MR phase-contrast imaging in pulmonary hypertension

Pulmonary Artery Stenosis After an Orthotopic Heart Transplantation: A Case Report With Cardiac Imaging Findings and a Literature Review

Pulmonary artery stenosis is a rare complication of heart transplantation. It is typically a congenital condition or can be secondary to rheumatic fever, systemic vasculitis like Behcet's disease, or Takayasu's arteritis. It can also occur as a rarity of a delayed complication post-heart transplant. In this report, we describe the imaging findings of pulmonary artery stenosis in a patient who underwent an orthotopic heart transplant more than 10 years prior. Dynamic cardiac magnetic resonance imaging (MRI), phase contrast imaging, and MR angiography in the management of pulmonary artery stenosis helped in heart and pulmonary circulation. Functional evaluation can be achieved with current multichannel transmit-receive coils. Cardiac gated pre- and dynamic contrast-enhanced MR was performed with phase-contrast imaging for further evaluation confirming the diagnosis of pulmonary artery stenosis.

MRI pulmonary artery flow detects lung vascular pathology in preterms with lung disease

BACKGROUND

Pulmonary vascular disease (PVD) affects the majority of preterm neonates with bronchopulmonary dysplasia (BPD) and significantly determines long-term mortality through undetected progression into pulmonary hypertension. Our objectives were to associate characteristics of pulmonary artery (PA) flow and cardiac function with BPD-associated PVD near term using advanced magnetic resonance imaging (MRI) for improved risk stratification.

METHODS

Preterms <32 weeks postmenstrual age (PMA) with/without BPD were clinically monitored including standard echocardiography and prospectively enrolled for 3 T MRI in spontaneous sleep near term (AIRR (Attention to Infants at Respiratory Risks) study). Semi-manual PA flow quantification (phase-contrast MRI; no BPD n=28, mild BPD n=35 and moderate/severe BPD n=25) was complemented by cardiac function assessment (cine MRI).

RESULTS

We identified abnormalities in PA flow and cardiac function, i.e. increased net forward volume right/left ratio, decreased mean relative area change and pathological right end-diastolic volume, to sensitively detect BPD-associated PVD while correcting for PMA (leave-one-out area under the curve 0.88, sensitivity 0.80 and specificity 0.81). We linked these changes to increased right ventricular (RV) afterload (RV-arterial coupling (p=0.02), PA mid-systolic notching (t2; p=0.015) and cardiac index (p=1.67×10-8)) and correlated echocardiographic findings. Identified in moderate/severe BPD, we successfully applied the PA flow model in heterogeneous mild BPD cases, demonstrating strong correlation of PVD probability with indicators of BPD severity, i.e. duration of mechanical ventilation (rs=0.63, p=2.20×10-4) and oxygen supplementation (rs=0.60, p=6.00×10-4).

CONCLUSIONS

Abnormalities in MRI PA flow and cardiac function exhibit significant, synergistic potential to detect BPD-associated PVD, advancing the possibilities of risk-adapted monitoring.

Quantifying 4D flow cardiovascular magnetic resonance vortices in patients with pulmonary hypertension: A pilot study

In this 4D flow cardiovascular magnetic resonance (CMR) study, vortical blood flow in the main pulmonary artery (MPA) is quantified using circulation (ᴦ), a metric used in fluid dynamics to quantify the rotational components of flow. Circulation (ᴦ) is a 4D flow CMR metric that quantifies the vortical blood flow pattern in the MPA of patients with pulmonary hypertension (PH), distinguishes them from healthy controls, and shows high correlation with invasive markers of PH severity.

Qualification of Ventricular Flow in Patients With Precapillary Pulmonary Hypertension With 4-dimensional Flow Magnetic Resonance Imaging

PURPOSE

Our goal was to study both right and left ventricular blood flow in patients with precapillary pulmonary hypertension (pre-PH) with 4-dimensional (4D) flow magnetic resonance imaging (MRI) and to analyze their correlation with cardiac functional metrics on cardiovascular magnetic resonance (CMR) and hemodynamics from right heart catheterization (RHC).

MATERIALS AND METHODS

129 patients (64 females, mean age 47 ± 13 y) including 105 patients with pre-PH (54 females, mean age 49 ± 13 y) and 24 patients without PH (10 females, mean age 40 ± 12 y) were retrospectively included. All patients underwent CMR and RHC within 48 hours. 4D flow MRI was acquired using a 3-dimensional retrospectively electrocardiograph-triggered, navigator-gated phase contrast sequence. Right and left ventricular flow components including the percentages of direct flow (PDF), retained inflow (PRI), delayed ejection flow (PDE), and residual volume (PRVo) were respectively quantified. The ventricular flow components between patients with pre-PH and non-PH were compared and correlations of flow components with CMR functional metrics and hemodynamics measured with RHC were analyzed. Biventricular flow components were compared between survivors and deceased patients during the perioperative period.

