Imaging of pulmonary hypertension: an update

Comprehensive imaging in patients with suspected pulmonary arterial hypertension

Currently, several imaging techniques are being used for a comprehensive evaluation of patients with suspected pulmonary hypertension (PH), in order to provide information that may clarify the presence and identify the aetiology of this complex pathology. The current paper is focused on recent updates regarding the importance of comprehensive imaging techniques for patients with suspected PH. Transthoracic echocardiography that can mainly detect right ventricle pressure overload and dysfunction is the cornerstone of imaging evaluation, while right heart catheterisation remains the gold standard assessment method. Chest radiography that may exclude pleuroparenchymal lung diseases, CT, the primary imaging modality for the assessment of lung parenchyma and CT pulmonary angiography, that allows for the non-invasive assessment of the pulmonary arteries, are equally important. Imaging techniques like dual-energy CT, single photon emission CT and ventilation perfusion scan may provide accurate diagnostic information for patients with chronic thromboembolic PH. Cardiac MRI provides the most accurate three-dimensional characterisation of the right ventricle. Accurate use of diagnostic imaging algorithms allows early detection of the disease, with the constant goal of improved PH patients prognosis.

Unmasking a Silent Threat: Improving Pulmonary Hypertension Screening Methods for Interstitial Lung Disease Patients

This article provides a comprehensive overview of the latest literature on the diagnostics and treatment of pulmonary hypertension (PH) associated with interstitial lung disease (ILD). Heightened suspicion for PH arises when the advancement of dyspnoea in ILD patients diverges from the expected pattern of decline in pulmonary function parameters. The complexity of PH associated with ILD (PH-ILD) diagnostics is emphasized by the limitations of transthoracic echocardiography in the ILD population, necessitating the exploration of alternative diagnostic approaches. Cardiac magnetic resonance imaging (MRI) emerges as a promising tool, offering insights into hemodynamic parameters and providing valuable prognostic information. The potential of biomarkers, alongside pulmonary function and cardiopulmonary exercise tests, is explored for enhanced diagnostic and prognostic precision. While specific treatments for PH-ILD remain limited, recent studies on inhaled treprostinil provide new hope for improved patient outcomes.

Vascular Applications of Dual-Energy Computed Tomography

Dual- or multi-energy CT imaging provides several advantages over conventional CT in the context of vascular imaging. Specific advantages include the use of low-energy virtual monoenergetic images (VMIs) to boost iodine attenuation to salvage suboptimal enhanced studies, perform low-contrast material dose studies, and increase conspicuity of small vessels and lesions. Alternatively, high-energy VMIs reduce artifacts caused by some metals, endoprosthesis, calcium blooming, and beam hardening. Virtual non-contrast (VNC) images reduce radiation dose by eliminating the need for a true non-contrast acquisition in multiphasic CT studies. Iodine maps can be used to evaluate perfusion of tissues and lesions.

In Situ Pulmonary Arterial Thrombosis-Literature Review and Clinical Significance of a Distinct Entity

Filling defects identified in the pulmonary arterial tree are commonly presumed to represent an embolic phenomenon originating from thrombi formed in remote veins, particularly lower-extremity deep venous thrombosis (DVT). However, accumulating evidence supports an underappreciated cause for pulmonary arterial thrombosis (PAT), namely, de novo thrombogenesis-where thrombosis arises within the pulmonary arteries in the absence of DVT. Although historically underrecognized, in situ PAT has become of heightened importance with the emergence of SARS-CoV-2 infection. In situ PAT is attributed to endothelial dysfunction, systemic inflammation, and acute lung injury, and has been described in a range of conditions including COVID-19, trauma, acute chest syndrome in sickle cell disease, pulmonary infections, and severe pulmonary arterial hypertension. The distinction between pulmonary embolus and in situ PAT may have important implications regarding management decisions and clinical outcomes. In this review, we summarize the pathophysiology, imaging appearances, and management of in situ PAT in various clinical situations. This understanding will promote optimal tailored treatment strategies for this increasingly recognized entity.

