Effect of aging on lung structure in vivo: assessment with densitometric and fractal analysis of high-resolution computed tomography data

Prospective cross-organ analysis for the causes of fever and increased inflammatory response after endoscopic resection

OBJECTIVES

Fever and increased inflammatory responses sometimes occur following endoscopic resection (ER). However, the differences in causes according to the organ are scarcely understood, and several modified ER techniques have been proposed. Therefore, we conducted a comprehensive prospective study to investigate the cause of fever and increased inflammatory response across multiple organs after ER.

METHODS

We included patients who underwent gastrointestinal endoscopic submucosal dissection (ESD) and duodenal endoscopic mucosal resection at our hospital between January 2020 and April 2022. Primary endpoints were fever and increased C-reactive protein (CRP) levels following ER. The secondary endpoints were risk factors for aspiration pneumonia. Blood tests and radiography were performed on the day after ER, and computed tomography was performed if the cause was unknown.

RESULTS

Among the 822 patients included, aspiration pneumonia was the most common cause of fever and increased CRP levels after ER of the upper gastrointestinal tract (esophagus, 53%; stomach, 48%; and duodenum, 71%). Post-ER coagulation syndrome was most common after colorectal ESD (38%). On multivariate logistic regression analysis, lesions located in the esophagus (odds ratio [OR] 3.57; P < 0.001) and an amount of irrigation liquid of ≥1 L (OR 3.71; P = 0.003) were independent risk factors for aspiration pneumonia.

CONCLUSIONS

Aspiration pneumonia was the most common cause of fever after upper gastrointestinal ER and post-ER coagulation syndrome following colorectal ESD. Lesions in the esophagus and an amount of irrigation liquid of ≥1 L were independent risk factors for aspiration pneumonia.

GOLD stage-specific phenotyping of emphysema and airway disease using quantitative computed tomography

Background

In chronic obstructive pulmonary disease (COPD) abnormal lung function is related to emphysema and airway obstruction, but their relative contribution in each GOLD-stage is not fully understood. In this study, we used quantitative computed tomography (QCT) parameters for phenotyping of emphysema and airway abnormalities, and to investigate the relative contribution of QCT emphysema and airway parameters to airflow limitation specifically in each GOLD stage.

Methods

Non-contrast computed tomography (CT) of 492 patients with COPD former GOLD 0 COPD and COPD stages GOLD 1-4 were evaluated using fully automated software for quantitative CT. Total lung volume (TLV), emphysema index (EI), mean lung density (MLD), and airway wall thickness (WT), total diameter (TD), lumen area (LA), and wall percentage (WP) were calculated for the entire lung, as well as for all lung lobes separately. Results from the 3rd-8th airway generation were aggregated (WT3-8, TD3-8, LA3-8, WP3-8). All subjects underwent whole-body plethysmography (FEV1%pred, VC, RV, TLC).

Results

EI was higher with increasing GOLD stages with 1.0 ± 1.8% in GOLD 0, 4.5 ± 9.9% in GOLD 1, 19.4 ± 15.8% in GOLD 2, 32.7 ± 13.4% in GOLD 3 and 41.4 ± 10.0% in GOLD 4 subjects (p < 0.001). WP3-8 showed no essential differences between GOLD 0 and GOLD 1, tended to be higher in GOLD 2 with 52.4 ± 7.2%, and was lower in GOLD 4 with 50.6 ± 5.9% (p = 0.010 - p = 0.960). In the upper lobes WP3-8 showed no significant differences between the GOLD stages (p = 0.824), while in the lower lobes the lowest WP3-8 was found in GOLD 0/1 with 49.9 ± 6.5%, while higher values were detected in GOLD 2 with 51.9 ± 6.4% and in GOLD 3/4 with 51.0 ± 6.0% (p < 0.05). In a multilinear regression analysis, the dependent variable FEV1%pred can be predicted by a combination of both the independent variables EI (p < 0.001) and WP3-8 (p < 0.001).

Conclusion

QCT parameters showed a significant increase of emphysema from GOLD 0-4 COPD. Airway changes showed a different spatial pattern with higher values of relative wall thickness in the lower lobes until GOLD 2 and subsequent lower values in GOLD3/4, whereas there were no significant differences in the upper lobes. Both, EI and WP5-8 are independently correlated with lung function decline.

S1P lyase inhibition prevents lung injury following high pressure-controlled mechanical ventilation in aging mice

Ventilator-induced Lung Injury (VILI) is characterized by hypoxia, inflammatory cytokine influx, loss of alveolar barrier integrity, and decreased lung compliance. Aging influences lung structure and function and is a predictive factor in the severity of VILI; however, the mechanisms of aging that influence the progression or increased susceptibility remain unknown. Aging impacts immune system function and may increase inflammation in healthy individuals. Recent studies suggest that the bioactive sphingolipid mediator sphingosine-1-phosphate (S1P) and the enzyme that degrades it S1P lyase (SPL) may be involved in lung pathologies including acute lung injury. It is unknown whether aging influences S1P and SPL expression that have been implicated in lung inflammation, injury, and cell apoptosis. We hypothesized that aging and injurious mechanical ventilation synergistically impair S1P levels and enhance S1P lyase (SPL) expression that amplifies alveolar barrier damage and diminishes pulmonary function. Young (2-3 mo) and old (20-25 mo) C57BL/6 mice were mechanically ventilated for 2 h using pressure-controlled mechanical ventilation (PCMV) at 45 cmH2O and 35 cmH2O, respectively. We assessed the impact of aging and PCMV on several indications of acute lung injury, immune cell recruitment, S1P levels and SPL activity. Furthermore, we evaluated the protective effects of inhibiting SPL by tetrahydroxybutylimidazol (THI) administration on the negative outcomes associated with aging and mechanical injury. PCMV exacerbated lung injury in old mice and increased neutrophil influx that was further exacerbated due to aging. SPL expression increased in the young and old ventilated mice and the old nonventilated group. THI treatment reduced several of the indicators of lung injury and resulted in elevated S1P levels in lung tissue and plasma from mice that were injured from mechanical ventilation. CD80 and CD206 activation markers of alveolar and interstitial macrophages were also influenced by THI. SPL inhibition may be a viable therapeutic approach for patients requiring mechanical ventilation by preventing or regulating the exaggerated inflammatory response and reducing lung injury.

