Looking beyond the thrombus: essentials of pulmonary artery imaging on CT

Nonthrombotic Pulmonary Embolism Associated With Non-Hodgkin Lymphoma

Nonthrombotic pulmonary embolism (NTPE) challenges the medical community with its diverse etiologies and potential life-threatening implications. The classification section delves into the multifaceted nature of NTPE, which includes various embolic agents that traverse the vascular system. From air and fat emboli to tumor and amniotic fluid emboli, this exploration of diverse etiologies sheds light on the complexity of NTPE. Diagnostic methods play a crucial role in the effective management of NTPE. This article describes a range of traditional and cutting-edge diagnostic techniques, from computed tomography angiography to novel biomarkers, enabling the accurate and timely identification of NTPE. NTPE treatment options are diverse and patient-specific, requiring customized approaches to address varying embolic sources. Anticoagulation, embolus removal, and emerging interventions under study are discussed, providing clinicians with a comprehensive understanding of management strategies. This article uncovers the rare but captivating association between NTPE and non-Hodgkin lymphoma. Although rare, documented cases have sparked curiosity among researchers and medical practitioners. We explore potential pathophysiological connections, discussing challenges and considerations when encountering this unique scenario. In conclusion, this captivating review encapsulates the multifaceted realm of NTPE, covering its classification, diagnostics, and treatment modalities. Moreover, it presents a fascinating connection with non-Hodgkin lymphoma. This article offers a comprehensive and concise review of NTPE, guiding readers through its intricate classification, diagnostic approaches, and therapeutic interventions.

MR Angiography of Pulmonary Vasculature

Pulmonary MR angiography (MRA) is a useful alternative to computed tomographic angiography (CTA) for the study of the pulmonary vasculature. For pulmonary hypertension and partial anomalous pulmonary venous return, a cardiac MR imaging and the pulmonary MRA are useful for flow quantification and planning treatment. For the diagnosis of pulmonary embolism (PE), MRA-PE has been shown to have non-inferior outcomes at 6 months when compared with CTA-PE. Over the last 15 years, pulmonary MRA has become a routine and reliable examination for the workup of pulmonary hypertension and the primary diagnosis of PE at the University of Wisconsin.

Canadian Society of Thoracic Radiology/Canadian Association of Radiologists Best Practice Guidance for Investigation of Acute Pulmonary Embolism, Part 2: Technical Issues and Interpretation Pitfalls

The investigation of acute pulmonary embolism is a common task for radiologists in Canada. Technical image quality and reporting quality must be excellent; pulmonary embolism is a life-threatening disease that should not be missed but overdiagnosis and unnecessary treatment should be avoided. The most frequently performed imaging investigation, computed tomography pulmonary angiogram (CTPA), can be limited by poor pulmonary arterial opacification, technical artifacts and interpretative errors. Image quality can be affected by patient factors (such as body habitus, motion artifact and cardiac output), intravenous (IV) contrast protocols (including the timing, rate and volume of IV contrast administration) and common physics artifacts (including beam hardening). Mimics of acute pulmonary embolism can be seen in normal anatomic structures, disease in non-vascular structures and pulmonary artery filling defects not related to acute pulmonary emboli. Understanding these pitfalls can help mitigate error, improve diagnostic quality and optimize patient outcomes. Dual energy computed tomography holds promise to improve imaging diagnosis, particularly in clinical scenarios where routine CTPA may be problematic, including patients with impaired renal function and patients with altered cardiac anatomy.

Multiple pulmonary artery aneurysms in a young female with patent ductus arteriosus on CT pulomnary angiography

Aneurysms of lobar branches of pulmonary artery are extremely rare with few reported cases in literature. The exact etiopathogenesis of pulmonary artery aneurysms is not clearly understood and no clear guidelines on their management is available. Aneurysms of the secondary and tertiary branches appear to be even more uncommon than those of the trunk and primary branches.

Here we report an unusual case of young female with multiple pulmonary artery aneurysms in bilateral lungs with fusiform dilation of main pulmonary trunk and a small patent ductus arteriosus.

Pulmonary arteries: imaging of pulmonary embolism and beyond

The pulmonary arteries are not just affected by thrombus. Various acquired and congenital conditions can also affect the pulmonary arteries. In this review we discuss cross sectional imaging modalities utilized for the imaging of the pulmonary arteries. Acquired pulmonary artery entities, including pulmonary artery sarcoma (PAS), vasculitis, aneurysm, and arteriovenous malformations, and congenital anomalies in adults, including proximal interruption of the pulmonary artery, pulmonary sling, pulmonary artery stenosis, and idiopathic dilatation of the pulmonary trunk, are also discussed. An awareness of these entities and their imaging findings is important for radiologists interpreting chest imaging.

