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

Abstract

<jats:title>Abstract</jats:title> <jats:p>Background. Q.Clear is a new Bayesian penalized-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. The 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 <jats:sup>18</jats:sup>F-FDG PET/CT scans in patients with lymphoma were performed for staging (sPET), for early treatment response (iPET), after the end of treatment (ePET) and when a relapse of the lymphoma was suspected (rPET). Scans were separately reconstructed with two algorithms: Q.Clear and OSEM and further compared.Results. The stage of lymphoma was concordantly diagnosed in 69/70 patients with both algorithms in sPET. Discordant assessment of Deauville score (p&lt;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 3 cases (4.3%) of iPET scans and 7 (10.0%) of ePET. 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 the assessment of treatment response.</jats:p>