Computed Tomography Lung Volume Research Articles

Computed tomography (CT) quantitative assessment of single lobe emphysema correlates with chronic obstructive pulmonary disease (COPD) severity: a cross-sectional study with retrospective data collection.

In the past, many researchers have studied the correlation between quantitative parameters of computed tomography (CT) and parameters of pulmonary function test (PFT) in patients with chronic obstructive pulmonary disease (COPD) with good results. Most of these studies have focused on the whole-lung level. In this study, we analyzed the biphasic CT lung volume parameters and the percentage of emphysema volume in different lobes of the lungs of patients with different grades of COPD and assessed their relationship with different lung function indices. We retrospectively collected patients who underwent PFTs at The First Affiliated Hospital of Guangzhou Medical University from 1 July 2019 to 27 January 2020, and underwent chest respiratory dual-phase CT scans within 1 week, including 112 non-COPD patients and 297 COPD patients. We quantified the biphasic CT lung volume parameters and the percentage of emphysema volume in different lobes using a pulmonary image analysis tool. One-way analysis of variance (ANOVA) and Kruskal-Wallis H method were used to compare the quantitative CT parameters of each lung lobe in different groups. The correlation between quantitative CT parameters of different lung lobes and lung function indices was assessed using multiple linear regression. Among the 3 biphasic CT lung volume parameters, only volume change/inspiratory lung volume (∆LV/LVin) in the non-COPD control, mildly to moderately severe, and severe to extremely severe groups had statistical differences in each lobe level (all P<0.05). Correlation was significant between LVin and different lung function indices and between low attenuation areas percent below the threshold of -950 in the inspiratory phase [low attenuation area below -950 in the inspiratory phase (%LAA-950in)] and lung function indices in the left lower lobe (all P<0.05). There was statistically significant correlation between expiratory lung volume and ∆LV/LVin and lung function indices in the right lower lung (all P≤0.001). In the remaining lobes, LVin, expiratory lung volume, ∆LV/LVin, and %LAA-950in correlated with only some of the lung function indices. The percentage of emphysema volume did not differ between lobes in the non-COPD control and severe to extremely severe COPD populations. LVin and %LAA-950in in the left upper lobe, expiratory lung volume and ∆LV/LVin in the right lower lobe were more reflective of the changes in lung function indices of the patients, whereas the correlation of the 3 biphasic CT lung volume parameters and the percentage of emphysema volume in the upper lobes of both lungs and the right middle lung with lung function indices was unclear.

Size-matching in lung transplantation by computed tomography for end-stage interstitial disease: a retrospective analysis.

Size matching between donors and recipients is a major issue in lung transplantation (LTx), especially in patients with restrictive lung disease (RLD). This study aims to evaluate computed tomography (CT) as an additional method for defining the total lung capacity (TLC) in patients with end-stage interstitial disease awaiting LTx. Clinical data and CT scans from patients who underwent a first LTx from January 2014 to July 2018 in Bichat Hospital, Paris, were prospectively included in a database. CT TLC (ctTLC) was retrospectively calculated after semi-automatic contouring of the parenchyma and compared with measured TLC (mTLC) and predicted TLC (pTLC) values. The study group included 89 patients (male:female =68:21; mean age, 59.5±10.0 years). The time between pulmonary function tests (PFTs) and CT scan was 162±270 days [median, 67 days; interquartile range (IQR), 0-233 days]. ctTLC was inferior to mTLC and pTLC (respectively 2,979±1,001 mL, 3,530±1,077 and 6,381±955 mL, P<0.001). The relative difference between CT lung volume (ctLV) and measured lung volume (mLV) was higher on the left than on the right side (25.4% vs. 16.3%, respectively, P=0.11). After exclusion of two outliers, we found a significant correlation between ctTLC and mTLC (r=0.762, P<0.001). CT volume is a feasible method to assess TLC in patients with end-stage interstitial disease awaiting LTx. This study highlights potential size-mismatch for graft selection before LTx and opens the perspective of a prospective trial evaluating impact of size-matching by donor-recipient (D-R) ctTLC ratio on postoperative outcomes.

