from October 2017 to August 2018, including 60 patients divided into three groups: patients on hemodialysis (HD) without DM2 (HD in NDM = 30); HD with DM2 (HD in DM = 15); Non-hemodialysis with DM2 (DM without HD = 15) aged 40 to 60 years, regardless of gender. Analyzed pulmonary function were: maximal inspiratory and expiratory pressures (MIP and MEP) and measures of lung capacities and volumes: Forced Vital Capacity (FVC) and Forced Expiratory Volume in one second (FEV1). Results In the DM group in HD: MIP, MEP, FVC and FEV1 showed significant differences (p = 0.008; and p = 0.000; p = 0.000; p = 0.000), respectively. In the HD without NDM group: only the MIP parameter showed no significant difference (p = 0.256), MEP, FVC and FEV1 showed a statistically significant difference (p = 0.001; p = 0.000; p = 0.000), respectively. In the DM group without HD: only MIP showed no statistically significant difference (p = 0.491), MEP, FVC and FEV1 showed a statistically significant difference (p = 0.000; p = 0.008; p = 0.000), respectively when compared to their predicted value. Significant difference was detected between the groups regarding VCAM-1 only between DM in HD and DM without HD (p = 0.040). Syndecan-1 and Angiopoietin-2 plasma levels were statistically different when compared between the groups (p = 0.000) for the two biomarkers, this difference was observed only between the dialysis groups and the diabetic group without dialysis. In the multivariate regression analysis, when the fact that the individual had DM was also added, there was a greater association of VCAM-1 with the fact that the patient did not reach the predicted MEP, this value increased to OR = 8.762 (CI = 2.317 - 33.136) times of chance of not achieving the expected (p = 0.001). However, no statistically significant difference was found when the fact that the patient underwent hemodialysis was included (p = 0.885). Regarding Spearman correlation between MIP and VCAM-1 / Syndecan-1 / angiopoietin-2 there was no significant difference. However, in the correlation between MEP and endothelial lesion biomarkers, there was a significant difference only when compared with VCAM-1 (r = -0.287, p = 0.036). The FEV1 and FVC parameters obtained statistically significant results when correlated only with angiopoietin-2 (r = -0.309; -0.361), respectively. Conclusion Inspiratory muscle strength is reduced only when DM and HD are present when compared to their predicted. Expiratory muscle strength is reduced in all three groups and this parameter is most affected in diabetic individuals undergoing hemodialysis. Pulmonary function is compromised in all three groups equally. Endothelial glycocalyx lesion biomarkers (Angiopoietin-2 and Syndecan-1) are increased mainly in subjects on hemodialysis. Endothelial dysfunction is evidenced in HD group DM by increased VCAM-1 levels. There is a relationship between the lack of expected expiratory muscle strength with high values of VCAM-1 and when added the fact of having DM this relationship increases, however when added the fact of being dialytic there is no significant relationship. There is an inversely proportional correlation between expiratory muscle strength with the adhesion molecule marker (VCAM-1) and between pulmonary function with the endothelial lesion marker (Angiopoietin-2).

Rethinking respiratory function laboratories in the era of coronavirus disease 2019: Considerations for today and the day after

Rethinking respiratory function laboratories in the era of coronavirus disease 2019: Considerations for today and the day after

Lung Volume Measurement and Ventilation Distribution During Invasive Mechanical Ventilation.

Lung volume measurement performed during invasive mechanical ventilation can be used to determine functional residual capacity, changes in end-expiratory lung volume with the application of PEEP, and lung strain. However, many bedside measurements provide useful information without the use of specialized equipment. Ventilation distribution through the lung has traditionally been assessed with computed tomography, but more recently electrical impedance tomography has brought the ability to monitor this at the bedside, and without exposure to radiation. This review will describe techniques to measure lung volumes in the ICU and the relationship between lung strain, stress, and other measurements. This review will also discuss monitoring ventilation distribution at the bedside and the clinical assessment of regional compliance that this technology provides.

Performance of Radiomics Features in the Quantification of Idiopathic Pulmonary Fibrosis from HRCT.

Background: Our study assesses the diagnostic value of different features extracted from high resolution computed tomography (HRCT) images of patients with idiopathic pulmonary fibrosis. These features are investigated over a range of HRCT lung volume measurements (in Hounsfield Units) for which no prior study has yet been published. In particular, we provide a comparison of their diagnostic value at different Hounsfield Unit (HU) thresholds, including corresponding pulmonary functional tests. Methods: We consider thirty-two patients retrospectively for whom both HRCT examinations and spirometry tests were available. First, we analyse the HRCT histogram to extract quantitative lung fibrosis features. Next, we evaluate the relationship between pulmonary function and the HRCT features at selected HU thresholds, namely −200 HU, 0 HU, and +200 HU. We model the relationship using a Poisson approximation to identify the measure with the highest log-likelihood. Results: Our Poisson models reveal no difference at the −200 and 0 HU thresholds. However, inferential conclusions change at the +200 HU threshold. Among the HRCT features considered, the percentage of normally attenuated lung at −200 HU shows the most significant diagnostic utility. Conclusions: The percentage of normally attenuated lung can be used together with qualitative HRCT assessment and pulmonary function tests to enhance the idiopathic pulmonary fibrosis (IPF) diagnostic process.