Tongue cleaning in the elderly and its role in the respiratory and swallowing functions: Benefits and medical perspectives

Oral dysfunction, including oral uncleanness and decline in tongue motor function, tongue pressure and swallowing function, precedes frailty. The tongue's dorsum is a reservoir of oral microbiota, desquamated epithelial mucosa and leukocytes due to the multi-papillate anatomy, and leads to tongue coating. The tongue coating is frequently found in older adults because of hyposalivation, immunity's hypoactivity, diminished motor function and compromised tongue's pressure with age. Anaerobe-driven volatile sulphur compounds in tongue coating are a major cause of intra-oral malodor. Dysbiosis of the tongue-coating microbiome rather than the amount of microorganisms is associated with a risk of aspiration pneumonia. Daily tongue cleaning with a brush or scraper is an easy way to control tongue coating deposits and quality. Using mouth wash or rinse-containing germicides is also a way to control the microbiota of tongue coating. The tongue function is closely related to swallowing. Tongue and suprahyoid muscles are linked with respiratory muscles through the endothoracic fascia. The mechanical stimulation during the cleaning of the tongue may stimulate the respiratory muscles. An intervention trial revealed that tongue cleaning by mucosal brush improves tongue pressure, swallowing and respiratory function in old residents of nursing homes, suggesting a rehabilitative effect of tongue cleaning on the swallowing and respiratory functions, preventing aspiration pneumonia. This narrative review assesses the tongue-cleaning benefits for respiratory and swallowing functions and the possibility of preventing aspiration pneumonia.

Factors Associated with Age-Related Changes in Non-Smoking Urban Men and Women in China Determined by Low-Dose Computed Tomography Imaging

Background

Respiratory function usually worsens in the elderly with aging. This study aimed to retrospectively investigate tracheal changes caused by “normal aging” through use of low-dose CT (LDCT) in non-smoking asymptomatic urban residents and the related factors influencing tracheal changes.

Material/Methods

A total of 733 Chinese subjects who underwent LDCT were recruited. The trachea shape, width, and calcification degree of the tracheal wall were measured and compared between males and females and among different age groups. The effects of age, sex, trachea morphology, BMI, BP, GLU, TC, TG, HDL, and LDL on the width and calcification of tracheal wall were analyzed by multiple linear regression.

Results

Significant sex differences in trachea shape were found, as type II and type I were found mainly in the males and females, respectively. The values of anterior-posterior inner diameter (AP), left-right inner diameter (LR), width, and calcification score of tracheae in the males were higher than that in the females. In both males and females, trachea AP, wall width, and calcification scores increased with age, but this trend was not observed in tracheal LR. Age, sex, and trachea shape had significant effects on the width and calcification scores of tracheal walls, and trachea calcification was one of the factors influencing tracheal wall width.

Conclusions

Tracheal aging can be evaluated by measuring trachea shape, thickness, and the degree of calcification of the tracheal wall by LDCT, while sex and age should be taken into consideration comprehensively for judging normal trachea aging. In addition, obesity may aggravate trachea aging.

Progression of Emphysema and Small Airways Disease in Cigarette Smokers

BACKGROUND

Little is known about factors associated with emphysema progression in cigarette smokers. We evaluated factors associated with change in emphysema and forced expiratory volume in 1 second (FEV1) in participants with and without chronic obstructive pulmonary disease (COPD).

METHODS

This retrospective study included individuals participating in the COPD Genetic Epidemiology study who completed the 5-year follow-up, including inspiratory and expiratory computed tomography (CT) and spirometry. All paired CT scans were analyzed using micro-mapping, which classifies individual voxels as emphysema or functional small airway disease (fSAD). Presence and progression of emphysema and FEV1 were determined based on comparison to nonsmoker values. Logistic regression analyses were used to identify clinical parameters associated with disease progression.

RESULTS

A total of 3088 participants were included with a mean ± SD age of 60.7±8.9 years, including 72 nonsmokers. In all Global initiative for chronic Obstructive Lung Disease (GOLD) stages, the presence of emphysema at baseline was associated with emphysema progression (odds ratio [OR]: GOLD 0: 4.32; preserved ratio-impaired spirometry [PRISm]; 5.73; GOLD 1: 5.16; GOLD 2: 5.69; GOLD 3/4: 5.55; all p ≤0.01). If there was no emphysema at baseline, the amount of fSAD at baseline was associated with emphysema progression (OR for 1% increase: GOLD 0: 1.06; PRISm: 1.20; GOLD 1: 1.7; GOLD 3/4: 1.08; all p ≤ 0.03).In 1735 participants without spirometric COPD, progression in emphysema occurred in 105 (6.1%) participants and only 21 (1.2%) had progression in both emphysema and FEV1.

CONCLUSIONS

The presence of emphysema is an important predictor of emphysema progression. In patients without emphysema, fSAD is associated with the development of emphysema. In participants without spirometric COPD, emphysema progression occurred independently of FEV1 decline.

COVID-19 pneumonia and the pulmonary vasculature - a marriage made in hell

Automated analysis of medical images is not new [1–3]. Researchers in the respiratory sciences and, particularly, the field of interstitial lung diseases, have long enthused about the potential for computers to analyse medical images thereby revealing “signals” hitherto invisible to the human eye: an enthusiasm only enhanced by recent developments in machine learning and artificial intelligence [4–6]. By leveraging the central importance of computed tomography (CT) scanning for diagnosis, treatment decisions and prognostication, a key aim is to identify imaging biomarkers to more accurately phenotype disease and, in so doing, move a step closer to truly patient-centric medicine. Another goal is to apply novel imaging analyses to pathogenesis, disease “behaviour” and prognostication in the hope that this might unlock new therapeutic approaches. Given the digital nature of the data and the potentially myriad imaging patterns, frequently compounded by patient, therapeutic and disease-based factors, lung imaging is ideally suited to more sophisticated analytic approaches.