Application of clinical and CT imaging features in the evaluation of disease progression in patients with COVID-19

BackgroundThe Corona Virus Disease 2019(COVID-19) pandemic has strained healthcare systems worldwide, necessitating the early prediction of patients requiring critical care. This study aimed to analyze the laboratory examination indicators, CT features, and prognostic risk factors in COVID-19 patients.MethodsA retrospective study was conducted on 90 COVID-19 patients at the First Affiliated Hospital of Gannan Medical University between December 17, 2022, and March 17, 2023. Clinical data, laboratory examination results, and computed tomography (CT) imaging data were collected. Logistic multivariate regression analysis was performed to identify independent risk factors, and the predictive ability of each risk factor was assessed using the area under the receiver operating characteristic (ROC) curve.ResultsMultivariate logistic regression analysis revealed that comorbid diabetes (odds ratio [OR] = 526.875, 95%CI = 1.384-1960.84, P = 0.053), lymphocyte count reduction (OR = 8.773, 95%CI = 1.432–53.584, P = 0.064), elevated D-dimer level (OR = 362.426, 95%CI = 1.228-984.995, P = 0.023), and involvement of five lung lobes (OR = 0.926, 95%CI = 0.026–0.686, P = 0.025) were risk factors for progression to severe COVID-19. ROC curve analysis showed the highest predictive value for 5 lung lobes (AUC = 0.782). Oxygen saturation was positively correlated with normally aerated lung volume and the proportion of normally aerated lung volume (P < 0.05).ConclusionsThe study demonstrated that comorbid diabetes, lymphocyte count reduction, elevated D-dimer levels, and involvement of the five lung lobes are significant risk factors for severe COVID-19. In CT lung volume quantification, normal aerated lung volume and the proportion of normal aerated lung volume correlated with blood oxygen saturation.

Improved donor lung size matching by estimation of lung volumes based on chest X-ray measurements.

Organ size matching is an important determinant of successful allocation and outcomes in lung transplantation. While computed tomography (CT) is the gold standard, it is rarely used in an organ-donor context, and chest X-ray (CXR) may offer a practical and accurate solution in estimating lung volumes for donor and recipient size matching. We compared CXR lung measurementsto CT-measured lung volumes and traditional estimates of lung volume in the same subjects. Our retrospective study analyzed clinically obtained CXR and CT lung images of 250 subjects without evidence of lung disease (mean age 9.9 ± 7.8 years; 129 M/121F). From CT, each lung was semi-automatically segmented and total lung volumes were quantified. From anterior-posterior CXR view, each lung was manually segmented and areas were measured. Lung lengths from the apices to the mid-basal regions of each lung were measured from CXR. Quantified CT lung volumes were compared to the corresponding CXR lung lengths, CXR lung areas, height, weight, and predicted total lung capacity (pTLC). There are strong and significant correlations between CT volumes and CXR lung areas in the right lung (R2 = .89, p < .0001), left lung (R2 = .87, p < .0001), and combined lungs (R2 = .89, p < .0001). Similar correlations were seen between CT volumes and CXR measured lung lengths in the right lung (R2 = .79, p < .0001) and left lung (R2 = .81, p < .0001). This correlation between anatomical lung volume (CT) and CXR was stronger than lung-volume correlation to height (R2 = .66, p < .0001), weight (R2 = .43, p < .0001), or pTLC (R2 = .66, p < .0001). CXR measures correlate much more strongly with true lung volumes than height, weight, or pTLC. The ability to obtain efficient and more accurate lung volume via CXR has the potential to change our current listing practices of using height as a surrogate for lung size, with a case example provided.

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

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. 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. 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. 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.

Evaluating the Use of CT-Derived Lung Volumes in Donor-Recipient Lung Size Matching for Lung Transplantation

