Blood oxygenation state in COVID-19 patients: Unexplored role of 2,3-bisphosphoglycerate

BACKGROUND

COVID-19 reduces lung functionality causing a decrease of blood oxygen levels (hypoxemia) often related to a decreased cellular oxygenation (hypoxia). Besides lung injury, other factors are implicated in the regulation of oxygen availability such as pH, partial arterial carbon dioxide tension (PaCO2), temperature, and erythrocytic 2,3-bisphosphoglycerate (2,3-BPG) levels, all factors affecting hemoglobin saturation curve. However, few data are currently available regarding the 2,3-BPG modulation in SARS-CoV-2 affected patients at the hospital admission.

MATERIAL AND METHODS

Sixty-eight COVID-19 patients were enrolled at hospital admission. The lung involvement was quantified using chest-Computer Tomography (CT) analysed with automatic software (CALIPER). Haemoglobin concentrations, glycemia, and routine analysis were evaluated in the whole blood, while partial arterial oxygen tension (PaO2), PaCO2, pH, and HCO3- were assessed by arterial blood gas analysis. 2,3-BPG levels were assessed by specific immunoenzymatic assays in RBCs.

RESULTS

A higher percentage of interstitial lung disease (ILD) and vascular pulmonary-related structure (VRS) volume on chest-CT quantified with CALIPER had been found in COVID-19 patients with a worse disease outcome (R = 0.4342; and R = 0.3641, respectively). Furthermore, patients with lower PaO2 showed an imbalanced acid-base equilibrium (pH, p = 0.0208; PaCO2, p = 0.0496) and a higher 2,3-BPG levels (p = 0.0221). The 2,3-BPG levels were also lower in patients with metabolic alkalosis (p = 0.0012 vs. no alkalosis; and p = 0.0383 vs. respiratory alkalosis).

CONCLUSIONS

Overall, the data reveal a different pattern of activation of blood oxygenation compensatory mechanisms reflecting a different course of the COVID-19 disease specifically focusing on 2,3-BPG modulation.

Assessment of interobserver concordance in radiomic tools for lung nodule classification, with a focus on BRODERS and SILA

While CT lung cancer screening reduces lung cancer-specific mortality, there are remaining challenges. Radiomic tools promiss to address these challenges, however, they are subject to interobserver variability if semi-automated segmentation techniques are used. Herein we report interobserver variability for two validated radiomic tools, BRODERS (Benign versus aggRessive nODule Evaluation using Radiomic Stratification) and CANARY (Computer-Aided Nodule Assessment and Risk Yield). We retrospectively analyzed the CT images of 95 malignant lung nodules of the adenocarcinoma spectrum using BRODERS and CANARY. Cases were identified at Mayo Clinic (n = 45) and Vanderbilt University Medical Center and Nashville/Veteran Administration Tennessee Valley Health Care System (n = 50). Three observers with different training levels (medical student, internal medicine resident and thoracic radiology fellow) each performed lung nodule segmentation. All methods were carried out in accordance with relevant guidelines and regulations. Interclass correlation coefficients (ICC) of 0.77, 0.98 and 0.97 for the average nodule volume, BRODERS cancer probability and Score Indicative of Lesion Aggression (SILA) which summarizes the distribution of the CANARY exemplars indicated good to excellent reliability, respectively. The dice similarity coefficient was 0.79 and 0.81 for the data sets from the two institutions. BRODERS and CANARY are robust radiomics tools with excellent interobserver variability. These tools are simple and reliable regardless the observer/operator's level of training.

Pulmonary vessel volume in idiopathic pulmonary fibrosis compared with healthy controls aged > 50 years

Idiopathic pulmonary fibrosis (IPF) is characterised by progressive fibrosing interstitial pneumonia with an associated irreversible decline in lung function and quality of life. IPF prevalence increases with age, appearing most frequently in patients aged > 50 years. Pulmonary vessel-like volume (PVV) has been found to be an independent predictor of mortality in IPF and other interstitial lung diseases, however its estimation can be impacted by artefacts associated with image segmentation methods and can be confounded by adjacent fibrosis. This study compares PVV in IPF patients (N = 21) with PVV from a healthy cohort aged > 50 years (N = 59). The analysis includes a connected graph-based approach that aims to minimise artefacts contributing to calculation of PVV. We show that despite a relatively low extent of fibrosis in the IPF cohort (20% of the lung volume), PVV is 2-3 times higher than in controls. This suggests that a standardised method to calculate PVV that accounts for tree connectivity could provide a promising tool to provide early diagnostic or prognostic information in IPF patients and other interstitial lung disease.

