Mimickers of chronic thromboembolic pulmonary hypertension on imaging tests: a review

Chronic thromboembolic pulmonary hypertension: Role of imaging in diagnosis and guiding the treatment

Chronic thromboembolic pulmonary hypertension is a life-threatening condition resulting from unresolved thromboemboli that obstructs pulmonary arteries, leading to increased pulmonary vascular resistance and right heart failure. Accurate and timely diagnosis is critical for effective management and improving patient outcomes. Imaging plays a crucial role in the diagnosis, with CT pulmonary angiography being the primary modality due to its ability to provide detailed visualization of pulmonary vasculature and parenchymal changes. The ventilation/perfusion scan remains an essential tool, particularly for initial screening, given its high sensitivity in detecting perfusion defects. Recent advancements in imaging, including dual-energy CT and magnetic resonance imaging, offer additional functional and anatomical insights, further aiding in comprehensive patient evaluation. Imaging is also crucial for pre-operative planning in candidates for pulmonary endarterectomy and for monitoring post-operative recovery and disease progression. By integrating multiple imaging modalities, clinicians can achieve a more accurate diagnosis, optimize treatment strategies, and improve long-term outcomes for patients with CTEPH.

Diagnostic Efficacy of Ventilation-Perfusion Single Photo Emission Computed Tomography/Computed Tomography for Pulmonary Hypertension due to Fibrinous Mediastinitis

RATIONALE AND OBJECTIVES

Comprehensive data on the use of ventilation-perfusion single-photo emission computed tomography/computed tomography (V/Q SPECT/CT), an established diagnostic tool for chronic thromboembolic pulmonary hypertension, in identifying pulmonary hypertension secondary to fibrinous mediastinitis (PH-FM) is scarce. This study aimed to assess its diagnostic efficacy for PH-FM.

MATERIALS AND METHODS

Patients with PH due to pulmonary artery stenosis were assessed using V/Q SPECT/CT, computed tomography pulmonary angiography (CTPA), and digital subtraction pulmonary angiography (PAG). Abnormal mediastinal or hilar features identified by V/Q SPECT/CT, correlating with perfusion defects, were used to diagnose PH-FM. Final clinical diagnosis is recognized as the gold standard for this study. Diagnostic accuracy was compared using receiver operating characteristic (ROC) analysis and Cohen's kappa coefficient to evaluate agreement among the imaging methods.

RESULTS

Among the patients included, 21 had PH-FM, and 76 had PH associated with non-FM. V/Q SPECT/CT showed higher sensitivity (90%), specificity (95%), and accuracy (94%) for detecting PH-FM compared to CTPA (sensitivity 86%, specificity 92%, accuracy 91%) and PAG (sensitivity 62%, specificity 87%, accuracy 81%). The areas under the ROC curve for V/Q SPECT/CT, CTPA, and PAG were 0.93, 0.89, and 0.74, respectively. V/Q SPECT/CT achieved better agreement with the gold standard than CTPA or PAG (κ=0.82, κ=0.69 and κ=0.49, respectively).

CONCLUSION

V/Q SPECT/CT demonstrates superior diagnostic efficacy and accuracy compared to CTPA and PAG in diagnosing PH-FM.

CLINICAL RELEVANCE STATEMENT

Compared to computed tomography pulmonary angiography and digital subtraction pulmonary angiography, ventilation-perfusion single-photo emission computed tomography/computed tomography demonstrates superior diagnostic efficiency for pulmonary hypertension secondary to fibrinous mediastinitis, leading to improved early detection and accuracy, thus optimizing diagnostic pathways.

KEY POINTS

Diagnostic accuracy and added value of dynamic chest radiography in detecting pulmonary embolism: A retrospective study

Purpose

This study aimed to assess the diagnostic performance of dynamic chest radiography (DCR) and investigate its added value to chest radiography (CR) in detecting pulmonary embolism (PE).

Methods

Of 775 patients who underwent CR and DCR in our hospital between June 2020 and August 2022, individuals who also underwent contrast-enhanced CT (CECT) of the chest within 72 h were included in this study. PE or non-PE diagnosis was confirmed by CECT and the subsequent clinical course. The enrolled patients were randomized into two groups. Six observers, including two thoracic radiologists, two cardiologists, and two radiology residents, interpreted each chest radiograph with and without DCR using a crossover design with a washout period. Diagnostic performance was compared between CR with and without DCR in the standing and supine positions.