Quantitative CT of the pulmonary vasculature is potentially important in COVID-19 associated pneumoniahttps://bit.ly/3vUTTRM

Tongue cleaning maintains respiratory function in older individuals: A 1-year randomised controlled trial

OBJECTIVE

The aim of this 1-year longitudinal randomised controlled trial was to evaluate the effectiveness of tongue cleaning on the maintenance of respiratory function in older adults requiring care.

METHODS

The participants included 24 residents of two nursing homes in Kitakyushu, Japan. The participants were randomised to receive tongue cleaning with routine oral care (intervention group, n = 12), or routine oral care alone (control group, n = 12). Among the participants, three in the intervention group and four in the control group had cerebrovascular disease history, four in the intervention group and four in the control group had a history of cardiac disease, and five in the intervention group and four in the control group were without medical history. Respiratory function was assessed on the basis of the peak expiratory flow rate (PEFR). Tongue pressure, swallowing function, oral health status, activities of daily living and nutritional status were also measured at baseline and at the end of the 1-year follow-up period.

RESULTS

The number of analysed participants in each group was 12. In the control group, the PEFR (1.6 [0.4-4.2] L s^-1 vs 1.4 [0.4-3.2] L s^-1 , P = .034) and tongue pressure (16.4 [1.7-35.2] kPa vs 8.0 [1.4-38.6] kPa, P = .032) significantly declined after 1-year. However, the PEFR (1.5 [0.8-2.9] L s^-1 vs 1.6 [0.7-4.2] L s^-1 , P = .366) and tongue pressure (18.1 [4.2-37.1] kPa vs 16.1 [5.2-41] kPa, P = .307) were maintained in the intervention group. The change in the PEFR was significantly greater in the intervention group compared with the control group (0.130 [-0.45-1.70] L s^-1 vs -1.70 [-10.00-10.00] L s^-1 , P = .028).

CONCLUSION

Our findings suggest that tongue cleaning may help maintain tongue and respiratory function in older adults requiring care.

Impact of Tongue Pressure and Peak Expiratory Flow Rate on Nutritional Status of Older Residents of Nursing Homes in Japan: A Cross-Sectional Study

OBJECTIVES

Swallowing function is critical for continuing oral feeding to prevent frailty in older adults. In this study, we investigated the impact of tongue pressure and pulmonary function on the nutritional status of older adults.

DESIGN, SETTING, PARTICIPANTS

This cross-sectional study was conducted in Kitakyushu, Japan from August 2017 to November 2018. Fifty-two residents aged >65 years of age from three nursing care insurance facilities in Kitakyushu City, Japan were recruited.

MEASUREMENTS

Oral health status, swallowing function, nutritional status using a mini nutritional assessment short form (MNA-SF), cognitive function, activities of daily living, peak expiratory flow rate (PEFR) for pulmonary function, and tongue pressure were assessed. The associations between nutritional status and the above factors were analysed using a logistic regression model.

RESULTS

Participants were divided into two groups: well-nourished group (MNA-SF ≤12) and undernutrition group (MNA-SF <12). Multivariate logistic regression analysis revealed that the correlations of PEFR [odds ratio (OR) = 0.23, 95% confidence interval (CI) = 0.23-0.89 p=0.033) and tongue pressure (OR = 0.88, 95% CI = 0.88-0.99, p=0.029) remained significant even after adjustment with possible confounders.

CONCLUSION

Maximum tongue pressure and PEFR in older adults were significantly associated with their nutritional status. These findings suggest that maintaining oral and pulmonary function may be a preventive factor against a decrease in the nutritional status of older frail adults.

Atrial Rotor Dynamics Under Complex Fractional Order Diffusion

The mechanisms of atrial fibrillation (AF) are a challenging research topic. The rotor hypothesis states that the AF is sustained by a reentrant wave that propagates around an unexcited core. Cardiac tissue heterogeneities, both structural and cellular, play an important role during fibrillatory dynamics, so that the ionic characteristics of the currents, their spatial distribution and their structural heterogeneity determine the meandering of the rotor. Several studies about rotor dynamics implement the standard diffusion equation. However, this mathematical scheme carries some limitations. It assumes the myocardium as a continuous medium, ignoring, therefore, its discrete and heterogeneous aspects. A computational model integrating both, electrical and structural properties could complement experimental and clinical results. A new mathematical model of the action potential propagation, based on complex fractional order derivatives is presented. The complex derivative order appears of considering the myocardium as discrete-scale invariant fractal. The main aim is to study the role of a myocardial, with fractal characteristics, on atrial fibrillatory dynamics. For this purpose, the degree of structural heterogeneity is described through derivatives of complex order γ = α + jβ. A set of variations for γ is tested. The real part α takes values ranging from 1.1 to 2 and the imaginary part β from 0 to 0.28. Under this scheme, the standard diffusion is recovered when α = 2 and β = 0. The effect of γ on the action potential propagation over an atrial strand is investigated. Rotors are generated in a 2D model of atrial tissue under electrical remodeling due to chronic AF. The results show that the degree of structural heterogeneity, given by γ, modulates the electrophysiological properties and the dynamics of rotor-type reentrant mechanisms. The spatial stability of the rotor and the area of its unexcited core are modulated. As the real part decreases and the imaginary part increases, simulating a higher structural heterogeneity, the vulnerable window to reentrant is increased, as the total meandering of the rotor tip. This in silico study suggests that structural heterogeneity, described by means of complex order derivatives, modulates the stability of rotors and that a wide range of rotor dynamics can be generated.

