High resolution fluorescence imaging of the alveolar scaffold as a novel tool to assess lung injury

Acute lung injury (ALI) represents an aetiologically diverse form of pulmonary damage. Part of the assessment and diagnosis of ALI depends on skilled observer-based scoring of brightfield microscopy tissue sections. Although this readout is sufficient to determine gross alterations in tissue structure, its categorical scores lack the sensitivity to describe more subtle changes in lung morphology. To generate a more sensitive readout of alveolar perturbation we carried out high resolution immunofluorescence imaging on 200 μm lung vibratome sections from baseline and acutely injured porcine lung tissue, stained with a tomato lectin, Lycopersicon Esculentum Dylight-488. With the ability to resolve individual alveoli along with their inner and outer wall we generated continuous readouts of alveolar wall thickness and circularity. From 212 alveoli traced from 10 baseline lung samples we established normal distributions for alveolar wall thickness (27.37; 95% CI [26.48:28.26]) and circularity (0.8609; 95% CI [0.8482:0.8667]) in healthy tissue. Compared to acutely injured lung tissue baseline tissue exhibited a significantly lower wall thickness (26.86 ± 0.4998 vs 50.55 ± 4.468; p = 0.0003) and higher degree of circularityϕ≤ (0.8783 ± 0.01965 vs 0.4133 ± 0.04366; p < 0.0001). These two components were subsequently combined into a single more sensitive variable, termed the morphological quotient (MQ), which exhibited a significant negative correlation (R2 = 0.9919, p < 0.0001) with the gold standard of observer-based scoring. Through the utilisation of advanced light imaging we show it is possible to generate sensitive continuous datasets describing fundamental morphological changes that arise in acute lung injury. These data represent valuable new analytical tools that can be used to precisely benchmark changes in alveolar morphology both in disease/injury as well as in response to treatment/therapy.

A preliminary study of dynamic interactive simulation and computational CT scan of the ideal alveolus model

BACKGROUND

While the development of CT imaging technique has brought cognition of in vivo organs, the resolution of CT images and their static characteristics have gradually become barriers of microscopic tissue research.

PURPOSE

Previous research used the finite element method to study the airflow and gas exchange in the alveolus and acinar to show the fate of inhaled aerosols and studied the diffusive, convective, and sedimentation mechanisms. Our study combines these techniques with CT scan simulation to study the mechanisms of respiratory movement and its imaging appearance.

METHODS

We use 3D fluid-structure interaction simulation to study the movement of an ideal alveolus under regular and forced breathing situations and ill alveoli with different tissue elasticities. Additionally, we use the Monte Carlo algorithm within the OpenGATE platform to simulate the computational CT images of the dynamic process with different designated resolutions. The resolutions show the relationship between the kinematic model of the human alveolus and its imaging appearance.

RESULTS

The results show that the alveolus and the wall thickness can be seen with an image resolution smaller than 15.6 μm. With ordinary CT resolution, the alveolus is expressed with four voxels.

CONCLUSIONS

This is a preliminary study concerning the imaging appearance of the dynamic alveolus model. This technique will be used to study the imaging appearance of the dynamic bronchial tree and the lung lobe models in the future.

Diffuse Alveolar Hemorrhage Secondary to Human Metapneumovirus Pulmonary Infection

A 67-year-old man presented with a week of flu-like symptoms, hypoxia, and fever. Respiratory viral panel was positive for human metapneumovirus. Initial chest imaging showed left lower lobe opacification, suggesting a bacterial superimposed on viral pneumonia. Despite antibiotics, the patient became tachycardic and increasingly hypoxic, requiring 40 L high-flow nasal cannula. Repeat imaging demonstrated worsening of a left lower lobe process. Elective bronchoscopy with bronchoalveolar lavage revealed hemorrhage. Subsequent autoimmune, bacterial, and fungal workup was negative. The patient was diagnosed with diffuse alveolar hemorrhage (DAH) secondary to human metapneumovirus pneumonia. DAH is defined as bleeding into the alveolar spaces of the lungs, a process which carries high rates of morbidity and mortality.1 While dramatic in name and often associated with hemoptysis, DAH may only present with clinically subtle and nonspecific features with a variety of alternative etiologies to consider. We present this case of DAH secondary to human metapneumovirus (hMPV) to promote discussion of etiologies of DAH aside from systemic vasculitis.

Ultrasound findings in neonates with alveolar capillary dysplasia with misalignment of the pulmonary veins: report of two cases

Alveolar capillary dysplasia with misalignment of the pulmonary veins (ACDMPV) is a rare congenital pulmonary disease that affects newborns. Most patients with ACDMPV are born at full term and are healthy. The main clinical manifestations are refractory pulmonary hypertension and pulmonary failure with gastrointestinal, urinary, or cardiac malformations. ACDMPV often progresses rapidly, but no conventional biological or imaging tests other than genetic testing are available for its diagnosis. Lung biopsy is currently the gold standard for diagnosis. We herein report two cases of ACDMPV confirmed by pathological examination and discuss their ultrasonographic findings.

Hemoptysis and a Newly Formed Lung Bulla in a Case of Convalescent COVID-19 Pneumonia

Coronavirus disease 2019 (COVID-19) is a novel infectious disease affecting the general population worldwide. A fever and cough are the common clinical presentations of COVID-19. In most of these patients, computed tomography (CT) shows bilateral peripheral ground-glass opacities. We herein report a case of hemoptysis and lung bulla in the convalescent phase of COVID-19. Based on the clinical observations, alveolar destruction was likely associated with hemoptysis and bulla formation. Therefore, we suggest the follow-up of COVID-19 patients whose clinical parameters indicate alveolar damage, even after their symptoms improve.

