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Everything you need to know about Computed Tomography (CT) & CT Scanning

Chest: Svc Imaging Pearls - Learning Modules | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
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  • Pulmonary Artery Aneurysm: Causes
    • Congenital (50%)
    • In general, it is presumed that increased flow caused by left-to-right shunt results in increased hemodynamic shear stress on the vessel walls and therefore promotes aneurysm formation in the PAs.The 3 most frequent congenital heart defects associated with a PAA are, in decreasing order, persistent ductus arteriosus, ventricular septal defects, and atrial septal defects.
  • Pulmonary Artery Aneurysm: Causes
    • Congenital (50%)
    • Pulmonary valve stenosis
    • Ehlers-Danlos syndrome
    • Marfan syndrome
    • Cystic medial necrosis
    • Untreated syphilis and tuberculosis
    • IVDA
    • Vasculitis (Behcet Syndrome) 
  • “In general, clinical manifestations of PAA remain nonspecific, whereas most patients with a PAA, even those with large PAA diameters up to 70 mm, have no complaints.Clinical symptoms include dyspnea, chest pain, hoarseness, palpitation, and syncopal episodes. Bronchus compression by a large PAA may be responsible for cyanosis, cough, and increasing dyspnea, pneumonia, fever, and bronchiectasis. In addition, patients with PAA have a high incidence of pulmonary emboli.”


    Aneurysms of the Pulmonary Artery
Maximilian Kreibich et al.
 Circulation. 2015;131:310-316 

  • “Overall, surgery remains the cornerstone of therapy for lesions involving the main pulmonary trunk, and evidence suggesting an absolute diameter threshold for surgery of the main PA is lacking. However, from our clinical experience and scientific knowledge of all the available data about aortic aneurysms, we suggest operating on adults with pulmonary trunk aneurysms >5.5 cm according to the guidelines for aortic disease.”


    Aneurysms of the Pulmonary Artery
Maximilian Kreibich et al.
 Circulation. 2015;131:310-316 

  • “In case of conservative treatment, it is our opinion that patients should be re-evaluated regularly, and a change in treatment should strongly be considered in case of compression of adjacent structures, thrombus formation in the aneurysm sack, ≥5-mm increase in the diameter of the aneurysm in 6 months, the appearance of clinical symptoms, evidence of valvular pathologies or shunt flow, and verification of PAH.”


    Aneurysms of the Pulmonary Artery
Maximilian Kreibich et al.
 Circulation. 2015;131:310-316 

  • “The largest meta-analysis to date exam- ined over 10,000 patients up to the year 2009 and reported incidental PE had a prevalence of 2.6% (95% CI, 1.9–3.4%), with a higher prevalence in patients with VTE risk factors such as malignancy (3.1%) and inpatient status (4.0%).”

    
Management of the Incidental Pulmonary Embolism 
Victor Chiu, Casey O’Connell 
AJR 2017; 208:485–488 

  • “Although treatment of symptomatic PE with anticoagulation results in a clear reduction in mortality, the bene ts of treating incidental PE have not yet been evaluated in a large prospective study. The risk of major bleeding while on anticoagulation for any VTE is 7.2 per 100 patient-years, making the decision to treat one of great consequence, particularly in higher risk patients such as those in the ICU and those with cancer.”


    Management of the Incidental Pulmonary Embolism 
Victor Chiu, Casey O’Connell 
AJR 2017; 208:485–488 

  • “The National Comprehensive Cancer Network also recommends treatment of incidental PE similar to that for symptomatic PE in patients with cancer and recommends against routinely obtaining repeat imaging.”

    
Management of the Incidental Pulmonary Embolism 
Victor Chiu, Casey O’Connell 
AJR 2017; 208:485–488 

  • “Pulmonary CTA is well established as a fast and reliable means of excluding or diagnosing PE. Continued developments in CT system hardware and postprocessing techniques will allow incremental reductions in radiation and contrast material requirements while improving image quality. Advances in risk strati cation and prognostication from pulmonary CTA examinations should further re ne its clinical value while minimizing the potential harm from overutilization and overdiagnosis."


    State-of-the-Art Pulmonary CT Angiography for Acute Pulmonary Embolism 
Moritz H. Albrecht et al.
 AJR 2017; 208:495–504
  • “This technique is effective despite the variable embrace by clinicians of the d-dimer test, a test that suffers from low specificity. However, the advantage of this laboratory marker lies in its high negative predictive value, so that acute PE can be safely excluded by a negative d-dimer result. In case of elevated d-dimer values, pulmonary CTA should be performed."