Aging-related trajectories of lung function in the general population-The Doetinchem Cohort Study

The objective of this study was to explore trajectories of lung function decline with age in the general population, and to study the effect of sociodemographic and life style related risk factors, in particular smoking and BMI. For this purpose, we used data from the Doetinchem Cohort Study (DCS) of men and women, selected randomly from the general population and aged 20–59 years at inclusion in 1987–1991, and followed until the present. Participants in the DCS are assessed every five years. Spirometry has been performed as part of this assessment from 1994 onwards. Participants were included in this study if spirometric measurement of FEV₁, which in this study was the main parameter of interest, was acceptable and reproducible on at least one measurement round, leading to the inclusion of 5727 individuals (3008 females). Statistical analysis revealed three typical trajectories. The majority of participants followed a trajectory that closely adhered to the Global Lung Initiative Reference values (94.9% of men and 96.4% of women). Two other trajectories showed a more pronounced decline. Smoking and the presence of respiratory complaints were the best predictors of a trajectory with stronger decline. A greater BMI over the follow-up period was associated with a more unfavorable FEV₁ course both in men (β = -0.027 (SD = 0.002); P < 0.001) and in women (β = -0.008 (SD = 0.001); P < 0.001). Smokers at baseline who quit the habit during follow-up, showed smaller decline in FEV₁ in comparison to persistent smokers, independent of BMI change (In men β = -0.074 (SD = 0.020); P < 0.001. In women β = -0.277 (SD = 0.068); P < 0.001). In conclusion, three typical trajectories of age-related FEV1 decline could be distinguished. Change in the lifestyle related risk factors, BMI and smoking, significantly impact aging-related decline of lung function. Identifying deviant trajectories may help in early recognition of those at risk of a diagnosis of lung disease later in life.

Fractal Analysis May Improve the Preoperative Identification of Atypical Meningiomas

Background

There is no objective and readily accessible method for the preoperative determination of atypical characteristics of a meningioma grade.

Objective

To evaluate the feasibility of using fractal analysis as an adjunctive tool to conventional radiological techniques in visualizing histopathological features of meningiomas.

Methods

A group of 27 patients diagnosed with atypical (WHO grade II) meningioma and a second group of 27 patients with benign (WHO grade I) meningioma were enrolled in the study. Preoperative brain magnetic resonance (MR) studies (T1-wieghted, post-gadolinium) were processed and analyzed to determine the average fractal dimension (FDa) and maximum fractal dimension (FDm) of the contrast-enhancing region of the tumor using box-count method. FDa and FDm as well as particular radiological features were included in the logistic regression model as possible predictors of malignancy.

Results

The cohort consisted of 34 women and 20 men, mean age of 62 ± 15 yr. Fractal analysis showed good interobserver reproducibility (Kappa >0.70). Both FDa and FDm were significantly higher in the atypical compared to the benign meningioma group (P < .0001). Multivariate logistic regression model reached statistical significance with P = .0001 and AUC = 0.87. The FDm, which was greater than 1.31 (odds ratio [OR], 12.30; P = .039), and nonskull base localization (OR, .052; P = .015) were confirmed to be statistically significant predictors of the atypical phenotype.

Conclusion

Fractal analysis of preoperative MR images appears to be a feasible adjunctive diagnostic tool in identifying meningiomas with potentially aggressive clinical behavior.

Recent advances in managing/understanding meningioma

Meningiomas are the most common adult primary intracranial tumor. Despite their higher incidence, there have not—until recently—been as many advances in understanding and managing meningiomas. Thus far, two broad classes of meningiomas have emerged on the basis of their mutational profile: those driven by neurofibromatosis 2 (NF2) inactivation and those with non-NF2 driver gene alterations, such as mammalian target of rapamycin and Hedgehog, Wingless/b-catenin, Notch, transforming growth factor-b receptor, mitogen-activated protein kinase, and phospholipase C pathway alterations. In addition to improvements in molecular diagnostics, advances in imaging are being studied to better predict tumor behavior, stratify risk, and potentially monitor for disease response. Management consists primarily of surgery and radiation therapy and there has been limited success from medical therapies, although novel targeted agents are now in clinical trials. Advances in imaging and understanding of the genetic makeup of meningiomas demonstrate the huge potential in revolutionizing the classification, diagnosis, management, and prognosis of meningiomas..

Metrics of lung tissue heterogeneity depend on BMI but not age

Altered parenchymal microstructure and complexity have been observed in older age. How to distinguish between healthy, expected changes and early signs of pathology remains poorly understood. An objective quantitative analysis of computed tomography imaging was conducted to compare mean lung density, tissue density distributions, and tissue heterogeneity in 16 subjects, 8 aged >60 yr who were gender and body mass index matched with 8 subjects aged <30 yr. Subjects had never been smokers, with no prior respiratory disease, and no radiologically identified abnormalities on computed tomography. Volume-controlled breath hold imaging acquired at 80% vital capacity (end inspiration) and 55% vital capacity (end expiration) were used for analysis. Mean lung density was not different between the age groups at end inspiration ( P = 0.806) but was larger in the younger group at end expiration (0.26 ± 0.033 vs. 0.22 ± 0.026, P = 0.008), as is expected due to increased air trapping in the older population. However, gravitational gradients of tissue density did not differ with age; the only difference in distribution of tissue density between the two age groups was a lower density in the apices of the older group at end expiration. The heterogeneity of the lung tissue assessed using two metrics showed significant differences between end inspiration and end expiration, no dependence on age, and a significant relationship with body mass index at both lung volumes when heterogeneity was calculated using quadtree decomposition but only at end expiration when using a fractal dimension. NEW & NOTEWORTHY Changes to lung tissue heterogeneity can be a normal part of aging but can also be an early indicator of disease. We use novel techniques, which have previously not been used on thoracic computed tomography imaging, to quantify lung tissue heterogeneity in young and old healthy subjects. Our results show no dependence on age but a significant correlation with body mass index.

Regional Distribution of Pulmonary Blood Volume with Dual-Energy Computed Tomography: Results in 42 Subjects

RATIONALE AND OBJECTIVES

The noninvasive approach of lung perfusion generated from dual-energy computed tomography acquisitions has entered clinical practice. The purpose of this study was to analyze the regional distribution of iodine within distal portions of the pulmonary arterial bed on dual-source, dual-energy computed tomography examinations in a cohort of subjects without cardiopulmonary pathologies.

MATERIALS AND METHODS

The study population included 42 patients without cardiorespiratory disease, enabling quantitative and qualitative analysis of pulmonary blood volume after administration of a 40% contrast agent. Qualitative analysis was based on visual assessment. Quantitative analysis was obtained after semiautomatic division of each lung into 18 areas.

