The effect of digital PET/CT and reconstruction algorithms on semi-quantitative values and Deauville scoring in...

Fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is widely used in lymphoma for diagnosis, interim evaluation, and treatment response assessment, utilizing both visual and semiquantitative analyses. However, factors such as image reconstruction algorithms may influence maximum standardized uptake value (SUVmax), mean SUV (SUVmean), and Deauville scores. This study aims to evaluate the impact of ordered subset expectation maximization (OSEM) and Q.Clear reconstruction methods on these parameters in lymphoma patients.

This study included 48 patients diagnosed with lymphoma who underwent ¹⁸F-FDG PET/CT imaging between January 1 and April 12, 2024, for interim evaluation, post-treatment assessment, or relapse investigation. Positron emission tomography data were reconstructed using OSEM and Q.Clear algorithms, routinely applied in our clinic. The lymph node with the highest SUVmax in each scan was selected as the target lesion. Additionally, subcentimetric lymph nodes (<1cm) were analyzed to assess the impact of reconstruction algorithms on detectability. Maximum SUV and SUVmean values of the liver and mediastinal blood pool were also recorded for Deauville scoring. Statistical analyses were conducted to evaluate significant differences between the two reconstruction methods.

Liver and mediastinal blood pool SUVmax values were significantly higher with OSEM, while SUVmax values of both <1cm and >1cm lesions were higher with Q.Clear. For SUVmean, OSEM yielded higher values in the mediastinal blood pool, while Q.Clear showed higher values in lesions >1cm. Deauville 4-5 scores were more frequent with Q.Clear in both lesion size groups.

This results refers to the comparative use of ¹⁸F-FDG PET/CT imaging with different reconstruction algorithms in treatment response evaluation . and restaging changes to the standardization and that caution should be exercised in the DS evaluation based on semiquantitative values. This leads to a challenge in single and multicenter comparative evaluations with PET/CT scanners using different reconstruction algorithms including digital systems. In this study, we have shown that the reconstruction algorithms used in digital PET/CT devices cause changes in Deauville scoring in patients diagnosed with lymphoma. Therefore, it is important to perform ¹⁸F-FDG PET/CT imaging with the same reconstruction algorithms under standardized conditions or to take this into consideration if not done.