Results

Sixty patients (15 PE, 45 non-PE) were retrospectively enrolled. The addition of DCR to CR significantly improved the sensitivity, specificity, accuracy, and area under the curve (AUC) in the standing (35.6-70.0 % [P < 0.0001], 84.8-93.3 % [P = 0.0010], 72.5-87.5 % [P < 0.0001], and 0.66-0.85 [P < 0.0001], respectively) and supine (33.3-65.6 % [P < 0.0001], 78.5-92.2 % [P < 0.0001], 67.2-85.6 % [P < 0.0001], and 0.62-0.80 [P = 0.0002], respectively) positions for PE detection. No significant differences were found between the AUC values of DCR with CR in the standing and supine positions (P = 0.11) or among radiologists, cardiologists, and radiology residents (P = 0.14-0.68).

Conclusions

Incorporating DCR with CR demonstrated moderate sensitivity, high specificity, and high accuracy in detecting PE, all of which were significantly higher than those achieved with CR alone, regardless of scan position, observer expertise, or experience.

Chronic thromboembolic pulmonary disease

Chronic thromboembolic pulmonary hypertension is a complication of pulmonary embolism and a treatable cause of pulmonary hypertension. The pathology is a unique combination of mechanical obstruction due to failure of clot resolution, and a variable degree of microvascular disease, that both contribute to pulmonary vascular resistance. Accordingly, multiple treatments have been developed to target the disease components. However, accurate diagnosis is often delayed. Evaluation includes high-quality imaging modalities, necessary for disease confirmation and for appropriate treatment planning. All patients with chronic thromboembolic pulmonary disease, and especially those with pulmonary hypertension, should be referred to expert centres for multidisciplinary team decision on treatment. The first decision remains assessment of operability, and the best improvement in symptoms and survival is achieved by the mechanical therapies, pulmonary endarterectomy and balloon pulmonary angioplasty. With the advances in multimodal therapies, excellent outcomes can be achieved with 3-year survival of >90%.

Non-contrasted computed tomography (NCCT) based chronic thromboembolic pulmonary hypertension (CTEPH) automatic diagnosis using cascaded network with multiple instance learning

Objective.The diagnosis of chronic thromboembolic pulmonary hypertension (CTEPH) is challenging due to nonspecific early symptoms, complex diagnostic processes, and small lesion sizes. This study aims to develop an automatic diagnosis method for CTEPH using non-contrasted computed tomography (NCCT) scans, enabling automated diagnosis without precise lesion annotation.Approach.A novel cascade network (CN) with multiple instance learning (CNMIL) framework was developed to improve the diagnosis of CTEPH. This method uses a CN architecture combining two Resnet-18 CNN networks to progressively distinguish between normal and CTEPH cases. Multiple instance learning (MIL) is employed to treat each 3D CT case as a 'bag' of image slices, using attention scoring to identify the most important slices. An attention module helps the model focus on diagnostically relevant regions within each slice. The dataset comprised NCCT scans from 300 subjects, including 117 males and 183 females, with an average age of 52.5 ± 20.9 years, consisting of 132 normal cases and 168 cases of lung diseases, including 88 cases of CTEPH. The CNMIL framework was evaluated using sensitivity, specificity, and the area under the curve (AUC) metrics, and compared with common 3D supervised classification networks and existing CTEPH automatic diagnosis networks.Main results. The CNMIL framework demonstrated high diagnostic performance, achieving an AUC of 0.807, accuracy of 0.833, sensitivity of 0.795, and specificity of 0.849 in distinguishing CTEPH cases. Ablation studies revealed that integrating MIL and the CN significantly enhanced performance, with the model achieving an AUC of 0.978 and perfect sensitivity (1.000) in normal classification. Comparisons with other 3D network architectures confirmed that the integrated model outperformed others, achieving the highest AUC of 0.8419.Significance. The CNMIL network requires no additional scans or annotations, relying solely on NCCT. This approach can improve timely and accurate CTEPH detection, resulting in better patient outcomes.

The Importance of Topographical Recognition of Pulmonary Arteries in Diagnostics and Treatment of CTEPH, Based on an Analysis of a Dissected Case Model-A Pilot Study

BACKGROUND

Knowledge of the anatomy of pulmonary arteries is essential in many invasive procedures concerning pulmonary circulation. In the diagnosis and treatment of chronic thromboembolic pulmonary hypertension (CTEPH), two-dimensional (2D) pulmonary angiography is used. Recognizing the topographic course of the pulmonary arteries and understanding the status in three dimensions (3D) is paramount. This study aimed to evaluate and describe the branching variant of pulmonary arteries in a single case, as well as morphological parameters of the segmental arteries, like length, diameter and branching angles.

