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.

Lung density changes with growth and inflation

BACKGROUND

With body growth from childhood, the lungs can enlarge by either increasing the volume of air in the periphery (as would occur with inspiration) or by increasing the number of peripheral acinar units. In the former case, the lung tissue density would decrease with inflation, whereas in the latter case, the lung density would be relatively constant as the lung grows. To address this fundamental structural issue, we measured the CT scan density in human subjects of widely varying size at two different lung volumes.

METHODS

Five hundred one subjects were enrolled in the study. They underwent a chest CT scan at full inspiration and another scan at end expiration. Spirometry, body plethysmography, and diffusing capacity of the lung for carbon monoxide were also measured.

RESULTS

There was a strong correlation between the size of the lungs measured at full inspiration on CT scan and the mean lung density (r = -0.72, P = .001). People with larger lungs had significantly lower mean lung density. These density changes among different subjects overlapped the density changes within subjects at different lung volumes.

CONCLUSIONS

Lung structure in subjects with larger lungs is different from that in subjects with smaller lungs. Tissue volume does not increase in proportion to lung size, as would be required if larger lungs just had more alveoli. These observations suggest that the growth of the lung into adulthood is not accompanied by new alveoli, but rather by enlargement of existing structures. The presence of greater air spaces in larger lungs could impact the occurrence and pathogenesis of spontaneous pneumothorax or COPD.

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.