Pulmonary vascular diseases

A new segment method for pulmonary artery and vein

Accurate differentiation between pulmonary arteries and veins (A/V) holds pivotal importance in the realm of diagnosing and treating pulmonary ailments. This study presents a new approach that leverages grayscale differences between A/V. Distinctions are measured using median and mean grayscale values within the vessel area. Initially, adherent regions are removed based on vessel structure. The trunk regions are segmented using gray level information near the heart region of the lung boundary. Incorrectly segmented vessels are corrected based on connectivity. For distal lung vessels, a similar distance field is established using a graph-cut method. Experimental results show the algorithm's superior segmentation accuracy, achieving 97.26% compared to the CNN-based average accuracy of 91.67%. Error branches are more concentrated, aiding subsequent manual and automatic correction. This demonstrates the algorithm's effective segmentation of pulmonary A/V.

Automated identification of pulmonary arteries and veins depicted in non-contrast chest CT scans

We present a novel integrative computerized solution to automatically identify and differentiate pulmonary arteries and veins depicted on chest computed tomography (CT) without iodinated contrast agents. We first identified the central extrapulmonary arteries and veins using a convolutional neural network (CNN) model. Then, a computational differential geometry method was used to automatically identify the tubular-like structures in the lungs with high densities, which we believe are the intrapulmonary vessels. Beginning with the extrapulmonary arteries and veins, we progressively traced the intrapulmonary vessels by following their skeletons and differentiated them into arteries and veins. Instead of manually labeling the numerous arteries and veins in the lungs for machine learning, this integrative strategy limits the manual effort only to the large extrapulmonary vessels. We used a dataset consisting of 120 chest CT scans acquired on different subjects using various protocols to develop, train, and test the algorithms. Our experiments on an independent test set (n = 15) showed promising performance. The computer algorithm achieved a sensitivity of ∼98% in labeling the pulmonary artery and vein branches when compared with a human expert's results, demonstrating the feasibility of our computerized solution in pulmonary artery/vein labeling.

Post-interventional Evaluation and Follow-Up in Children With Patent Ductus Arteriosus Complicated With Moderate to Severe Pulmonary Arterial Hypertension: A Retrospective Study

Background: Transcatheter closure is an important treatment for patent ductus arteriosus (PDA) complicated with moderate and severe pulmonary arterial hypertension (PAH). This report presents our experience with transcatheter closure of PDA complicated with moderate and severe PAH.

Methods: The 49 cases of PDA complicated with moderate and severe PAH were collected in the Second Affiliated Hospital and Yuying Children's Hospital from January 2014 to December 2019 with transcatheter closure of PDA and follow-up. All patients were invited for transthoracic echocardiography, electrocardiogram, and thoracic radiography check-up.

Results: Device implantation was successful in 48 of 49 patients (98.0%). Among them, 30 cases were in the PAH after defect correction (CD) group, and 19 examples were in the Non-PAH after defect correction (NCD) group. Pulmonary systolic pressure, left atrial diameter, and left ventricular end-diastolic diameter immediately after interventional therapy and 6 months later were lower than the pre-operative levels (p < 0.05). The incidence of the immediate residual shunt (RS) in this study was 34.9%, most of which were minimal amount shunt. RS disappeared in all patients within 1 year of therapy. Four patients had thrombocytopenia and one patient had left pulmonary artery stenosis. No other serious adverse event occurred during the follow-up period. The pressure gradient tricuspid valve regurgitation (PGTI) and the right heart catheterization (RHC) consistency points were 93.75% (15/16) and were within the 95% consistency limit by the Bland-Altman method. The Logistic regression analysis concluded that the pre-operative Pp/Ps and the narrowest diameter of PDA are risk factors for post-operative PAH (p < 0.05). The cut-off point of the pre-operative Pp/Ps and the narrowest diameter of PDA were calculated to be 0.595 and 4.75 mm, respectively.