METHODS

One pair of embalmed human cadaver lungs was dissected by a scalpel and surgical forceps and was measured up to the subsegmental arteries.

RESULTS

The diameters (ranging from 3.04 to 9.29 mm) and lengths (ranging from 9.09 to 53.91 mm) of the pulmonary segmental arteries varied. The proximal branching angles were wide and close to perpendicular, while distally, the angles between the segmental and subsegmental arteries were narrower (30-45°). Upon evaluating the branching, rare variations were identified and delineated, notably in the lower lobes of both lungs.

CONCLUSIONS

Utilizing knowledge and data in clinical settings is instrumental for effectively diagnosing and treating CTEPH. Further research is required to explore the complications in invasive procedures related to various anatomical variations.

Resveratrol as an adjuvant prebiotic therapy in the management of pulmonary thromboembolism

Pulmonary thromboembolism (PTE) presents a grave threat to patient lives, often marked by arterial occlusion in the pulmonary vasculature, frequently stemming from deep vein thrombosis (DVT). While current anticoagulant therapies offer temporary relief, they fall short of addressing the long-term management of PTE. Notably, PTE-associated mortality rates continue to rise annually, positioning it as a crucial concern within the cardiovascular landscape. An intriguing suspect underlying compromised prognoses is the intricate interplay between the gut microbiome and PTE outcomes. The gut-derived metabolite, trimethylamine N-oxide (TMAO), has emerged as a direct contributor to accelerated thrombogenesis, thereby heightening PTE susceptibility. In pursuit of remedies, research has delved into diverse prebiotic and probiotic interventions, with Resveratrol (RSV) emerging as a promising candidate. This paper explores the potential of RSV, a polyphenolic compound, as an adjuvant prebiotic therapy. The proposed therapeutic approach not only augments anticoagulant potency through strategic pharmacokinetic interactions but also introduces a novel avenue for attenuating future PTE incidents through deliberate gut microbiome modulation. RSV's multifaceted attributes extend beyond its role in PTE prevention. Recognized for its anti-inflammatory, antioxidant, and cardioprotective properties, RSV stands as a versatile therapeutic candidate. It exhibits the ability to curtail platelet aggregation, augment warfarin bioavailability, and mitigate pulmonary arterial wall thickening - an ensemble of effects that substantiate its potential as an adjunct prebiotic for PTE patients. This literature review weaves together the latest insights, culminating in a compelling proposition: RSV is an instrumental player in the trajectory of PTE management.

Pulmonary Vein Stenosis after Catheter Ablation for Atrial Fibrillation: An Early Diagnosis Using Unenhanced Computed Tomography

Pulmonary vein stenosis (PVS) is a serious complication of catheter ablation (CA) for atrial fibrillation (AF). PVS generally occurs several months after CA and presents with non-specific symptoms and imaging findings. There have been reports of delayed diagnoses due to a misdiagnosis as infection, interstitial pneumonia, or organizing pneumonia. We introduced six cases of PVS after CA, all of which showed narrowing of the unilateral pulmonary vessels with or without lobar volume loss in the left lung on unenhanced computed tomography. We report these findings as important results indicating the possibility of PVS after CA for AF and contributing to the early diagnosis and management of PVS.

Status and Future Directions for Balloon Pulmonary Angioplasty in Chronic Thromboembolic Pulmonary Disease With and Without Pulmonary Hypertension: A Scientific Statement From the American Heart Association

Balloon pulmonary angioplasty continues to gain traction as a treatment option for patients with chronic thromboembolic pulmonary disease with and without pulmonary hypertension. Recent European Society of Cardiology guidelines on pulmonary hypertension now give balloon pulmonary angioplasty a Class 1 recommendation for inoperable and residual chronic thromboembolic pulmonary hypertension. Not surprisingly, chronic thromboembolic pulmonary hypertension centers are rapidly initiating balloon pulmonary angioplasty programs. However, we need a comprehensive, expert consensus document outlining critical concepts, including identifying necessary personnel and expertise, criteria for patient selection, and a standardized approach to preprocedural planning and establishing criteria for evaluating procedural efficacy and safety. Given this lack of standards, the balloon pulmonary angioplasty skill set is learned through peer-to-peer contact and training. This document is a state-of-the-art, comprehensive statement from key thought leaders to address this gap in the current clinical practice of balloon pulmonary angioplasty. We summarize the current status of the procedure and provide a consensus opinion on the role of balloon pulmonary angioplasty in the overall care of patients with chronic thromboembolic pulmonary disease with and without pulmonary hypertension. We also identify knowledge gaps, provide guidance for new centers interested in initiating balloon pulmonary angioplasty programs, and highlight future directions and research needs for this emerging therapy.