Quantitative texture-based analysis of pulmonary parenchymal features on chest CT: comparison with densitometric indices and short-term effect of changes in smoking habit

Purpose

To investigate the correlations between densitometric and CALIPER-derived indices of pulmonary emphysema and their change in the short-term period for groups of patients with different smoking habits.

Method

This retrospective study included 284 subjects from the ITALUNG trial (198 men and 86 women; mean age±sd, 60±4) who underwent low-dose chest CT at baseline and 2-year follow-up. Subjects were divided in four groups (persistent smokers, restarters, quitters, and former smokers) according to their smoking habit at baseline and follow-up. Densitometric and texture analyses were performed, using CALIPER software. A correlation analysis was conducted between CALIPER-derived low-attenuation-areas (LAAs) and densitometric indices, including the 15th percentile of the whole-lung attenuation histogram (Perc15) and the relative areas below −950HU (RA950). Densitometric indices and LAAs were evaluated at baseline and variation assessed longitudinally with comparisons between groups with different smoking habit. Further analysis of parenchymal changes per pulmonary zone was performed.

Results

LAAs were strongly correlated with Perc15 (rs=0.81; p<0.001) and RA950 (rs=0.905; p<0.001). At baseline, the group of smokers showed higher Perc15, lower RA950, lower LAAs (particularly mild sub-class of LAAs) than the group of ex-smokers (p<0.001). At 2-year follow-up, densitometric indices and LAAs increased in persistent smokers, former smokers and quitters (p<0.05). The progression was larger and statistically more significant in quitters (p<0.001).

Conclusion

CALIPER texture analysis provides an objective measure comparable to traditional density/histogram features to assess the lung parenchymal changes in relation to different smoking habit.

POS0325 RADIOMIC BIOMARKER OF PULMONARY VASCULAR RELATED STRUCTURES PREDICTS MORTALITY IN SYSTEMIC SCLEROSIS

Background:

Quantitative computed tomography (QCT) extracts features from high-resolution CT scans and quantifies lung parenchymal and vascular abnormalities which may not be discernable by qualitative review. The threshold values of individual parenchymal abnormalities and vascular features measured by QCT methods which associate with mortality in systemic sclerosis (SSc) are currently unknown.

Objectives:

To determine whether QCT measures, specifically pulmonary parenchymal abnormalities and pulmonary vascular related structures (PVRS), can predict mortality in SSc and to determine the optimal quantitative thresholds for those parameters.

Methods:

A total of 133 subjects (76% women) meeting 2013 ACR/EULAR classification criteria for SSc with a baseline CT within 3 years of diagnosis were retrospectively identified for inclusion. CALIPER (Computer-Aided Lung Informatics for Pathology Evaluation and Rating) was used to quantitatively measure volume of ground glass opacities (GGO), reticular densities, and honeycombing (HC). Total interstitial lung disease (ILD) was the summation of these features. PVRS was also quantified using CALIPER. Values for each feature were expressed as a percentage of total lung volume. Cox models evaluated the hazard ratio (HR) for mortality for each parameter adjusting for age at SSc diagnosis, sex, diffuse SSc subtype, and history of smoking. The optimal thresholds for mortality prediction for each parameter were determined using consensus between 4 methods: Contal and O’Quigley Method, Cox Model Hazard Ratio, Cox Model Wald P-value, and False Discovery Rate. The c-statistic was used to assess each models’ ability to predict mortality.

Results:

Mean ±SD for age at SSc diagnosis was 61 ± 13 years and length of follow-up was 4.7 ± 3.0 years. There were 32 deaths (24%). A Cox model including age (HR 1.05, 95% CI: 1.01-1.09), female sex (HR 0.49, 95% CI: 0.22-1.08), diffuse SSc subtype (HR 1.50, 95% CI: 0.69-3.30), and history of smoking (HR 2.09, 95% CI: 0.97-4.53) (Model 1) significantly predicted mortality (C-statistic 0.72, 95% CI: 0.63-0.81). Adjusting for Model 1, reticular densities% (HR 1.19, 95% CI: 1.05-1.35), total ILD% (HR 1.02, 95% CI: 1.00-1.03), and PVRS% (HR 1.19, 95% CI: 1.05-1.35) were associated with mortality on univariable analyses; GGO% (HR 1.01, 95% CI: 0.98-1.04) was not significantly associated with mortality. The optimal thresholds for mortality prediction were then determined and were as follows: GGO=20%, reticular densities=8%, total ILD=20%, and PVRS=5%. While the risk of mortality was significantly increased in subjects with GGO ≥20% (HR 2.70, 95% CI: 1.21-6.05), reticular densities ≥8% (HR 4.64, 95% CI: 1.68-12.81), and total ILD ≥20% (2.59, 95% CI: 1.12-5.99), these baseline thresholds did not improve upon mortality prediction when added individually to Model 1 (C-statistic 0.73 for each). PVRS ≥5%, which had an over six-fold increase in mortality (HR 6.42, 95% CI: 2.60-15.88), did improve mortality prediction when added to Model 1 (C-statistic 0.78, 95% CI: 0.70-0.86).