Computed tomography assessment of PEEP-induced alveolar recruitment in patients with severe COVID-19 pneumonia

BACKGROUND

There is a paucity of data concerning the optimal ventilator management in patients with COVID-19 pneumonia; particularly, the optimal levels of positive-end expiratory pressure (PEEP) are unknown. We aimed to investigate the effects of two levels of PEEP on alveolar recruitment in critically ill patients with severe COVID-19 pneumonia.

METHODS

A single-center cohort study was conducted in a 39-bed intensive care unit at a university-affiliated hospital in Genoa, Italy. Chest computed tomography (CT) was performed to quantify aeration at 8 and 16 cmH2O PEEP. The primary endpoint was the amount of alveolar recruitment, defined as the change in the non-aerated compartment at the two PEEP levels on CT scan.

RESULTS

Forty-two patients were included in this analysis. Alveolar recruitment was median [interquartile range] 2.7 [0.7-4.5] % of lung weight and was not associated with excess lung weight, PaO2/FiO2 ratio, respiratory system compliance, inflammatory and thrombophilia markers. Patients in the upper quartile of recruitment (recruiters), compared to non-recruiters, had comparable clinical characteristics, lung weight and gas volume. Alveolar recruitment was not different in patients with lower versus higher respiratory system compliance. In a subgroup of 20 patients with available gas exchange data, increasing PEEP decreased respiratory system compliance (median difference, MD - 9 ml/cmH2O, 95% CI from - 12 to - 6 ml/cmH2O, p < 0.001) and the ventilatory ratio (MD - 0.1, 95% CI from - 0.3 to - 0.1, p = 0.003), increased PaO2 with FiO2 = 0.5 (MD 24 mmHg, 95% CI from 12 to 51 mmHg, p < 0.001), but did not change PaO2 with FiO2 = 1.0 (MD 7 mmHg, 95% CI from - 12 to 49 mmHg, p = 0.313). Moreover, alveolar recruitment was not correlated with improvement of oxygenation or venous admixture.

CONCLUSIONS

In patients with severe COVID-19 pneumonia, higher PEEP resulted in limited alveolar recruitment. These findings suggest limiting PEEP strictly to the values necessary to maintain oxygenation, thus avoiding the use of higher PEEP levels.

A semi-automated method for unbiased alveolar morphometry: Validation in a bronchopulmonary dysplasia model

Reproducible and unbiased methods to quantify alveolar structure are important for research on many lung diseases. However, manually estimating alveolar structure through stereology is time consuming and inter-observer variability is high. The objective of this work was to develop and validate a fast, reproducible and accurate (semi-)automatic alternative. A FIJI-macro was designed that automatically segments lung images to binary masks, and counts the number of test points falling on tissue and the number of intersections of the air-tissue interface with a set of test lines. Manual selection remains necessary for the recognition of non-parenchymal tissue and alveolar exudates. Volume density of alveolar septa (VVsep) and mean linear intercept of the airspaces (Lm) as measured by the macro were compared to theoretical values for 11 artificial test images and to manually counted values for 17 lungs slides using linear regression and Bland-Altman plots. Inter-observer agreement between 3 observers, measuring 8 lungs both manually and automatically, was assessed using intraclass correlation coefficients (ICC). VVsep and Lm measured by the macro closely approached theoretical values for artificial test images (R² of 0.9750 and 0.9573 and bias of 0.34% and 8.7%). The macro data in lungs were slightly higher for VVsep and slightly lower for Lm in comparison to manually counted values (R² of 0.8262 and 0.8288 and bias of -6.0% and 12.1%). Visually, semi-automatic segmentation was accurate. Most importantly, manually counted VVsep and Lm had only moderate to good inter-observer agreement (ICC 0.859 and 0.643), but agreements were excellent for semi-automatically counted values (ICC 0.956 and 0.900). This semi-automatic method provides accurate and highly reproducible alveolar morphometry results. Future efforts should focus on refining methods for automatic detection of non-parenchymal tissue or exudates, and for assessment of lung structure on 3D reconstructions of lungs scanned with microCT.

Diagnostic impact of bedside chest X-ray features of 2019 novel coronavirus in the routine admission at the emergency department: case series from Lombardy region

PURPOSE

To evaluate the diagnostic accuracy and the imaging features of routine admission chest X-ray in patients suspected for novel Coronavirus 2019 (SARS-CoV-2) infection.

METHOD

We retrospectively evaluated clinical and X-ray features in all patients referred to the emergency department for suspected SARS-CoV-2 infection between March 1st and March 13th. A single radiologist with more than 15 years of experience in chest-imaging evaluated the presence and extent of alveolar opacities, reticulations, and/or pleural effusion. The percentage of lung involvement (range <25 % to 75-100 %) was also calculated. We stratified patients in groups according to the time interval between symptoms onset and X-ray imaging (≤ 5 and > 5 days) and according to age (≤ 50 and > 50 years old).

RESULTS

A total of 518 patients were enrolled. Overall 314 patients had negative and 204 had positive RT-PCR results. Lung lesions in patients with SARS-Cov2 pneumonia primarily manifested as alveolar and interstitial opacities and were mainly bilateral (60.8 %). Lung abnormalities were more frequent and more severe by symptom duration and by increasing age. The sensitivity and specificity of chest X-ray at admission in the overall cohort were 57 % (95 % CI = 47-67) and 89 % (83-94), respectively. Sensitivity was higher for patients with symptom onset > 5 days compared to ≤ 5 days (76 % [62-87] vs 37 % [24-52]) and in patients > 50 years old compared to ≤ 50 years (59 % [48-69] vs 47 % [23-72]), at the expense of a slightly lower specificity (68 % [45-86] and 82 % [73-89], respectively).