Diagnosis and Management of Pulmonary Hypertension and Right Ventricular Failure in the Cardiovascular Intensive Care Unit

Pulmonary hypertension (PH) encompasses a broad range of conditions, including pulmonary artery hypertension, left-sided heart disease, and pulmonary and thromboembolic disorders. Successful diagnosis and management rely on an integrated clinical assessment of the patient's physiology and right heart function. Right ventricular (RV) heart failure is often a result of PH, but may result from varying abnormalities in preload, afterload, and intrinsic myocardial dysfunction, which require distinct management strategies. Consideration of an individual's hemodynamic phenotype and physiologic circumstances is paramount in management of PH and RV failure, particularly when there is clinical instability in the intensive care setting.

Primary Systemic Vasculitides as a Cause of Group IV Pulmonary Hypertension

The primary systemic vasculitides are rare diseases characterized by vessel wall inflammation. Isolated pulmonary vasculitis, large-vessel vasculitis, and Behçet's disease are mimickers of chronic thromboembolic pulmonary hypertension (CTEPH); group IV pulmonary hypertension (PH) can occur as a devastating complication in the course of these diseases. Pulmonary endarterectomy, balloon angioplasty, anticoagulation and pulmonary vasodilator agents are the main treatment options for CTEPH. There is no specific recommendation for the treatment of patients having group IV PH due to primary systemic vasculitides. We reviewed herein data about group IV PH due to primary systemic vasculitides.

[Chronic thromboembolic pulmonary hypertension]

Chronic thromboembolic pulmonary disease (CTEPD) is an important late complication of acute pulmonary embolism, in which the thrombi transform into fibrous tissue, become integrated into the vessel wall, and lead to chronic obstructions. CTEPD is differentiated into cases without pulmonary hypertension (PH), characterized by a mean pulmonary arterial pressure up to 20 mmHg and a form with PH. Then, it is still referred to as chronic thromboembolic pulmonary hypertension (CTEPH).When there is suspicion of CTEPH, initial diagnostic tests should include echocardiography and ventilation/perfusion scan to detect perfusion defects. Subsequently, referral to a CTEPH center is recommended, where further imaging diagnostics and right heart catheterization are performed to determine the appropriate treatment.Currently, three treatment modalities are available. The treatment of choice is pulmonary endarterectomy (PEA). For non-operable patients or patients with residual PH after PEA, PH-targeted medical therapy, and the interventional procedure of balloon pulmonary angioplasty (BPA) are available. Increasingly, PEA, BPA, and pharmacological therapy are combined in multimodal concepts.Patients require post-treatment follow-up, preferably at (CTE)PH centers. These centers are required to perform a minimum number of PEA surgeries (50/year) and BPA interventions (100/year).

Chronic thromboembolic pulmonary hypertension-medical, interventional, and surgical therapy

Chronic thromboembolic pulmonary hypertension (CTEPH) is an important late sequela of pulmonary embolism and a common form of pulmonary hypertension. Currently, three specific treatment modalities are available: pulmonary endarterectomy, balloon pulmonary angioplasty, and targeted medical therapy. The treatment decision depends mainly on the exact localization of the underlying pulmonary arterial obstructions. Pulmonary endarterectomy is the gold standard treatment of CTEPH. For inoperable patients, riociguat and treprostinil are approved. In addition, interventional therapy is recommended if appropriate target lesions are proven. Evaluation and treatment of patients with CTEPH in experienced centers are mandatory.