RESULTS

Right ventricular (RV) PDF and PDE significantly correlated with RVEDV and RV ejection fraction. RV PDF negatively correlated with pulmonary arterial pressure (PAP) and pulmonary vascular resistance. When the RV PDF was <11%, the sensitivity and specificity of RV PDF for predicting mean PAP ≥25 mm Hg were 88.6% and 98.7%, respectively, with an area under the curve value of 0.95 ± 0.02. When RV PRVo was more than 42%, the sensitivity and specificity of RV PRVo for predicting mean PAP ≥25 mm Hg were 85.7% and 98.5%, respectively, with an area under the curve value of 0.95 ± 0.01. Nine patients died during the perioperative period. Biventricular PDF, RV PDE, and PRI of survivors were higher than nonsurvivors whereas RV PRVo increased in deceased patients.

CONCLUSIONS

Biventricular flow analysis with 4D flow MRI provides comprehensive information about the severity and cardiac remodeling of PH and may be a predictor of perioperative death of patients with pre-PH.

Cardiovascular Magnetic Resonance Imaging Patterns in Rare Cardiovascular Diseases

Rare cardiovascular diseases (RCDs) have low incidence but major clinical impact. RCDs' classification includes Class I-systemic circulation, Class II-pulmonary circulation, Class III-cardiomyopathies, Class IV-congenital cardiovascular diseases (CVD), Class V-cardiac tumors and CVD in malignancy, Class VI-cardiac arrhythmogenic disorders, Class VII-CVD in pregnancy, Class VIII-unclassified rare CVD. Cardiovascular Magnetic Resonance (CMR) is useful in the diagnosis/management of RCDs, as it performs angiography, function, perfusion, and tissue characterization in the same examination. Edema expressed as a high signal in STIRT2 or increased T2 mapping is common in acute/active inflammatory states. Diffuse subendocardial fibrosis, expressed as diffuse late gadolinium enhancement (LGE), is characteristic of microvascular disease as in systemic sclerosis, small vessel vasculitis, cardiac amyloidosis, and metabolic disorders. Replacement fibrosis, expressed as LGE, in the inferolateral wall of the left ventricle (LV) is typical of neuromuscular disorders. Patchy LGE with concurrent edema is typical of myocarditis, irrespective of the cause. Cardiac hypertrophy is characteristic in hypertrophic cardiomyopathy (HCM), cardiac amyloidosis (CA) and Anderson-Fabry Disease (AFD), but LGE is located in the IVS, subendocardium and lateral wall in HCM, CA and AFD, respectively. Native T1 mapping is increased in HCM and CA and reduced in AFD. Magnetic resonance angiography provides information on aortopathies, such as Marfan, Turner syndrome and Takayasu vasculitis. LGE in the right ventricle is the typical finding of ARVC, but it may involve LV, leading to the diagnosis of arrhythmogenic cardiomyopathy. Tissue changes in RCDs may be detected only through parametric imaging indices.

Prediction of pulmonary hypertension using central-to-peripheral pulmonary vascular volume ratio on three-dimensional cardiothoracic CT in patients with congenital heart disease

PURPOSE

To evaluate whether the central-to-peripheral pulmonary vascular volume ratio measured using three-dimensional cardiothoracic CT can serve as a potential predictor of pulmonary hypertension (PH) in patients with congenital heart disease.

METHODS

Cardiothoracic CT was used to quantify right and left total, central, and peripheral pulmonary vascular volumes segmented based on a three-dimensional threshold-based approach in 60 patients with congenital heart disease (group with PH, n = 30; group without PH, n = 30). The CT-based central-to-peripheral pulmonary vascular volume ratios were correlated with the echocardiography-based maximum velocity of tricuspid regurgitation (TR Vmax) and systolic pulmonary arterial pressure (PAP) values. The diagnostic ability of the central-to-peripheral pulmonary vascular volume ratio to predict PH was analyzed.

