Impact of Q.Clear reconstruction algorithm on the interpretation of PET/CT images in patients with lymphoma

Abstract

Background. Q.Clear is a new Bayesian penalised-likelihood PET reconstruction algorithm. It has been documented that Q.Clear increases SUVmax values of different malignant lesions. Purpose. As SUVmax values are crucial for interpretation of PET/CT images in patients with lymphoma, particularly when early and final response to treatment is evaluated, aim of the study was to systematically analyze the impact of the use of Q.Clear on interpretation of PET/CT in patients with lymphoma. Methods. 280 18F-FDG PET/CT scans in patients with lymphoma performed for staging (sPET), for early treatment response (iPET), after the end of treatment (ePET) and when a lymphoma relapse was suspected (rPET) were retrospectively analyzed. Scans separately reconstructed with two algorithms: Q.Clear and OSEM were compared. Results. The lymphoma stage was concordantly diagnosed in 69/70 patients with both algorithms in sPET. Discordant assessment of Deauville score (p < 0.001) was found in 11 cases (15.7%) of 70 iPET scans and in 11 cases of 70 ePET scans. An upgrade from negative to positive scan by Q.Clear resulted in case of 3 (4.3%) iPET scans and 7 (10.0%) ePET scans that resulted in alteration of management. Results of all 70 r-PET scans were concordant. SUVmax values of the target lymphoma lesions measured with Q.Clear were higher than with OSEM in 88.8% scans. Conclusion. Although the Q.Clear algorithm may alter interpretation of PET/CT only in a small proportion of patients, we recommend to use standard OSEM reconstruction for assessment of treatment response.

Bayesian penalized likelihood PET reconstruction impact on quantitative metrics in diffuse large B-cell lymphoma

“…In 2020 Wyrzykowski et al evaluated the impact of BPL (Q.Clear) compared to OSEM on lymphoma DS using lesion SUVmax to normal liver/ blood pool thresholding and found an overall discordance of 15.7% with 7.1% converting to DS4/DS5 with BPL. [36] The visual DS method of this study found an overall discordance of 25% when using the median DS of the 4 Radiologists. Our group had statistically significant elevations of DS with BPL compared to OSEM, most shifted from DS4 to DS5 (7.7%) which may not be clinically significant.…”