Schematic diagrams of the different approaches to Rasmussenâ€™s aneurysm embolization. (a) Via the bronchial artery, only proximal embolization may be achieved because the inflow artery is small and tortuous. (b) Using the conventional approach via the pulmonary artery, selective catheterization of the aneurysm may be easy, but an unintended reflux of the NBCA cast and subsequent incomplete embolization of the aneurysm may occur with the retrograde flow. (c) Using our approach, proximal coil blocking via the pulmonary artery prevents unintended reflux of the NBCA cast and allows continuous retrograde retention of the NBCA in the aneurysm, as well as in the inflow and outflow arteries. NBCA, n-butyl-2-cyanoacrylate.