RESULTS

The central-to-peripheral pulmonary vascular volume ratios were significantly higher in the group with PH compared to the group without PH (1.6 ± 0.9 vs. 0.8 ± 0.3 for the right side, p < 0.001; 2.4 ± 2.2 vs. 1.0 ± 1.4 for the left side, p < 0.004). The right central-to-peripheral pulmonary volume ratios were significantly positively correlated with the TR Vmax and estimated systolic PAP values (R = 0.627 and 0.633, respectively; p < 0.001) in patients with and without PH, while the ratios were moderately correlated with the TR Vmax and estimated systolic PAP values (R = 0.431 and 0.435, respectively; p < 0.020) in the group with PH. The right and left central-to-peripheral pulmonary vascular volume ratios demonstrated a good diagnostic ability for predicting the presence of PH (area under the receiver-operating characteristic curve = 0.867, p < 0.001 and 0.859, p < 0.001 for the right and left, respectively).

CONCLUSION

The CT-based central-to-peripheral pulmonary vascular volume ratio can be used to predict PH in patients with congenital heart disease.

Pulmonary Arteriovenous Pressure Gradient and Time-Averaged Mean Velocity of Small Pulmonary Arteries Can Serve as Sensitive Biomarkers in the Diagnosis of Pulmonary Arterial Hypertension: A Preclinical Study by 4D-Flow MRI

(1) Background: Pulmonary arterial hypertension (PAH) is a serious condition that is associated with many cardiopulmonary diseases. Invasive right heart catheterization (RHC) is currently the only method for the definitive diagnosis and follow-up of PAH. In this study, we sought a non-invasive hemodynamic biomarker for the diagnosis of PAH. (2) Methods: We applied prospectively respiratory and cardiac gated 4D-flow MRI at a 9.4T preclinical scanner on three different groups of Sprague Dawley rats: baseline (n = 11), moderate PAH (n = 8), and severe PAH (n = 8). The pressure gradients as well as the velocity values were analyzed from 4D-flow data and correlated with lung histology. (3) Results: The pressure gradient between the pulmonary artery and vein on the unilateral side as well as the time-averaged mean velocity values of the small pulmonary arteries were capable of distinguishing not only between baseline and severe PAH, but also between the moderate and severe stages of the disease. (4) Conclusions: The current preclinical study suggests the pulmonary arteriovenous pressure gradient and the time-averaged mean velocity as potential biomarkers to diagnose PAH.

Evaluation and management of patients with chronic thromboembolic pulmonary hypertension - consensus statement from the ISHLT

ISHLT members have recognized the importance of a consensus statement on the evaluation and management of patients with chronic thromboembolic pulmonary hypertension. The creation of this document required multiple steps, including the engagement of the ISHLT councils, approval by the Standards and Guidelines Committee, identification and selection of experts in the field, and the development of 6 working groups. Each working group provided a separate section based on an extensive literature search. These sections were then coalesced into a single document that was circulated to all members of the working groups. Key points were summarized at the end of each section. Due to the limited number of comparative trials in this field, the document was written as a literature review with expert opinion rather than based on level of evidence.

[Possibilities of Magnetic Resonance Tomography in Diagnosis of Pulmonary Arterial Hypertension]

The emergence of more effective methods for treatment of pulmonary arterial hypertension (PAH) has called for more reliable methods of diagnostics, monitoring, and evaluating responses to the treatment. More reports have become available about the relevance of using magnetic resonance imaging (MRI) for examination of patients with PAH. This review provides data on the significance of MRI for noninvasive evaluation of the heart structure and function in patients with PAH, as well as for visualization and evaluation of the remodeling of the pulmonary circulation. According to the data presented in this review, the results obtained with various, modern MRI technologies can be used for monitoring the effect of treatment and for risk stratification in patients with PAH.

Overview of MRI for pulmonary functional imaging

Morphological evaluation of the lung is important in the clinical evaluation of pulmonary diseases. However, the disease process, especially in its early phases, may primarily result in changes in pulmonary function without changing the pulmonary structure. In such cases, the traditional imaging approaches to pulmonary morphology may not provide sufficient insight into the underlying pathophysiology. Pulmonary imaging community has therefore tried to assess pulmonary diseases and functions utilizing not only nuclear medicine, but also CT and MR imaging with various technical approaches. In this review, we overview state-of-the art MR methods and the future direction of: (1) ventilation imaging, (2) perfusion imaging and (3) biomechanical evaluation for pulmonary functional imaging.

Advanced Imaging in Pulmonary Vascular Disease

Although the diagnosis of pulmonary hypertension requires invasive testing, imaging serves an important role in the screening, classification, and monitoring of patients with pulmonary vascular disease (PVD). The development of advanced imaging techniques has led to improvements in the understanding of disease pathophysiology, noninvasive assessment of hemodynamics, and stratification of patient risk. This article discusses the current role of advanced imaging and the emerging novel techniques for visualizing the lung parenchyma, mediastinum, and heart in PVD.

From Early Morphometrics to Machine Learning-What Future for Cardiovascular Imaging of the Pulmonary Circulation?