    State-of-the-Art Pulmonary CT Angiography for Acute Pulmonary Embolism 
Moritz H. Albrecht et al.
 AJR 2017; 208:495–504
  • “For example, pulmonary CTA has emerged as a formidable prognostic marker to gauge the 
severity of hemodynamic compromise from acute PE and identify patients at heightened risk for fatal or nonfatal adverse events, thus guiding clinical management toward more aggressive therapy. The main methods that have been described to categorize the hemodynamic relevance and severity of PE are imaging markers of right heart strain, methods for clot burden quantification, and lung perfusion measurements."


    State-of-the-Art Pulmonary CT Angiography for Acute Pulmonary Embolism 
Moritz H. Albrecht et al.
 AJR 2017; 208:495–504
  • “For clinical purposes, across all endpoints, the right ventricle (RV) diameter–left ventricle (LV) diameter ratio on pulmonary CTA has the strongest predictive value and most robust evidence base for adverse clin- ical outcomes in patients with acute PE. A ratio of more than 1 on traverse images and of more than 0.9 using true four-chamber view reconstructions is considered indicative of right heart strain and has been shown to predict adverse outcomes and early death."


    State-of-the-Art Pulmonary CT Angiography for Acute Pulmonary Embolism 
Moritz H. Albrecht et al.
 AJR 2017; 208:495–504
  • “One study investigating spectral optimization in monochromatic dual-energy pulmonary CTA with reduced iodine load suggested that 60 keV may be the optimal energy level to analyze the thoracic circulation . Other investigators have also concluded that iodine load can be reduced when virtual monoenergetic images extrapolated to photon energies of 50 or 70 keV are used ."


    State-of-the-Art Pulmonary CT Angiography for Acute Pulmonary Embolism 
Moritz H. Albrecht et al.
 AJR 2017; 208:495–504
  • “Pulmonary CTA is well established as a fast and reliable means of excluding or diagnosing PE. Continued developments in CT system hardware and postprocessing techniques will allow incremental reductions in radiation and contrast material requirements while improving image quality. Advances in risk stratification and prognostication from pulmonary CTA examinations should further refine its clinical value while minimizing the potential harm from overutilization and overdiagnosis."


    State-of-the-Art Pulmonary CT Angiography for Acute Pulmonary Embolism 
Moritz H. Albrecht et al.
 AJR 2017; 208:495–504
  • “In this rare vascular developmental anomaly, the left pulmonary artery arises from the posterior aspect of the right pulmonary artery and passes between the trachea and esophagus to reach the left hilum. The left pulmonary artery thus forms a sling around the distal trachea and the proximal right main bronchus.”


    Congenital and Acquired Pulmonary Artery Anomalies in the Adult: Radiologic Overview
Castañer E et al.
RadioGraphics 2006 26:2, 349-371
  • “Those affected by pulmonary artery sling may be classified generally into two groups: one with a normal bronchial pattern and the other with one or more malformations of the bronchotracheal tree (eg, stenosis of a long segment of the trachea or absence of the pars membranacea) as well as cardiovascular abnormalities. In the latter group, mortality and morbidity are high during infancy.The former group includes very few asymptomatic adults. In asymptomatic cases, a pulmonary artery sling may mimic a mediastinal mass on chest radiographs . CT and magnetic resonance (MR) imaging may be used to establish the diagnosis with certainty.”


    Congenital and Acquired Pulmonary Artery Anomalies in the Adult: Radiologic Overview
Castañer E et al.
RadioGraphics 2006 26:2, 349-371
  • “Idiopathic dilatation of the pulmonary trunk is a rare congenital anomaly that involves abnormal enlargement of the pulmonary trunk, with or without dilatation of the right and left pulmonary arteries . To reach this diagnosis, it is necessary to exclude pulmonary and cardiac diseases (mainly pulmonary valve stenosis) and to confirm the presence of normal pressure in the right ventricle and pulmonary artery .”

    Congenital and Acquired Pulmonary Artery Anomalies in the Adult: Radiologic Overview
Castañer E et al.
RadioGraphics 2006 26:2, 349-371
  • “Aneurysms or pseudoaneurysms of the pulmonary arteries, whether congenital or acquired, are rare. They may occur in association with a congenital cardiovascular anomaly, especially patent ductus arteriosus; infection (mycotic aneurysm); trauma, most commonly as a result of pulmonary artery perforation (due to improper placement of a catheter) or penetrating injury and very rarely as a result of blunt injury; vascular abnormality (eg, cystic medial necrosis, Behçet disease, Marfan syndrome, and Takayasu disease); and pulmonary hypertension.”

    Congenital and Acquired Pulmonary Artery Anomalies in the Adult: Radiologic Overview
Castañer E et al.
RadioGraphics 2006 26:2, 349-371
  • “Most mycotic aneurysms are secondary to endovascular seeding due to septic pulmonary emboli and are found in patients with endocarditis. Aneurysms secondary to a direct extension of infection from the adjacent parenchyma are seen in patients with necrotizing pneumonia or chronic tuberculosis. Mycotic aneurysms can be single or multiple and can be located centrally or peripherally.”

