AUTHOR=Lietz Philipp , Brüntgens Manon , Wang-Leandro Adriano , Volk Holger Andreas , Meller Sebastian , Merhof Kristina 

TITLE=Virtual non-contrast images of detector-based spectral computed tomography in dogs: a promising alternative to true non-contrast images in veterinary medicine

JOURNAL=Frontiers in Veterinary Science

VOLUME=Volume 10 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2023.1251535

DOI=10.3389/fvets.2023.1251535

ISSN=2297-1769

ABSTRACT=In veterinary medicine, abdominal computer tomographic (CT) examinations regularly require a minimum of two scans with a native scan (true unenhanced, TUE) being a reference for the subsequent contrast-enhanced CT scan (CECT). Spectral-detector-CT (SDCT) offers the possibility to calculate virtual noncontrast (VNC) images from the post contrast scan but this has not yet been investigated in veterinary medicine. The purpose of this study was to assess the reliability of VNC images for abdominal organs in 44 dogs without abdominal pathologies by evaluating its quantitative and qualitative parameters compared to TUE images. Our hypotheses were that the subtraction of iodine is sufficient in the VNC series compared to the TUE series and that the image quality of SDCT series is superior to conventional CT images.: Corresponding attenuation values in the VNC and TUE series regarding the regions of interests (ROI) in different parenchymal organs and major vessels of the abdominal cavity were assessed by means of two one-sided t-test (TOST) and Bland-Altmann-Plots. Additionally, the signal-to-noise ratio (SNR) was calculated for each ROI in the different series. In a second step, two board-certified veterinary radiologists made a qualitative assessment of VNC images versus TUE images in consensus by rating the iodine subtraction, image noise and image quality of VNC images based on a specific 5-point Likert scale.The difference in corresponding Hounsfield units (HUs) between TUE and VNC images was less than 10 HU in 78,67% of all ROIs. Regarding the limit of less than 10 HU, in the performed TOST significant p-values of < 0.05 were reached for the liver, spleen, pancreas and musculature, implying equivalence of both modalities.Quality of spectral base image (SBI) data was rated equivalent to calculated conventional images in the subjective assessment by reaching an average Likert-scale score of 3.2 points.Discussion: VNC images calculated from SDCT data prove a valid alternative to conventional TUE images in abdominal organs of canine patients without abdominal pathology. VNC offers the possibility to reduce time under general anesthesia and minimize radiation exposure. Future studies are needed to prove application of this method in clinically diseased patients.