Imaging plays a cardinal role in the diagnosis and management of diseases of the pulmonary circulation. Behind the picture itself, every digital image contains a wealth of quantitative data, which are hardly analysed in current routine clinical practice and this is now being transformed by radiomics. Mathematical analyses of these data using novel techniques, such as vascular morphometry (including vascular tortuosity and vascular volumes), blood flow imaging (including quantitative lung perfusion and computational flow dynamics), and artificial intelligence, are opening a window on the complex pathophysiology and structure-function relationships of pulmonary vascular diseases. They have the potential to make dramatic alterations to how clinicians investigate the pulmonary circulation, with the consequences of more rapid diagnosis and a reduction in the need for invasive procedures in the future. Applied to multimodality imaging, they can provide new information to improve disease characterization and increase diagnostic accuracy. These new technologies may be used as sophisticated biomarkers for risk prediction modelling of prognosis and for optimising the long-term management of pulmonary circulatory diseases. These innovative techniques will require evaluation in clinical trials and may in themselves serve as successful surrogate end points in trials in the years to come.

[Cardiac magnetic resonance imaging : Trends and developments]

Hintergrund

Durch die Entwicklung robuster Techniken und deren umfassender Validierung hat sich die kardiale Magnetresonanztomographie (CMR) in ihrem knapp 25-jährigen klinischen Einsatz ein breites Indikationsspektrum erarbeitet. Die Erfassung kardialer Volumina und systolischer Ventrikelfunktion sowie die Charakterisierung fokaler Myokardnarben sind heute Teil der CMR-Standard-Bildgebung. Zuletzt haben die Einführung beschleunigter Bildakquisitionstechnologien, die neuen Bildgebungsmethoden des myokardialen T1- und T2-Mappings und der 4‑D-Flussmessungen sowie die neue Postprocessing-Technik des myokardialen Feature-Trackings an Relevanz gewonnen.

Methode

Diese Überblicksarbeit basiert auf einer umfassenden Literaturrecherche in der PubMed-Datenbank zu neuen CMR-Techniken und ihrer klinischen Anwendung.

Ergebnisse und Schlussfolgerung

Dieser Artikel zeigt eine Übersicht über die neuesten technischen Entwicklungen im Bereich der CMR sowie deren Anwendungsmöglichkeiten anhand der wichtigsten klinischen Fragestellungen.

Pulmonary flow assessment by phase-contrast MRI can predict short-term mortality of fibrosing interstitial lung diseases

BACKGROUND

Phase-contrast magnetic resonance imaging (PC-MRI) can determine pulmonary hemodynamics non-invasively. Pulmonary hypertension causes changes in pulmonary hemodynamics and is a factor for acute exacerbation and death in interstitial lung diseases (ILD).

PURPOSE

To determine associations between pulmonary hemodynamics measured by PC-MRI and short-term mortality in patients with ILD.

MATERIAL AND METHODS

Pulmonary hemodynamics, measured by PC-MRI in 43 patients with ILD, were reviewed retrospectively. Evaluation parameters included heart rate, right cardiac output, average flow, average velocity, acceleration time, acceleration volume (AV), maximal change in flow rate during ejection (M), M/AV, maximum area, minimum area, and relative area change in the pulmonary artery (PA). All causes of death within one year from the day of the MRI examination were assessed by reviewing medical records. Associations between evaluation parameters and outcome were determined by univariate and multivariate Cox regression analysis.

RESULTS

Six patients (13.9%) died by the one-year follow-up. Age (hazard ratio [HR] 1.116, 95% confidence interval [CI] 1.015-1.269), average flow (HR 0.932, 95% CI 0.870-0.984), average velocity (HR 0.778, 95% CI 0.573-0.976), right cardiac output (HR 0.870, 95% CI 0.758-0.967), AV (HR 0.840, 95% CI 0.669-0.985), M/AV (HR 1.008, 95% CI 1.001-1.014), and PA relative area change (HR 0.715, 95% CI 0.459-0.928) predicted death in univariate Cox analysis. Multivariate Cox analysis showed decreased right cardiac output (HR 0.547, 95% CI 0.160-0.912) and decreased PA relative area change (HR 0.538, 95% CI 0.177-0.922) were independently associated with death.

CONCLUSION

Reduction in right cardiac output and decreased PA relative area change, detected by PC-MRI, were associated with increased mortality in ILD.