CONCLUSIONS

Overall chest X-ray sensitivity for SARS-CoV-2 pneumonia was 57 %. Sensitivity was higher when symptoms had started more than 5 days before, at the expense of lesser specificity, while slightly higher in older patients in comparison to younger ones.

The effects of 1α,25-dihydroxyvitamin D3 on alveolar repair and bone mass in adiponectin-deficient mice

Chronic obstructive pulmonary disease (COPD) is a major cause of death worldwide. However, no drugs can regenerate lung tissue in COPD patients, and differentiation-inducing drugs that can effectively treat damaged alveoli are needed. In addition, the presence of systemic comorbidities is also considered problematic. Our previous study revealed that a retinoic acid derivative improved emphysema in elastase-induced COPD model mice at a dose of 1.0 mg/kg, whereas 1α,25-dihydroxyvitamin D3 (1,25(OH)₂D₃) showed an emphysema-improving effect in the same model at 0.1 μg/kg. Elastase-induced COPD model mice do not exhibit a systemic disease state, so evaluation in a model that better reflects the human disease state is considered necessary. To solve this problem, we focused on the adiponectin-deficient mouse and examined the effects of 1,25(OH)₂D₃ on alveolar regeneration. Fifty-week-old adiponectin-deficient mice were treated with 1,25(OH)₂D₃ (0.1 μg/kg) twice a week, for 30 weeks. The effects of pulmonary administration on alveolar repair were evaluated according to the distance between alveolar walls (Lm values) and computed tomography (CT) parameters. Bone density was evaluated based on CT. The administration of 1,25(OH)₂D₃ was confirmed to show a significant therapeutic effect. The Lm values in the control and 1,25(OH)₂D₃-treated groups were 98 ± 4 μm and 63 ± 1 μm, respectively. However, on CT, the average CT value and % of low attenuation area showed no significant change. In adiponectin-deficient mice, the reduction of bone density (cortical, spongy, and total bone), which is a systemic symptom of COPD, was significantly suppressed by 1,25(OH)₂D₃ at 80 weeks of age. The present study suggests that 1,25(OH)₂D₃ could be a potential candidate drug that may provide a radical cure for the lung disease and comorbidities of COPD patients. This work can lead to the development drugs that may provide a radical cure for COPD.

New Insight into the Development of the Respiratory Acini in Rabbits: Morphological, Electron Microscopic Studies, and TUNEL Assay

This study investigated the histomorphological features of developing rabbit respiratory acini during the postnatal period. On the 1st day of postnatal life, the epithelium of terminal bronchiole consisted of clear cells which intercalated between few ciliated and abundant non-ciliated (Clara) cells. At this age, the rabbit lung was in the alveolar stage. The terminal bronchioles branched into several alveolar ducts, which opened into atria that communicated to alveolar sacs. All primary and secondary inter-alveolar septa were thick and showed a double-capillary network (immature septa). The primitive alveoli were lined largely by type-I pneumocytes and mature type-II pneumocytes. The type-I pneumocytes displayed an intimate contact with the endothelial cells of the blood capillaries forming the blood-air barrier (0.90 ± 0.03 µm in thickness). On the 3rd day, we observed intense septation and massive formation of new secondary septa giving the alveolar sac a crenate appearance. The mean thickness of the air-blood barrier decreased to reach 0.78 ± 0.14 µm. On the 7th day, the terminal bronchiole epithelium consisted of ciliated and non-ciliated cells. The non-ciliated cells could be identified as Clara cells and serous cells. New secondary septa were formed, meanwhile the inter-alveolar septa become much thinner and the air-blood barrier thickness was 0.66 ± 0.03 µm. On the 14th day, the terminal bronchiole expanded markedly and the pulmonary alveoli were thin-walled. Inter-alveolar septa become much thinner and single capillary layers were observed. In the 1st month, the secondary septa increased in length forming mature cup-shaped alveoli. In the 2nd month, the lung tissue grew massively to involve the terminal respiratory unit. In the 3rd month, the pulmonary parenchyma appeared morphologically mature. All inter-alveolar septa showed a single-capillary layer, and primordia of new septa were also observed. The thickness of the air-blood barrier was much thinner; 0.56 ± 0.16 µm. TUNEL assay after birth revealed that the apoptotic cells were abundant and distributed in the epithelium lining of the pulmonary alveoli and the interstitium of the thick interalveolar septa. On the 7th day, and onward, the incidence of apoptotic cells decreased markedly. This study concluded that the lung development included two phases: the first phase (from birth to the 14th days) corresponds to the period of bulk alveolarization and microvascular maturation. The second phase (from the 14th days to the full maturity) corresponds to the lung growth and late alveolarization.

En-face optical coherence tomography/fluorescence endomicroscopy for minimally invasive imaging using a robotic scanner

We report a compact rigid instrument capable of delivering en-face optical coherence tomography (OCT) images alongside (epi)-fluorescence endomicroscopy (FEM) images by means of a robotic scanning device. Two working imaging channels are included: one for a one-dimensional scanning, forward-viewing OCT probe and another for a fiber bundle used for the FEM system. The robotic scanning system provides the second axis of scanning for the OCT channel while allowing the field of view (FoV) of the FEM channel to be increased by mosaicking. The OCT channel has resolutions of 25  /  60  μm (axial/lateral) and can provide en-face images with an FoV of 1.6  ×  2.7  mm2. The FEM channel has a lateral resolution of better than 8  μm and can generate an FoV of 0.53  ×  3.25  mm2 through mosaicking. The reproducibility of the scanning was determined using phantoms to be better than the lateral resolution of the OCT channel. Combined OCT and FEM imaging were validated with ex-vivo ovine and porcine tissues, with the instrument mounted on an arm to ensure constant contact of the probe with the tissue. The OCT imaging system alone was validated for in-vivo human dermal imaging with the handheld instrument. In both cases, the instrument was capable of resolving fine features such as the sweat glands in human dermal tissue and the alveoli in porcine lung tissue.

