Iterative Reconstruction Techniques: What do they Mean for Cardiac CT?

Abstract

Cardiac computed tomography (CT) is a highly demanding and relatively new CT application that has evolved during the last two decades and for the last decade has been regarded as a routine technology. The success of cardiac CT mainly depends on two classes of technology: CT hardware and image reconstruction software. The technical requirements of cardiac CT are easy to state: increased temporal resolution, increased spatial resolution, decreased patient dose, and improved workflow. Faster rotation times, dual source dual detector gantries, improved z-coverage, smaller slice thicknesses and improved dose management are solutions on the hardware side that help to fulfil these requirements. The solutions on the software side are more complex. There have been several new developments in the area of reconstruction techniques and these are typically subsumed under the term “iterative image reconstruction” to indicate that this is a step beyond conventional filtered back projection. The main developments in iterative image reconstruction for clinical CT aim at noise reduction, contrast enhancement and motion artifact reduction. The major CT vendors implement different approaches in their products, while in parallel, research departments are proposing future solutions. Most of the well-known iterative approaches are not specific to cardiac CT. Some vendors, however, provide specific cardiac CT solutions. This article reviews the current approaches, product as well as prototype software, with a focus on vendor activities.