Imaging Pearls ❯ Chest ❯ Pulmonary Arteries Beyond PE
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- “The main PA has a normal diameter of up to 28 mm in adults.1 The right and left PAs are approximately of equal diameter; however, the right PA has a longer course than its counterpart. The pulmonary trunk arises from the right ventricular outflow tract at the level of the pulmonic valve, and then divides into the left and right pulmonary arteries (PA). The main, right, and left PAs are contained within the pericardium. The right and left PA both divide into two lobar branches at the hilar level. The right PA passes anterior to the right mainstem bronchus and divides into the truncus anterior and the interlobar artery. Most commonly, the truncus anterior supplies the right upper lobe (RUL) and the right interlobar artery supplies the right middle (RML) and right lower lobe (RLL). The posterior RUL is often supplied by a branch of the interlobar artery. The left PA courses superior to the left mainstem bronchus and divides into the left upper lobe artery and the left interlobar artery. The left interlobar artery gives rise to segmental branches that supply the lingula and left lower lobe. The segmental pulmonary arteries to each lobe travel with an accompanying branch of the bronchial tree and are named accordingly. Once the segmental arteries divide, they are then considered subsegmental arteries.”
Diseases of the pulmonary arteries: imaging appearances and pearl
Isabel O. Cortopassi, Babina Gosangi, Daniella Asch et al.
Clinical Imaging, Volume 91, 2022,Pages 111-125, - An aneurysm caused by infection is known as a mycotic aneurysm. Mycotic PA aneurysms are most often secondary to endocarditis with septic emboli. A Rasmussen aneurysm is a subtype of mycotic aneurysm, where a cavitary lesion caused by tuberculosis weakens the adjacent PA wall resulting in aneurysm formation. This occurs from direct extension rather than hematogenous spread of infection. These types of aneurysms can be single or multiple in number and can be located centrally or peripherally in the lungs. Rasmussen aneurysms are extremely rare and typically present with hemoptysis. Chest X-ray can suggest the diagnosis by a protrusion/nodule within the cavity and a rapidly growing mass representing the PA aneurysm, which would be confirmed with a CECT.
Diseases of the pulmonary arteries: imaging appearances and pearl
Isabel O. Cortopassi, Babina Gosangi, Daniella Asch et al.
Clinical Imaging, Volume 91, 2022,Pages 111-125, - Systemic inflammatory disorders can also result in aneurysms. Behçet's disease is a systemic vasculitis of unknown etiology characterized by recurrent oral and genital ulcers, eye inflammation (uveitis), skin lesions, and joint pain. Involvement of the gastrointestinal tract and central nervous system, as well as other organs can also be seen. These patients may develop arterial aneurysms or occlusions of the PA.2 Aneurysms usually develop in central PAs and may be single or multiple.2 On chest radiograph, a rounded opacity in the perihilar region or hilar enlargement could be suggestive of pulmonary artery aneurysm in patients with a history of underlying systemic inflammatory disorder with new onset of hemoptysis. On CECT, the aneurysms are usually focal and saccular. Mural thrombus may be seen in some cases.
Diseases of the pulmonary arteries: imaging appearances and pearl
Isabel O. Cortopassi, Babina Gosangi, Daniella Asch et al.
Clinical Imaging, Volume 91, 2022,Pages 111-125, - ”PA aneurysms can also be iatrogenic, such as aneurysms caused by right heart catheterization and PA catheter placement, although this complication remains rare. CECT imaging is the diagnostic modality of choice in these cases. A focal dilatation or outpouching is seen within the involved pulmonary arterial segment. PA aneurysm formation carries a poor prognosis with 30% mortality within 2 years of diagnosis if left untreated.2 Rupture of a PA aneurysm is always fatal.2 PA aneurysms are managed conservatively, when possible, by aggressively controlling PA hypertension and monitoring the patient with serial echocardiograms or CTA. Surgical techniques employed in the management of PA aneurysms,aneurysmorraphy, aneurysmectomy, lobectomy, pneumonectomy.
Diseases of the pulmonary arteries: imaging appearances and pearl
Isabel O. Cortopassi, Babina Gosangi, Daniella Asch et al.