The role of three-dimensional reconstructions in understanding the intersegmental plane: an anatomical study of segment 6.

The identification of the intersegmental plane during lung segmentectomies remains a practical difficulty, notably with minimally invasive approaches. The intraoperative techniques are based on demarcating either the bronchial or the vascular territories. The goal of this study was to evaluate the use of 3-dimensional reconstructions in understanding the intersegmental plane of segment 6. Between March and September 2018, Synapse 3-dimensional programme was used to carry out bilateral venous, arterial and bronchial segmentations of segment 6. All computed tomography (CT) scans were contrast-enhanced and of a high resolution (0.6 mm slices). The patients had normal results on respiratory function tests. The volumes obtained from each of the 3 modalities were then compared. The results are presented as mean and standard deviation and as median and interquartile ranges for lung volume measurements. During the aforementioned period, 15 high-resolution chest CT scans were selected (8 men and 7 women). The median age was 70 years. In all of the studied segments (N = 30, 15 right S6 and 15 left S6), the segmental volume of the vein was greater than the segmental volumes of the bronchus and the artery. A significant difference was found between the segmental volumes obtained from the 3 modalities (P = 0.001). The segmental volume of the vein was significantly higher than the segmental volume of the bronchus (P < 0.001) and the segmental volume of the artery (P < 0.001). On the other hand, the segmental volume of the artery was significantly higher than the segmental volume of the bronchus (P = 0.01). Within the limits of this study, the segmental venous volume of S6 was greater than the volumes of the segmental bronchial and arterial volumes. Thus, depending solely on bronchial techniques might lead to leaving a border zone in venous congestion.

Inter- and intra-software reproducibility of computed tomography lung density measurements.

Multiple commercial, open-source, and academic software tools exist for objective quantification of lung density in computed tomography (CT) images. The purpose of this study was to evaluate the intersoftware reproducibility of CT lung density measurements. Computed tomography images from 50 participants from the COPDGeneTM cohort study were randomly selected for analysis; n=10 participants across each global initiative for chronic obstructive lung disease (GOLD) grade (GOLD 0-IV). Academic-based groups (n=4) and commercial vendors (n=4) participated anonymously to generate CT lung density measurements using their software tools. Computed tomography total lung volume (TLV), percentage of the low attenuation areas in the lung with Hounsfield unit (HU) values below -950HU (LAA950 ), and the HU value corresponding to the 15th percentile on the parenchymal density histogram (Perc15) were included in the analysis. The intersoftware bias and reproducibility coefficient (RDC) was generated with and without quality assurance (QA) for manual correction of the lung segmentation; intrasoftware bias and RDC was also generated by repeated measurements on the same images. Intersoftware mean bias was within ±0.22mL, ±0.46%, and ±0.97HU for TLV, LAA950 and Perc15, respectively. The RDC was 0.35L, 1.2% and 1.8HU for TLV, LAA950 and Perc15, respectively. Intersoftware RDC remained unchanged following QA: 0.35L, 1.2% and 1.8HU for TLV, LAA950 and Perc15, respectively. All software investigated had an intrasoftware RDC of 0. The RDC was comparable for TLV, LAA950 and Perc15 measurements, respectively, for academic-based groups/commercial vendor-based software tools: 0.39L/0.32L, 1.2%/1.2%, and 1.7HU/1.6HU. Multivariable regression analysis showed that academic-based software tools had greater within-subject standard deviation of TLV than commercial vendors, but no significant differences between academic and commercial groups were found for LAA950 or Perc15 measurements. Computed tomography total lung volume and lung density measurement bias and reproducibility was reported across eight different software tools. Bias was negligible across vendors, reproducibility was comparable for software tools generated by academic-based groups and commercial vendors, and segmentation QA had negligible impact on measurement variability between software tools. In summary, results from this study report the amount of additional measurement variability that should be accounted for when using different software tools to measure lung density longitudinally with well-standardized image acquisition protocols. However, intrasoftware reproducibility was deterministic for all cases so use of the same software tool to reduce variability for serial studies is highly recommended.

Ultra-high-resolution computed tomography can demonstrate alveolar collapse in novel coronavirus (COVID-19) pneumonia.