RESULTS

The iodine concentration did not significantly differ between the right (R) and left (L) lungs (P = .49), with a mean attenuation of 41.35 Hounsfield units (HU) and 41.14 HU, respectively. Three regional gradients of attenuation were observed between: (a) lung bases and apices (P < .001), linked to the conditions of examination (mean Δ: 6.23 in the R lung; 5.96 in the L lung); (b) posterior and anterior parts of the lung (P < .001) due to gravity (mean Δ: 11.92 in the R lung ; 15.93 in the L lung); and (c) medullary and cortical lung zones (P < .001) (mean Δ: 9.35 in the R lung ; 8.37 in the L lung). The intensity of dependent-nondependent (r = 0.42; P < .001) and corticomedullary (r = 0.58; P < .0001) gradients was correlated to the overall iodine concentration.

CONCLUSION

Distribution of pulmonary blood volume is influenced by physiological gradients and scanning conditions.

Lung densitometry: why, how and when

Lung densitometry assesses with computed tomography (CT) the X-ray attenuation of the pulmonary tissue which reflects both the degree of inflation and the structural lung abnormalities implying decreased attenuation, as in emphysema and cystic diseases, or increased attenuation, as in fibrosis. Five reasons justify replacement with lung densitometry of semi-quantitative visual scales used to measure extent and severity of diffuse lung diseases: (I) improved reproducibility; (II) complete vs. discrete assessment of the lung tissue; (III) shorter computation times; (IV) better correlation with pathology quantification of pulmonary emphysema; (V) better or equal correlation with pulmonary function tests (PFT). Commercially and open platform software are available for lung densitometry. It requires attention to technical and methodological issues including CT scanner calibration, radiation dose, and selection of thickness and filter to be applied to sections reconstructed from whole-lung CT acquisition. Critical is also the lung volume reached by the subject at scanning that can be measured in post-processing and represent valuable information per se. The measurements of lung density include mean and standard deviation, relative area (RA) at -970, -960 or -950 Hounsfield units (HU) and 1st and 15th percentile for emphysema in inspiratory scans, and RA at -856 HU for air trapping in expiratory scans. Kurtosis and skewness are used for evaluating pulmonary fibrosis in inspiratory scans. The main indication for lung densitometry is assessment of emphysema component in the single patient with chronic obstructive pulmonary diseases (COPD). Additional emerging applications include the evaluation of air trapping in COPD patients and in subjects at risk of emphysema and the staging in patients with lymphangioleiomyomatosis (LAM) and with pulmonary fibrosis. It has also been applied to assess prevalence of smoking-related emphysema and to monitor progression of smoking-related emphysema, alpha1 antitrypsin deficiency emphysema, and pulmonary fibrosis. Finally, it is recommended as end-point in pharmacological trials of emphysema and lung fibrosis.

The computed tomography-based fractal analysis of trabecular bone structure may help in detecting decreased quality of bone before urgent spinal procedures

BACKGROUND CONTEXT

To date, no reliable method is available to determine the parameters of bone density based on the routine spinal computed tomography (CT) in the emergency setup. We propose the use of fractal analysis to detect patients with poor quality of bone before urgent or semi-urgent spinal procedures.

PURPOSE

This study aimed to validate the hypothesis that the CT-based fractal analysis of the trabecular bone structure may help in detecting patients with poor quality of bone before urgent spinal procedures.

STUDY DESIGN

This is a retrospective analysis of prospectively collected data.

METHODS

Patients in whom the dual-energy x-ray absorptiometry (DEXA) scan and lumbar spine CT were performed at an interval of no more than 3 months were randomly selected from a prospectively collected database. Diagnostic axial CT scans of L2, L3, and L4 vertebrae were processed to determine the fractal dimension (FD) of the trabecular structure of each spinal level. Box-count method and ImageJ 1.49 software were used. The FD was compared with the results of the DEXA scan: bone mineral density (BMD) and T-score by mean of correlation coefficients. Receiver operating characteristic curve analysis was later performed to determine the cutoff value of FD.

RESULTS

A total of 102 vertebral levels obtained from 35 patients (mean age 60±18 years; 29 female) were analyzed. The FD was significantly higher in the group of patients with decreased bone density (DBD) (T-score<-1.0) (1.67 vs. 1.43; p<.0001) and negatively correlated with BMD (R Spearman, -0.53; p<.0001) and T-score (-0.49; p<.0001). Receiver operating characteristic curve analysis revealed that a cutoff value of FD>1.53 indicates DBD (p<.0001; area under the ROC curve [AUC], 0.84; 95% confidence interval [CI], 0.76-0.91).

CONCLUSIONS

This study shows that fractal analysis of the lumbar spine CT images may be used to determine bone density before spinal instrumentation (eg, metastatic or traumatic cord compression). Further prospective studies comparing results of the fractal analysis of CT scans with quantitative CT (qCT) are warranted.

Aging Airways: between Normal and Disease. A Multidimensional Diagnostic Approach by Combining Clinical, Functional, and Imaging Data

The lack of data on lung function decline in the aging process as well as the lack of gold standards to define obstructive and restrictive respiratory disease in older people point out the need for a multidimensional assessment and interpretation of the aging airways. By integrating clinical data together with morphologic and morphometric findings clinicians can assess the airways with a more comprehensive perspective, helpful in the interpretation of the "grey zone" between normal aging and disease. This review focuses on the value of a multidimensional approach in the study of the aging airways, including clinical findings, respiratory function tests, and imaging as parts of a whole. Nowadays this multidimensional diagnostic approach can be used in daily clinical practice. In next future, it can be implemented by the analysis of exhaled gases, post-processing imaging techniques, and genetic analysis, that will hopefully reduce the gaps in knowledge of normal aging and airway disease in older people.

