Subtraction of Single-Photon Emission Computed Tomography (SPECT) in Radioembolization: A Comparison of Four Methods

• Main Authors: Kerckhaert, C. E., de Jong, H. W., Meddens, M. B., Rooij, R. van, Smits, M. L., Rakvongthai, Y., Dietze, M. M.
• Format: Conference Proceeding
• Language: English
• Subjects: Imaging phantoms; Iterative methods; Liver; Microwave integrated circuits; Semiconductor detectors; Torso; Visualization
• ISSN: 2577-0829
• DOI: 10.1109/NSS/MIC/RTSD57108.2024.10658548

Subtraction of SPECT images has several clinical applications, but can be challenging due to high noise levels and poor resolution. In this work, we compared four methods of obtaining a difference SPECT image. As a use case, we investigated the technical performance of SPECT subtraction to quantify the effect of angiotensin-II on the { }^{99 \mathrm{~m}} \mathrm{Tc}-MAA liver distribution during hepatic radioembolization using an innovative hybrid C-arm scanner. The included methods were (i) straightforward image subtraction, (ii) projection subtraction, (iii) projection addition during iterative reconstruction and (iv) image addition during iterative reconstruction. Utilizing digital simulations (XCAT) and phantom studies (NEMA-IQ and anthropomorphic torso), we found that all methods were able to generate difference images. Image subtraction showed the best quantitative performance but the worst visual quality due to high noise levels. Image addition resulted in the best visual image quality but had a quantitative bias when the two images to subtract contained opposing features. Since quantitative accuracy is most important for the dosimetric investigation of angiotensin-II, we recommend using the image subtraction method for this purpose.