Pictorial review of the pulmonary vasculature: from arteries to veins

Pathology of the pulmonary vasculature involves an impressive array of both congenital and acquired conditions. While some of these disorders are benign, disruption of the pulmonary vasculature is often incompatible with life, making these conditions critical to identify on imaging. Many reviews of pulmonary vascular pathology approach the pulmonary arteries, pulmonary veins and bronchial arteries as individual topics. The goal of this review is to provide an integrated overview of the high-yield features of all major disorders of the pulmonary vasculature. This approach provides a more cohesive and comprehensive conceptualisation of respiratory pathology. In this review, we present both the salient clinical and imaging features of congenital and acquired disorders of the pulmonary vasculature, to assist the radiologist in identifying pathology and forming a robust differential diagnosis tailored to the presenting patient. TEACHING POINTS: • Abnormalities of the pulmonary vasculature are both congenital and acquired. • Pathology of a single pulmonary vascular territory often affects the entire pulmonary vasculature. • Anomalous pulmonary venous flow is named as a function of its location and severity. • Bronchial arteries often undergo dilatation secondary to cardio-respiratory pathology.

Pulmonary artery aneurysms: diagnosis & endovascular therapy

Pulmonary artery aneurysms (PAAs) and pseudoaneurysms are rare entities in the spectrum of pulmonary arterial diseases. The etiology of these aneurysms is varied and patients present with nonspecific symptoms which make their diagnosis both difficult and less often considered. In this review, we will discuss the clinical manifestations, etiologies, methods of detection, imaging features, and the current role of endovascular treatment in the management of PAAs.

Computational Fluid Dynamics Modeling of the Human Pulmonary Arteries with Experimental Validation

Pulmonary hypertension (PH) is a chronic progressive disease characterized by elevated pulmonary arterial pressure, caused by an increase in pulmonary arterial impedance. Computational fluid dynamics (CFD) can be used to identify metrics representative of the stage of PH disease. However, experimental validation of CFD models is often not pursued due to the geometric complexity of the model or uncertainties in the reproduction of the required flow conditions. The goal of this work is to validate experimentally a CFD model of a pulmonary artery phantom using a particle image velocimetry (PIV) technique. Rapid prototyping was used for the construction of the patient-specific pulmonary geometry, derived from chest computed tomography angiography images. CFD simulations were performed with the pulmonary model with a Reynolds number matching those of the experiments. Flow rates, the velocity field, and shear stress distributions obtained with the CFD simulations were compared to their counterparts from the PIV flow visualization experiments. Computationally predicted flow rates were within 1% of the experimental measurements for three of the four branches of the CFD model. The mean velocities in four transversal planes of study were within 5.9 to 13.1% of the experimental mean velocities. Shear stresses were qualitatively similar between the two methods with some discrepancies in the regions of high velocity gradients. The fluid flow differences between the CFD model and the PIV phantom are attributed to experimental inaccuracies and the relative compliance of the phantom. This comparative analysis yielded valuable information on the accuracy of CFD predicted hemodynamics in pulmonary circulation models.

Acquired peripheral pulmonary artery aneurysms: morphological spectrum of disease and multidetector computed tomography angiography findings-cases series and literature review

BACKGROUND

Acquired peripheral or intraparenchymal pulmonary artery aneurysms (PPAA) are rare entities but are important to recognize because of the associated morbidity. Hemoptysis is their principal complication and is a potentially fatal condition.

PURPOSE

To illustrate the causes, multidetector CT angiography (MDCTA) findings and differential diagnosis of acquired PPAA.

MATERIALS AND METHODS

The institutional review boards approved this study. We conducted a retrospective review of the demographic data and the results of clinical and laboratory examinations, and imaging studies of patients managed between January 2012 and January 2017 in two institutions.

RESULTS

A total of 19 patients had acquired PPAA that were detected at MDCTA, 9 patients with normal pulmonary artery pressures and 10 with pulmonary hypertension. Nine patients developed PPAA-related acute symptoms. MDCTA features of PPAA include: a lobulated vascular mass, an indistinct irregular arterial wall, aneurysmal thrombosis or wall calcification, findings of impending rupture including perianeurysmal edema, gas or a soft tissue mass.

CONCLUSION

PPAA are rare. In our series, endocarditis and pulmonary hypertension are the PPAA leading causes. The treatment modality preferred is embolization, especially as surgery poses a very high risk for patients with severe pulmonary hypertension. Further clarification of the natural history of these rare arterial aneurysms is needed.