Pseudo-diffusion effects in lung MRI

Magnetic resonance imaging of lung tissue is strongly influenced by susceptibility effects between spin-bearing water molecules and air-filled alveoli. The measured lineshape, however, also depends on the interplay between susceptibility effects and blood-flow around alveoli that can be approximated as pseudo-diffusion. Both effects are quantitatively described by the Bloch-Torrey-equation, which was so far only solved for dephasing on the alveolar surface. In this work, we extend this model to the whole range of physiological relevant air volume fractions. The results agree very well with in vivo measurements in human lung tissue.

An object-oriented computational model to study cardiopulmonary hemodynamic interactions in humans

BACKGROUND AND OBJECTIVE

This work introduces an object-oriented computational model to study cardiopulmonary interactions in humans.

METHODS

Modeling was performed in object-oriented programing language Matlab Simscape, where model components are connected with each other through physical connections. Constitutive and phenomenological equations of model elements are implemented based on their non-linear pressure-volume or pressure-flow relationship. The model includes more than 30 physiological compartments, which belong either to the cardiovascular or respiratory system. The model considers non-linear behaviors of veins, pulmonary capillaries, collapsible airways, alveoli, and the chest wall. Model parameters were derisved based on literature values. Model validation was performed by comparing simulation results with clinical and animal data reported in literature.

RESULTS

The model is able to provide quantitative values of alveolar, pleural, interstitial, aortic and ventricular pressures, as well as heart and lung volumes during spontaneous breathing and mechanical ventilation. Results of baseline simulation demonstrate the consistency of the assigned parameters. Simulation results during mechanical ventilation with PEEP trials can be directly compared with animal and clinical data given in literature.

CONCLUSIONS

Object-oriented programming languages can be used to model interconnected systems including model non-linearities. The model provides a useful tool to investigate cardiopulmonary activity during spontaneous breathing and mechanical ventilation.

Acute diffuse alveolar haemorrhage accompanied by gastrointestinal bleeding in a patient with serious systemic lupus erythematosus: A case report

Systemic lupus erythematosus (SLE) is an autoimmune disease that affects many organs, but multisystem dysfunction is rare. Here, we report a case of a 29-year-old woman who was initially diagnosed with SLE complications including lupus nephritis, lupus encephalopathy, renal hypertension, thrombocytopenia, anaemia and hyperkalaemia. She recovered following treatment with high dose methylprednisolone, intravenous immunoglobulin (IVIG) and continuous renal replacement therapy (CRRT). However, a few days after hospital discharge, she developed gastrointestinal bleeding. Although intensive treatment was administered, the patient deteriorated rapidly and had a progressive decline in oxygen saturation followed by diffuse alveolar haemorrhage and acute left heart failure. Inotropic therapy, mechanical ventilation, blood transfusion, CRRT, antibiotics, intravenous glucocorticoids and other support therapies were initiated and gradually the patient's vital signs stabilized and haemoptysis subsided. This case report emphasises that complications of SLE can occur at any stage of the disease, especially in patients with active SLE. Therefore, it is important for clinicians to be aware of the rare presentations of SLE and its complex management. For multisystem dysfunction, early intensive treatment with high dose corticosteroids and cyclophosphamide is advocated.

Automated computer-assisted quantitative analysis of intact murine lungs at the alveolar scale

Using state-of-the-art X-ray tomographic microscopy we can image lung tissue in three dimensions in intact animals down to a micrometer precision. The structural complexity and hierarchical branching scheme of the lung at this level of details, however, renders the extraction of biologically relevant quantities particularly challenging. We have developed a methodology for a detailed description of lung inflation patterns by measuring the size and the local curvature of the parenchymal airspaces. These quantitative tools for morphological and topological analyses were applied to high-resolution murine 3D lung image data, inflated at different pressure levels under immediate post mortem conditions. We show for the first time direct indications of heterogeneous intra-lobar and inter-lobar distension patterns at the alveolar level. Furthermore, we did not find any indication that a cyclic opening-and-collapse (recruitment) of a large number of alveoli takes place.

Congenital Pulmonary Alveolar Proteinosis: From Birth to Ten-years of Age

Pulmonary alveolar proteinosis is a rare lung disease in which lipoproteinaceous material accumulates within the alveoli, interfering with gas exchange. The disease is classified into congenital, secondary, and acquired. The congenital form includes inborn errors of surfactant metabolism, lysinuric protein intolerance and mutations in the components of granulocyte-macrophage colony-stimulating factor receptor. The main symptoms are non-specific. The radiologic appearance of pulmonary alveolar proteinosis is bilateral, symmetric and perihilar airspace consolidation. Bronchoalveolar lavage is crucial for diagnosis of the disease. There is only one ten-year-old patient with diagnosed congenital form in Croatia. What makes him different from other children in the world is that since the ninth month of his life he has been mechanically ventilated. Diagnosis of postnatal alveolar proteinosis should be considered in every infant with respiratory distress with diffuse alveolar and interstitial infiltrate.

A hybrid multibreath wash-in wash-out lung function quantification scheme in human subjects using hyperpolarized 3 He MRI for simultaneous assessment of specific ventilation, alveolar oxygen tension, oxygen uptake, and air trapping

PURPOSE

To present a method for simultaneous acquisition of alveolar oxygen tension (PA O2 ), specific ventilation (SV), and apparent diffusion coefficient (ADC) of hyperpolarized (HP) gas in the human lung, allowing reinterpretation of the PA O2 and SV maps to produce a map of oxygen uptake (R).