Conclusion: Interventional occlusion in children with PDA complicated with moderate and severe PAH is safe, effective, and has few complications. Targeted drug therapy has a good clinical effect. The narrowest diameter of PDA and the pre-operative Pp/Ps may be one of the risk factors of residual PAH after interventional therapy.

Differential expression and hypoxia-mediated regulation of the N-myc downstream regulated gene family

Many organisms rely on oxygen to generate cellular energy (adenosine triphosphate or ATP). During severe hypoxia, the production of ATP decreases, leading to cell damage or death. Conversely, excessive oxygen causes oxidative stress that is equally damaging to cells. To mitigate pathological outcomes, organisms have evolved mechanisms to adapt to fluctuations in oxygen levels. Zebrafish embryos are remarkably hypoxia-tolerant, surviving anoxia (zero oxygen) for hours in a hypometabolic, energy-conserving state. To begin to unravel underlying mechanisms, we analyze here the distribution of the N-myc Downstream Regulated Gene (ndrg) family, ndrg1-4, and their transcriptional response to hypoxia. These genes have been primarily studied in cancer cells and hence little is understood about their normal function and regulation. We show here using in situ hybridization that ndrgs are expressed in metabolically demanding organs of the zebrafish embryo, such as the brain, kidney, and heart. To investigate whether ndrgs are hypoxia-responsive, we exposed embryos to different durations and severity of hypoxia and analyzed transcript levels. We observed that ndrgs are differentially regulated by hypoxia and that ndrg1a has the most robust response, with a ninefold increase following prolonged anoxia. We further show that this treatment resulted in de novo expression of ndrg1a in tissues where the transcript is not observed under normoxic conditions and changes in Ndrg1a protein expression post-reoxygenation. These findings provide an entry point into understanding the role of this conserved gene family in the adaptation of normal cells to hypoxia and reoxygenation.

Adaptation and Maladaptation of the Right Ventricle in Pulmonary Vascular Diseases

The right ventricle is coupled to the low-pressure pulmonary circulation. In pulmonary vascular diseases, right ventricular (RV) adaptation is key to maintain ventriculoarterial coupling. RV hypertrophy is the first adaptation to diminish RV wall tension, increase contractility, and protect cardiac output. Unfortunately, RV hypertrophy cannot be sustained and progresses toward a maladaptive phenotype, characterized by dilation and ventriculoarterial uncoupling. The mechanisms behind the transition from RV adaptation to RV maladaptation and right heart failure are unraveled. Therefore, in this article, we explain the main traits of each phenotype, and how some early beneficial adaptations become prejudicial in the long-term.

The Diagnostic Value of FDG PET/CT and Thin-Slice High-Resolution Chest CT in Pulmonary Intravascular Metastasis

OBJECTIVE. Pulmonary intravascular metastasis is a special type of pulmonary metastasis of malignancies; however, few relevant studies have been performed. This study aimed to determine the characteristics of pulmonary intravascular metastasis and improve understanding of the disease by retrospective analysis of FDG PET/CT and thin-layer high-resolution CT (HRCT) imaging of the chest in patients with tumors. MATERIALS AND METHODS. We identified all patients who underwent FDG PET/CT at two hospitals between January 2016 and February 2019 and conducted a comparative analysis of HRCT and PET/CT images. In total, 84 patients (38 women and 46 men) ranging in age from 35 to 82 years old (mean age, 54.7 ± 14.5 [SD] years) participated in the study. Patient characteristics were summarized, and diagnosis was confirmed by chest CT or PET/CT follow-up. RESULTS. A total of 260 pulmonary intravascular metastases were found, which were classified as type I (no significant abnormality, n = 5), type II (abrupt and uneven thickening of the pulmonary vessel, n = 118), type III (simultaneous invasion of adjacent pulmonary vessel, n = 121), and type IV (large strip-shaped high-density mass, n = 16). The majority were located in peripheral pulmonary vessels (94.2% [245/260]). FDG up-take was increased in 252 lesions, and the mean SUV_max was 4.6 ± 2.5. CONCLUSION. The combination of PET/CT and chest HRCT is an effective approach for detecting pulmonary intravascular metastasis. The linear pattern of FDG uptake, abnormal pulmonary blood vessel morphology, and location (below the lung segment) are specific indicators for the diagnosis of pulmonary intravascular metastasis and should be recognized by clinicians and radiologists.

