Iodine Concentration and Optimization in Computed Tomography Angiography: Current Issues.

Computed tomography (CT) technology has seen a dramatic evolution in the recent past that has deeply changed the face of this diagnostic modality. Since the early days of helical single-slice and then multislice CT, CT angiography (CTA) has been one of the most technically demanding applications, both in terms of scanning technique and contrast medium (CM) injection protocol, due to the need to acquire a large amount of high-resolution data over a limited period corresponding to the peak contrast enhancement of the arterial system. Iodine concentration is one of the main determinants of arterial enhancement in CTA, and current low-osmolar and iso-osmolar nonionic CM for intravascular administration still come in a handful of molecules, but a relatively wide range of different iodine concentrations. This gives the opportunity to optimize CTA protocols as a function of several factors such as patient characteristics, CT technology, and CM features in an attempt to maximize the diagnostic yield of CTA examinations while considering patient safety and avoiding unnecessary extra costs. Our aim is to provide an up-to-date overview of the existing evidence on how changing iodine concentration can have an impact on CTA performance, especially with the use of state-of-the-art CT and power injector technology, in the perspective of improving patient care while minimizing overall exposure to iodinated CM and ionizing radiation.