Evaluation and Management of Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a treatable form of pulmonary hypertension and right heart failure. CTEPH (group 4 pulmonary hypertension) is caused by persistent organized thromboembolic obstruction of the pulmonary arteries from incompletely resolved acute pulmonary embolism. CTEPH also may present without prior VTE history, which can contribute to its underrecognition. The true incidence of CTEPH is unclear, but is estimated to be approximately 3% after acute pulmonary embolism. V˙/Q˙ scintigraphy is the best screening test for CTEPH, with CT scan imaging and other advanced imaging methods now playing a larger role in disease detection and confirmation. Perfusion defects on V˙/Q˙ scintigraphy in the setting of pulmonary hypertension are suggestive of CTEPH, but pulmonary angiography and right heart catheterization are required for confirmation and treatment planning. CTEPH potentially is curative with pulmonary thromboendarterectomy surgery, with mortality rates of approximately 2% at expert centers. Advances in operative techniques are allowing more distal endarterectomies to be performed successfully with favorable outcomes. However, more than one-third of patients may be considered inoperable. Although these patients previously had minimal therapeutic options, effective treatments now are available with pharmacotherapy and balloon pulmonary angioplasty. Diagnosis of CTEPH should be considered in all patients with suspicion of pulmonary hypertension. Treatments for CTEPH have advanced with improvements in outcomes for both operable and inoperable patients. Therapy should be tailored based on multidisciplinary team evaluation to ensure optimal treatment response.

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-whereby 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 embolism 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.

Anthracofibrosis mimicking chronic thromboembolic pulmonary hypertension

We present the case of a 78-year-old female undergoing pulmonary endarterectomy (PEA) because of suspected chronic thromboembolic pulmonary hypertension (CTEPH). During surgery firm black masses were encountered in the aortopulmonary window and on the cranial part of the right pulmonary artery (PA). After PA arteriotomy we visualized intraluminal black firm stenosing plaques at the orifices of the three right and of the left lingular and lower lobar branches. Since no dissection plane could be obtained the procedure was discontinued. Subsequent bronchoscopy visualized a submucosal dark black-blue discoloration in both main bronchi. Pathological analysis revealed anthracofibrosis, which could be explained by biomass smoke exposure in the past. We are the first to provide intravascular pictures and pathologic images of this very rare entity. Moreover, we report stenoses at the orifices of the three right-sided lobar and of the left-sided lingular and lower lobe arteries, in contrast to three previous reports that report on single locations caused by extrinsic PA compression from lymphadenopathy. Our case, however, suggests extension of fibrosis with anthracotic pigment into the PA wall. We conclude that in the absence of a clear history of exposure to carbon smoke and with consequently no diagnostic bronchoscopy, anthracofibrosis of the lungs may mimic CTEPH not only by external compression but also by extension into pulmonary vascular structures. PEA-surgery should not be attempted in these cases.

[The lungs: starting point for many diseases]

The lungs are a frequent site for the manifestation of systemic, neoplastic and immunological multiorgan diseases. In the clinical routine, patients frequently present with symptoms from the respiratory spectrum of disorders, such as dyspnea. After a clinical examination, lung function testing and imaging an initial pulmonary manifestation can often be detected; however, the ultimate assignment to a systemic disease is usually only successful in the synopsis of the clinical results, pulmonary involvement, extrapulmonary manifestation and further diagnostics. This review article presents three systemic diseases that become clinically relevant due to the primary pulmonary manifestations.

Therapie der chronisch thromboembolischen pulmonalen Hypertonie

Die chronisch thromboembolische pulmonale Hypertonie (CTEPH) ist eine wichtige und oft gut behandelbare Form der pulmonalen Hypertonie. Es stehen aktuell 3 Therapiemodalitäten zur Verfügung: die pulmonale Endarteriektomie, die pulmonale Ballonangioplastie und die gezielte medikamentöse Behandlung. Das therapeutische Konzept hängt maßgeblich von der Lokalisation der zugrunde liegenden pulmonalarteriellen fibrösen Obstruktionen ab. Die pulmonale Endarteriektomie ist der Goldstandard in der Behandlung der CTEPH. Für inoperable Patienten stehen mittlerweile 2 zugelassene Substanzen (Riociguat und Treprostinil) zur Verfügung. Daneben wird bei Vorhandensein entsprechender Zielgebiete die interventionelle Therapie empfohlen. Evaluation und Behandlung von CTEPH-Patienten sollte in entsprechend erfahrenen Zentren erfolgen.

Evaluating cardiopulmonary function following acute pulmonary embolism

INTRODUCTION

Pulmonary embolism is a common cause of cardiopulmonary mortality and morbidity worldwide. Survivors of acute pulmonary embolism may experience dyspnea, report reduced exercise capacity, or develop overt pulmonary hypertension. Clinicians must be alert for these phenomena and appreciate the modalities and investigations available for evaluation.