Incidentally Identified Pulmonary AVM: An Unusual Cause for Stroke in a Young Patient

Pulmonary arteriovenous malformation is an uncommon though important potential source for embolic right-to-left extracardiac shunt as a cause for both silent and clinically evident stroke. We present this case to highlight this pathology as a cause for stroke, the importance of treating this malformation, even if incidentally identified, and finally the role of echocardiography in screening for extracardiac shunt and indicating those patients that may benefit from further investigations looking for extracardiac shunt.

Kv7 Channels in Lung Diseases

Lung diseases constitute a global health concern causing disability. According to WHO in 2016, respiratory diseases accounted for 24% of world population mortality, the second cause of death after cardiovascular diseases. The Kv7 channels family is a group of voltage-dependent K⁺ channels (Kv) encoded by KCNQ genes that are involved in various physiological functions in numerous cell types, especially, cardiac myocytes, smooth muscle cells, neurons, and epithelial cells. Kv7 channel α-subunits are regulated by KCNE1–5 ancillary β-subunits, which modulate several characteristics of Kv7 channels such as biophysical properties, cell-location, channel trafficking, and pharmacological sensitivity. Kv7 channels are mainly expressed in two large groups of lung tissues: pulmonary arteries (PAs) and bronchial tubes. In PA, Kv7 channels are expressed in pulmonary artery smooth muscle cells (PASMCs); while in the airway (trachea, bronchus, and bronchioles), Kv7 channels are expressed in airway smooth muscle cells (ASMCs), airway epithelial cells (AEPs), and vagal airway C-fibers (VACFs). The functional role of Kv7 channels may vary depending on the cell type. Several studies have demonstrated that the impairment of Kv7 channel has a strong impact on pulmonary physiology contributing to the pathophysiology of different respiratory diseases such as cystic fibrosis, asthma, chronic obstructive pulmonary disease, chronic coughing, lung cancer, and pulmonary hypertension. Kv7 channels are now recognized as playing relevant physiological roles in many tissues, which have encouraged the search for Kv7 channel modulators with potential therapeutic use in many diseases including those affecting the lung. Modulation of Kv7 channels has been proposed to provide beneficial effects in a number of lung conditions. Therefore, Kv7 channel openers/enhancers or drugs acting partly through these channels have been proposed as bronchodilators, expectorants, antitussives, chemotherapeutics and pulmonary vasodilators.

Pulmonary arteriovenous malformations: what the interventional radiologist needs to know

Pulmonary arteriovenous malformations (PAVMs) or fistulas are rare direct pathological connections between pulmonary arterial and venous circulation. Most of PAVMs are congenital and closely associated with hereditary hemorrhagic telangiectasia, but acquired PAVMs have also been described in the literature. Diagnosis of PAVMs is a priority for clinicians, in order to prevent potentially fatal events such as cerebrovascular stroke, systemic septic embolization, hemoptysis and hemothorax. In this scenario, the radiologist plays a key role in both diagnostic and therapeutic workups of PAVMs: Chest X-ray, computed tomography and magnetic resonance are effective tools for PAVMs identification and confirmation of the suspected diagnosis. Furthermore, imaging modalities provide most of the elements for PAVMs classification according to their angioarchitecture (simple and complex) and help the clinicians in establishing which lesion requires prompt treatment and which one will benefit of imaging follow-up alone. Endovascular management of PAVMs has grown up as the first-line treatment in respect of surgery during last decades, showing lower risk of intra- and post-procedural complications and offering a wide number of treatment options and materials, ensuring effective management in virtually any clinical situation; interventional treatment aims to exclude PAVMs from pulmonary circulation, and specific technique and embolic agents should be selected according to pre-treatment imaging, in order to obtain the best procedural outcome. This paper proposes a review of the clinical and radiological features that a radiologist needs to know for PAVMs diagnosis and proper management, also showing an overview of the most common endovascular treatment strategies and embolization materials.