<h3>Purpose</h3> Practices for donor and recipient size matching for lung transplantation vary. The objective of this study was to assess the accuracy of CT-derived lung volumes to predict donor-recipient lung size match for bilateral lung transplantation. <h3>Methods</h3> We studied 62 patients who underwent bilateral lung transplantation for Interstitial Lung Disease/Idiopathic Pulmonary Fibrosis during 2018-2019. Recipient data was retrieved from medical records and our transplant database. Donor data was obtained from UNOS DonorNet. Data collected included demographic data, lung heights, estimated donor total lung capacity (TLC) and recipient measured TLC from plethysmography; Computed Tomography (CT) derived lung volumes both pre- and post-transplant in recipients and clinical data. The recipient post-transplant CT-derived lung volume was used as a surrogate for donor lung CT volumes due to unavailable or poor donor data. Techniques included thresholding, region growing and cutting using Computer-Aided Design. Preoperative CT-derived lung volumes in recipients were compared with the plethysmography TLC, Frustum Model, and donor estimated TLC. We studied the ratio of recipient's pre- and post-operative CT-derived volumes, and the ratio of preoperative CT-derived lung volume and donor estimated TLC and correlated with one-year outcomes. <h3>Results</h3> The recipient preoperative CT-derived volume correlated with the recipient preoperative plethysmography TLC (Pearson correlation coefficient (PCC) of 0.688, p-value of 1.75e-07) and with the recipient Frustum model volume (PCC of 0.593, p-value of 2.766e-07). The recipient postoperative CT-derived volume correlated with the recipient postoperative plethysmography TLC (PCC of 0.651, p-value of 9.424e-06). There was no statistical correlation between recipient CT-derived preoperative or postoperative volume with donor estimated TLC. The ratio of preoperative CT-derived volume to donor estimated TLC correlated inversely with length of ventilation (p value: 0.0031). Lung oversizing (post- to preoperative CT lung volume ratio of over 1.2) did not affect outcomes. <h3>Conclusion</h3> CT-derived lung volume is a valid and convenient method for evaluating lung sizing for transplants. Donor estimated TLC should be interpreted cautiously. Matching donor and recipient CT lung volumes will be the scope of further research.

Quantitative computerized tomography evaluation of the effects of COVID-19 pneumonia on lung volume

Purpose: The aim of this study was o assess the relationship between lung volume decrease and computed tomography (CT) findings in patients with COVID-19 pneumonia in early period.&#x0D; Materials and Methods: Fifty-four patients were included in the study. The lung volume (LV) was calculated separately for each lung by software-based quantitative CT (QCT). Patient demographics, comorbidity and smoking status, CT findings, visual semi-quantitative CT severity scoring (CT-SS), and decrease of LV were analyzed. &#x0D; Results: The rate of volume decrease was not statistically related to, age, gender, smoking, or hospitalization status. When the correlation between follow-up CT (FUCT) LV and CT-SS was examined there were good inverse correlation on the right lung (r = -0.583; p = 0.001) and left lung (r = -0.478; p = 0.001). The rate of decrease in the right LV was significantly higher in patients with comorbidities compared to other patients. There was a statistically moderate inverse correlation between decrease of LV and CT-SS in the right lung (r = -0.294; p = 0.031), and no significant correlation was found between the decrease of LV and CT-SS in the left lung (r = -0.096; p = 0.489). &#x0D; Conclusion: The rate of lung damage and associated volume decrease both increase with the amount of parenchymal involvement in patients with COVID-19 pneumonia. This change is more frequent in patients with multiple comorbidities. Accurate interpretation of CT findings with quantitative data can help physicians to manage the disease.

Pulmonary vascular enlargement and lesion extent on computed tomography are correlated with COVID-19 disease severity.

PurposeTo assess the relationships among pulmonary vascular enlargement, computed tomography (CT) findings quantified with software, and coronavirus disease (COVID-19) severity.Materials and methodsUltra-high-resolution (UHR) CT images of 87 patients (50 males, 37 females; median age, 63 years) with COVID-19 confirmed using real-time polymerase chain reaction were analyzed. The maximum subsegmental vascular diameter was measured on CT. Total CT lung volume (CTLV total) and lesion extent (ratio of lesion volume to CTLV total) of ground-glass opacities, reticulation, and consolidation were measured using software. Maximum pulmonary vascular diameter and lesion extent were analyzed using Spearman’s correlation analysis. Logistic regression analysis was performed on CT results to predict disease severity. We also assessed changes in these measures on follow-up scans in 16 patients.ResultsAll 23 patients with severe and critical illness had vascular enlargement (> 4 mm). Pulmonary vascular enlargement (odds ratio 3.05, p = 0.018) and CT lesion extent (odds ratio 1.07, p = 0.002) were independent predictors of disease severity after adjustment for age and comorbidities. On follow-up CT, vascular diameter and CT lesion volume decreased (p = 0.001, p = 0.002; respectively), but CTLV total did not change significantly.ConclusionSubsegmental vascular enlargement is a notable finding to predict acute COVID-19 disease severity.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11604-020-01085-2.