Conclusion:

PVRS strongly associates with early mortality in patients with SSc and represents a novel radiomic biomarker that provides prognostic information on mortality beyond pulmonary parenchymal abnormalities. CALIPER derived PVRS quantifies CT data through a function that defines connected tubular branching structures. This extracts pulmonary arteries and veins from the adjacent parenchyma but could potentially also include regions of adjoining of fibrosis.1 Larger studies examining the association between PVRS and progression of cardiopulmonary disease are warranted.

References:

[1]Jacob J, Bartholmai BJ, Rajagopalan S, et al. Predicting Outcomes in Idiopathic Pulmonary Fibrosis Using Automated Computed Tomographic Analysis. Am J Respir Crit Care Med 2018;198:767-76.

Acknowledgements:

This project was supported by the Mayo Clinic Margaret Harvey Schering Clinician Career Development Award.

Disclosure of Interests:

Alicia Hinze: None declared, Yasser Radwan: None declared, Mamoun Elnagar: None declared, Reto Kurmann: None declared, Shreyasee Amin: None declared, Robert Vassallo Grant/research support from: Pfizer, Bristol Myers Squibb, Sun Pharma, Cynthia S. Crowson: None declared, Brian Bartholmai Consultant of: AstraZenica, Boehringer Ingelheim, Promedior LLC (all <$5,000 annually)

Automated computed tomography quantification of fibrosis predicts prognosis in combined pulmonary fibrosis and emphysema in a real-world setting: a single-centre, retrospective study

BACKGROUND

Combined pulmonary fibrosis and emphysema (CPFE) is a heterogeneous clinico-radiological syndrome without a consensus definition. There are limited data on the relation between the amount of parenchymal fibrosis and prognosis. In this study, we assessed the prognostic implications of the extent of fibrosis assessed by an automated quantitative computed tomography (CT) technique and the radiological and functional change over time in patients with a broad spectrum of fibrotic interstitial lung diseases (ILDs) encountered in a real-world setting.

METHODS

We conducted a single-centre, retrospective study of 228 consecutive patients with CPFE, encountered from 2007 to 2015 at Kameda Medical Center, Chiba, Japan. We investigated the prognostic value of automated CT fibrosis quantification and the subsequent course of CPFE.

RESULTS

Among 228 patients with CPFE, 89 had fibrosis affecting < 5% of their lungs, 54 had 5 to < 10% fibrosis, and 85 had ≥ 10% fibrosis at the time of diagnosis. Lower volume of fibrosis correlated with lower rates of mortality and acute exacerbation (p < 0.001). In particular, among those with < 5% fibrosis, only 4.5% died and none experienced acute exacerbation during follow-up, whereas 57.6% and 29.4% of those with ≥ 10% fibrosis experienced death and acute exacerbation, respectively. Although, the ≥ 10% fibrosis group had the poorest overall survival as well as the highest incidence of acute exacerbation, the incidence of decline in pulmonary function tests, change per year in total lung volume, and progression of fibrosis on chest CT was highest in the 5 to < 10% fibrosis group. The Cox proportional hazard model for CPFE progression (defined by composite criteria of death, acute exacerbation, and decline in forced vital capacity or diffusing capacity) showed fibrosis proportion was a risk factor independent of age, sex, smoking pack-years, the Charlson Comorbidity Index, lung cancer, connective tissue disease, and idiopathic pulmonary fibrosis.

CONCLUSIONS

Less severe (< 5%) fibrosis at baseline was associated with disease stability and better prognosis compared to more severe fibrosis in CPFE occurring with fibrotic ILDs. Further studies including a validation cohort will be needed. Trial Registration Retrospectively registered.

