Reduced Metal Artifacts on CT Utilizing the Medtronic MVP TM Microvascular Plug System

E mbolotherapy has become a major component of modern interventional radiology practice. Whether treating life-threatening hemorrhage, occluding debilitating vascular malformations, or blocking unwanted vessels for flow redistribution, interventional radiologists must have complete understanding of the various embolic platforms at their disposal. This understanding includes not just the benefits of each device, but also the relative weaknesses. One area of great interest, which is common to every device, is the ability to evaluate treatment response on imaging after embolization. A major limitation of many of the currently available embolic devices is metallic artifact, particularly when using CT imaging. Typically, metal artifact presents as light and dark streaks emanating from the embolic device resulting in obscuration of adjacent image quality. Metal artifact results from several factors, including beam hardening, Compton scatter, photon depletion (decreased signal to noise), and edge effects from nonlinear partial volume. The end result of all of these factors is loss of useful information around the embolic device, rendering accurate interpretation almost impossible. There have been many metal artifact reduction strategies developed to mitigate the effects of metal artifacts in both conventional and C-arm CT scans. Many of these strategies involve altering acquisition conditions (adjusting scan parameters, utilizing dual energy techniques, etc), modifying preprocessed data (noise suppression and beam hardening/scatter reduction techniques), employing novel reconstruction algorithms (projection completion, iterative reconstruction), or optimizing postprocessed images.1 Despite the relative successes of each of these strategies, none have found mainstream utility due to various reasons, such as possible increased patient radiation doses,2 need for time-consuming and expensive processes,3 or limitations in licensing due to proprietary