METHOD

An imaging scheme was designed with a series of identical normoxic HP gas wash-in breaths to measure ADC, SV, PA O2 , and R in less than 2 min. Signal dynamics were fit to an iterative recursive model that regionally solved for these parameters. This measurement was successfully performed in 12 subjects classified in three healthy, smoker, and chronic obstructive pulmonary disease (COPD) cohorts.

RESULTS

The overall whole lung ADC, SV, PA O2 , and R in healthy, smoker, and COPD subjects was 0.20 ± 0.03 cm2 /s, 0.39 ± 0.06,113 ± 2 Torr, and 1.55 ± 0.35 Torr/s, respectively, in healthy subjects; 0.21 ± 0.03 cm2 /s, 0.33 ± 0.06, 115.9 ± 4 Torr, and 0.97 ± 0.2 Torr/s, respectively, in smokers; and 0.25 ± 0.06 cm2 /s, 0.23 ± 0.08, 114.8 ± 6.0Torr, and 0.94 ± 0.12 Torr/s, respectively, in subjects with COPD. Hetrogeneity of SV, PA O2 , and R were indicators of both smoking-related changes and disease, and the severity of the disease correlated with the degree of this heterogeneity. Subjects with symptoms showed reduced oxygen uptake and specific ventilation.

CONCLUSION

High-resolution, nearly coregistered and quantitative measures of lung function and structure were obtained with less than 1 L of HP gas. This hybrid multibreath technique produced measures of lung function that revealed clear differences among the cohorts and subjects and were confirmed by correlations with global lung measurements. Magn Reson Med 78:611-624, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Dephasing and diffusion on the alveolar surface

We propose a surface model of spin dephasing in lung tissue that includes both susceptibility and diffusion effects to provide a closed-form solution of the Bloch-Torrey equation on the alveolar surface. The nonlocal susceptibility effects of the model are validated against numerical simulations of spin dephasing in a realistic lung tissue geometry acquired from synchotron-based μCT data sets of mouse lung tissue, and against simulations in the well-known Wigner-Seitz model geometry. The free induction decay is obtained in dependence on microscopic tissue parameters and agrees very well with in vivo lung measurements at 1.5 Tesla to allow a quantification of the local mean alveolar radius. Our results are therefore potentially relevant for the clinical diagnosis and therapy of pulmonary diseases.

In Vivo Measurements of T2 Relaxation Time of Mouse Lungs during Inspiration and Expiration

Purpose

The interest in measurements of magnetic resonance imaging relaxation times, T1, T2, T2*, with intention to characterize healthy and diseased lungs has increased recently. Animal studies play an important role in this context providing models for understanding and linking the measured relaxation time changes to the underlying physiology or disease. The aim of this work was to study how the measured transversal relaxation time (T2) in healthy lungs is affected by normal respiration in mouse.

Method

T2 of lung was measured in anaesthetized freely breathing mice. Image acquisition was performed on a 4.7 T, Bruker BioSpec with a multi spin-echo sequence (Car-Purcell-Meiboom-Gill) in both end-expiration and end-inspiration. The echo trains consisted of ten echoes of inter echo time 3.5 ms or 4.0 ms. The proton density, T2 and noise floor were fitted to the measured signals of the lung parenchyma with a Levenberg-Marquardt least-squares three-parameter fit.

Results

T2 in the lungs was longer (p<0.01) at end-expiration (9.7±0.7 ms) than at end-inspiration (9.0±0.8 ms) measured with inter-echo time 3.5 ms. The corresponding relative proton density (lung/muscle tissue) was higher (p<0.001) during end-expiration, (0.61±0.06) than during end-inspiration (0.48±0.05). The ratio of relative proton density at end-inspiration to that at end-expiration was 0.78±0.09. Similar results were found for inter-echo time 4.0 ms and there was no significant difference between the T2 values or proton densities acquired with different interecho times. The T2 value increased linearly (p< 0.001) with proton density.

Conclusion

The measured T2 in-vivo is affected by diffusion across internal magnetic susceptibility gradients. In the lungs these gradients are modulated by respiration, as verified by calculations. In conclusion the measured T2 was found to be dependent on the size of the alveoli.

Pulmonary alveolar hemorrhage mimicking a pneumopathy: a rare complication of dual antiplatelet therapy for ST elevation myocardial infarction

Diffuse alveolar hemorrhage after percutaneous coronary intervention (PCI) is a rare complication. The diagnosis is difficult and can mimic by clinical and radiological features other diagnosis as pneumopathy. We herein report the case of a 63-year-old female admitted to the hospital for ST elevation myocardial infarction. The patient underwent PCI and received dual antiplatelet therapy. Four days later, she developed dyspnea, hemoptysis and fever. Clinical, radiological and biological findings oriented to a pneumopathy and the patient received the treatment for it. Later and because of the non improvement, a thoracic computed tomography was performed and revealed patchy areas of ground-glass opacity consistent with a diffuse pulmonary hemorrhage. The combination therapy with aspirin and clopidogrel was therefore the most likely cause. Although the dual antiplatelet combination reduces systemic ischemic events after PCI, it is associated with increased risk of nonfatal and sometimes fatal bleeding. Hence the necessity of close and careful observation to watch for possible fatal complications.