Prognosis of pulmonary fibrosis presenting with a usual interstitial pneumonia pattern on computed tomography in patients with myeloperoxidase anti-neutrophil cytoplasmic antibody-related nephritis: a retrospective single-center study

BackgroundMyeloperoxidase anti-neutrophil cytoplasmic antibody-related nephritis (MPO-ANCA nephritis) is occasionally accompanied by lung abnormalities such as pulmonary fibrosis. However, the clinical features of pulmonary fibrosis in patients with MPO-ANCA nephritis have not been well documented. This study was performed to compare the prognosis of a usual interstitial pneumonia (UIP) pattern of lung fibrosis in patients with MPO-ANCA nephritis with the prognosis of idiopathic pulmonary fibrosis (IPF).MethodsWe retrospectively reviewed the medical records of 126 patients with MPO-ANCA nephritis and identified 31 with a UIP pattern of lung fibrosis on high-resolution or thin-slice computed tomography (CT). We compared the characteristics and prognosis of these patients with those of 32 patients with IPF. In 18 patients from both groups, we assessed and compared the decline in lung volume over time using three-dimensional (3D) CT images reconstructed from thin-section CT data.ResultsThe numbers of male and female patients were nearly equal among patients with MPO-ANCA nephritis exhibiting a UIP pattern; in contrast, significant male dominancy was observed among patients with IPF (p = 0.0021). Significantly fewer smokers were present among the patients with MPO-ANCA nephritis with a UIP pattern than among those with IPF (p = 0.0062). There was no significant difference in the median survival time between patients with MPO-ANCA nephritis with a UIP pattern (50.8 months) and IPF (55.8 months; p = 0.65). All patients with IPF in this cohort received antifibrotic therapy (pirfenidone or nintedanib). Almost half of the deaths that occurred in patients with MPO-ANCA nephritis with a UIP pattern were caused by non-respiratory-related events, whereas most deaths in patients with IPF were caused by respiratory failure such as acute exacerbation. In the 3D CT lung volume analyses, the rate of decline in lung volume was equivalent in both groups.ConclusionsMPO-ANCA nephritis with a UIP pattern on CT may have an unfavorable prognosis equivalent to that of IPF with a UIP pattern treated with antifibrotic agents.

Technical Note: Density correction to improve CT number mapping in thoracic deformable image registration.

To improve the accuracy of computed tomography (CT) number mapping inside the lung in deformable image registration with large differences in lung volume for applications in vertical CT imaging and adaptive radiotherapy. The deep inspiration breath hold (DIBH) CT image and the end of exhalation (EE) phase image in four-dimensional CT of 14 thoracic cancer patients were used in this study. Lung volumes were manually delineated. A Demons-based deformable registration was first applied to register the EE CT to the DIBH CT for each patient, and the resulting deformation vector field deformed the EE CT image to the DIBH CT space. Given that the mass of the lung remains the same during respiration, we created a mass-preserving model to correlate lung density variations with volumetric changes, which were characterized by the Jacobian derived from the deformation field. The Jacobian determinant was used to correct the lung CT numbers transferred from the EE CT image. The absolute intensity differences created by subtracting the deformed EE CT from the DIBH CT with and without density correction were compared. The ratio of DIBH CT to EE CT lung volumes was 1.6 on average. The deformable registration registered the lung shape well, but the appearance of voxel intensities inside the lung was different, demonstrating the need for density correction. Without density correction, the mean and standard deviation of the absolute intensity difference between the deformed EE CT and the DIBH CT inside the lung were 54.5±45.5 for all cases. After density correction, these numbers decreased to 18.1±34.9, demonstrating greater accuracy. The cumulative histogram of the intensity difference also showed that density correction improved CT number mapping greatly. Density correction improves CT number mapping inside the lung in deformable image registration for difficult cases with large lung volume differences.

Computed tomography lung volume estimation and its relation to lung capacities and spine deformation.