Perioperative CTEPH patient monitoring with 2D phase-contrast MRI reflects clinical, cardiac and pulmonary perfusion changes after pulmonary endarterectomy

Magnetic resonance imaging (MRI) is an emerging tool for diagnosis and treatment monitoring of chronic thromboembolic pulmonary hypertension (CTEPH). The current study aims to identify central pulmonary arterial hemodynamic parameters that reflect clinical, cardiac and pulmonary changes after PEA. 31 CTEPH patients, who underwent PEA and received pre- and postoperative MRI, were analyzed retrospectively. Central pulmonary arterial blood flow, lung perfusion and right heart function data were derived from MRI. Mean pulmonary arterial pressure (mPAP) and 5-month follow-up six-minute walk-distance (6MWD) were assessed. After PEA, mPAP decreased significantly and patients achieved a higher 6MWD. Central pulmonary arterial blood flow velocities, pulmonary blood flow (PBF) and right ventricular function increased significantly. Two-dimensional (2D) phase-contrast (PC) MRI-derived average mean velocity, maximum mean velocity and deceleration volume changes after PEA correlated with changes of 6MWD and right heart ejection fraction (RVEF). Deceleration volume is a novel 2D PC MRI parameter showing further correlation with PBF changes. In conclusion, 2D PC MRI-derived main pulmonary hemodynamic changes reflect changes of RVEF, PBF and 5-month follow-up 6MWD and may be used for future CTEPH patient monitoring after PEA.

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.

Pulmonary Vascular Disease Evaluation with Magnetic Resonance Angiography

Pulmonary vascular assessment commonly relies on computed tomography angiography (CTA), but continued advances in magnetic resonance angiography have allowed pulmonary magnetic resonance angiography (pMRA) to become a reasonable alternative to CTA without exposing patients to ionizing radiation. pMRA allows the evaluation of pulmonary vascular anatomy, hemodynamic physiology, lung parenchymal perfusion, and (optionally) right and left ventricular function with a single examination. This article discusses pMRA techniques and artifacts; performance in commonly encountered pulmonary vascular diseases, specifically pulmonary embolism and pulmonary hypertension; and recent advances in both contrast-enhanced and noncontrast pMRA.

Cardiovascular magnetic resonance 4D flow analysis has a higher diagnostic yield than Doppler echocardiography for detecting increased pulmonary artery pressure

Background

Pulmonary hypertension is definitively diagnosed by the measurement of mean pulmonary artery (PA) pressure (mPAP) using right heart catheterization. Cardiovascular magnetic resonance (CMR) four-dimensional (4D) flow analysis can estimate mPAP from blood flow vortex duration in the PA, with excellent results. Moreover, the peak systolic tricuspid regurgitation (TR) pressure gradient (TRPG) measured by Doppler echocardiography is commonly used in clinical routine to estimate systolic PA pressure. This study aimed to compare CMR and echocardiography with regards to quantitative and categorical agreement, and diagnostic yield for detecting increased PA pressure.

Methods

Consecutive clinically referred patients (n = 60, median [interquartile range] age 60 [48–68] years, 33% female) underwent echocardiography and CMR at 1.5 T (n = 43) or 3 T (n = 17). PA vortex duration was used to estimate mPAP using a commercially available time-resolved multiple 2D slice phase contrast three-directional velocity encoded sequence covering the main PA. Transthoracic Doppler echocardiography was performed to measure TR and derive TRPG. Diagnostic yield was defined as the fraction of cases in which CMR or echocardiography detected an increased PA pressure, defined as vortex duration ≥15% of the cardiac cycle (mPAP ≥25 mmHg) or TR velocity > 2.8 m/s (TRPG > 31 mmHg).

Results

Both CMR and echocardiography showed normal PA pressure in 39/60 (65%) patients and increased PA pressure in 9/60 (15%) patients, overall agreement in 48/60 (80%) patients, kappa 0.49 (95% confidence interval 0.27–0.71). CMR had a higher diagnostic yield for detecting increased PA pressure compared to echocardiography (21/60 (35%) vs 9/60 (15%), p < 0.001). In cases with both an observable PA vortex and measurable TR velocity (34/60, 56%), TRPG was correlated with mPAP (R² = 0.65, p < 0.001).

Conclusions

There is good quantitative and fair categorical agreement between estimated mPAP from CMR and TRPG from echocardiography. CMR has higher diagnostic yield for detecting increased PA pressure compared to echocardiography, potentially due to a lower sensitivity of echocardiography in detecting increased PA pressure compared to CMR, related to limitations in the ability to adequately visualize and measure the TR jet by echocardiography. Future comparison between echocardiography, CMR and invasive measurements are justified to definitively confirm these findings.

