Contrast medium dose optimization in the era of multi-energy CT

With the increasing use of contrast-enhanced CT, optimizing the iodinated contrast medium (ICM) dose while maintaining diagnostically adequate image quality is essential to mitigate potential adverse effects on patients, the environment, and public health, as well as to reduce medical costs and address potential supply shortages. Multi-energy CT technologies including dual-energy CT and photon-counting detector CT enable data acquisition at multiple energy spectra, allowing for material characterization beyond the capabilities of conventional single-energy CT. Recent technical advancements and the growing adoption of these technologies in clinical practice have enhanced patient care across various diagnostic tasks. Among the spectral-based imaging options offered by multi-energy CT, virtual monoenergetic imaging holds significant promise for substantial ICM dose reduction due to the drastic improvement in iodine contrast at lower energy levels. This article aims to provide an overview of multi-energy CT technology and its utility for ICM dose optimization across various clinical indications, while also discussing current issues and related topics.