Scoliosis is a three-dimensional deformity which is believed to impact lung function, mechanics of respiratory muscles, lung compliance, etc. It is thus of interest to investigated the relationship between degree of scoliosis in terms of apex rotation or Cobb angle respectively and normalized vital capacity (VC). Furthermore it is interesting to study the possibility of estimating lung volumes (and indirectly lung function) using CT volumetric reconstruction. The inclusion criteria were consecutive patients for whom surgery was planned and who underwent preoperative low-dose chest CT and preoperative spirometry/plethysmography. Lung capacities were normalized (based upon previous work involving the parameters gender, age, height and smoking). Preoperative CT-scans were used to measure apical rotation and scoliosis. We investigated the relationship between degree of scoliosis in terms of apex rotation or Cobb angle respectively and normalized VC from spirometry 63 patients who had a thoracic scoliosis curve (not necessarily as primary curve). We have tested a method for estimating normalized total lung capacity (TLC) from inspiratory chest CT of a group of 61 patients. The statistical level of significance used throughout the paper of 0.05. In the first part, we show that the group of 63 patients can, with respect to apical rotation or Cobb angle respectively, be divided into three subgroups in each case respectively, such that, pairwise, the mean of the normalized VC, for the group with higher apical rotation or Cobb angle respectively, is in some sense, at least 9% lower. We also give the result of the more simplistic analysis of subdividing into only two groups which give approximately 13% decrease for the group with higher spine deformation. A linear regression model seems inappropriate, due to the correlation coefficient for normalized VC versus apical rotation or Cobb angle respectively, being -0.53 (or in the case of Cobb angle -0.35). The correlation coefficient between apical rotation and Cobb angles, for the 63 patients, was 0.64. In the second part, the attempted linear regression model for describing the relation between lung volume estimation from inspiratory CT, and the normalized TLC from spirometry/plethysmography yields a correlation coefficient ≈0.71. In the first part, we show that there is a group subdivision with respect to apical rotation or Cobb angle respectively, whereby groups with a higher degree of thoracic vertebral deviation have, in some sense, a lower normalized VC. We propose that a linear regression model is inappropriate. In the second part, we propose that a linear regression model could describe the relationship between estimations of lung volume from inspiratory CT, and the normalized TLC from spirometry/plethysmography.

CT-lung volume estimates in trauma patients undergoing stabilizing surgery for flail chest

AimTo estimate and compare lung volumes from pre- and post-operative computed tomography (CT) images and correlate findings with post-operative lung function tests in trauma patients with flail chest undergoing stabilizing surgery. Patients and methodsPre- and post-operative CT images of the thorax were used to estimate lung volumes in 37 patients who had undergone rib plate fixation at least 6 months before inclusion for flail chest due to blunt thoracic trauma. Computed tomography lung volumes were estimated from airway distal to each lung hilum by outlining air-filled lung tissue either manually in images of 5 mm slice thickness or automatically in images of 0.6 mm slice thickness. Demographics, pain, range of motion in the thorax, breathing movements and Forced Vital Capacity (FVC) were assessed. Total Lung Capacity (TLC) measurements were also made in a subgroup of patients (n = 17) who had not been intubated at time of the initial CT. Post-operative CT lung volumes were correlated to FVC and TLC. ResultsPatients with a median age of 62 (19–90) years, a median Injury Severity Score (ISS) of 20 (9–54), and a median New Injury Severity Score (NISS) of 27 (17–66) were enrolled in the study. Median follow-up time was 3.9 (0.5–5.6) years. Two patients complained of pain at rest and when breathing. Pre-operative CT lung volumes were significantly different (p < 0.0001) from post-operative CT lung volumes, 3.51 l (1.50–6.05) vs. 5.59 l (2.18–7.78), respectively. At follow-up, median FVC was 3.76 l (1.48–5.84) and median TLC was 6.93 l (4.21–8.42). Post-operative CT lung volumes correlated highly with both FVC [rs = 0.75 (95% CI 0.57‒0.87, p < 0.0001)] and TLC [rs = 0.90 (95% CI 0.73‒0.96, p < 0.0001)]. The operated thoracic side showed decreased breathing movements. Range of motion in the lower thorax showed a low correlation with FVC [rs = 0.48 (95% CI 0.19‒0.70, p = 0.002)] and a high correlation with TLC [rs = 0.80 (95% CI 0.51‒0.92, p < 0.0001)]. ConclusionsPost-operative CT-lung volume estimates improve compared to pre-operative values in trauma patients undergoing stabilizing surgery for flail chest, and can be used as a marker for lung function when deciding which patient with chest wall injuries can benefit from surgery.