SAT0306 SEMIQUANTITATIVE AND QUANTITATIVE ANALYSIS OF LUNG CT IN THE ASSESSMENT OF INTERSTITIAL LUNG DISEASE IN IDIOPATHIC INFLAMMATORY MYOPATHIES WITH A FOCUS ON ANTISYNTHETASE

Background:

Interstitial lung disease (ILD), is common in patients with idiopathic inflammatory myopathies (IIM) and strongly impact on patients’ morbidity and mortality. Patients with anti-aminoacyl-transfer RNA-synthetases (anti-ARS) antibodies are associated with an increased risk of ILD.

Objectives:

Defining the radiological characteristics of IIM patients, with special focus on serological groups, through qualitative, semiquantitative and quantitative analysis of lung CT.

Methods:

This was a prospective study conducted from 2016 to 2019. Ninety-eight IIM patients (35 men, 63 women) were included. Myositis specific autoantibodies (MSA) were assessed with Myositis Prophyle III (Euroimmune, Lubeck).

Each patient had a baseline CT; the total score of Warrick (WS) was obtained at semiquantitative analysis. The radiological scores ILD% (interstitial lung disease %) and PVRS% (pulmonary vascular related structure) were the result of quantitative analysis in 61 patients (CALIPER). Pulmonary function tests (PFTs) included TLC%, FVC% and DLCO% (65 patients). The analysis was conducted in the whole group and divided in subgroups based on their MSA pattern: in particular anti-ARS (Group 1) and patients negative to MSA (Group 2) were analysed.

Results:

Positive correlations between ILD% and PVRS% (Rho=0.916; ρ=0.000), WS and ILD% (Rho=0.663; ρ=0.000) and WS and PVRS% (Rho=0.637; ρ<0.001) were found.

The most relevant inverse correlations were found between ILD% and DLCO% (Rho=-0.590; ρ=0.001), PVRS% and DLCO% (Rho=-0.549; ρ<0.001) and WS and DLCO% (Rho=-0.471; ρ<0.001).

Statistically significant higher values of WS, ILD% and PVRS% were found in Group 1 (WS=15, ILD%=11 and PVRS%=3.5), compared to Group 2 (WS=2.5, ILD%=0.84 and PVRS%=2.2). NSIP pattern resulted dominant represented in the two groups (80% Group 1, 75% Group 2). No statistically significant differences of DLCO%, FVC% and TLCO% were found.

Conclusion:

The inverse correlations between the radiological scores and the functional data TLC% and DLCO% (ρ<0.001) confirm the role of lung CT in the clinical management of ILD in IIM patients, and may represent a promising tool for clinical trials. For the first time anti-ARS and serological negative patients were defined through qualitative, semiquantitative and quantitative analysis of lung CT. Further study should be conducted in order to define the prognostic value of the quantitative analysis of lung CT in the follow up of IIM patients.

Disclosure of Interests:

None declared

A quantitative method for measuring the changes of lung surface wave speed for assessing disease progression of interstitial lung disease

Lung ultrasound surface wave elastography (LUSWE) is a novel non-invasive technique for measuring superficial lung tissue stiffness. The purpose of the study described here was to develop LUSWE for assessment of progression in patients with interstitial lung disease (ILD). In this study, LUSWE was used to measure changes in lung surface wave speeds at 100, 150 and 200 Hz through six intercostal lung spaces for 52 patients with ILD. The mean age was 63.1 ± 12.0 y (range: 20-85, 23 male and 29 female). The follow-up interval was 9.2 ± 3.5 mo depending on each patient's return appointment and availability. For each patient, disease progression between the baseline and follow-up tests was evaluated clinically using a 7-point Likert scale comprising three grades of improvement (mild, moderate, marked), unchanged status and three grades of worsening (mild, moderate, marked). Clinical assessments were based on changes in pulmonary function tests together with high-resolution computed tomography, echocardiography and clinical evaluations. This study illustrates the correlations between changes in lung surface wave speed and clinical assessments. Correlations of changes in lung surface wave speed at lower lateral and posterior portions of the lung portions with clinical assessments were good. LUSWE provides quantitative global and regional changes in lung surface wave speed that may be useful for quantitative assessment of progression of ILD.

Development of data integration and visualization tools for the Department of Radiology to display operational and strategic metrics

Visualizing process metrics can help identify targets for improvement initiatives. Dashboards and scorecards are tools to visualize important metrics in an easily interpretable manner. We describe the development of two visualization systems: a dashboard to provide real-time situational awareness to frontline coordinators, and a scorecard to display aggregate monthly performance metrics for strategic process improvement efforts. Both systems were designed by a multidisciplinary team of physicians, allied health staff, engineers and information technology specialists. We describe the process of defining important metrics, gathering and cleaning data, and designing the visualization interfaces. We also describe some improvement initiatives that stemmed. These systems were implemented in our hospital and improved the availability of data to our staff and leadership, making performance gaps visible and generating new targets for quality improvement projects.