Differential Regulation of the Extracellular Cysteine/Cystine Redox State (EhCySS) by Lung Fibroblasts from Young and Old Mice

Aging is associated with progressive oxidation of plasma cysteine (Cys)/cystine (CySS) redox state, expressed as E_hCySS. Cultured cells condition their media to reproduce physiological E_hCySS, but it is unknown whether aged cells produce a more oxidized extracellular environment reflective of that seen in vivo. In the current study, we isolated primary lung fibroblasts from young and old female mice and measured the media E_hCySS before and after challenge with Cys or CySS. We also measured expression of genes related to redox regulation and fibroblast function. These studies revealed that old fibroblasts produced a more oxidizing extracellular E_hCySS than young fibroblasts and that old fibroblasts had a decreased capacity to recover from an oxidative challenge due to a slower rate of reduction of CySS to Cys. These defects were associated with 10-fold lower expression of the Slc7a11 subunit of the xCT cystine-glutamate transporter. Extracellular superoxide dismutase (Sod3) was the only antioxidant or thiol-disulfide regulating enzyme among 36 examined that was downregulated in old fibroblasts by more than 2-fold, but there were numerous changes in extracellular matrix components. Thus, aging fibroblasts not only contribute to remodeling of the extracellular matrix but also have a profound effect on the extracellular redox environment.

Phenotype of Spirometric Impairment in an Aging Population

RATIONALE

The Global Lung Initiative (GLI) provides age-appropriate criteria for establishing spirometric impairment, including mild, moderate, and severe chronic obstructive pulmonary disease (COPD) and restrictive pattern, but its association with respiratory-related phenotypes has not been evaluated.

OBJECTIVES

To evaluate respiratory-related phenotypes in GLI-defined spirometric impairment.

METHODS

In COPDGene (N = 10,131 patients; age range, 45-81 yr; average smoking history, 44.3 pack-years), we evaluated spirometry, dyspnea (modified Medical Research Council grade, ≥2), poor respiratory health-related quality of life (St. George's Respiratory Questionnaire total score, ≥25), poor exercise performance (6-minute-walk distance, <391 m), bronchodilator reversibility (FEV1 change, >12% and ≥200 ml), and computed tomography-diagnosed emphysema and gas trapping (>5% and >15% of lung, respectively).

MEASUREMENTS AND MAIN RESULTS

GLI established normal spirometry in 5,100 patients (50.3%), mild COPD in 669 (6.6%), moderate COPD in 865 (8.5%), severe COPD in 2,522 (24.9%), and restrictive pattern in 975 (9.6%). Relative to normal spirometry, graded associations with respiratory-related phenotypes were found for mild, moderate, and severe COPD, with respective adjusted odds ratios (95% confidence intervals) as follows: dyspnea-1.31 (1.10-1.56), 2.20 (1.81-2.68), and 10.73 (8.04-14.33); poor respiratory health-related quality of life-1.49 (1.28-1.75), 2.69 (2.08-3.47), and 14.61 (10.09-21.17); poor exercise performance-1.11 (0.94-1.31), 1.58 (1.33-1.88), and 4.58 (3.42-6.12); bronchodilator reversibility-2.76 (2.24-3.40), 5.18 (4.29-6.27), and 6.21 (5.06-7.62); emphysema-4.86 (3.16-7.47), 6.41 (4.09-10.05), and 17.79 (10.79-29.32); and gas trapping-3.92 (3.12-4.93), 5.20 (3.82-7.07), and 16.28 (9.71-27.30). Restrictive pattern was also associated with multiple respiratory-related phenotypes at a level similar to moderate COPD, but it was otherwise not associated with emphysema (0.89 [0.60-1.32]) or gas trapping (1.15 [0.92-1.42]).

CONCLUSIONS

GLI-defined spirometric impairment establishes clinically meaningful respiratory disease, as validated by graded associations with respiratory-related phenotypes.

Phenotype of normal spirometry in an aging population

RATIONALE

In aging populations, the commonly used Global Initiative for Chronic Obstructive Lung Disease (GOLD) may misclassify normal spirometry as respiratory impairment (airflow obstruction and restrictive pattern), including the presumption of respiratory disease (chronic obstructive pulmonary disease [COPD]).

OBJECTIVES

To evaluate the phenotype of normal spirometry as defined by a new approach from the Global Lung Initiative (GLI), overall and across GOLD spirometric categories.

METHODS

Using data from COPDGene (n = 10,131; ages 45-81; smoking history, ≥10 pack-years), we evaluated spirometry and multiple phenotypes, including dyspnea severity (Modified Medical Research Council grade 0-4), health-related quality of life (St. George's Respiratory Questionnaire total score), 6-minute-walk distance, bronchodilator reversibility (FEV1 % change), computed tomography-measured percentage of lung with emphysema (% emphysema) and gas trapping (% gas trapping), and small airway dimensions (square root of the wall area for a standardized airway with an internal perimeter of 10 mm).

MEASUREMENTS AND MAIN RESULTS

Among 5,100 participants with GLI-defined normal spirometry, GOLD identified respiratory impairment in 1,146 (22.5%), including a restrictive pattern in 464 (9.1%), mild COPD in 380 (7.5%), moderate COPD in 302 (5.9%), and severe COPD in none. Overall, the phenotype of GLI-defined normal spirometry included normal adjusted mean values for dyspnea grade (0.8), St. George's Respiratory Questionnaire (15.9), 6-minute-walk distance (1,424 ft [434 m]), bronchodilator reversibility (2.7%), % emphysema (0.9%), % gas trapping (10.7%), and square root of the wall area for a standardized airway with an internal perimeter of 10 mm (3.65 mm); corresponding 95% confidence intervals were similarly normal. These phenotypes remained normal for GLI-defined normal spirometry across GOLD spirometric categories.

CONCLUSIONS

GLI-defined normal spirometry, even when classified as respiratory impairment by GOLD, included adjusted mean values in the normal range for multiple phenotypes. These results suggest that among adults with GLI-defined normal spirometry, GOLD may misclassify normal phenotypes as having respiratory impairment.

Pulmonary cysts identified on chest CT: are they part of aging change or of clinical significance?

OBJECTIVE

To investigate the prevalence and natural course of pulmonary cysts in a population-based cohort and to describe the CT image characteristics in association with participant demographics and pulmonary functions.

MATERIALS AND METHODS

Chest CT scans of 2633 participants (mean age 59.2 years; 50% female) of the Framingham Heart Study (FHS) were visually evaluated for the presence of pulmonary cysts and their image characteristics. These findings were correlated with participant demographics and results of pulmonary function tests as well as the presence of emphysema independently detected on CT. The interval change was investigated by comparison with previous CT scans (median interval 6.1 years).