Viewpoint: a multidisciplinary approach to the assessment of patients with systemic sclerosis-associated interstitial lung disease

Systemic sclerosis (SSc) is a rare and heterogeneous disease affecting the skin and internal organs. SSc-associated ILD (SSc-ILD) is a common and often early manifestation of SSc. This article discusses the rationale for a multidisciplinary approach (MDA) to the early identification and assessment of patients with SSc-ILD. Diagnosis of SSc-ILD is often challenging as patients with early disease can be asymptomatic, and SSc-ILD symptoms, such as exertional dyspnea and cough, are non-specific. High-resolution computed tomography (HRCT) of the lungs is the gold standard for diagnosis of SSc-ILD since pulmonary function tests lack sensitivity and specificity, especially in early disease. On HRCT, most patients with SSc-ILD have a non-specific interstitial pneumonia (NSIP) pattern. In addition, findings of pulmonary hypertension and esophageal dysmotility may be present. The multi-organ involvement of SSc and the diverse spectrum of symptoms support an MDA for the diagnosis and assessment of patients with SSc-ILD, with input from rheumatologists, pulmonologists, gastroenterologists, radiologists, and other specialists. Key Points • Interstitial lung disease (ILD) is a common manifestation of systemic sclerosis (SSc). • Early diagnosis is key to reducing the morbidity and mortality associated with SSc-ILD and other manifestations of SSc. • The multi-organ involvement of SSc supports a multidisciplinary approach to the diagnosis and assessment of patients with SSc-ILD, with input from rheumatologists, pulmonologists, gastroenterologists, radiologists, and other specialists.

The diagnostic performance of CT pulmonary angiography in the detection of chronic thromboembolic pulmonary hypertension-systematic review and meta-analysis

OBJECTIVES

To examine the diagnostic performance of CT of the pulmonary artery (CTPA) as a potential first-choice imaging modality in patients with pulmonary arterial hypertension and suspected chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS

A systematic review and meta-analysis were conducted in accordance with the PRISMA reporting checklist. Six scientific databases and registers (PubMed, EMBASE, Scopus, Web of Science, Cochrane, ClinicalTrials.gov ) were searched for studies evaluating the diagnostic performance of CTPA in suspected CTEPH in adult patients. Results were pooled separately for studies based on the evaluation of the pulmonary artery and those that relied solely on changes in parenchymal perfusion.

RESULTS

Ten single-center studies with 734 patients were eligible for pooling of the diagnostic performance of CTPA by evaluation of the pulmonary artery. The pooled sensitivity, specificity, PPV, NPV, accuracy, and diagnostic odds ratio (DOR) estimates for CTPA in the detection of CTEPH were 0.98, 0.99, 0.94, 1.00, 0.96, 0.96, and 292. Evaluation of perfusion changes yielded pooled estimates for sensitivity, specificity, PPV, NPV, accuracy, and DOR of 0.99, 0.84, 0.79, 0.98, 0.89, 0.89, and 98 across four studies with 278 patients. Scintigraphy, SPECT, digital subtraction angiography, right heart catheterization, pulmonary endarterectomy, and international guidelines were used to establish the diagnosis.

CONCLUSION

CTPA has high sensitivity and specificity in the detection of CTEPH when the examination is evaluated by expert radiologists. Evaluation of parenchymal perfusion alone is associated with slightly lower specificity. Further research is needed to determine the diagnostic performance of CTPA in excluding CTEPH in general radiology departments.

KEY POINTS

• CT pulmonary angiography (CTPA) is recommended in the diagnostic workup of chronic thromboembolic pulmonary hypertension (CTEPH). • CTPA has high sensitivity and specificity in the detection of CTEPH when evaluated by an expert radiologist. • Evaluation of changes in parenchymal perfusion alone is associated with slightly lower specificity. • Little is known about the diagnostic performance of CTPA in the detection of CTEPH in general radiology departments.