Supine, prone, right and left gravitational effects on human pulmonary circulation

BACKGROUND

Body position can be optimized for pulmonary ventilation/perfusion matching during surgery and intensive care. However, positional effects upon distribution of pulmonary blood flow and vascular distensibility measured as the pulmonary blood volume variation have not been quantitatively characterized. In order to explore the potential clinical utility of body position as a modulator of pulmonary hemodynamics, we aimed to characterize gravitational effects upon distribution of pulmonary blood flow, pulmonary vascular distension, and pulmonary vascular distensibility.

METHODS

Healthy subjects (n = 10) underwent phase contrast cardiovascular magnetic resonance (CMR) pulmonary artery and vein flow measurements in the supine, prone, and right/left lateral decubitus positions. For each lung, blood volume variation was calculated by subtracting venous from arterial flow per time frame.

RESULTS

Body position did not change cardiac output (p = 0.84). There was no difference in blood flow between the superior and inferior pulmonary veins in the supine (p = 0.92) or prone body positions (p = 0.43). Compared to supine, pulmonary blood flow increased to the dependent lung in the lateral positions (16-33%, p = 0.002 for both). Venous but not arterial cross-sectional vessel area increased in both lungs when dependent compared to when non-dependent in the lateral positions (22-27%, p ≤ 0.01 for both). In contrast, compared to supine, distensibility increased in the non-dependent lung in the lateral positions (68-113%, p = 0.002 for both).

CONCLUSIONS

CMR demonstrates that in the lateral position, there is a shift in blood flow distribution, and venous but not arterial blood volume, from the non-dependent to the dependent lung. The non-dependent lung has a sizable pulmonary vascular distensibility reserve, possibly related to left atrial pressure. These results support the physiological basis for positioning patients with unilateral pulmonary pathology with the "good lung down" in the context of intensive care. Future studies are warranted to evaluate the diagnostic potential of these physiological insights into pulmonary hemodynamics, particularly in the context of non-invasively characterizing pulmonary hypertension.

Assessing pulmonary hypertension in COPD. Is there a role for computed tomography?

Pulmonary hypertension (PH) is a common complication of chronic obstructive pulmonary disease (COPD) and is associated with increased morbidity and mortality. Reference standard method to diagnose PH is right heart catheterization. Several non-invasive imaging techniques have been employed in the detection of PH. Among them, computed tomography (CT) is the most commonly used for phenotyping and detecting complications of COPD. Several CT findings have also been described in patients with severe PH. Nevertheless, CT analysis is currently based on visual findings which can lead to reproducibility failure. Therefore, there is a need for quantification in order to assess objective criteria. In this review, progresses in automated analyses of CT parameters and their values in predicting PH and COPD outcomes are presented.

Multimodality cardiovascular imaging in pulmonary embolism

Acute pulmonary embolism (APE) is one of the leading causes of cardiovascular (CV) morbidity and mortality. To select appropriate therapeutic strategy and/or to minimize the mortality and morbidity, rapid and correct identification of life-threatening APE is very important. Also, right ventricular (RV) failure usually precedes acute hemodynamic compromise or death, and thus the identification of RV failure is another important step in risk stratification or treatment of APE. With advances in diagnosis and treatment, the prognosis of APE has been dramatically improving in most cases, but inadequate therapy or recurrent episodes of pulmonary embolism (PE) may result in negative outcomes or, so called, chronic thromboembolic pulmonary hypertension (CTEPH). CTEPH is a condition characterized by remaining chronic thromboembolic material in the pulmonary vasculature and subsequent chronic pulmonary hypertension. Various imaging modalities include chest computed tomography pulmonary angiography (CTPA), echocardiography, magnetic resonance imaging, and nuclear imaging and each are used for the assessment of varying status of PE. Assessment of thromboembolic burden by chest CTPA is the first step in the diagnosis of PE. Hemodynamic assessment can be achieved by echocardiography and also by chest CTPA. Nuclear imaging is useful in discriminating CTEPH from APE. Better perspectives on diagnosis, risk stratification and decision making in PE can be provided by combining multimodality CV imaging. Here, the advantages or pitfalls of each imaging modality in diagnosis, risk stratification, or management of PE will be discussed.

Turbulent flow artefact mimicking central pulmonary emboli in pulmonary hypertension: A report of two cases

Many artefacts can mimic pulmonary emboli (PE) on CT pulmonary angiography (CTPA), most commonly in the peripheral pulmonary arteries (PA's). We describe flow-related artefact mimicking PE in the central PA's of two patients, both with pulmonary arterial hypertension (PAH). To our knowledge, this is the first report of this PE mimic in the central PA's.

