Purpose/Objectives
To decribe the main anatomical considerations and illustrate chest computed tomography (CT) imaging findings in the diagnosis of pulmonary arteriovenous malformations (PAVM). To explore the importance, benefits and challenges of CT–guided percutaneous transcatheter embolization using coils and/or plugs in the treatment of PAVM using cases from our hospital.
Methods & Materials
PAVM are rare vascular anomalies of the lung, in which there is an abnormal anatomic shunt between the pulmonary and systemic circulation, without the interposition of pulmonary capillary blood vessels.  This low-resistance, high flow, fistulous communication between a pulmonary artery and vein creates an intrapulmonary right-to-left shunt, inhibiting the normally occurring gas exchange and resulting in hypoxemia. These thin-walled, dilated vascular structures rarely bleed, although they do represent an important cause of maternal death during pregnancy. Systemic artery angiography is the gold standard for diagnosing PAVM. In patients with documented intrapulmonary shunting, chest CT is useful in characterizing the PAVM. The treatment of PAVM in asymptomatic patients is recommended, as they are at risk of developing an array of life-long complications, such as hypoxemia, cerebrovascular accidents and haemorrhage, dyspnoea, haemoptysis, stroke, migraines and cerebral abscesses. CT–guided transcatheter embolotherapy is the current standard of care. Surgical PAVM resection is rarely required, and reserved for patients who are not candidates for interventional radiology embolization due to PAVM location, size or number. Recanalization and collateralization may occur after CT–guided transcatheter embolization therapy, so lifelong imaging follow-up is necessary.
Results
Firstly, PAVM are diagnosed and characterized using systemic artery angiography, chest computed tomography angiography and digital subtraction angiography. Taking into account the location, number and size of the PAVM, the appropriate treatment (interventional radiology vs. surgical resection) and materials (vascular plugs vs. coils) are selected. If coils are used, the diameter of the feeding vessel should not exceed 2 mm, as incomplete embolization with coil migration could result. Vascular plugs are most commonly used, as they are extremely versatile, with a low risk of migration and PAVM repermeabilization and can be repositioned if need be. They are generally recommended in the treatment of larger PAVM, as one plug can effectively occlude larger caliber arteries, reducing procedure times, exposure to radiation. A combination of vascular plugs and coils may also be employed. Under local anaesthesia, the right femoral vein is punctured, using the Seldinger technique, and systemic heparin is administered. Pulmonary arteriography is then performed to assess the lesion. PAMV location, number and diameters of feeding arteries are identified and materials selected accordingly. Embolization is performed using coils, plugs or a combination of both. A post-embolization angiogram is performed and if persistent patency is observed for more than 5 minutes, an additional device is employed to achieve complete occlusion.
Conclusion
The radiologist’s role in the management of a patient with PAVM is dual, both during diagnosis, using systemic artery angiography, chest CT angiography and digital subtraction angiography, in the interventional radiology embolization treatment, and in the life-long post-procedure follow up, in order to assess the occurrence of recanalization or other complications. Percutaneous percutaneous transcatheter embolization using vascular plugs and coils is a safe, minimally invasive, effective and repeatable procedure in the treatment of PAVM, that does not require general anaesthesia and allows for the prevention of lung parenchyma loss.

Pulmonary Arteriovenous Malformations: The Radiologist’s Role in Diagnosis and Treatment

The Winter Course 2021 covers a variety of topics from basics in interstitial lung disease, infections including Covid-19, malignancies, lung cancer screening, and artificial intelligence. The combination of topics is aimed to serve as a good introduction to radiologists embarking on a career in thoracic imaging as well as a solid refresher for experienced thoracic radiologists.

[ESTI Winter Course 2021 Evaluation Form](https://www.surveymonkey.com/r/PP9WFTJ?sid=%5Bsid_value%5D&uid=%5Buid_value%5D&tkn=%5Btkn_value%5D&cgrid=%5Bcgrid_value)