Towards clinical implementation of quantitative PET and SPECT imaging

Abstract

Quantitative positron emission tomography (PET) and Single Photon Emission Computed Tomography (SPECT) have made significant advancements in recent decades and are now incorporated into several clinical guidelines. However, there is considerable potential for their broader application across other indications. The aim of this thesis was to deepen the understanding of quantitative PET and SPECT in clinical settings, explore their potential beyond current applications, and establish a foundation for their broader implementation in clinical practice.

This thesis investigated the role of quantitative PET and SPECT in various clinical applications. Dynamic [⁸²Rb]Cl PET/CT showed potential to detect differences in renal hemodynamics between stress and rest conditions and may serve as a novel diagnostic tool for renal perfusion. Although [¹⁸F]FDG-PET/CT revealed no quantitative differences between long COVID patients and controls, the study contributes to the growing understanding of its utility in this context. The use of a digital PET system demonstrated the feasibility of substantially reducing tracer dose and/or scan time while maintaining EARL-compliant image quality. Moreover, (semi)quantitative SPECT showed promising value for therapy monitoring in coronary artery disease and response prediction in locally advanced breast cancer. In summary, these findings support broader implementation of quantitative PET and SPECT in clinical care.