PurposeTo review the chest computed tomography (CT) findings on the ultra-high-resolution CT (U-HRCT) in patients with the Novel coronavirus disease 2019 (COVID-19).Materials and MethodsIn February 2020, six consecutive patients with COVID-19 pneumonia (median age, 69 years) underwent U-HR CT imaging. U-HR-CT has a larger matrix size of 1024 × 1024 thinner slice thickness of 0.25 mm and can demonstrate terminal bronchioles in the normal lungs; as a result, Reid’s secondary lobules and their abnormalities can be identified. The distribution and hallmarks (ground-glass opacity, consolidation with or without architectural distortion, linear opacity, crazy paving) of the lung opacities on U-HRCT were visually evaluated on a 1 K monitor by two experienced reviewers. The CT lung volume was measured, and the ratio of the measured lung volume to the predicted total lung capacity (predTLC) based on sex, age and height was calculated.ResultsAll cases showed crazy paving pattern in U-HRCT. In these lesions, the secondary lobules were smaller than those in the un-affected lungs. CT lung volume decreased in two cases comparing predTLC.ConclusionU-HRCT can evaluate not only the distribution and hallmarks of COVID-19 pneumonia but also visualize local lung volume loss.

Prenatal prediction of postnatal survival in fetuses with congenital diaphragmatic hernia using MRI: lung volume measurement, signal intensity ratio, and effect of experience

Objective To evaluate various signal intensity ratios in isolated congenital diaphragmatic hernia (CDH) and to compare their potential in predicting survival with that of the observed-to-expected (O/E) ratio of total fetal lung volume (TFLV) using magnetic resonance imaging (MRI) measurements. Our second objective was to evaluate the impact of operator’s experience in comparing the prediction of postnatal survival by O/E-TFLV. Methods In 75 conservatively managed CDH fetuses and in 50 who underwent fetoscopic endoluminal tracheal occlusion (FETO), the fetal lung-to-amniotic fluid, lung-to-liver, lung-to-muscle, lung-to-spinal fluid signal intensity ratios, respectively LAFSIR, LLSIR, LMSIR, and LSFSIR, were measured, as was O/E-TFLV. Receiver operating characteristic (ROC) curves were constructed and used to compare the various signal intensity ratios with O/E-TFLV in the prediction of postnatal survival. In 72 MRI lung volumes assessed by the referring radiologists in Paris and Lille and secondarily by our expert radiologist in Brussels (M.M.C.) using the same MRI examinations, ROC curves were constructed and used to compare the value of O/E-TFLV determined by the two centers in the prediction of postnatal survival. Results In the total cohort of CDH fetuses, O/E-TFLV and LLSIR were predictive of postnatal survival whereas in the conservatively managed group O/E-TFLV, LLSIR, and LMSIR predicted postnatal survival. O/E-TFLV predicted postnatal survival far better than the signal intensity ratios: area under the ROC curve for prediction by O/E-TFLV in the total cohort was 0.866 (p < .001; standard error = 0.031). The area under the ROC curve for prediction of postnatal survival using O/E-TFLV by MRI evaluated at the referral centers was 0.640 (p = 102; standard error = 0.085), and with O/E-TFLV reevaluated by M.M.C., it was 0.872 (p < .001; standard error = 0.061). Pairwise comparison showed a significant difference between the areas under the ROC curves (difference = 0.187, p = .012; standard error = 0.075). Conclusion In fetuses with CDH with/without FETO, LLSIR was significantly correlated with the prediction of postnatal survival. However, measurement of O/E-TFLV was far better in predicting postnatal outcome. Operator experience in measurement of lung volumes using MRI seem to play a role in the predictive value of the technique.

Standard Normal Fetal Lung Volume by MRI Measurement

Background: Pulmonary hypoplasia is a significant decrease in lung volume by any cause in comparison to the normal volume for gestational age. Objectives: To evaluate the application of prenatal magnetic resonance imaging in order to predict pulmonary hypoplasia, measurement of fetal lung volume (FLV) was aimed to establish a reference data in normal fetuses. Patients and Methods: Three hundred forty two fetuses with abnormal ultrasound findings underwent fast spin-echo T2-weighted MR imaging at a single tertiary care hospital (Shahid Faghihi Hospital, Shiraz, Iran). Data of 241 fetuses at 18 - 36 weeks’ gestation without thoracic malformations were obtained for a FLV normative curve. To acquire a best-fit formula for the mean total fetal lung volume based on each gestational week with 95% confidence interval (CI), we used the regression model applied by Rypens et al. This resulted in a formula calculating the expected fetal lung volume based on gestational age. A one-sample t-test was also carried out to compare the mean total fetal lung volume at each gestational week with the expected mean total fetal lung volume predicted by the formula by Rypens et al., Meyers et al., and Osada et al. Results: Normal FLV increased with gestational age as the spread of values. The expected fetal lung volume was derived from the following formula: Fetal lung volume (mL) = 0.002 × (gestational age [GA]2.913), in which GA is gestational weeks. FLV in our population had a more consistent correlation with Japanese fetuses than European or American fetuses. Conclusion: In fetuses with normal lungs, FLV distribution against gestational age is simply measured prenatally with MR imaging. A single universal formula might not be suitable for fetuses worldwide. In our region, acquired data were more consistent with Asian normal values.