Lung Ultrasound Surface Wave Elastography for Assessing Interstitial Lung Disease

OBJECTIVE

Our goal is to translate lung ultrasound surface wave elastography (LUSWE) for assessing patients with interstitial lung disease (ILD) and various connective tissue diseases including systemic sclerosis (SSc).

METHODS

LUSWE was used to measure the surface wave speed of lung at 100, 150, and 200 Hz through six intercostal lung spaces for 91 patients with ILD and 30 healthy control subjects. In addition, skin viscoelasticity was measured on both forearms and upper arms for patients and controls.

RESULTS

The surface wave speeds of patients' lungs were significantly higher than those of control subjects. Patient skin elasticity and viscosity were significantly higher than those of control subjects. In dividing ILD patients into two groups, ILD with SSc patients and ILD without SSc patients, significant differences between each patient group with the control group were found for both the lung and skin. No significant differences were found between the two patient groups, although there were some differences at a few locations and at 100 Hz for skin viscoelasticity.

CONCLUSION

Significant differences of surface wave speed were found between ILD patients and healthy control subjects for both the lung and skin.

SIGNIFICANCE

LUSWE may be useful for assessing ILD and SSc and screening early stage patients.

Effect of Recombinant Human Pentraxin 2 vs Placebo on Change in Forced Vital Capacity in Patients With Idiopathic Pulmonary Fibrosis: A Randomized Clinical Trial

IMPORTANCE

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease with poor prognosis. Approved therapies do not halt disease progression.

OBJECTIVE

To determine the effect of recombinant human pentraxin 2 vs placebo on change from baseline to week 28 in mean forced vital capacity (FVC) percentage of predicted value.

DESIGN, SETTING, AND PARTICIPANTS

Phase 2, randomized, double-blind, placebo-controlled trial conducted at 18 sites in 7 countries of eligible patients with IPF (N = 117; aged 40-80 years; FVC ≥50% and ≤90% predicted; ratio of forced expiratory volume in the first second/FVC >0.70; diffusing capacity for carbon monoxide [Dlco] ≥25% and ≤90% predicted; and distance of ≥150 m on the 6-minute walk test). Study period was August 2015-May 2017.

INTERVENTIONS

Patients were randomized to receive either recombinant human pentraxin 2 (10 mg/kg intravenous every 4 weeks, n = 77) or placebo (n = 39) for 24 weeks, and stratified by concurrent IPF treatment status.

MAIN OUTCOMES AND MEASURES

The primary end point was the least-squares mean change in FVC percentage of predicted value from baseline to week 28 (minimal clinically important difference, decline of 2%-6%). Secondary end points included mean change in lung volumes (total, normal, and interstitial lung abnormalities) on high-resolution computed tomography (HRCT) and 6-minute walk distance (minimal clinically important difference, 24-45 m).

RESULTS

Of 117 randomized patients, 116 received at least 1 dose of study drug (mean age, 68.6 years; 81.0% men; mean time since IPF diagnosis, 3.8 years), and 111 (95.7%) completed the study. The least-squares mean change in FVC percentage of predicted value from baseline to week 28 in patients treated with recombinant human pentraxin 2 was -2.5 vs -4.8 for those in the placebo group (difference, +2.3 [90% CI, 1.1 to 3.5]; P = .001). No significant treatment differences were observed in total lung volume (difference, 93.5 mL [90% CI, -27.7 to 214.7]), quantitative parenchymal features on HRCT (normal lung volume difference, -1.2% [90% CI, -4.4 to 1.9]; interstitial lung abnormalities difference, 1.1% [90% CI, -2.2 to 4.3]), or measurement of Dlco (difference, -0.4 [90% CI, -2.6 to 1.7]). The change in 6-minute walk distance was -0.5 m for patients treated with recombinant human pentraxin 2 vs -31.8 m for those in the placebo group (difference, +31.3 m [90% CI, 17.4 to 45.1]; P < .001). The most common adverse events in the recombinant human pentraxin 2 vs placebo group were cough (18% vs 5%), fatigue (17% vs 10%), and nasopharyngitis (16% vs 23%).