Clinical Imaging, Volume 91, 2022,Pages 111-125, - Pulmonary artery aneurysm and pseudoaneurysm
An aneurysm is focal dilatation of a blood vessel that contains all three layers (tunica externa, media, and intima) of the arterial wall, while a pseudoaneurysm is missing at least one of the layers of the wall. PA aneurysms and pseudoaneurysms can be caused by cardiovascular anomalies (such as patent ductus arteriosus), infectious processes, neoplasms, trauma/iatrogenic injuries , vasculitis such as Behcet's disease , and pulmonary hypertension (HTN). PA aneurysms are often times discovered incidentally in an asymptomatic patient or can present with hemoptysis. PA aneurysms are very rare in occurrence and an autopsy series revealed that the incidence of PA aneurysm is 0.057%. - Takayasu arteritis is an idiopathic inflammatory process most frequently seen in young Asian women and commonly involves the aorta and its branches with an incidence rate of 0.3 to 3.3 per million per year. The PAs are involved in 50–80% of patients and usually present as a late manifestation in the course of the disease. This entity typically results in stenosis or occlusion of segmental and subsegmental arteries, although less commonly may also affect the larger, more central PAs. Typical clinical features of Takayasu arteritis include fever, weight loss, night sweats.
Diseases of the pulmonary arteries: imaging appearances and pearl
Isabel O. Cortopassi, Babina Gosangi, Daniella Asch et al.
Clinical Imaging, Volume 91, 2022,Pages 111-125, - “Angiosarcoma is an extremely rare type of cancer that forms in the lining of blood vessels and can cause filling defects in the main or proximal PAs. These are more prevalent in females and have a reported incidence of 0.001–0.03% (33). The two most common types seen in practice are undifferentiated sarcomas and leiomyosarcomas. Initial imaging characteristics may mimic a PE, but there are key distinguishing features which include the following: a filling defect that often fills or expands the arterial lumen, extension into mediastinum or lung, delayed enhancement or heterogenous appearance on CTA, and a filling defect that does not resolve or increases on follow-up imaging.2 These have a poor prognosis and even with treatment, carry an average survival of 12–18 months from the time of diagnosis”
Diseases of the pulmonary arteries: imaging appearances and pearl
Isabel O. Cortopassi, Babina Gosangi, Daniella Asch et al.
Clinical Imaging, Volume 91, 2022,Pages 111-125, - Primary (or idiopathic PA HTN) typically occurs in young females and is a diagnosis of exclusion. Pulmonary HTN is often diagnosed at a late stage when right heart failure has become evident as a direct result of the high pressures in the pulmonary circulation. CT findings suggest pulmonary artery HTN when the main PA diameter is >29 mm, segmental artery-to-bronchus ratio is >1, and ratio of the diameter of the main PA to the diameter of the aorta is >1.2. A mosaic perfusion pattern can also be seen in the lungs due to vasoconstriction of peripheral vessels, enlarged right heart chambers, as well as reflux of contrast material into prominent IVC and hepatic veins due to elevated right heart pressures.
Diseases of the pulmonary arteries: imaging appearances and pearl
Isabel O. Cortopassi, Babina Gosangi, Daniella Asch et al.
Clinical Imaging, Volume 91, 2022,Pages 111-125, - Anomalous origin of the left pulmonary artery from the right pulmonary artery (pulmonary artery sling)
This is a rare congenital anomaly that occurs when the left PA arises from the posterior aspect of right PA and crosses the midline between the trachea and the esophagus. It is proposed that this pathology is a result of the obliteration of the left sixth aortic arch.9 PA sling comprises <1% of all congenital heart disorders.
- Shone Complex
- Shone complex is a congenital heart defect consisting of four obstructive defects in the left heart: a mitral supravalvular ring, sub-aortic stenosis, parachute mitral valve, and coarctation of the aorta (CoA), which affects only a small minority of people. - Shone Complex
- Its complete form associates a supra-mitral valve ring, sub aortic stenosis, parachute mitral valve (PMV), and coarctation of the aorta. Otherwise, the incomplete form, which is the most common, consists of a left ventricle inlet defect (PMV, Mitral stenosis congenitally or supravalvular mitral ring) associated with at least one left ventricular escape lesion (bicuspid aortic valve, subvalvular aortic stenosis, coarctation of the aorta) - The complete Shone syndrome consists of four cardinal left-sided cardiac defects
- supravalvular mitral membrane
- subvalvular aortic stenosis (membranous or muscular)
- parachute mitral valve
- coarctation of the aorta
- Although four features were originally described, it is more common for patients to have incomplete Shone syndrome with only some of the obstructive lesions
- “Septic emboli are seen most commonly in patients with infective endocarditis, patients with infected venous catheters or pace-maker leads, and patients with periodontal disease.”
