The Role of Time-Resolved MRA for Post-treatment Assessment of Pulmonary Arteriovenous Malformations: A Pictorial Essay

Excerpt

Pulmonary arteriovenous malformation (PAVM) is defined as a direct connection between the branches of a pulmonary artery and a pulmonary vein that do not pass through the alveolar capillaries. The major treatment strategy for PAVM is coil embolotherapy [1, 2]. Because the rates of recanalization of treated PAVMs are relatively high, periodic assessment of the patency of PAVMs is needed [3]. However, standard follow-up methods have not been established. Time-resolved MRA (TR-MRA) is the latest MR technology, and it provides the ability to acquire a consecutive dynamic angiography [4]. It provides high-quality dynamic contrast-enhanced images based on a 3-dimensional gradient-recalled echo (3D-GRE) T1-weighted sequence while maintaining adequate spatial and temporal resolution by a ‘keyhole method.’ Recently, the usefulness of TR-MRA for follow-up of treated PAVMs has been reported with a high diagnostic ability (sensitivity and specificity >90 %) [5]. This essay describes the principles of the TR-MRA imaging technique and the practical steps in obtaining high-quality angiography of the pulmonary artery that is adequate for the detection of recanalization of PAVM. Case examples are provided that demonstrate the utility of this technique in evaluating the patency of PAVMs treated with embolotherapy with platinum coils in comparison with transcatheter digital subtraction pulmonary angiography. …