CONCLUSIONS AND RELEVANCE

In this preliminary study, recombinant human pentraxin 2 vs placebo resulted in a slower decline in lung function over 28 weeks for patients with idiopathic pulmonary fibrosis. Further research should more fully assess efficacy and safety.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02550873.

Computer Aided Nodule Analysis and Risk Yield (CANARY) characterization of adenocarcinoma: radiologic biopsy, risk stratification and future directions

The majority of incidentally and screen-detected lung cancers are adenocarcinomas. Optimal management of these tumors is clinically challenging due to variability in tumor histopathology and behavior. Invasive adenocarcinoma (IA) is generally aggressive while adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) may be extremely indolent. Computer Aided Nodule Analysis and Risk Yield (CANARY) is a quantitative computed tomography (CT) analysis tool that allows non-invasive assessment of tumor characteristics. This analysis may obviate the need for tissue biopsy and facilitate the risk stratification of adenocarcinoma of the lung. CANARY was developed by unsupervised machine learning techniques using CT data of histopathologically-characterized adenocarcinomas of the lung. This technique identified 9 distinct exemplars that constitute the spectrum of CT features found in adenocarcinoma of the lung. The distributions of these features in a nodule correlate with histopathology. Further automated clustering of CANARY nodules defined three distinct groups that have distinctly different post-resection disease free survival (DFS). CANARY has been validated within the NLST cohort and multiple other cohorts. Using semi-automated segmentation as input to CANARY, there is excellent repeatability and interoperator correlation of results. Confirmation and longitudinal tracking of indolent adenocarcinoma with CANARY may ultimately add decision support in nuanced cases where surgery may not be in the best interest of the patient due to competing comorbidity. Currently under investigation is CANARY's role in detecting differing driver mutations and tumor response to targeted chemotherapeutics. Combining the results from CANARY analysis with clinical information and other quantitative techniques such as analysis of the tumor-free surrounding lung may aid in building more powerful predictive models. The next step in CANARY investigation will be its prospective application, both in selecting low-risk stage 1 adenocarcinoma for active surveillance and investigation in selecting high-risk early stage adenocarcinoma for adjuvant therapy.

An Ultrasound Surface Wave Technique for Assessing Skin and Lung Diseases

Systemic sclerosis (SSc) is a multi-organ connective tissue disease characterized by immune dysregulation and organ fibrosis. Severe organ involvement, especially of the skin and lung, is the cause of morbidity and mortality in SSc. Interstitial lung disease (ILD) includes multiple lung disorders in which the lung tissue is fibrotic and stiffened. The purpose of this study was to translate ultrasound surface wave elastography (USWE) for assessing patients with SSc and/or ILD via measuring surface wave speeds of both skin and superficial lung tissue. Forty-one patients with both SSc and ILD and 30 healthy patients were enrolled in this study. An external harmonic vibration was used to generate the wave propagation on the skin or lung. Three excitation frequencies of 100, 150 and 200 Hz were used. An ultrasound probe was used to measure the wave propagation in the tissue non-invasively. Surface wave speeds were measured on the forearm and upper arm of both left and right arm, as well as the upper and lower lungs, through six intercostal spaces of patients and healthy patients. Viscoelasticity of the skin was calculated by the wave speed dispersion with frequency using the Voigt model. The magnitudes of surface wave speed and viscoelasticity of patients' skin were significantly higher than those of healthy patients (p <0.0001) for each location and each frequency. The surface wave speeds of patients' lung were significantly higher than those of healthy patients (p <0.0001) for each location and each frequency. USWE is a non-invasive and non-ionizing technique for measuring both skin and lung surface wave speed and may be useful for quantitative assessment of SSc and/or ILD.

Lung Ultrasound Surface Wave Elastography: A Pilot Clinical Study

A lung ultrasound surface wave elastography (LUSWE) technique is developed to measure superficial lung tissue elastic properties. The purpose of this paper was to translate LUSWE into clinical studies for assessing patients with interstitial lung disease (ILD) and present the pilot data from lung measurements on 10 healthy subjects and 10 patients with ILD. ILD includes multiple lung disorders in which the lung tissue is distorted and stiffened by tissue fibrosis. Chest radiography and computed tomography are the most commonly used techniques for assessing lung disease, but they are associated with radiation and cannot directly measure lung elastic properties. LUSWE provides a noninvasive and nonionizing technique to measure the elastic properties of superficial lung tissue. LUSWE was used to measure regions of both lungs through six intercostal spaces for patients and healthy subjects. The data are presented as wave speed at 100, 150, and 200 Hz at the six intercostal spaces. As an example, the surface wave speeds are, respectively, 1.88 ± 0.11 m/s at 100 Hz, 2.74 ± 0.26 m/s at 150 Hz, and 3.62 ± 0.13 m/s at 200 Hz for a healthy subject in the upper right lung; this is in comparison to measurements from an ILD patient of 3.3 ± 0.37 m/s at 100 Hz, 4.38 ± 0.33 m/s at 150 Hz, and 5.24 ± 0.44 m/s at 200 Hz in the same lung space. Significant differences in wave speed between healthy subjects and ILD patients were found. LUSWE is a safe and noninvasive technique which may be useful for assessing ILD.