The repeatability of computed tomography lung volume measurements: Comparisons in healthy subjects, patients with obstructive lung disease, and patients with restrictive lung disease.

In this study, we examined the repeatability of computed tomography (CT) lung volume measurements in healthy individuals and patients with obstructive and restrictive lung diseases. To do this, we retrospectively enrolled 200 healthy individuals (group 1), 100 patients with obstructive lung disease (group 2), and 100 patients with restrictive lung disease (group 3) who underwent two consecutive chest CT scans within a 1-year period. The CT lung volume was measured using a threshold-based, three-dimensional auto-segmentation technique at a default range from –200 to –1024 HU. The within-subject standard deviation, repeatability coefficient, within-subject coefficient variability, and intraclass correlation coefficient were evaluated. No significant differences were identified between the two consecutive CT lung volume measurements in any of the groups (p> 0.05). The within-subject standard deviations for groups 1, 2, and 3 were 441.1, 387.0, and 288.6, respectively, while the repeatability coefficients were 1222.6, 1072.6, and 800.1, respectively. The within-subject coefficient variabilities for groups 1, 2, and 3 were 0.097, 0.083, and 0.090, respectively, while the intraclass correlation coefficients were 0.818, 0.881, and 0.910, respectively. The two CT lung volume measurements showed excellent agreement in healthy individuals and patients with obstructive or restrictive lung disease. However, the repeatability was lower in healthy individuals than it was in patients with lung diseases.

Follow-up of CT-derived airway wall thickness: Correcting for changes in inspiration level improves reliability

ObjectivesAirway wall thickness (AWT) is affected by changes in lung volume. This study evaluated whether correcting AWT on computed tomography (CT) for differences in inspiration level improves measurement agreement, reliability, and power to detect changes over time. MethodsParticipants of the Dutch-Belgian lung cancer screening trial who underwent 3-month repeat CT for an indeterminate pulmonary nodule were included. AWT on CT was calculated by the square root of the wall area at a theoretical airway with an internal perimeter of 10mm (Pi10). The scan with the highest lung volume was labelled as the reference scan and the scan with the lowest lung volume was labelled as the comparison scan. Pi10 derived from the comparison scan was corrected by multiplying it with the ratio of CT lung volume of the comparison scan to CT lung volume on the reference scan. Agreement of uncorrected and corrected Pi10 was studied with the Bland-Altman method, reliability with intra-class correlation coefficients (ICC), and power to detect changes over time was calculated. Results315 male participants were included. Limit of agreement and reliability for Pi10 was −0.61 to 0.57mm (ICC=0.87), which improved to −0.38 to 0.37mm (ICC=0.94) after correction for inspiration level. To detect a 15% change over 3 months, 71 subjects are needed for Pi10 and 26 subjects for Pi10 adjusted for inspiration level. ConclusionsCorrecting Pi10 for differences in inspiration level improves reliability, agreement, and power to detect changes over time.

Lung Tissue Volume is Elevated in Obesity and Reduced by Bariatric Surgery.

Bariatric surgery (BS) in severely obese subjects causes a significant reduction of body weight with lung function improvement. We have shown that abnormalities in pulmonary gas exchange in morbidly obese subjects are substantially improved with BS. These abnormalities were thought to be related to reduced lung volumes as well as to abnormal endothelial function induced by low-grade chronic inflammation linked to perivascular adipose tissue (PVAT). In this study, we used computed tomography (CT) to assess whether BS also caused measurable structural changes in the lung tissue volume (Vtiss) and cross-sectional vessel analysis, hypothesizing that these measures could be related to the previously reported lung functional changes. This is a post hoc analysis of a previous reported prospective study. Pulmonary vessels and lung volumes, including Vtiss, were quantified in thoracic CT scans. We compared findings in 12 obese women before and after BS and in 8 healthy lean women. Vtiss was significantly elevated in obese subjects before BS compared to control subjects and systematically reduced after BS (by 8%); other CT lung volumes or vascular areas were not affected in a consistent manner. No relationship was observed between BS-induced individual changes in Vtiss and pulmonary vessel area. Vtiss is elevated in morbidly obese subjects, compared to lean individuals of similar body height, and is systematically reduced by BS. These effects do not appear related to vascular changes but may be caused by elevated extravascular lung water, due to low-grade inflammation, and/or hypertrophic PVAT in severe obesity.