The role of serial right heart catheterization in risk stratification and management of pulmonary arterial hypertension

INTRODUCTION

Pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial blood pressure secondary to increased pulmonary vascular resistance.

AREAS COVERED

Invasive hemodynamic assessment by heart catheterization (RHC) remains the gold standard to confirm the diagnosis, to determine the severity of right ventricular dysfunction and to test for pulmonary vasoreactivity. After diagnosis and initiation of therapy, many PAH centers continue to perform RHC at regular intervals to monitor for disease progression and alter management. We discuss the importance of risk stratification in PAH, the role of RHC in the evaluation and treatment of these patients and compare non-invasive risk assessment tools to that of RHC.

EXPERT OPINION

RHC is useful for diagnosis of PAH, assessing the risk of mortality and morbidity, directing the escalation and de-escalation of therapy, and monitoring for disease progression. In the current era of improved non-invasive cardiac hemodynamic assessment, the role for routine follow-up serial RHC in patients with PAH needs to be reassessed in future studies. With the availability of non-invasive risk assessment tools such as REVEAL Lite 2, it may be reasonable to reconsider the role of annual or protocoled RHC, and instead, move on to an "as needed" and individual approach.

Diagnostic test accuracy of artificial intelligence analysis of cross-sectional imaging in pulmonary hypertension: a systematic literature review

OBJECTIVES

To undertake the first systematic review examining the performance of artificial intelligence (AI) applied to cross-sectional imaging for the diagnosis of acquired pulmonary arterial hypertension (PAH).

METHODS

Searches of Medline, Embase and Web of Science were undertaken on 1 July 2020. Original publications studying AI applied to cross-sectional imaging for the diagnosis of acquired PAH in adults were identified through two-staged double-blinded review. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies and Checklist for Artificial Intelligence in Medicine frameworks. Narrative synthesis was undertaken following Synthesis Without Meta-Analysis guidelines. This review received no funding and was registered in the International Prospective Register of Systematic Reviews (ID:CRD42020196295).

RESULTS

Searches returned 476 citations. Three retrospective observational studies, published between 2016 and 2020, were selected for data-extraction. Two methods applied to cardiac-MRI demonstrated high diagnostic accuracy, with the best model achieving AUC=0.90 (95% CI: 0.85-0.93), 89% sensitivity and 81% specificity. Stronger results were achieved using cardiac-MRI for classification of idiopathic PAH, achieving AUC=0.97 (95% CI: 0.89-1.0), 96% sensitivity and 87% specificity. One study reporting CT-based AI demonstrated lower accuracy, with 64.6% sensitivity and 97.0% specificity.

CONCLUSIONS

Automated methods for identifying PAH on cardiac-MRI are emerging with high diagnostic accuracy. AI applied to cross-sectional imaging may provide non-invasive support to reduce diagnostic delay in PAH. This would be helped by stronger solutions in other modalities.

ADVANCES IN KNOWLEDGE

There is a significant shortage of research in this important area. Early detection of PAH would be supported by further research advances on the promising emerging technologies identified.

Estimates of Prevalence of Pulmonary Hypertension according to Different International Definitions

Background

Pulmonary hypertension is a dreaded disease associated with considerable morbidity and mortality. The pulmonary hypertension developing due to chronic respiratory disease is a unique subset with symptoms often getting masqueraded by the underlying respiratory condition. The importance of early detection of this complication has been realized worldwide, and recently, the definition of pulmonary hypertension was revised to set the cutoff of mean pulmonary artery pressure (mPAP) at 20 mmHg instead of 25 mmHg at rest. In our study, we have tried to estimate the difference this new definition brings to the prevalence of pulmonary hypertension among interstitial lung disease patients at our centre.

Methods

This was a cross-sectional study in which all the patients of ILDs (n = 239) attending the outdoor and indoor Department of Respiratory Medicine, King George's Medical University, India, for the duration of one year were subjected to transthoracic echocardiography along with measurement of serum pro-B-type natriuretic peptide (BNP) and troponin T values. The data were analyzed using the different definitions, and the prevalence was compared.