Imaging informatics: challenges in multi-site imaging trials

Multi-site imaging research has several specialized needs that are substantially different from what is commonly available in clinical imaging systems. An attempt to address these concerns is being led by several institutes including the National Institutes of Health and the National Cancer Institute. With the exception of results reporting (which has an infrastructure for standard reports, albeit with several competing lexicons), medical imaging has been largely standardized by the efforts of DICOM, HL7, and IHE. What are not well developed in this area are the tools required for multi-site imaging collaboration and data mining. The goal of this paper is to identify existing clinical interoperability methods that can be used to harmonize the research and clinical worlds, and identify gaps where they exist. To do so, we will detail the approaches of a specific multi-site trial, point out the current deficiencies and workarounds developed in that trial, and finally point to work that seeks to address multi-site imaging challenges.

Airway count and emphysema assessed by chest CT imaging predicts clinical outcome in smokers

BACKGROUND

Recently, it has been shown that emphysematous destruction of the lung is associated with a decrease in the total number of terminal bronchioles. It is unknown whether a similar decrease is visible in the more proximal airways. We aimed to assess the relationships between proximal airway count, CT imaging measures of emphysema, and clinical prognostic factors in smokers, and to determine whether airway count predicts the BMI, airflow obstruction, dyspnea, and exercise capacity (BODE) index.

METHODS

In 50 smokers, emphysema was measured on CT scans and airway branches from the third to eighth generations of the right upper lobe apical bronchus were counted manually. The sum of airway branches from the sixth to eighth generations represented the total airway count (TAC). For each subject, the BODE index was determined. We used logistic regression to assess the ability of TAC to predict a high BODE index (≥ 7 points).

RESULTS

TAC was inversely associated with emphysema (r = -0.54, P < .0001). TAC correlated with the modified Medical Research Council dyspnea score (r = -0.42, P = .004), FEV(1)% predicted (r = 0.52, P = .0003), 6-min walk distance (r = 0.36, P = .012), and BODE index (r = -0.55, P < .0001). The C-statistics, which correspond to the area under the receiver operating characteristic curve, for the ability of TAC alone and TAC, emphysema, and age to predict a high BODE index were 0.84 and 0.92, respectively.

CONCLUSIONS

TAC is lower in subjects with greater emphysematous destruction and is a predictor of a high BODE index. These results suggest that CT imaging-based TAC may be a unique COPD-related phenotype in smokers.

Gender influences Health-Related Quality of Life in IPF

BACKGROUND

HRQL in IPF patients is impaired. Data from other respiratory diseases led us to hypothesize that significant gender differences in HRQL in IPF also exist.

METHODS

Data were drawn from the NIH-sponsored Lung Tissue Research Consortium (LTRC). Demographic and pulmonary physiology data along with MMRC, SF-12, and SGRQ scores from women vs. men were compared with two-sample t-tests. Multivariate linear regression was used to examine the association between SF-12 component scores and gender while adjusting for other relevant variables.

RESULTS

The study sample consisted of 147 men and 74 women. Among several baseline variables, only DL(CO)% predicted differed between women and men, (43.7 vs. 38.0, p=0.03). In general, men exhibited lower (better) MMRC scores (1.7 vs. 2.4, p=0.02), particularly those with milder disease as measured by DL(CO)% predicted. In an adjusted analysis, SF-12 PCS scores in men were lower (worse) than women (p=0.01), an effect that was more pronounced in men with greater dyspnea scores. In a similar analysis, SF-12 MCS scores in women were lower than men (worse) (48.3 vs. 54.4, p=0.0004), an effect that was more pronounced in women with greater dyspnea scores.

CONCLUSIONS

Significant gender differences in HRQL exist in IPF. As compared to women, men reported less severe dyspnea, had worse SF-12 PCS scores, but better SF-12 MCS scores. Dyspnea appears to have a greater impact on the physical HRQL of men and the emotional HRQL of women. An improved understanding of the mechanism behind these differences is needed to better target interventions.