    Congenital and Acquired Pulmonary Artery Anomalies in the Adult: Radiologic Overview
Castañer E et al.
RadioGraphics 2006 26:2, 349-371
  • “Rasmussen aneurysm is a rare condition caused by weakening of the pulmonary artery wall from adjacent cavitary tuberculosis. Hemoptysis is the usual symptom at initial manifestation. Although the source of hemoptysis in cavitary tuberculosis is usually the bronchial arteries, Rasmussen aneurysm usually occurs in a peripheral pulmonary artery (. Chest radiographic findings that may suggest the formation of a pseudoaneurysm include an intracavitary protrusion, the replacement of a cavity by a nodule, or a rapidly growing mass.”

    Congenital and Acquired Pulmonary Artery Anomalies in the Adult: Radiologic Overview
Castañer E et al.
RadioGraphics 2006 26:2, 349-371
  • SVC Syndrome: Facts
    - Malignancies responsible for SVC syndrome in 78-97% of cases
    - Lung cancer and lymphoma are most common cause of SVC syndrome
    - Other causes of SVC syndrome include metastatic adenopathy (i.e. breast cancer). Germ cell tumors, thymoma
  • SVC Obstruction: Facts
    - Lung cancer is most common cause
    - Collaterals are many and include azygous, hemiazygous, vertebral venous plexus, internal mammary veins, intercostal veins, lateral thoracic system
    - Common etiologies are lung cancer, metastases (like breast cancer), lymphoma, fibrosing mediastinitis, radiation change
  • Persistent Left SVC: Facts
    - Represents persistence of the left common cardinal vein
    - Usually drains into the coronary sinus
    - Usually associated with absent left brachiocephalic vein
    - Usually has SVC present as well
    - Occurs in 0.2-0.4% of patients
  • “ Multidetector CT is an alternative tool helpful in establishing the primary diagnosis, defining anatomic landmarks and their relationships, and identifying associated cardiovascular anomalies. It is also an adjunct in the evaluation of complications during follow-up.”
    Uncommon Congenital and Acquired Aortic Disease: Role of Multidetector CT Angiography
    Kimura-Hayama ET, et al
    RadioGraphics 2010; 30;79-98
  • “ With its high spatial resolution and isotropic and volumetric information multidetector CT performed with or without ECG-gated technique allows accurate and fast noninvasive characterization of aortic pathologic conditions.”
    Uncommon Congenital and Acquired Aortic Disease: Role of Multidetector CT Angiography
    Kimura-Hayama ET, et al
    RadioGraphics 2010; 30;79-98
  • Patent Ductus Arteriosus: Facts
    - Connects the proximal descending aorta, immediately distal to the origin of the left subclavian artery, with the proximal left pulmonary artery at the junction of the main pulmonary artery
    - Closes functionally 18-24 hours after birth and anatomically at one month
    - If it is patent after 3 months it is a PDA
  • Patent Ductus Arteriosus: Facts
    - PDA occurs in 1 of 2,000 children born full term
    - More common in woman (2-1)
    - Treatment includes surgical closure or percutaneous placement of an occluder devise
  • Persistent Left SVC: Facts
    - Represents persistence of the left common cardinal vein
    - Usually drains into the coronary sinus
    - Usually associated with absent left brachiocephalic vein
    - Usually has SVC present as well
    - Occurs in 0.2-0.4% of patients
  • “ Multidetector CT is an alternative tool helpful in establishing the primary diagnosis, defining anatomic landmarks and their relationships, and identifying associated cardiovascular anomalies. It is also an adjunct in the evaluation of complications during follow-up.”
    Uncommon Congenital and Acquired Aortic Disease: Role of Multidetector CT Angiography
    Kimura-Hayama ET, et al
    RadioGraphics 2010; 30;79-98
  • “ With its high spatial resolution and isotropic and volumetric information multidetector CT performed with or without ECG-gated technique allows accurate and fast noninvasive characterization of aortic pathologic conditions.”
    Uncommon Congenital and Acquired Aortic Disease: Role of Multidetector CT Angiography
    Kimura-Hayama ET, et al
    RadioGraphics 2010; 30;79-98
  • Patent Ductus Arteriosus: Facts
    - Connects the proximal descending aorta, immediately distal to the origin of the left subclavian artery, with the proximal left pulmonary artery at the junction of the main pulmonary artery
    - Closes functionally 18-24 hours after birth and anatomically at one month
    - If it is patent after 3 months it is a PDA
  • Patent Ductus Arteriosus: Facts
    - PDA occurs in 1 of 2,000 children born full term
    - More common in woman (2-1)
    - Treatment includes surgical closure or percutaneous placement of an occluder devise
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