Result

Incidence of pulmonary hypertension among ILD patients at mPAP cutoff ≥ 25 was 28.9%, while that at value ≥20 mmHg, incidence of pulmonary hypertension increased to 46.0%. An increment of 15-20% in incidence of pulmonary hypertension was observed among different types of ILD when cutoff of mPAP was changed.

Conclusion

The new definition helps in a significant increase in the detection of pulmonary hypertension, which certainly helps in earlier detection and better management of patients.

Performance of a 3D convolutional neural network in the detection of hypoperfusion at CT pulmonary angiography in patients with chronic pulmonary embolism: a feasibility study

BACKGROUND

Chronic pulmonary embolism (CPE) is a life-threatening disease easily misdiagnosed on computed tomography. We investigated a three-dimensional convolutional neural network (CNN) algorithm for detecting hypoperfusion in CPE from computed tomography pulmonary angiography (CTPA).

METHODS

Preoperative CTPA of 25 patients with CPE and 25 without pulmonary embolism were selected. We applied a 48%-12%-40% training-validation-testing split (12 positive and 12 negative CTPA volumes for training, 3 positives and 3 negatives for validation, 10 positives and 10 negatives for testing). The median number of axial images per CTPA was 335 (min-max, 111-570). Expert manual segmentations were used as training and testing targets. The CNN output was compared to a method in which a Hounsfield unit (HU) threshold was used to detect hypoperfusion. Receiver operating characteristic area under the curve (AUC) and Matthew correlation coefficient (MCC) were calculated with their 95% confidence interval (CI).

RESULTS

The predicted segmentations of CNN showed AUC 0.87 (95% CI 0.82-0.91), those of HU-threshold method 0.79 (95% CI 0.74-0.84). The optimal global threshold values were CNN output probability ≥ 0.37 and ≤ -850 HU. Using these values, MCC was 0.46 (95% CI 0.29-0.59) for CNN and 0.35 (95% CI 0.18-0.48) for HU-threshold method (average difference in MCC in the bootstrap samples 0.11 (95% CI 0.05-0.16). A high CNN prediction probability was a strong predictor of CPE.

CONCLUSIONS

We proposed a deep learning method for detecting hypoperfusion in CPE from CTPA. This model may help evaluating disease extent and supporting treatment planning.

Thoracic Manifestations of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is one of the most common chronic systemic inflammatory diseases and the most common chronic inflammatory arthritis. Classically a progressive symmetric polyarthritis, RA is characterized by inflammation, erosions, bone loss, and joint destruction. Up to half of patients with RA exhibit extra-articular manifestations (EAMs), which may precede articular disease and are more common in patients with seropositive RA (patients with detectable serum levels of rheumatoid factor and/or anticitrullinated peptide antibodies). Cardiovascular and pulmonary EAMs are the largest contributors to morbidity and mortality in RA and may be especially devastating. Imaging has a significant role in diagnosing these EAMs and assessing response to treatment. Although treatment with disease-modifying antirheumatic drugs has redefined the natural history of RA and helped many patients achieve low disease activity, patients are at risk for treatment-related complications, as well as infections. The clinical features of drug-induced lung disease and infection can overlap considerably with those of EAMs, presenting a diagnostic challenge. Radiologists, by recognizing the imaging characteristics and evolution of these various processes, are essential in diagnosing and distinguishing among EAMs, treatment-related complications, and unrelated processes and formulating an appropriate differential diagnosis. Moreover, recognizing these disease processes at imaging and contextualizing imaging findings with clinical information and laboratory and pathologic findings can facilitate definitive diagnosis and proper treatment. The authors review the articular and extra-articular thoracic imaging manifestations of RA, including cardiovascular, respiratory, and pleural diseases, as well as treatment-related complications and common infections. ^©RSNA, 2021.