EXPRESS: Statement on imaging and pulmonary hypertension from the Pulmonary Vascular Research Institute (PVRI)

Pulmonary hypertension (PH) is highly heterogeneous and despite treatment advances it remains a life-shortening condition. There have been significant advances in imaging technologies, but despite evidence of their potential clinical utility, practice remains variable, dependent in part on imaging availability and expertise. This statement summarizes current and emerging imaging modalities and their potential role in the diagnosis and assessment of suspected PH. It also includes a review of commonly encountered clinical and radiological scenarios, and imaging and modeling-based biomarkers. An expert panel was formed including clinicians, radiologists, imaging scientists, and computational modelers. Section editors generated a series of summary statements based on a review of the literature and professional experience and, following consensus review, a diagnostic algorithm and 55 statements were agreed. The diagnostic algorithm and summary statements emphasize the key role and added value of imaging in the diagnosis and assessment of PH and highlight areas requiring further research.

Imaging of acute pulmonary embolism: an update

Imaging plays an important role in the evaluation and management of acute pulmonary embolism (PE). Computed tomography (CT) pulmonary angiography (CTPA) is the current standard of care and provides accurate diagnosis with rapid turnaround time. CT also provides information on other potential causes of acute chest pain. With dual-energy CT, lung perfusion abnormalities can also be detected and quantified. Chest radiograph has limited utility, occasionally showing findings of PE or infarction, but is useful in evaluating other potential causes of chest pain. Ventilation-perfusion (VQ) scan demonstrates ventilation-perfusion mismatches in these patients, with several classification schemes, typically ranging from normal to high. Magnetic resonance imaging (MRI) also provides accurate diagnosis, but is available in only specialized centers and requires higher levels of expertise. Catheter pulmonary angiography is no longer used for diagnosis and is used only for interventional management. Echocardiography is used for risk stratification of these patients. In this article, we review the role of imaging in the evaluation of acute PE.

Approach to pulmonary vascular disease in the ICU

PURPOSE OF REVIEW

Pulmonary vascular disease (PVD) complicates the course of many cardiovascular, pulmonary and other systemic diseases in children. The physiological sequelae (pulmonary hypertension and elevated pulmonary vascular resistance) can overwhelm the right ventricle and lead to circulatory collapse. Despite the common end-point, the preceding pathophysiology is complex and variable and requires a tailored approach to diagnosis and management. In this article, we will review the most recent evidence and explore an approach to current controversies in the diagnosis and management of common or challenging patient subgroups.

RECENT FINDINGS

New methods of interpreting data derived from echocardiography and cardiac magnetic resonance imaging may assist in risk stratification and response to therapy. In specific patient subgroups, standard pharmacological therapies to reduce right ventricle afterload may be overutilized, ineffective and in some cases harmful. In the patient failing pharmacological therapy, new and novel techniques are being explored including temporary extracorporeal mechanical circulatory support, pumpless lung assist devices and novel surgical and catheterization procedures.

SUMMARY

PVD is a diverse entity, and attention to the underlying pathophysiology is essential for appropriate management. Despite significant advances in our understanding, the majority of data comes from small uncontrolled studies and must be interpreted with caution.

Sutureless Versus Conventional Pulmonary Vein Repair: A Magnetic Resonance Pilot Study

BACKGROUND

Two different surgical techniques are used to repair anomalous pulmonary venous connection or pulmonary vein (PV) stenosis: the classic repair (CR) and the sutureless repair (SR). The purpose of this study was to compare the prevalence of PV stenosis between the two surgical approaches.

METHODS

Patients were prospectively recruited irrespective of symptoms or previous imaging findings. Cardiac magnetic resonance imaging and echocardiography were performed in a blinded fashion on the same day.

RESULTS

Twenty-five patients (13 male) after PV repair completed the study. Twelve patients had undergone CR and 13 SR (in 1 patient as a reoperation after CR). The median age at operation was 2 months (range: 1 day to 5 years) and was similar for both groups; the median age at the time of cardiac magnetic resonance was 9 years (range: 6 to 17 years) and 9 years (range: 6 to 14 years) for the CR and SR, respectively. Four patients had PV stenosis. All 4 patients had had total anomalous pulmonary venous connection, 1 patient had undergone repair with the CR and 2 with a primary SR; 1 patient had first undergone a CR, followed by a SR for stenosis. Echocardiography provided complete visualization of all PVs in only 11 patients (44%). Notable stenosis of at least one PV was missed by echocardiography in 2 patients.

CONCLUSIONS

This pilot study indicates that not only CR but also SR may be burdened by a risk of postoperative PV stenosis. Magnetic resonance imaging should be used routinely for the postoperative monitoring for the development of PV obstruction.