Intravascular Large B Cell Lymphoma as a Rare Cause of Reversed Halo Sign: A Case Report

Intravascular large B cell lymphoma (IVLBCL) is a rare type of extranodal diffused large B-cell lymphoma. IVLBCL with primary lung lesion is very rare and it is very difficult to diagnose. Radiographic findings of pulmonary IVLBCL are nonspecific and resembling interstitial lung diseases. Reversed halo sign (RHS) was initially reported in patients diagnosed with cryptogenic organizing pneumonia and then described in a variety of diseases with inflammatory, infectious, autoimmune, and malignant causes. This is the first case of IVLBCL that has presented with RHSs on CT scan.A 59-year-old Chinese man presented with a 4-month history of a nonproductive cough and a weight loss of 5 kg. Physical examination was unremarkable. High-resolution computed tomography scan of the chest showed bilateral patchy ground glass opacities (GGOs) and RHSs. Laboratory tests were unremarkable except elevated serum lactate dehydrogenase (LDH). Surgical lung biopsy was performed. Light microscopic examination of the specimen disclosed diffuse alveolar septal widening caused by neoplastic lymphocytes, which were positive for CD20 and infiltrated in the alveolar capillaries. The patient was diagnosed with IVLBCL and underwent chemotherapy and autologous blood stem cell transplantation. The patient is still alive 5 years after diagnosis.IVLBCL is a rare cause of RHS and should be considered in differential diagnosis of RHS. An increased serum LDH concentration is another important clue.

A Conjugate Fluid-Porous Approach for Simulating Airflow in Realistic Geometric Representations of the Human Respiratory System

Simulation of flow in the human lung is of great practical interest as a means to study the detailed flow patterns within the airways for many physiological applications. While computational simulation techniques are quite mature, lung simulations are particularly complicated due to the vast separation of length scales between upper airways and alveoli. Many past studies have presented numerical results for truncated airway trees, however, there are significant difficulties in connecting such results with respiratory airway models. This article presents a new modeling paradigm for flow in the full lung, based on a conjugate fluid-porous formulation where the upper airway is considered as a fluid region with the remainder of the lung being considered as a coupled porous region. Results are presented for a realistic lung geometry obtained from computed tomography (CT) images, which show the method's potential as being more efficient and practical than attempting to directly simulate flow in the full lung.

Diffuse alveolar hemorrhage with predominantly right-sided infiltration resulting from cardiac comorbidities

OBJECTIVE

Radiographic findings in patients with diffuse alveolar hemorrhage (DAH) are usually diffuse and bilateral, although they may occasionally be unilateral. The clinical aspects of predominantly unilateral DAH are not well known. Therefore, our objective was to describe the clinical characteristics of predominantly right-sided DAH.

METHODS

We retrospectively reviewed data for 460 bronchoalveolar lavage fluid (BALF) samples collected between January 2009 and July 2013. Patients who presented with increasingly hemorrhagic BALF were diagnosed with DAH, and unilateral predominance was determined based on the degree of infiltration on chest radiographs.

RESULTS

The records of 54 patients with DAH were evaluated. The leading etiology was pulmonary congestion due to heart failure (n=15). The radiographs showed right-sided infiltration in 18 patients (33%), left-sided infiltration in six patients (11%) and bilateral infiltration in 30 patients (56%). Predominantly right-sided DAH was often caused by pulmonary congestion resulting from heart failure (10 of 18 patients). A multivariate logistic regression analysis revealed a previous history of cardiovascular disease to be the only significant predictor of right-sided DAH (OR 13.1, 95% CI 2.9-95.4).

CONCLUSION

Predominantly right-sided DAH is frequently caused by pulmonary congestion resulting from heart failure and is significantly related to comorbidities with cardiovascular disease.

[High resolution computed tomographic findings in infants with diffuse lung disease]

OBJECTIVE

To investigate the high-resolution computed tomographic (HRCT) features of infants with diffuse lung disease (DLD) for improving the diagnostic accuracy clinically.

METHOD

Totally 75 infants under 2 years of age with DLD (2010-2013) were involved in this study. Among them, 56 were males and 19 females, aged from 2 days to 24 months (mean age was 10.9 months). According to the clinical or pathological data, the cases were enrolled into three groups, including systemic diseases-associated infantile DLD (30 cases), alveolar structure disorders-associated infantile DLD (23 cases), and infantile DLD specific to infancy (22 cases). Retrospectively, HRCT images, from the three groups respectively, were analyzed and compared. HRCT presentations including airway disorders, interstitial disorders and air space disorders were reviewed. Inter-reviewers consistency check was performed, the consistency between reviewers was good (K = 0.64;P = 0.03, < 0.05), as well as χ(2) test.

RESULT

Among the three groups, some of the HRCT sings (bronchiectasis, thickened bronchiolar wall, mosaic sign, reticular, intralobular nodules and consolidations) had significant differences (χ(2) = 24.52, 6.08, 18.00, 12.56, 9.11 and 11.50, P < 0.05) .

CONCLUSION

The HRCT features of infantile pulmonary DLD/interstitial LD with different causes were as follows, compared to the other two groups, intralobular nodules was the main feature of the systemic diseases-associated infantile DLD, thickened bronchiolar wall, mosaic sign and consolidations were rare as well. Meanwhile, bronchiectasis was more common in alveolar structural disorders-associated infantile DLD, and reticular opacity was rarely seen. Associated clinical data, the HRCT presentations would help clinicians to make accurate diagnosis.

[The clinicopathological features of acute fibrinous and organizing pneumonia]

OBJECTIVE

To improve understanding of the clinical, radiological and pathological characteristics of acute fibrinous and organizing pneumonia (AFOP).

METHODS

The clinical data of 5 AFOP patients were retrospectively analyzed. AFOP was diagnosed via percutaneous lung biopsy guided by chest computerized tomography (CT) in the Affiliated Drum Tower Hospital of Nanjing University Medical School during March 2011 to June 2012. The clinical, radiological and pathological characteristics of those patients were summarized.