Low-dose computed tomography volumetry for subtyping chronic lung allograft dysfunction

The long-term success of lung transplantation is challenged by the development of chronic lung allograft dysfunction (CLAD) and its distinct subtypes of bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). However, the current diagnostic criteria for CLAD subtypes rely on total lung capacity (TLC), which is not always measured during routine post-transplant assessment. Our aim was to investigate the utility of low-dose 3-dimensional computed tomography (CT) lung volumetry for differentiating RAS from BOS. This study was a retrospective evaluation of 63 patients who had developed CLAD after bilateral lung or heart‒lung transplantation between 2006 and 2011, including 44 BOS and 19 RAS cases. Median post-transplant follow-up was 65 months in BOS and 27 months in RAS. The median interval between baseline and the disease-onset time-point for CT volumetry was 11 months in both BOS and RAS. Chronologic changes and diagnostic accuracy of CT lung volume (measured as percent of baseline) were investigated. RAS showed a significant decrease in CT lung volume at disease onset compared with baseline (mean 3,916 ml vs 3,055 ml when excluding opacities, p < 0.0001), whereas BOS showed no significant post-transplant change (mean 4,318 ml vs 4,396 ml, p = 0.214). The area under the receiver operating characteristic curve of CT lung volume for differentiating RAS from BOS was 0.959 (95% confidence interval 0.912 to 1.01, p < 0.0001) and the calculated accuracy was 0.938 at a threshold of 85%. In bilateral lung or heart‒lung transplant patients with CLAD, low-dose CT volumetry is a useful tool to differentiate patients who develop RAS from those who develop BOS.

New Predictive Equation for Lung Volume Using Chest Computed Tomography for Size Matching in Lung Transplantation

PurposeLung size matching is important in lung transplantation (LT). With advances in computed tomography (CT) technology, multidetector row CT can accurately measure the thoracic cage and lung volumes. The objective of this study was to generate a new regression equation using demographic data based on the measured CT lung volume in a healthy population to predict the CT lung volume of the donor in LT size matching. Materials and MethodsThe medical records of healthy subjects who underwent chest CT scans to screen for lung cancer were retrospectively reviewed. CT lung volume was semi-automatically measured using a threshold-based auto-segmentation technique. New regression equations for CT lung volume were generated by multiple linear regression analysis using demographic data including height (H, cm), weight (W, kg), and age (A, years). The percentage error rate (%) of the equations were calculated as ([Estimated CT lung volume – Measured CT lung volume]/Measured CT lung volume × 100). A percentage error rate within ±20% was considered acceptable. ResultsA total of 141 men aged 27 to 55 years (mean, 46.7 ± 6.2 years) and 128 women aged 20 to 55 years (mean, 45.4 ± 7.2 years) were enrolled. The final regression equations for CT lung volume were (−5.890 + 0.067H – 0.030W + 0.020A) in men and (−6.698 + 0.072H – 0.024W) in women. The mean absolute error rate was 10.9 ± 9.0% and 11.0 ± 8.5% in men and women, respectively. Percentage error rates were within ±20% in 121 of 141 (85.8%) men and 113 of 128 (88.3%) women. ConclusionThese equations could predict the CT lung volume of healthy subjects using demographic data. Using these equations, the predicted CT lung volume of donors could be matched to the measured CT lung volume of recipients in lung transplantation.

Computed Tomography Lung Volume Changes After Surgical Treatment for Early-Onset Scoliosis

