ABSTRACT
The development and introduction of spectral photon counting CT (SPCCT) into clinical practice will primarily be driven by image quality improvements, decreased radiation exposure, and improved detection of conventional contrast media. It seems to be mandatory that the new scanner generation will match conventional single- or dual-energy machines in acquisition and reconstruction speed to succeed in clinical practice. A parallel development of SPCCT specific contrast agents will continue and probably lead to the initial steps toward molecular imaging using targeting agents designed for SPCCT. But there are challenges that are beyond the new scanner and nanoparticle technologies that will have direct influence on the development. Every aspect from the logistic challenges to coordinate the application of a targeting K-edge detectable nanoparticle with the actual scan – which might vary from minutes to days depending on the targeted structure – to the regulatory hurdles and the substantial costs for the development and commercialization of any new contrast agent will influence the progress. This process will take years or even decades if the historic development of the currently used CT contrast agents can be taken as reference. But it is also safe to predict that photon counting CT scanners will improve the current status quo from day 1 of clinical introduction and benefit patients with less radiation dose, improved sensitivity and spatial resolution, improved contrast agent detection with the potential to reduce the used contrast volume and concentration – which will help to further reduce significant side effects like the contrast induced nephropathy or even enable contrast enhanced scans for patients that are now not eligible due to borderline renal function of limited cardiac capacity. The reduction of contrast use will help to justify repeat enhanced scans for follow-up and therapy monitoring but might potentially also contribute to the cost effectiveness of SPCCT. The clinical introduction of the new scanner technology will enable the search for the most sensitive and specific combination of SPCCT specific contrast media but it will take years before the results of the corresponding research will become part of the clinical routine.