ROC study of four LCD displays under typical medical center lighting conditions

Nine observers reviewed a previously assembled library of 320 chest computed radiography (CR) images. Observers participated in four sessions, reading a different 1/4 of the sample on each of four liquid crystal displays: a 2-megapixel (MP) consumer color display, a 2-MP business color display, a 2-MP medical-grade gray display, and a 3-MP gray display. Each display was calibrated according to the DICOM Part 14 standard. The viewing application required observer log-in, then randomized the order of the subsample seen on the display, and timed the responses of the observer to render a 1-5 judgment on the absence or presence of ILD on chest CRs. Selections of 1-2 were considered negative, 3 was indeterminate, and 4-5 were positive. The order of viewing sessions was also randomized for each observer. The experiment was conducted under controlled lighting, temperature, and sound conditions to mimic conditions typically found in a patient examination room. Lighting was indirect, and illuminance at the display face was 195 +/- 8% lux and was monitored over the course of the experiment. The average observer sensitivity for the 2 MP color consumer, 2 MP business color, 2 MP gray, and 3 MP gray displays were 83.7%, 84.1%, 85.5%, and 86.7%, respectively. The only pairwise significant difference was between the 2-MP consumer color and the 2-MP gray (P = 0.05). Effect of order within a session was not significant (P = 0.21): period 1 (84.3%), period 2 (86.2%), period 3 (85.4%), period 4 (84.1%). Observer specificity for the various displays was not statistically significant (P = 0.21). Finally, a timing analysis showed no significant difference between the displays for the user group (P = 0.13), ranging from 5.3 s (2 MP color business) to 5.9 s (3 MP Gray). There was, however, a reduction in time over the study that was significant (P < 0.001) for all users; the group average decreased from 6.5 to 4.7 s per image. Physical measurements of the resolution, contrast, and noise properties of the displays were acquired. Most notably, the noise of the displays varied by 3.5x between the lowest and highest noise displays. Differences in display noise were indicative of observer performance. However, the large difference in the magnitude of the noise was not predictive of the small difference (3%) in the observer sensitivity for various displays. This is likely because detection of interstitial lung disease is limited by "anatomical noise" rather than display or x-ray image noise.

SCAR R&D Symposium 2003: comparing the efficacy of 5-MP CRT versus 3-MP LCD in the evaluation of interstitial lung disease

The efficacy of two medical-grade, self-calibrating, gray scale displays were compared with regard to impact on sensitivity and specificity for the detection of interstitial lung disease (ILD) on computed radiographs (CR). The displays were a 5-megapixel (MP) cathode ray tube (CRT) device and a 3-MP liquid crystal display (LCD). A sample consisting of 230 anteroposterior (AP), posteroanterior (PA), and lateral views of the chest with CT-proven findings characteristic for ILD as well as 80 normal images were compared. This double-blinded trial produced a sample sufficient to detect if the sensitivity of the LCD was 10% or more reduced (one-sided) from the "gold standard" CRT display. Both displays were calibrated to the DICOM gray scale standard and the coefficient of variation of the luminance function varied less than 2% during the study. Five board-certified radiologists specializing in thoracic radiology interpreted the sample on both displays and the intraobserver Az (area under the ROC curve) showed no significant correlation to the display used. In addition, an interobserver kappa analysis showed that the relative disagreement between any observer pair remained relatively constant between displays, and thus was display invariant. This study demonstrated there is no significant change in observer performance sensitivity on 5-MP CRT versus 3-MP LCD displays for CR examinations demonstrating ILD of the chest.

Computer-aided detection and diagnosis at the start of the third millennium

Computer-aided diagnosis has been under development for more than 3 decades. The rate of progress appears exponential, with either recent approval or pending approval for devices focusing on mammography, chest radiographs, and chest CT. Related technologies improve diagnosis for many other types of medical images including virtual colonography, vascular imaging, as well as automated quantitation of image-derived metrics. A variety of techniques are currently employed with success, likely reflecting the variety of imagery used, as well as the variety of tasks. Most areas of medical imaging have had efforts at computer assistance, and some have even received FDA approval and can be reimbursed. We anticipate that the rapid advance of these technologies will continue, and that application will broaden to cover much of medical imaging. Acceptance of, and integration of computer-aided diagnosis technology with the electronic radiology practice is a current challenge. These challenges will be overcome, and we expect that computer-aided diagnosis will be routinely applied to medical images.