Study DesignSingle-center review of prospectively collected data. ObjectivesTo document anatomic lung volume and thoracic parameter changes in early-onset scoliosis patients undergoing rib-based (RB), or spine-based (SB) distraction surgical treatment who were too young to perform pulmonary function tests. MethodsTwenty patients undergoing growth-sparing treatment had computed tomography lung volumes (CTvol) determined by controlled-ventilation CT scanning preoperatively and at a mean of 2.7 years later under an institutional review board (IRB)-approved protocol. Twelve patients had non-congenital curves and 8 had congenital curves. Eleven patients had SB constructs and 9 had RB ones. Computed tomography lung volumes were correlated to T1–12 length, T6 coronal width, pelvic width, and curve magnitude, and were normalized by comparison with age standards and pelvic width. ResultsAll patients had increased CTvol at follow-up (RB 51%, SB 46%; p < .001). All increased T1–12 length from 128 mm (range, 39–160 mm) preoperatively to 154 mm (range, 61–216 mm) at follow-up. Both RB and SB gained 2.6 cm; this measurement was significant in RB (p < .001) owing to the shorter preoperative length. The T1–12 length correlated well with CTvol preoperatively (p = .002) and at follow-up (p = .007). The T6 width correlated best with CTvol (r = 0.76; p < .001 preoperatively and at follow-up). Main thoracic curves improved 21° in SB (preoperatively, 78°) versus 1.5° correction in RB (preoperatively, 60.2°). There was no correlation between curve magnitude and CTvol preoperatively or at follow-up. Follow-up CTvol percentile decreased in 10 patients, increased in 6, and was unchanged in 4. The T1–12 length was less than the fifth percentile in all patients preoperatively and increased in 9 patients at follow-up, whereas 11 remained at less than the fifth percentile. ConclusionsThe CTvol quantitates anatomic results of early-onset scoliosis growth-sparing surgery in patients too young for standard pulmonary function tests. Thoracic length and width correlate well with absolute CTvol and are possible surrogate measures. Curve magnitude and correction correlate poorly and assume less importance in outcome evaluation. Thoracic volume and length gains exceeded normal growth in about half of the patients.

Clinical Utility of Computed Tomographic Lung Volumes in Patients with Chronic Obstructive Pulmonary Disease

Background: Published data concerning the utility of computed tomography (CT)-based lung volumes are limited to correlation with lung function. Objectives: The aim of this study was to evaluate the clinical utility of the CT expiratory-to-inspiratory lung volume ratio (CT V_ratio) by assessing the relationship with clinically relevant outcomes. Methods: A total of 75 stable chronic obstructive pulmonary disease (COPD) patients having pulmonary function testing and volumetric CT at full inspiration and expiration were retrospectively evaluated. Inspiratory and expiratory CT lung volumes were measured using in-house software. Correlation of the CT V_ratio with patient-centered outcomes, including the modified Medical Research Council (MMRC) dyspnea score, the 6-min walk distance (6MWD), the St. George's Respiratory Questionnaire (SGRQ) score, and multidimensional COPD severity indices, such as the BMI, airflow obstruction, dyspnea, and exercise capacity index (BODE) and age, dyspnea, and airflow obstruction (ADO), were analyzed. Results: The CT V_ratio correlated significantly with BMI (r = −0.528, p < 0.001). The CT V_ratio was also significantly associated with MMRC dyspnea (r = 0.387, p = 0.001), 6MWD (r = −0.459, p < 0.001), and SGRQ (r = 0.369, p = 0.001) scores. Finally, the CT V_ratio had significant correlations with the BODE and ADO multidimensional COPD severity indices (r = 0.605, p < 0.001; r = 0.411, p < 0.001). Conclusion: The CT V_ratio had significant correlations with patient-centered outcomes and multidimensional COPD severity indices.

Airway closure on imaging relates to airway hyperresponsiveness and peripheral airway disease in asthma

The regional pattern and extent of airway closure measured by three-dimensional ventilation imaging may relate to airway hyperresponsiveness (AHR) and peripheral airways disease in asthmatic subjects. We hypothesized that asthmatic airways are predisposed to closure during bronchoconstriction in the presence of ventilation heterogeneity and AHR. Fourteen asthmatic subjects (6 women) underwent combined ventilation single photon emission computed tomography/computed tomography scans before and after methacholine challenge. Regional airway closure was determined by complete loss of ventilation following methacholine challenge. Peripheral airway disease was measured by multiple-breath nitrogen washout from which S(cond) (index of peripheral conductive airway abnormality) was derived. Relationships between airway closure and lung function were examined by multiple-linear regression. Forced expiratory volume in 1 s was 87.5 ± 15.8% predicted, and seven subjects had AHR. Methacholine challenge decreased forced expiratory volume in 1 s by 23 ± 5% and increased nonventilated volume from 16 ± 4 to 29 ± 13% of computed tomography lung volume. The increase in airway closure measured by nonventilated volume correlated independently with both S(cond) (partial R(2) = 0.22) and with AHR (partial R(2) = 0.38). The extent of airway closure induced by methacholine inhalation in asthmatic subjects is greater with increasing peripheral airways disease, as measured by ventilation heterogeneity, and with worse AHR.