RESULTS

Among the 5 patients, 2 were male and 3 were female, aging 43-61 years. They were all subacute onset. The main clinical manifestations were dyspnea, productive cough, fever and chest pain with hypoxemia via blood gas analysis. Bilateral infiltrates with diffuse and pathy distribution were the predominant features in chest HRCT. The pathological examination revealed slightly widened alveolar septa, 1ymphocyte and plasma cell infiltration and the presence of intra-alveolar fibrin in the form of fibrin "balls" (organization) within the alveolar spaces. No neutrophil, and eosinophil infiltration and hyaline membrane formation were detected, which was different from other well-recognized histologic patterns of acute lung injury, such as diffuse alveolar damage, cryptogenic organizing pneumonia and eosinophilic pneumonia. All patients were treated by corticosteroids and showed significant clinical and radiological improvement.

CONCLUSIONS

AFOP has nospecific features, and its diagnosis depends on pathological examination. Treatment with corticosteroids is optimal. However, whether it is a unique interstitial disease needs to be further clinically investigated.

[Alveolar haemorrhage associated with the primary antiphospholipid syndrome]

INTRODUCTION

Thrombotic events, particularly pulmonary embolism, are well known presentations of the antiphospholipid syndrome. Other pulmonary manifestations of the disease like alveolar haemorrhage are rare but can represent a catastrophic aspect of this disease. Alveolar haemorrhage in this context is important to recognize since it can be either a complication of anticoagulation therapy or a manifestation of the disease. The therapeutic implications are then very different.

CASE PRESENTATION

We present the case of a woman with massive pulmonary embolism treated with thrombolytic therapy. This was complicated by alveolar hemorrhage initially attributed to thrombolytics and recurrent bleeding considered to be a manifestation of the antiphospholipid syndrome. The complicated course necessitated a protracted stay in the intensive care unit, mechanical ventilation, and treatment with intravenous corticosteroids and plasmapheresis.

CONCLUSION

Alveolar haemorrhage associated with the antiphospholipid syndrome can be catastrophic and require prompt and aggressive therapy. Plasmapheresis, usually reserved for the catastrophic aspects of this condition, was felt to be useful in this case.

How to assess positive end-expiratory pressure-induced alveolar recruitment?

Randomized trials fail to demonstrate a decrease in mortality when high Positive End-Expiratory Pressure (PEEP) is applied to patients with acute respiratory distress syndrome. Use of PEEP in all patients without taking into consideration specific lung morphology, potential for recruitment and risk of lung hyperinflation could be one of explanations. Assessment of alveolar recruitment in each individual patient appears to reach a good compromise between optimization of mechanical ventilation and reduction of lung injury due to systematic application of high PEEP. The purpose of the review was to discuss different methods to measure alveolar recruitment aimed at selecting optimal PEEP. The revision of the literature includes relevant human and animal studies published in the past ten years describing validated and promising methods. Computed tomography remains the reference method to assess regional PEEP-induced alveolar recruitment and hyperinflation. Lung ultrasound and pressure-volume (P-V) curve method are simple and repeatable at the bedside, but they can't provide information on lung hyperinflation. Electrical impedance tomography allows bedside assessment of tidal recruitment in dependent and nondependent regions. By measuring functional residual capacity, alveolar recruitment and strain can be estimated. Decremental PEEP titration preceded by recruitment maneuver has been suggested to define optimal PEEP that sustains oxygenation benefit of recruitment maneuver. Different methods are available to assess PEEP-induced alveolar recruitment. Lung ultrasound and P-V curve method can be easily used at bedside to assess lung recruitability and test optimal PEEP. Further development is required for bedside assessment combing alveolar recruitment with hyperinflation.

[Intra-alveolar hemorrhage associated with dengue and leptospirosis]

The intra-alveolar hemorrhage syndrome is defined by the presence of red cells in the alveolar lumen and can lead to acute respiratory failure. Among the infectious etiologies of this syndrome, leptospirosis is a common cause, whereas in dengue, the intra-alveolar hemorrhage is exceptional. We report a patient aged 46 years, with no particular history, who presented a clinical picture involving acute respiratory failure, hemoptysis, bilateral alveolar images and anemia. The intra-alveolar hemorrhage has been authenticated by bronchoalveolar lavage. The etiological showed infection by both dengue and leptospirosis.

[Contrast-enhancend sonography (CEUS) in pneumonia: typical patterns and clinical value - a retrospective study on n = 50 patients]

PURPOSE

To describe contrast-enhanced ultrasound (CEUS) patterns of pneumonia, to characterize CEUS patterns and to determine the clinical value of deviant CEUS patterns.

PATIENTS AND METHODS

N = 50 patients with radiologically diagnosed alveolar pneumonia were investigated by CEUS and retrospectively evaluated. Pulmonary enhancement was differentiated from bronchial arterial enhancement by measurement of time to enhancement from the application of the contrast agent (CA). The echogenicity of the CA enhancement was evaluated (isoechoic/hypoechoic) using the spleen as an "in vivo reference". In addition, the homogeneity of the CA enhancement (homogeneous/ inhomogeneous) was recorded. The patients were divided into two groups according to the CEUS pattern (type 1/type 2) and compared to each other in terms of age, days of hospitalization, comorbidity, rate of complications and the presence of pleural effusion.

RESULTS

The majority showed a type 1 CEUS pattern consisting of a pulmonary arterial supply (92 %), an isoechoic extent of enhancement (74 %) and a homogeneous enhancement (78 %) of the CA in the pulmonary lesions. The only significant difference found between the two groups was the average age.