Pulmonary hypertension secondary to pulmonary fibrosis: clinical data, histopathology and molecular insights

Pulmonary hypertension (PH) developing secondarily in pulmonary fibrosis (PF) patients (PF-PH) is a frequent co-morbidity. The high prevalence of PH in PF patients is very concerning since the presence of PH is a strong predictor of mortality in PF patients. Until recently, PH was thought to arise solely from fibrotic destruction of the lung parenchyma, leading to hypoxic vasoconstriction and loss of vascular bed density. Thus, potential cellular and molecular dysregulation of vascular remodeling as a driver of PF-PH has been under-investigated. The recent demonstrations that there is no correlation between the severity of the fibrosis and development of PH, along with the finding that significant vascular histological and molecular differences exist between patients with and without PH have shifted the etiological paradigm of PF-PH. This review aims to provide a comprehensive translational overview of PH in PF patients from clinical diagnosis and outcome to the latest understanding of the histology and molecular pathophysiology of PF-PH.

Comparative accuracy of non-invasive imaging versus right heart catheterization for the diagnosis of pulmonary hypertension: A systematic review and meta-analysis

BACKGROUND

Right heart catheterization (RHC) is the gold-standard in the diagnosis of pulmonary hypertension (PH) but at the cost of procedure-related complications. We sought to determine the comparative accuracy of RHC versus non-invasive imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), and transthoracic echocardiography (TTE).

METHODS

Pulmonary hypertension was defined as a mean pulmonary artery pressure (mPAP) of>20 mmHg. Multiple databases were queried for relevant articles. Raw data were pooled using a bivariate model to calculate the measures of diagnostic accuracy and to estimate Hierarchical Summary Receiver Operating Characteristic (HSROC) on Stata 13.

RESULTS

A total of 51 studies with a total patient population of 3947 were selected. The pooled sensitivity and specificity of MRI for diagnosing PH was 0.92(95% confidence interval (CI) 0.88-0.96) and 0.86 (95% CI, 0.77-0.95), respectively. The net sensitivities for CT scan and TTE were 0.79 (95% CI 0.72-0.89) and 0.85 (95% CI 0.83-0.91), respectively. The overall specificity was 0.82 (0.76-0.92) for the CT scan and 0.71 (95% CI 0.61-0.84) for TTE. The diagnostic odds ratio (DOR) for MRI was 124 (95% CI 36-433) compared to 30 (95% CI 11-78) and 24 (95% 11-38) for CT scan and TTE, respectively. Chi-squared (x2) test showed moderate heterogeneity on the test for equality of sensitivities and specificities.

CONCLUSIONS

MRI has the highest sensitivity and specificity compared to CT and TTE. MRI can potentially serve as a surrogate technique to RHC for the diagnosis of PH.

Mapping cardiopulmonary dynamics within the microvasculature of the lungs using dissolved 129Xe MRI

Magnetic resonance (MR) imaging and spectroscopy using dissolved hyperpolarized (HP) 129Xe have expanded the ability to probe lung function regionally and noninvasively. In particular, HP 129Xe imaging has been used to quantify impaired gas uptake by the pulmonary tissues. Whole-lung spectroscopy has also been used to assess global cardiogenic oscillations in the MR signal intensity originating from 129Xe dissolved in the red blood cells of pulmonary capillaries. Herein, we show that the magnitude of these cardiogenic dynamics can be mapped three dimensionally using radial MRI, because dissolved 129Xe dynamics are encoded directly in the raw imaging data. Specifically, 1-point Dixon imaging is combined with postacquisition keyhole image reconstruction to assess regional blood volume fluctuations within the pulmonary microvasculature throughout the cardiac cycle. This "oscillation mapping" was applied in healthy subjects (mean amplitude 9% of total RBC signal) and patients with pulmonary arterial hypertension (PAH; mean 4%) and idiopathic pulmonary fibrosis (IPF; mean 14%). Whole-lung mean values from these oscillation maps correlated strongly with spectroscopy and clinical pulmonary function testing, but exhibited significant regional heterogeneity, including gravitationally dependent gradients in healthy subjects. Moreover, regional oscillations were found to be sensitive to disease state. Greater percentages of the lungs exhibit low-amplitude oscillations in PAH patients, and longitudinal imaging shows high-amplitude oscillations increase significantly over time (4-14 mo, P = 0.02) in IPF patients. This technique enables regional dynamics within the pulmonary capillary bed to be measured, and in doing so, provides insight into the origin and progression of pathophysiology within the lung microvasculature.NEW & NOTEWORTHY Spatially heterogeneous abnormalities within the lung microvasculature contribute to pathology in various cardiopulmonary diseases but are difficult to assess noninvasively. Hyperpolarized 129Xe MRI is a noninvasive method to probe lung function, including regional gas exchange between pulmonary air spaces and capillaries. We show that cardiogenic oscillations in the raw dissolved 129Xe MRI signal from pulmonary capillary red blood cells can be imaged using a postacquisition reconstruction technique, providing a new means of assessing regional lung microvasculature function and disease state.