High-Resolution MDCT of Pulmonary Septic Embolism: Evaluation of the Feeding Vessel Sign Dodd JD et al. AJR 2006; 187:623–629 - “Septic emboli are seen most commonly in patients with infective endocarditis, patients with infected venous catheters or pace-maker leads, and patients with periodontal disease.”
High-Resolution MDCT of Pulmonary Septic Embolism: Evaluation of the Feeding Vessel Sign Dodd JD et al. AJR 2006; 187:623–629 - “The CT appearance of septic emboli includes nodules and wedge-shaped subpleural opacities with or without cavitation and the feeding vessel sign. The feeding vessel sign consists of a distinct vessel leading directly into the center of a nodule. This sign has been considered highly suggestive of septic embolism, the prevalence varying from 67–100% in various series.”
High-Resolution MDCT of Pulmonary Septic Embolism: Evaluation of the Feeding Vessel Sign Dodd JD et al. AJR 2006; 187:623–629 - “Septic emboli are seen most commonly in patients with infective endocarditis, patients with infected venous catheters or pacemaker leads, and in patients with periodontal disease.”
High-Resolution MDCT of Pulmonary Septic Embolism: Evaluation of the Feeding Vessel Sign Dodd JD et al. AJR 2006; 187:623–629 - “In conclusion, septic embolism is charac- terized by the presence of multiple nodules in various stages of cavitation and pleura-based wedge-shaped opacities. Although many of these nodules appear to have a central vessel on cross-sectional images, multiplanar reconstructions and MIP images show that in most cases these vessels course around the nodule. The “feeding vessel” seen in the other cases represents a pulmonary vein.”
High-Resolution MDCT of Pulmonary Septic Embolism: Evaluation of the Feeding Vessel Sign Dodd JD et al. AJR 2006; 187:623–629 - “We conclude that SPE presents with variable and often nonspecific clinical and radiographic features. The diagnosis is usually suggested by the presence of a predisposing factor, febrile illness, and CT findings of multiple, nodular lung infiltrates peripherally, with or without cavitation.”
Septic pulmonary embolism: presenting features and clinical course of 14 patients. Cook RJ et al. Chest. 2005 Jul;128(1):162-6.
"There is a moderately strong relationship between the size of the segmental pulmonary arteries and mean pulmonary arterial pressure (mPAP)"
Detection of Pulmonary Hypertension with Multidetector CT and Echocardiography Alone and in Combination
Devaraj A et al.
Radiology 2010; 254:609-616" Measuring pulmonary arterial size by using coronal oblique reformats to calculate the ratio of the cross sectional area of the main pulmonary artery to the diameter of the ascending aorta does not strengthen correlations with mPAP compared with the ratio of the simple axial diameter of the main pulmonary artery to the diameter of the ascending aorta."
Detection of Pulmonary Hypertension with Multidetector CT and Echocardiography Alone and in Combination
Devaraj A et al.
Radiology 2010; 254:609-616- Bronchial Artery Aneurysm: Etiologies
- Bronchiectasis
- Mycotic origin
- Osler Weber Rendu sydrome - "By providing thin section transaxial,multiplanar reconstruction, and 3D images, CT angiography using MDCT allows comparable or better images than conventional angiography with respect to the depiction of bronchial or nonbronchial systemic arteries."
Bronchial and Nonbronchial Systemic Arteries in patients with Hemoptysis: Detection on MDCT Angiography
Chung MJ et al.
AJR 2006;186:649-655 - Pulmonary Artery Stenosis: Etiology
- Systematic vasculitis
- Behcet disease
- Takayasu arteritis
- Inflammatory disease (TB, histoplasmosis) - Mycotic Pseudoaneurysm of the Pulmonary Artery
- Right sided endocarditis
- Necrotizing pneumonia
- Syphilis
- Tuberculosis (Rasmussen pseudoaneurysm) - Pulmonary Artery Aneurysms: Facts
- Rare
- May be congenital or required
- Syphilis
- Pulmonary hypertension is common
- Complications are hemoptysis which can lead to rupture and may prove fatal