Treatment response assessment in [18F]FDG-PET/CT oncology scans: Impact of count statistics variation and reconstruction protocol

• Published in: Physica medica Vol. 57; pp. 177 - 182
• Main Authors: Dolci, Carlotta, Spadavecchia, Chiara, Crivellaro, Cinzia, De Ponti, Elena, Todde, Sergio, Morzenti, Sabrina, Turolla, Elia Anna, Crespi, Andrea, Guerra, Luca, Landoni, Claudio
• Format: Journal Article
• Language: English
• Published: Italy Elsevier Ltd 01.01.2019
• Subjects: FDG quantification stability; Large FOV/high sensitivity PET/CT scanner; Regularized algorithm; Treatment metabolic response assessment; Regularized algorithm; Treatment metabolic response assessment; Large FOV/high sensitivity PET/CT scanner; FDG quantification stability
• ISSN: 1120-1797; 1724-191X
• DOI: 10.1016/j.ejmp.2018.12.038

•SULpeak and max were higher in BPL reconstructions than in OSEM-PSF ones.•Both with OSEM-PSF and BPL SULpeak at different time/FOV didn’t significantly change.•Agreement in therapy response was 95% regardless counts statistic and reconstruction. To investigate influences of reconstruction algorithms and count statistics variation on quantification and treatment response assessment in cancer patients, by using a large field of view-FOV scanner. 54 cancer patients underwent PET/CT scan: 1) at baseline: 1.5 min/FOV, reconstructed by ordered-subset expectation maximization + point-spread-function-OSEM-PSF and bayesian penalised-likelihood-BPL algorithm 2) at restaging: 2 min/FOV, reconstructed also at 1.5 and 1 min/FOV, using OSEM-PSF and BPL. SUL (lean-body mass SUV) peak and max were measured for each target-lesion (n = 59). Differences in quantification obtained from datasets with different reconstruction algorithms and different time/FOV were evaluated. For any pair of PET datasets, metabolic response was assessed by using SULpeak, with a threshold of 30% in variation considered as significant. Both at baseline and restaging, SULpeak and max values were higher in BPL reconstructions than in OSEM-PSF (p < 0.0001). SULpeak at different time/FOV reconstructions showed no statistically significant differences both with OSEM-PSF and BPL; SULmax depended on acquisition time (p < 0.05). In 56/59 lesions (95%) therapy response was concordant regardless count statistics variation and reconstruction algorithm; 2/59 (3%) showed different responses according to count statistics, both for OSEM-PSF and BPL; in 1/59 lesion (2%) response was different depending on reconstruction algorithm used. BPL provided higher SULpeak and max than OSEM-PSF. With a large FOV/high sensitivity scanner, variation of time/FOV in restaging PET scans gave stable and reproducible results in terms of SULpeak, both for OSEM-PSF and BPL. Thus, metabolic response defined by SULpeak variation proved to be quite independent from count statistics.