Emerging role of cardiovascular magnetic resonance imaging in the management of pulmonary hypertension

Pulmonary hypertension (PH) is a clinical condition characterised by elevation of pulmonary arterial pressure (PAP) above normal range due to various aetiologies. While cardiac right-heart catheterisation (RHC) remains the gold standard and mandatory for establishing the diagnosis of PH, noninvasive imaging of the heart plays a central role in the diagnosis and management of all forms of PH. Although Doppler echocardiography (ECHO) can measure a range of haemodynamic and anatomical variables, it has limited utility for visualisation of the pulmonary artery and, oftentimes, the right ventricle. Cardiovascular magnetic resonance (CMR) provides comprehensive information about the anatomical and functional aspects of the pulmonary artery and right ventricle that are of prognostic significance for assessment of long-term outcomes in disease progression. CMR is suited for serial follow-up of patients with PH due to its noninvasive nature, high sensitivity to changes in anatomical and functional parameters, and high reproducibility. In recent years, there has been growing interest in the use of CMR derived parameters as surrogate endpoints for early-phase PH clinical trials. This review will discuss the role of CMR in the diagnosis and management of PH, including current applications and future developments, in comparison to other existing major imaging modalities.

Changes in heart morphometric parameters over the course of a monocrotaline-induced pulmonary arterial hypertension rat model

Background

Aim of this study was to assess changes in cardiac morphometric parameters at different stages of pulmonary arterial hypertension (PAH) using a monocrotaline-induced rat model.

Methods

Four groups were distinguished: I–control, non-PAH (n = 18); II–early PAH (n = 12); III–end-stage PAH (n = 23); and IV–end-stage PAH with myocarditis (n = 7).

Results

Performed over the course of PAH in vivo echocardiography showed significant thickening of the right ventricle free wall (end-diastolic dimension), tricuspid annular plane systolic excursion reduction and decrease in pulmonary artery acceleration time normalized to cycle length. No differences in end-diastolic left ventricle free wall thickness measured in echocardiography was observed between groups. Significant increase of right ventricle and decrease of left ventricle systolic pressure was observed over the development of PAH. Thickening and weight increase (241.2% increase) of the right ventricle free wall and significant dilatation of the right ventricle was observed over the course of PAH (p < 0.001). Reduction in the left ventricle free wall thickness was also observed in end-stage PAH (p < 0.001). Significant trend in the left ventricle free wall weight decrease was observed over the course of PAH (p < 0.001, 24.3% reduction). Calculated right/left ventricle free wall weight ratio gradually increased over PAH stages (p < 0.001). The reduction of left ventricle diameter was observed in rats with end-stage PAH both with and without myocarditis (p < 0.001).

Conclusions

PAH leads to multidimensional changes in morphometric cardiac parameters. Right ventricle morphological and functional failure develop gradually from early stage of PAH, while left ventricle changes develop at the end stages of PAH.

