Spectral detector computed tomography imaging of histologically confirmed splenic pathologies in 1 30 canine patients: A comparison of virtual non-contrast images and true unenhanced images

Alkje van Gemmeren^1*Lydia Claußen¹Philipp Lietz¹Sebastian Meller¹Adriano Wang- Leandro¹Andreas Beineke²Verena Nerschbach¹Holger Andreas Volk¹Kristina Merhof¹

• ¹Clinic for Small Animals, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
• ²Institute of Pathology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany

Spectral detector computed tomography (SDCT), a cutting-edge technique in veterinary medicine, 16 offers various options for characterizing soft tissues. One such option is the virtual non-contrast 17 (VNC) algorithm, which reconstructs pre-contrast images from post-contrast spectral data by 18 identifying and subtracting iodine pixels. This method has demonstrated accuracy in assessing 19 abdominal organs in healthy canine patients. To determine whether this algorithm can be applied in 20 a clinical setting to reduce radiation dose, scan time, and, consequently, the duration of general 21 anesthesia, its accuracy in patients with pathology must be evaluated. Our study compared the 22 Hounsfield units (HUs) measured in VNC and true unenhanced (TUE) images for splenic pathologies 23 in general, as well as for specific types of pathologies based on their imaging characteristics. 24 Additionally, image quality and iodine subtraction were evaluated using a five-point Likert scale. 28 pathologies, the VNC technique demonstrated high efficiency in contrast medium subtraction and 29 exhibited a strong agreement with TUE images regarding their HUs. In 305 drawn regions of interest 30 (ROIs), the differences in HUs between TUE and VNC were ≤ 15 HUs in 98.0%, ≤ 10 HUs in 93.1%, and 31 at least 66.2% were below the limit of 5 HUs. SDCT images provide better image quality than 32 conventional computed tomography images. 33 Our study suggests that VNC images reconstructed from post-contrast SDCT data may serve as a 34 promising alternative to the standard use of a pre-and post-contrast series. The VNC images provide 35 high quality and reliability in imaging structurally altered splenic tissue, but show a potential 36 weakness in the calculation of some mineralized lesions.