CONCLUSION

Pneumonia most likely shows a type 1 CEUS pattern consisting of a pulmonary arterial supply, an isoechoic extent of enhancement compared to the spleen and a homogeneous enhancement of the CA in the pulmonary lesions. Prognostic value of a type 2 CEUS pattern (bronchial arterial supply and/or hypoechoic extent of enhancement and/or inhomogeneous enhancement) in pneumonia regarding days of hospitalization, comorbidity, rate of complications and the presence of pleural effusion could not be shown.

A case of pulmonary alveolar microlithiasis

Pulmonary alveolar microlithiasis (PAM) is a rare disease with unknown etiology and pathogenesis. It is characterized by diffuse, innumerable, and minute calculi, called microlithiasis in the alveoli. More than half of reported cases are asymptomatic at the time of diagnosis. We describe the first case of PAM in Korea. A 19-yr-old man without respiratory symptoms presented with interstitial thickening on the chest radiograph. His chest high resolution CT scan showed diffusely scattered, ill defined tiny micronodules and interstitial thickening. Open lung biopsy confirmed the diagnosis of PAM. He was followed up for 6 months without treatment, and no progression was noticed.

[Alveolar hemorrhage as a complication of thrombolytic therapy]

Coronary thrombolysis is used as a strategy for coronary reperfusion for acute myocardial infarction. Bleeding is the main complication described. Although most of these events occur at sites of vascular access and are mild, in some cases gastrointestinal, retroperitoneal, genitourinary, lung and central nervous system bleeding may occur. These episodes are usually serious and sometimes fatal. The following report describes the case of a patient who received thrombolytic therapy with streptokinase as a treatment for myocardial infarction. Subsequently he developed acute respiratory failure, bilateral pulmonary infiltrates and fall of hematocrit compatible with diagnosis of alveolar hemorrhage.

Mutation analysis and serum FGF23 level in a patient with pulmonary alveolar microlithiasis

Pulmonary alveolar microlithiasis (PAM) is a rare, hereditary disorder characterized by ectopic formation of calcium-phosphate microliths in the alveolar space. PAM has been reported to arise from inactivating mutations in SLC34A2, encoding a sodium-dependent phosphate co-transporter essential for phosphate transport in the lungs and small intestine. Serum levels of the phosphaturic hormone fibroblast growth factor-23 (FGF23) in PAM have not been determined. Our objectives were to investigate the genetic etiology and circulating level of FGF23 in a 50-year-old male with clinical characteristics of PAM and extra-pulmonary calcifications. The SLC34A2 and FGF23 genes were sequenced for mutations and serum FGF23 analyzed by ELISA. We found no disease-causing mutations or single nucleotide polymorphisms in the genes investigated. Importantly, repeated measurements revealed undetectable or markedly low serum FGF23 (<3-11 RU/ml). Surprisingly, in the face of low serum FGF23, 1,25-dihydroxy vitamin D₃ level was low-normal and parathyroid hormone mildly elevated. Total 24-h urinary excretion of phosphate and calcium were low, as was fractional urinary excretion of calcium. In contrast, fractional excretion of phosphate was above normal, likely due to elevated PTH. Collectively, PAM may be a polygenic disorder that arises from mutations other than in SLC34A2. The low FGF23 level in our PAM patient supports an intestinal-bone axis, leading to decreased FGF23 expression when intestinal phosphate absorption is compromised.

A frame-shift mutation in the SLC34A2 gene in three patients with pulmonary alveolar microlithiasis in an inbred family

Pulmonary alveolar microlithiasis (PAM) is a rare disease characterized by the presence of small calculi in the alveolar space. The SLC34A2 is thought to be responsible for the disease. We encountered three siblings of an inbred family who have PAM. We examined the family of the proband who was admitted with dyspnea on exertion and cough, and eventually was diagnosed with PAM. Genetic analysis revealed that both parents (a consanguineous marriage) of the proband were carriers with heterozygous mutation of SLC34A2 gene, and three of their children were diagnosed with PAM with homozygous mutation in the SLC34A2 gene. These findings suggest that impaired activity of the SLC34A2 gene may be responsible for familial PAM.

[Various aspects of acinar lesions--the key finding of pulmonary tuberculosis on HRCT]

Acinar lesions, a pathologist's naming for granulomatous lesions formed in the peripheral air space, that is, in the bronchiole or its adjacent alveolar space, is very characteristic and pathognomonic for tuberculosis on HRCT imaging. As a radiological term, it is equal to centrilobular nodule or branching shadow, or tree-in-bud appearance in the recent trend. It is universally seen in most of tuberculosis cases, irrespective of its stage or extensity. Although thus common, its appearance is not always uniform. Firstly they are not well defined in some cases. Exudative tendency in pathological process may explain for this appearance. Secondarily they are not always arranged in an orderly manner or in other words centrilobular manner on CT, but often in a random fashion. Pathologically this phenomenon can be explained by the randomness of formation site of granulomas or by scarring in spontaneous healing process of the disease. Finally, although rare, an extreme pattern, in which acinar lesions are diffusely disseminated in both lung fields without other type of lesions, is well known as Oka's Classification of Pulmonary Tuberculosis Type IIB. This rare type of tuberculosis could be formed through indolent dissemination of bacilli via the airway or from the hematogenous dissemination. It should also be noted that in tuberculous pneumonia, especially when it develops in emphysematous lung, acinar lesions is not seen, making differential diagnosis difficult.

Pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis is a rare cause of respiratory distress in neonates. We present a 4 month old infant who presented with progressive respiratory distress since birth and failure to thrive. He was initially treated as a case of diffuse alveolar disease but on open lung biopsy was diagnosed as pulmonary alveolar proteinosis. The child expired at 7 months of age.