RESULTS

Pulmonary cysts were seen in 7.6% (95% CI 6.6% to 8.7%; 200/2633). They were not observed in participants younger than 40 years old, and the prevalence increased with age. Multiple cysts (at least five) were seen in 0.9% of all participants. Participants with pulmonary cysts showed significantly lower body mass index (BMI) (p<0.001). Pulmonary cysts were most likely to appear solitary in the peripheral area of the lower lobes and remain unchanged or slightly increase in size over time. Pulmonary cysts showed no significant influence on pulmonary functions (p=0.07-0.6) except for diffusing capacity of the lung for carbon monoxide (DLCO) (p=0.03) and no association with cigarette smoking (p=0.1-0.9) or emphysema (p=0.7).

CONCLUSIONS

Pulmonary cysts identified on chest CT may be a part of the aging changes of the lungs, occurring in asymptomatic individuals older than 40 years, and are associated with decreased BMI and DLCO. Multiple pulmonary cysts may need to be evaluated for the possibility of cystic lung diseases.

Quantification of structural changes in acute inflammation by fractal dimension, angular second moment and correlation

The aim of the study was to examine alteration and possible application of fractal dimension, angular second moment, and correlation for quantification of structural changes in acutely inflamed tissue. Acute inflammation was induced by injection of turpentine oil into the right and left hind limb muscles of mice, whereas control animals received intramuscular saline injection. After 12 h, animals were anesthetised and treated muscles collected. The tissue was stained by hematoxylin and eosin, digital micrographs produced, enabling determination of fractal dimension of the cells, angular second moment and correlation of studied tissue. Histopathological analysis showed presence of inflammatory infiltrate and tissue damage in inflammatory group, whereas tissue structure in control group was preserved, devoid of inflammatory infiltrate. Fractal dimension of the cells, angular second moment and correlation of treated tissue in inflammatory group decreased in comparison to the control group. In this study, we were first to observe and report that fractal dimension of the cells, angular second moment, and correlation were reduced in acutely inflamed tissue, indicating loss of overall complexity of the cells in the tissue, the tissue uniformity and structure regularity. Fractal dimension, angular second moment and correlation could be useful methods for quantification of structural changes in acute inflammation.

The Senile Lung as a Possible Source of Pitfalls on Chest Ultrasonography and Computed Tomography

BACKGROUND

Age-associated changes in the pulmonary system could be detected with imaging techniques. Widespread use of lung ultrasonography (US) requires characterization of a normal pattern.

OBJECTIVES

To compare US and computed tomography (CT) findings in healthy subjects undergoing both techniques (with CT as the gold standard).

METHODS

We prospectively selected 59 subjects undergoing chest CT and US on the same day, without a history of smoking, respiratory symptoms, or known pulmonary pathologies. There were 44 patients in group 1 (age ≥60 years - elderly) and 15 patients in group 2 (age ≤50 years - young). Lung US was performed with a convex and a linear probe, and 10 chest areas per patient were analyzed. Convex and linear probe agreement was evaluated by means of the Cohen κ statistic; Fisher's exact test was used to compare categorical variables between groups.

RESULTS

Isolated B-lines were frequent in both group 1 (54.5%) and group 2 (40.0%); the number of chest areas positive for B-lines increased with age (16.1% in group 1 vs. 5.3% in group 2, p = 0.0028). In group 2, we found that 37.5% of subjects with B-lines had at least 1 chest area with multiple B-lines, but only 2 subjects had 2 or more. Moreover, in group 1 the chest CT documented a reticular pattern (2.3%), areas of increased density (9.1%), ground glass (6.8%), cysts (2.3%), bronchiectasis (22.7%), and bronchial thickening (6.8%); in group 2, only cysts (6.7%) and bronchiectasis (6.7%) were found.

CONCLUSIONS

The senile lung is characterized by mild changes on CT and US. Chest areas positive for B-lines increase with age, and focal multiple B-lines can be found. However, diffuse patterns, especially in symptomatic subjects, suggest a different diagnosis.

Sonography of the normal lung: Comparison between young and elderly subjects

BACKGROUND

The senile lung undergoes physiologic changes that are well known but have not been investigated with ultrasound (US). Thus, the aim of our study was to compare the US appearances of the lungs in a group of healthy, nonsmoker elderly subjects with those in a group of young subjects.

METHODS

One hundred elderly subjects older than 65 years of age (mean age ± SD, 79 ± 7 years) and 50 younger subjects less than 56 years of age (mean age ± SD, 33 ± 12) underwent US examination of the lungs. We analyzed the anterior, midlateral, and posterobasal surface of each lung to evaluate the presence or absence of A-lines and B-lines. Fisher's exact test and Pearson's χ² test were used to compare the findings in the two groups.

RESULTS

A-lines were absent in 94/100 (94%) elderly subjects versus 2/50 (4%) young subjects (p < 0.0001). B-lines were found in 37/100 (37%) elderly subjects: ≤3 lines per field of view in 27/37 (73%); >3 lines in 2/37 (5%); both ≤3 lines and >3 lines (depending on the region scanned) in 8/37 (22%). In contrast, only in 5/50 (10%) young subjects were B-lines visible (≤3 lines per field of view in all cases [p < 0.001]).

CONCLUSIONS

The majority of the elderly subjects did not have A-lines, and B-lines were observed in a high percentage. The reduction of impedance between lung parenchyma and soft tissues of the chest wall and the increased thickness of interlobular septa might explain these results. © 2014 Wiley Periodicals, Inc. J Clin Ultrasound 43:230-234, 2015.