Unilateral pulmonary artery pre-operative occlusion test: technical feasibility and safety prior to pneumonectomy or pleuropneumonectomy for malignancy

OBJECTIVE

The aim of the present study was to assess the technical feasibility and safety of the unilateral pulmonary artery occlusion (UPAO) test in pre-operative evaluation of pneumonectomy or pleuropneumonectomy for lung or pleural tumours.

METHODS

The UPAO test was performed on 91 patients who were scheduled to undergo or were being considered for pneumonectomy or pleuropneumonectomy between June 2003 and July 2016. There were 74 males and 17 females, with a median age of 65 years (range, 23-80). The technical success rate, procedure time and complication rate were evaluated. Technical success was defined as completion of the UPAO test.

RESULTS

The diagnoses of the 91 patients were as follows: lung cancer in 63, malignant pleural mesothelioma in 21, thymoma in 5, lung metastasis in 1 and lung carcinoid in 1. The UPAO test was performed successfully on 88 out of 91 patients (technical success rate: 97%). The median procedure time was 57 min (range, 34-120). Cardiac arrest due to migration of the balloon catheter to the pulmonary trunk occurred in 1 patient (complication rate: 1.1%).

CONCLUSION

The UPAO test in pre-operative evaluation of pneumonectomy or pleuropneumonectomy for lung or pleural tumours appears to be technically feasible. However, it needs to be performed with care in order to avoid severe complications. Advances in knowledge: The UPAO test can be safely performed and is helpful in evaluating patients for pneumonectomy or pleuropneumonectomy.

Breath-hold and free-breathing 2D phase-contrast MRI for quantification of oxygen-induced changes of pulmonary circulation dynamics in healthy volunteers

PURPOSE

To evaluate the effect of inhaled 100% oxygen on pulmonary circulation dynamics in healthy volunteers using 2D phase-contrast magnetic resonance imaging (2D PC MRI).

MATERIALS AND METHODS

Twenty-one healthy volunteers were examined at 1.5T. Through-plane 2D PC MRI measurements were performed in the main pulmonary artery during free-breathing and breath-hold. Acceleration time and volume, maximum and minimum area, area change, average and maximum mean velocity, forward volume, heart rate, as well as blood pressure were determined. At baseline, subjects breathed room air. After application of a closed-fit full face mask, three further measurements were conducted: at room air (control), directly after starting 15 L/min 100% oxygen (wash-in), and after 5 minutes during continuous oxygen supply (saturation). Data were analyzed with a mixed linear model. Skewed distributed variables were rank-transformed. Tukey contrasts with family-wise adjusted P-values were applied for pairwise comparisons.

RESULTS

Inhaled oxygen affected several hemodynamic parameters. Average mean velocity (P < 0.01: breath-hold during wash-in and saturation, P = 0.03: free-breathing during saturation) and maximum mean velocity (P < 0.01: breath-hold and free-breathing during saturation) decreased. When obtained during free-breathing, acceleration volume (P = 0.02: saturation), area change (P = 0.02: saturation), and maximum area (P = 0.02: wash-in, P = 0.03: saturation) increased, while minimum area and forward volume did not change.

CONCLUSION

Oxygen alters pulmonary circulation dynamics in the main pulmonary artery of healthy volunteers, which can be reliably detected using 2D phase-contrast MRI.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1698-1706.

Imaging of acute and chronic thromboembolic disease: state of the art

Acute pulmonary embolism (PE) is a life-threatening condition that requires prompt diagnosis and treatment. Recent advances in imaging allow acute and rapid recognition even by the non-specialist radiologist. Most acute emboli resolve on anticoagulation without sequelae; however, some emboli fail to fully resolve becoming endothelialised with the development of chronic thromboembolic disease (CTED). Increased pulmonary vascular resistance arising from CTED may lead to chronic thromboembolic pulmonary hypertension (CTEPH) a debilitating disease affecting up to 5% of survivors of acute PE. Diagnostic evaluation is more complex in CTEPH/CTED than acute PE with subtle imaging features often being overlooked or misinterpreted. Differentiation of acute from chronic PE and from other forms of pulmonary hypertension has profound therapeutic implications. Diverse imaging techniques are available to diagnose and monitor PEs both in the acute and chronic setting. Broadly they include techniques that provide data on lung parenchymal perfusion (ventilation-perfusion [VQ] scintigraphy), angiographic techniques (computed tomography [CT], magnetic resonance imaging [MRI], and invasive angiography) or a combination of both (MR angiography and time-resolved angiography or dual-energy CT angiography). This review aims to describe state of the art imaging highlighting the strength and weaknesses of individual techniques in the diagnosis of acute and chronic PE.