AREAS COVERED

In this review, the current understanding of available contemporary imaging and physiologic modalities is discussed, based on available literature and professional society guidelines. The purpose of the review is to provide clinicians with an overview of these modalities, their strengths and disadvantages, and how and when these investigations can support the clinical work-up of patients post-pulmonary embolism.

EXPERT OPINION

Echocardiography is a first test in symptomatic patients post-pulmonary embolism, with ventilation/perfusion scanning vital to determination of whether there is chronic residual emboli. The role of computed tomography and magnetic resonance in assessing the pulmonary arterial tree in post-pulmonary embolism patients is evolving. Functional testing, in particular cardiopulmonary exercise testing, is emerging as an important modality to quantify and determine cause of functional limitation. It is possible that future investigations of the post-pulmonary embolism recovery period will better inform treatment decisions for acute pulmonary embolism patients.

Molecular imaging as a tool for evaluation of COVID-19 sequelae – A review of literature

Coronavirus disease 2019 (COVID-19) is caused by the novel viral pathogen, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 primarily involves the lungs. Nucleic acid testing based on reverse-transcription polymerase chain reaction of respiratory samples is the current gold standard for the diagnosis of SARS-CoV-2 infection. Imaging modalities have an established role in triaging, diagnosis, evaluation of disease severity, monitoring disease progression, extra-pulmonary involvement, and complications. As our understanding of the disease improves, there has been substantial evidence to highlight its potential for multi-systemic involvement and development of long-term sequelae. Molecular imaging techniques are highly sensitive, allowing non-invasive visualization of physiological or pathological processes at a cellular or molecular level with potential for detection of functional changes earlier than conventional radiological imaging. The purpose of this review article is to highlight the evolving role of molecular imaging in evaluation of COVID-19 sequelae. Though not ideal for diagnosis, the various modalities of molecular imaging play an important role in assessing pulmonary and extra-pulmonary sequelae of COVID-19. Perfusion imaging using single photon emission computed tomography fused with computed tomography (CT) can be utilized as a first-line imaging modality for COVID-19 related pulmonary embolism. ¹⁸F-fluorodeoxyglucose positron emission tomography (PET)/CT is a sensitive tool to detect multi-systemic inflammation, including myocardial and vascular inflammation. PET in conjunction with magnetic resonance imaging helps in better characterization of neurological sequelae of COVID-19. Despite the fact that the majority of published literature is retrospective in nature with limited sample sizes, it is clear that molecular imaging provides additional valuable information (complimentary to anatomical imaging) with semi-quantitative or quantitative parameters to define inflammatory burden and can be used to guide therapeutic strategies and assess response. However, widespread clinical applicability remains a challenge owing to longer image acquisition times and the need for adoption of infection control protocols.

Pulmonary Hypertension Caused by Fibrosing Mediastinitis

Pulmonary hypertension (PH) is a progressive and severe disorder in pulmonary hemodynamics. PH can be fatal if not well managed. Fibrosing mediastinitis (FM) is a rare and benign fibroproliferative disease in the mediastinum, which may lead to pulmonary vessel compression and PH. PH caused by FM (PH-FM) is a pathologic condition belonging to group 5 in the World Health Organization PH classification. PH-FM has a poor prognosis because of a lack of effective therapeutic modalities and inappropriate diagnosis. With the development of percutaneous pulmonary vascular interventional therapy, the prognosis of PH-FM has been greatly improved in recent years. This article provides a comprehensive review on the epidemiology, pathophysiologic characteristics, clinical manifestations, diagnostic approaches, and treatment modalities of PH-FM based on data from published reports and our medical center with the goal of facilitating the diagnosis and treatment of this fatal disease.

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PH-FM, as a type of rare condition in group 5 PH, has a poor prognosis because of a lack of effective therapeutic modalities and frequent misdiagnosis and underdiagnosis.

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The most prevalent trigger of FM is H-FM in the United States and TB-FM in China.

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Imaging findings, including mismatched perfusion defects in the V/Q scan, FM dyad, and FM triad are important diagnostic clues, and clinical classification facilitates decision making in diagnosis and therapeutics.

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Because of the limited efficacy of drug therapy as well as the uncertain effectiveness and high risk of surgical treatment, endovascular interventional modality is currently the preferred therapeutic option, although procedure-related complications and intrastent restenosis after PV intervention need to be addressed.