Applying fractal dimension and image analysis to quantify fibrotic collagen deposition and organization in the normal and hypertensive heart

Hearts of mice with reduction of function mutation in STAT3 (SA/SA) develop fibrotic collagen foci and reduced systolic function with hypertension. This model was used to determine if fractal dimension and image analysis can provide a quantitative description of myocardial fibrosis using routinely prepared trichome-stained material. Collagen was characterized by relative density [integrated optical density/area (IOD/A)] and fractal dimension (D), an index of complexity. IOD/A of collagen in wild type mice increased with hypertension while D decreased, suggesting tighter collagen packing that could eventually stiffen the myocardium as in diastolic heart failure. Reduced STAT3 function caused modest collagen fibrosis with increased IOD/A and D, indicating more tightly packed, but more disorganized collagen than normotensive and hypertensive controls. Hypertension in SA/SA mice resulted in large regions where myocytes were lost and replaced by fibrotic collagen characterized by decreased density and increased disorder. This indicates that collagen associated with reparative fibrosis in SA/SA hearts experiencing hypertension was highly disorganized and more space filling. Loss of myocytes and their replacement by disordered collagen fibers may further weaken the myocardium leading to systolic heart failure. Our findings highlight the utility of image analysis in revealing importance of a cellular protein for normal and reparative extracellular matrix deposition.

Automated measurement of heterogeneity in CT images of healthy and diseased rat lungs using variogram analysis of an octree decomposition

Background

Assessing heterogeneity in lung images can be an important diagnosis tool. We present a novel and objective method for assessing lung damage in a rat model of emphysema. We combined a three-dimensional (3D) computer graphics method–octree decomposition–with a geostatistics-based approach for assessing spatial relationships–the variogram–to evaluate disease in 3D computed tomography (CT) image volumes.

Methods

Male, Sprague-Dawley rats were dosed intratracheally with saline (control), or with elastase dissolved in saline to either the whole lung (for mild, global disease) or a single lobe (for severe, local disease). Gated 3D micro-CT images were acquired on the lungs of all rats at end expiration. Images were masked, and octree decomposition was performed on the images to reduce the lungs to homogeneous blocks of 2 × 2 × 2, 4 × 4 × 4, and 8 × 8 × 8 voxels. To focus on lung parenchyma, small blocks were ignored because they primarily defined boundaries and vascular features, and the spatial variance between all pairs of the 8 × 8 × 8 blocks was calculated as the square of the difference of signal intensity. Variograms–graphs of distance vs. variance–were constructed, and results of a least-squares-fit were compared. The robustness of the approach was tested on images prepared with various filtering protocols. Statistical assessment of the similarity of the three control rats was made with a Kruskal-Wallis rank sum test. A Mann-Whitney-Wilcoxon rank sum test was used to measure statistical distinction between individuals. For comparison with the variogram results, the coefficient of variation and the emphysema index were also calculated for all rats.

Results

Variogram analysis showed that the control rats were statistically indistinct (p = 0.12), but there were significant differences between control, mild global disease, and severe local disease groups (p < 0.0001). A heterogeneity index was calculated to describe the difference of an individual variogram from the control average. This metric also showed clear separation between dose groups. The coefficient of variation and the emphysema index, on the other hand, did not separate groups.

Conclusion

These results suggest the octree decomposition and variogram analysis approach may be a rapid, non-subjective, and sensitive imaging-based biomarker for characterizing lung disease.

Quantifying left ventricular trabeculae function - application of image-based fractal analysis

The ventricular-blood interface is geometrically complex due to the presence of ventricular trabeculae carneae (VTC). We introduce a new image-based framework to quantify VTC function using high-resolution computed tomography (CT) imaging and offer new insights into the active role of VTCs during ejection. High-resolution Cine CT scans of a patient with normal cardiac function were acquired at a resolution of 0.77 mm per pixel at 10 phases of the cardiac cycle. The images were segmented and the VTC surface was obtained by triangulating the segmented data. Fractal dimension of the VTC surface was calculated for each cardiac phase as a function of scale size using the box-counting algorithm. The fractal dimension, D corresponding to VTCs ranged between 2.05 and 2.2 and varied as a function of time during the cardiac cycle. Fractal dimension is highest at diastole and lowest at peak systole with the change being significantly different (P < 0.003). This variation of D when plotted against stroke volume (i.e., D-V loop) revealed an active VTC role due to hysteresis in the loop. Physically the hysteresis in the D-V loop indicates a new mechanical function of VTCs as structures that provide mechanical leverage during early systolic ejection through contraction. VTC relaxation is noted to occur during late diastole at larger ventricular volume. D-V loop of VTCs quantifies VTC function. A new dynamic physical role of VTCs is suggested by way of mechanical leverage, as opposed to the traditionally accepted passive role.

Quantification of left ventricular trabeculae using fractal analysis

BACKGROUND

Left ventricular noncompaction (LVNC) is a myocardial disorder characterized by excessive left ventricular (LV) trabeculae. Current methods for quantification of LV trabeculae have limitations. The aim of this study is to describe a novel technique for quantifying LV trabeculation using cardiovascular magnetic resonance (CMR) and fractal geometry. Observing that trabeculae appear complex and irregular, we hypothesize that measuring the fractal dimension (FD) of the endocardial border provides a quantitative parameter that can be used to distinguish normal from abnormal trabecular patterns.

METHODS

Fractal analysis is a method of quantifying complex geometric patterns in biological structures. The resulting FD is a unitless measure index of how completely the object fills space. FD increases with increased structural complexity. LV FD was measured using a box-counting method on CMR short-axis cine stacks. Three groups were studied: LVNC (defined by Jenni criteria), n=30(age 41±13; men, 16); healthy whites, n=75(age, 46±16; men, 36); healthy blacks, n=30(age, 40±11; men, 15).

RESULTS

In healthy volunteers FD varied in a characteristic pattern from base to apex along the LV. This pattern was altered in LVNC where apical FD were abnormally elevated. In healthy volunteers, blacks had higher FD than whites in the apical third of the LV (maximal apical FD: 1.253±0.005 vs. 1.235±0.004, p<0.01) (mean±s.e.m.). Comparing LVNC with healthy volunteers, maximal apical FD was higher in LVNC (1.392±0.010, p<0.00001). The fractal method was more accurate and reproducible (ICC, 0.97 and 0.96 for intra and inter-observer readings) than two other CMR criteria for LVNC (Petersen and Jacquier).

CONCLUSIONS

FD is higher in LVNC patients compared to healthy volunteers and is higher in healthy blacks than in whites. Fractal analysis provides a quantitative measure of trabeculation and has high reproducibility and accuracy for LVNC diagnosis when compared to current CMR criteria.