Quantitative Spectral K-Edge Imaging in Preclinical Photon-Counting X-Ray Computed Tomography

Abstract

This preclinical proof-of-concept study shows the in vivo quantification of iodine concentrations in tissues using spectral CT. Our multimodal imaging approach with spectral CT and SPECT using radiolabeled iodinated emulsions together with ICP-based quantification allows a direct comparison of all methods. Benchmarked against ICP-MS data, spectral CT in the present implementation shows a slight underestimation of organ iodine concentrations compared with SPECT but with a more narrow distribution. This slight deviation is most likely caused by experimental rather than technical issues.

Evaluation of spectral photon counting computed tomography K-edge imaging for determination of gold nanoparticle biodistribution in vivo

“…detection of contrast material close to calcified structures. Moreover, a good linear correlation in phantom imaging between SPCCT and prepared concentrations, and in vivo imaging between ICP-OES and SPCCT derived concentrations has been demonstrated, indicating that SPCCT is a non-invasive quantitative imaging technique 5,28,35 . This capacity is promising as a new tool for assessing non-invasively the biodistribution of materials that have a K-edge between ~40–100 keV, as opposed to ICP-OES based approaches, in which multiple groups of animals have to be sacrificed in a serial fashion and their organs dissected to obtain the biodistribution of contrast media at different time points.…”

“…This was due to the low photon flux needed to avoid pulse pileup in the detectors and limited number of detector rows. The small FOV SPCCT prototype scanner used for this study is equipped with detectors that have high flux capacity allowing high temporal resolution (1–1.5 seconds) compared to the previously reported prototypes 32 , allowing for the dynamic and repetitive imaging in vivo reported herein 33 .…”

“…For instance, De Vries et al . investigated the feasibility and the accuracy of a small animal SPCCT scanner to determine the concentration and localization of iodine-based contrast agents in mice 5 .…”

“…However, to the best of our knowledge, studying the biodistribution of agents over extended timeframes with SPCCT has not been previously reported. This was due to the limitations of early SPCCT systems, such as very long scan times 5 that prevented in vivo image acquisitions. SPCCT systems have now been developed with image acquisition times of 1 second that allow dynamic and repetitive imaging in vivo , such as a small field of vue (FOV) SPCCT prototype system derived from a modified clinical CT system 4 .…”

Image quality in coronary CT angiography: challenges and technical solutions

“…55 However, it is currently not clinically implemented as the limited count rate, energyintegrating detection, increased detector pixel crosstalk and electronic noise are major limitations of this technology. 56 Eventually, photon counting is expected to improve soft-tissue discrimination, to reduce the radiation dose and to provide higher spatial resolution.…”