Interventional Management of Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension is a distinct form of pulmonary hypertension characterized by the nonresolution of thrombotic material in the pulmonary tree; whenever feasible and safe, first-line treatment should be pulmonary thromboendarterectomy. In patients who are not operative candidates, balloon pulmonary angioplasty (BPA) has emerged as an effective treatment modality that results in improvements in functional class, symptoms, hemodynamics, 6-minute walk distance, and right ventricular and pulmonary artery mechanics. Careful attention to procedural technique and rapid identification and treatment of complications are critical for a successful BPA program.

Giant Pulmonary Artery Thrombotic Material, Due to Chronic Thromboembolic Pulmonary Hypertension, Mimics Pulmonary Artery Sarcoma

In this article, we present the case of a 38-year-old female who suffered from serious respiratory distress. After an extensive pulmonary artery imaging diagnostic work-up (CTPA, MRA and PET), we were unable to differentiate between chronic thromboembolic pulmonary hypertension (CTEPH) vs. pulmonary artery sarcoma (PAS) due to extensive filling defects and extraluminal findings. Although surgery was postponed for nine months due to the COVID-19 pandemic, CTEPH diagnosis, due to a high-thrombus burden, was finally confirmed after pulmonary endarterectomy (PEA). Conclusively, imaging findings of rare cases of CTEPH might mimic PAS and the surgical removal of the lesion are both needed for a final diagnosis. What is Already Known about This Topic? Pulmonary artery sarcoma (PAS) is a rare but aggressive malignancy, which originates from the intimal layer of the pulmonary artery (PA); Chronic thromboembolic pulmonary hypertension (CTEPH) is based on chronic, organized flow-limiting thrombi inside PA circulation and subsequent pulmonary hypertension. What Does This Study Contribute? Since radiological findings of CTEPH cases might rarely mimic PAS, pulmonary artery endarterectomy and subsequent histopathologic study are needed for a final diagnosis.

Lung Perfusion Scintigraphy in Pulmonary Vein Occlusion After Radiofrequency Ablation

ABSTRACT

We describe functional and anatomical imaging findings in an 86-year-old woman who was treated for paroxysmal atrial fibrillation 5 years ago with radiofrequency ablation. She had been symptom-free for 4 years. Five years after the ablation, she presented with exertional dyspnea of several months' duration. She had left bundle branch block and aortic insufficiency with normal ejection fraction on 2-dimensional echocardiogram, none of which explained her symptoms. A CT coronary angiogram showed no obstructive coronary artery disease: Coronary Artery Disease Reporting and Data System category 1. Complete occlusion of the left superior pulmonary vein was, however, noted at its origin. Lung perfusion scintigraphy was obtained to evaluate differential perfusion.

Optimizing the diagnosis and assessment of chronic thromboembolic pulmonary hypertension with advancing imaging modalities

Imaging is key to nearly all aspects of chronic thromboembolic pulmonary hypertension including management for screening, assessing eligibility for pulmonary endarterectomy, and post-operative follow-up. While ventilation/perfusion scintigraphy, the gold standard technique for chronic thromboembolic pulmonary hypertension screening, can have excellent sensitivity, it can be confounded by other etiologies of pulmonary malperfusion, and does not provide structural information to guide operability assessment. Conventional computed tomography pulmonary angiography has high specificity, though findings of chronic thromboembolic pulmonary hypertension can be visually subtle and unrecognized. In addition, computed tomography pulmonary angiography can provide morphologic information to aid in pre-operative workup and assessment of other structural abnormalities. Advances in computed tomography imaging techniques, including dual-energy computed tomography and spectral-detector computed tomography, allow for improved sensitivity and specificity in detecting chronic thromboembolic pulmonary hypertension, comparable to that of ventilation/perfusion scans. Furthermore, these advanced computed tomography techniques, compared with conventional computed tomography, provide additional physiologic data from perfused blood volume maps and improved resolution to better visualize distal chronic thromboembolic pulmonary hypertension, an important consideration for balloon pulmonary angioplasty for inoperable patients. Electrocardiogram-synchronized techniques in electrocardiogram-gated computed tomography can also show further information regarding right ventricular function and structure. While the standard of care in the workup of chronic thromboembolic pulmonary hypertension includes a ventilation/perfusion scan, computed tomography pulmonary angiography, direct catheter angiography, echocardiogram, and coronary angiogram, in the future an electrocardiogram-gated dual-energy computed tomography angiography scan may enable a "one-stop" imaging study to guide diagnosis, operability assessment, and treatment decisions with less radiation exposure and cost than traditional chronic thromboembolic pulmonary hypertension imaging modalities.