Pulmonary arteriovenous malformations: diagnosis

Pulmonary arteriovenous malformations (PAVMs) are rare, abnormal low resistance vascular structures that connect a pulmonary artery to a pulmonary vein, thereby bypassing the normal pulmonary capillary bed and resulting in an intrapulmonary right-to-left shunt. The spectrum of PAVMs extends from microscopic lesions causing profound hypoxemia and ground glass appearance on computed tomography (CT) but with normal catheter angiographic findings to classic pulmonary aneurysmal connections that abnormally connect pulmonary veins and arteries. These malformations most commonly are seen in hereditary hemorrhagic telangiectasia (HHT). They are rarely due to secondary conditions such as post congenital heart disease surgery or hepatopulmonary syndrome (HPS). The main complications of PAVM result from intrapulmonary shunt and include stroke, brain abscess, and hypoxemia. Local pulmonary complications include PAVM rupture leading to life-threatening hemoptysis or hemothorax. The preferred screening test for PAVM is transthoracic contrast echocardiography (TTCE). CT has become the gold standard imaging test to establish the presence of PAVM. Endovascular occlusion of the feeding artery is the treatment of choice. Collateralization and recanalization of PAVM following treatment may occur, and hence long term clinical and imaging follow-up is required to assess PAVM enlargement and PAVM reperfusion.

What people with Down Syndrome can teach us about cardiopulmonary disease

Down syndrome is the most common chromosomal abnormality among live-born infants. Through full or partial trisomy of chromosome 21, Down syndrome is associated with cognitive impairment, congenital malformations (particularly cardiovascular) and dysmorphic features. Immune disturbances in Down syndrome account for an enormous disease burden ranging from quality-of-life issues (autoimmune alopecia) to more serious health issues (autoimmune thyroiditis) and life-threatening issues (leukaemia, respiratory tract infections and pulmonary hypertension). Cardiovascular and pulmonary diseases account for ∼75% of the mortality seen in persons with Down syndrome. This review summarises the cardiovascular, respiratory and immune challenges faced by individuals with Down syndrome, and the genetic underpinnings of their pathobiology. We strongly advocate increased comparative studies of cardiopulmonary disease in persons with and without Down syndrome, as we believe these will lead to new strategies to prevent and treat diseases affecting millions of people worldwide.

Imaging in vascular diseases of the lung

PURPOSE OF REVIEW

The present review focuses on the recent developments in the field of pulmonary angiography and perfusion by means of computed tomography and magnetic resonance imaging.

RECENT FINDINGS

Computed tomography allows for a detailed analysis of large and small pulmonary vascular pathologies and simultaneously allows for evaluation of the lung parenchyma. Magnetic resonance imaging allows for large and small vessel evaluation as well as noninvasive pressure assessment. Furthermore, recently non-breath-hold contrast-enhanced and noncontrast-enhanced techniques have been developed making magnetic resonance imaging an ideal tool for comprehensive thoracic imaging, even in challenging patients.

SUMMARY

Noninvasive imaging using computed tomography and magnetic resonance imaging further increases their value in daily clinical practice when it comes to assessment of large and small pulmonary artery disease. As computed tomography is more easy to use and widely available, it remains the diagnostic modality of choice. However, magnetic resonance imaging is the modality of choice when a comprehensive angiographic and functional assessment is deemed necessary.