Increased main pulmonary artery diameter and main pulmonary artery to ascending aortic diameter ratio in smokers undergoing lung cancer screening

OBJECTIVES

Pulmonary hypertension (PH) is a progressive, potentially fatal disease, difficult to diagnose early due to non-specific nature of symptoms. PH is associated with increased morbidity and death in many respiratory and cardiac disorders, and with all-cause mortality, independent of age and cardiopulmonary disease. The main pulmonary artery diameter (MPA), and ratio of MPA to adjacent ascending aorta (AA), MPA:AA, on Chest CT are strong indicators of suspected PH. Our goal was to determine the prevalence of abnormally high values of these indicators of PH in asymptomatic low-dose CT (LDCT) screening participants at risk of lung cancer, and determine the associated risk factors.

METHODS

We reviewed consecutive baseline LDCT scans of 1949 smokers in an IRB-approved study. We measured the MPA and AA diameter and calculated MPA:AA ratio. We defined abnormally high values as being more than two standard deviations above the average (MPA ≥ 34 mm and MPA:AA ≥ 1.0). Regression analyses were used to identify risk factors and CT findings of participants associated with high values.

RESULTS

The prevalence of MPA ≥ 34 mm and MPA:AA ≥ 1.0 was 4.2% and 6.9%, respectively. Multivariable regression demonstrated that BMI was a significant risk factor, both for MPA ≥ 34 mm (OR = 1.07, p < 0.0001) and MPA:AA ≥ 1.0 (OR = 1.04, p = 0.003). Emphysema was significant in the univariate but not in the multivariate analysis.

CONCLUSIONS

We determined that the possible prevalence of PH as defined by abnormally high values of MPA and of MPA:AA was greater than previously described in the general population and that pulmonary consultation be recommended for these participants, in view of the significance of PH.

The changing face of pulmonary hypertension diagnosis: a historical perspective on the influence of diagnostics and biomarkers

Pulmonary hypertension is a complex, multifactorial disease that results in right heart failure and premature death. Since the initial reports of pulmonary hypertension in the late 1800s, the diagnosis of pulmonary hypertension has evolved with respect to its definition, screening tools, and diagnostic techniques. This historical perspective traces the earliest roots of pulmonary hypertension detection and diagnosis through to the current recommendations for classification. We highlight the diagnostic tools used in the past and present, and end with a focus on the future directions of early detection. Early detection of pulmonary hypertension and pulmonary arterial hypertension and the proper determination of etiology are vital for the early therapeutic intervention that can prolong life expectancy and improve quality of life. The search for a non-invasive screening tool for the identification and classification of pulmonary hypertension is ongoing, and we discuss the role of animal models of the disease in this search.

State of the art: utility of multi-energy CT in the evaluation of pulmonary vasculature

Multi-energy computed tomography (MECT) refers to acquisition of CT data at multiple energy levels (typically two levels) using different technologies such as dual-source, dual-layer and rapid tube voltage switching. In addition to conventional/routine diagnostic images, MECT provides additional image sets including iodine maps, virtual non-contrast images, and virtual monoenergetic images. These image sets provide tissue/material characterization beyond what is possible with conventional CT. MECT provides invaluable additional information in the evaluation of pulmonary vasculature, primarily by the assessment of pulmonary perfusion. This functional information provided by the MECT is complementary to the morphological information from a conventional CT angiography. In this article, we review the technique and applications of MECT in the evaluation of pulmonary vasculature.

Assessment of Right Ventricular Function in Pulmonary Hypertension with Multimodality Imaging

Pulmonary hypertension (PH) is defined as resting mean pulmonary artery pressure ≥ 25 mmHg and is caused by multiple etiologies including heart, lung or other systemic diseases. Evaluation of right ventricular (RV) function in PH is very important to plan treatment and determine prognosis. However, quantification of volume and function of the RV remains difficult due to complicated RV geometry. A number of imaging tools has been utilized to diagnose PH and assess RV function. Each imaging technique including conventional echocardiography, three-dimensional echocardiography, strain echocardiography, computed tomography and cardiac magnetic resonance imaging has-advantages and limitations and can provide unique information. In this article, we provide a comprehensive review of the utility, advantages and shortcomings of the multimodality imaging used to evaluate patients with PH.