Chronic Thromboembolic Pulmonary Hypertension: JACC Focus Seminar

Chronic thromboembolic pulmonary hypertension (CTEPH) is the result of pulmonary arterial obstruction by organized thrombotic material stemming from incompletely resolved acute pulmonary embolism. The exact incidence of CTEPH is unknown but appears to approximate 2.3% among survivors of acute pulmonary embolism. Although ventilation/perfusion scintigraphy has been supplanted by computed tomographic pulmonary angiography in the diagnostic approach to acute pulmonary embolism, it has a major role in the evaluation of patients with suspected CTEPH, the presence of mismatched segmental defects being consistent with the diagnosis. Diagnostic confirmation of CTEPH is provided by digital subtraction pulmonary angiography, preferably performed at a center familiar with the procedure and its interpretation. Operability assessment is then undertaken to determine if the patient is a candidate for potentially curative pulmonary endarterectomy surgery. When pulmonary endarterectomy is not an option, pulmonary arterial hypertension-targeted pharmacotherapy and balloon pulmonary angioplasty represent potential therapeutic alternatives.

Pulmonary angioplasty: A step further in the continuously changing landscape of chronic thromboembolic pulmonary hypertension management

Chronic thromboembolic pulmonary hypertension (CTEPH) is a potentially fatal and frequently undiagnosed form of pulmonary hypertension (PH), classified within group 4 by the World Health Organization (WHO). It is a type of precapillary PH, which uncommonly develops as a peculiar sequel of acute pulmonary embolism due to the partial resolution of the mechanically obstructing thrombus with a coexisting inflammatory response from pulmonary vessels. CTEPH is one of the potentially treatable forms of PH whose current standard of care is surgical pulmonary endarterectomy. Medical therapy with few drugs in non-operable disease is approved and has shown improvement in patients' hemodynamic condition and functional ability. Recently, balloon pulmonary angioplasty (BPA) has shown promising results as a treatment option for technically inoperable patients, those with unacceptable risk-to-benefit ratio and in a case of residual PH after endarterectomy. Lack of meticulous CTEPH screening programs in post-pulmonary embolism patients leading to underdiagnosis of this condition, complex operability assessment, and diversity in BPA techniques among different institutions are still the issues that need to be addressed. In this paper, we review the recent achievements in the management of non-operable CTEPH, their outcome and safety, based on available data.

Beyond the clot: perfusion imaging of the pulmonary vasculature after COVID-19

A compelling body of evidence points to pulmonary thrombosis and thromboembolism as a key feature of COVID-19. As the pandemic spread across the globe over the past few months, a timely call to arms was issued by a team of clinicians to consider the prospect of long-lasting pulmonary fibrotic damage and plan for structured follow-up. However, the component of post-thrombotic sequelae has been less widely considered. Although the long-term outcomes of COVID-19 are not known, should pulmonary vascular sequelae prove to be clinically significant, these have the potential to become a public health problem. In this Personal View, we propose a proactive follow-up strategy to evaluate residual clot burden, small vessel injury, and potential haemodynamic sequelae. A nuanced and physiological approach to follow-up imaging that looks beyond the clot, at the state of perfusion of lung tissue, is proposed as a key triage tool, with the potential to inform therapeutic strategies.

Chronic Thromboembolic Pulmonary Hypertension: the Bedside

PURPOSE OF REVIEW

Chronic thromboembolic pulmonary hypertension (CTEPH), included in group 4 PH, is an uncommon complication of acute pulmonary embolism (PE), in which emboli in the pulmonary vasculature do not resolve but rather form into an organized scar-like obstruction which can result in right ventricular (RV) failure. Here we provide an overview of current diagnosis and management of CTEPH.

RECENT FINDINGS

CTEPH management is complex with treatments that range from surgery, percutaneous interventions, to medical therapies. Current CTEPH medical therapies have largely been repurposed from pulmonary arterial hypertension (PAH). The diagnosis of CTEPH can be challenging, requiring a multimodality approach to differentiate from disease mimics. While these treatments improve symptoms, they may not reverse the underlying pathology of CTEPH.