Contrast opacification on thoracic CT angiography: challenges and solutions

Contrast flow and enhancement patterns seen on thoracic CT angiography (CTA) can often be challenging and may often reveal more than is immediately apparent. A non-diagnostic CTA following the initial contrast injection can be secondary to many causes; these include both extrinsic factors, such as injection technique/equipment failure (iv cannula, power injector), and intrinsic, patient-related factors. Contrast pressure and flow graphs often contain useful information regarding the etiology of a non-diagnostic scan. Understanding these graphs will help the radiologist plan a repeat contrast injection to overcome the deficiencies of the first injection and thus obtain a diagnostic scan. The current review article outlines normal and abnormal intravenous contrast dynamics, discusses how to recognize etiologies of non-diagnostic scans, and ultimately addresses techniques to overcome obstacles towards obtaining normal contrast opacification of the target vessel. In addition, there are some life-threatening findings, which unless sought for, may remain hidden in plain sight.

Key Points

• Using contrast enhancement and flow patterns to identify the cause of a non-diagnostic CTA.

• Recognize life threatening causes of altered contrast dynamics such as cardiac asystole.

• Non-target vessel opacification may hold key to underlying pathophysiology.

Clinical Characteristics and Treatment Outcomes of Primary Pulmonary Artery Sarcoma in Korea

Pulmonary artery sarcomas (PAS) are rare malignant neoplasms. Right heart failure due to tumour location is the main cause of death in PAS patients. The hemodynamic influence of PAS may effect prognosis, but this has not been proven. We aimed to identify the clinical characteristics and prognostic factors of PAS in Korea, their association with pulmonary hypertension (PH). PAS patients treated at the Asan Medical Center between 2000 and 2014 were reviewed. We examined demographic characteristics, diagnostic and treatment modalities. Potential prognostic factors were evaluated by univariate and multivariate analysis. Twenty patients were diagnosed with PAS. Ten patients were male, the median age was 54 years (range, 33-75 years). The most common symptom observed was dyspnea (65%). The most common histologic type was spindle cell sarcoma (30%). Ten patients had a presumptive diagnosis of pulmonary embolism (PE) and received anticoagulation therapy. Seventeen patients underwent surgery, but only 5 patients had complete resection. Eleven patients received post-operative treatment (chemotherapy = 3, radiotherapy = 5, chemoradiotherapy = 3). PH was observed in 12 patients before treatment and in 6 patients after treatment. Overall median survival was 24 months. Post-treatment PH was associated with poor prognosis (HR 9.501, 95% CI 1.79-50.32; P = 0.008) while chemotherapy was negatively associated with mortality (HR 0.102, 95% CI 0.013-0.826; P = 0.032) in univariate analysis. Post-treatment PH was also associated with poor prognosis in multivariate analysis (HR 5.7, 95% CI 1.08-30.91; P = 0.041). PAS patients are frequently misdiagnosed with PE in Korea. Post-treatment PH is associated with a poor prognosis.

Pulmonary Artery Sarcoma - Multimodality Imaging

Pulmonary artery sarcoma (PAS) is a rare and fatal disease. PAS can often be misdiagnosed as pulmonary thromboembolism. Moreover, the correct diagnosis is frequently delayed due to nonspecific signs and symptoms. The prognosis of patients with PAS is poor. We report a case of a woman with a primary PAS who was initially diagnosed with pulmonary thromboembolism.

Imaging adults on extracorporeal membrane oxygenation (ECMO)

Extracorporeal membrane oxygenation (ECMO) is increasingly being used in adults following failure to wean from cardiopulmonary bypass, after cardiac surgery or in cases of severe respiratory failure. Knowledge of the different types of ECMO circuits, expected locations of cannulas and imaging appearance of complications is essential for accurate imaging interpretation and diagnosis. Commonly encountered complications are malposition of cannulas, adjacent or distal haemorrhage, stroke, stasis thrombus in access vessels, and distal emboli. This article will describe the imaging appearance of different ECMO circuits in adults as well as commonly encountered complications. If a CT (computed tomography) angiogram is being performed on these patients to evaluate for pulmonary embolism, the scan may be suboptimal from siphoning off of the contrast by the ECMO. In such cases, an optimal image can be obtained by lowering the flow rate of the ECMO circuit or by disabling the circuit for the duration of image acquisition.

Key Points

• Femoroatrial VV ECMO: femoral vein drainage cannula and right atrial return cannula.

• Femorofemoral VV ECMO: return and drainage cannulas placed in femoral veins.

• Dual-lumen single cannula VV ECMO: via the right IJ/Femoral vein with the tip in the IVC/SVC.

• Peripheral VA ECMO: peripheral venous drainage cannula and peripheral arterial return cannula.

• Central VA ECMO: direct right atrial drainage cannula and aortic return cannula.