Research articleQuantification accuracy of neuro-oncology PET data as a function of emission scan duration in PET/MR compared to PET/CT

•Clinical PET benefits from reduction of injected tracer activity or emission time.•Scan time and administered activity are directly correlated to emission counts.•Image noise shows less effect on RCA50 (SUVA50) than on RCmax (SUVmax).•Reductions of up to 30% of standard frame duration are statistically non-significant.

ObjectivesTo evaluate and compare the effect of reduced acquisition time, as a surrogate of injected activity, on the PET quantification accuracy in PET/CT and PET/MR imaging.MethodsTwenty min 18F-FDG phantom measurements and 10 min 18F-FET brain scans were acquired in a Biograph-True-Point-True-View PET/CT (n = 8) and a Biograph mMR PET/MR (n = 16). Listmode data were repeatedly split into frames of 1 min to 10 min length and reconstructed using two different reconstruction settings of a 3D-OSEM algorithm: with post-filtering (“OSEM”), and without post-filtering but with resolution recovery (“PSF”). Recovery coefficients (RCmax, RCA50) and standard uptake values (SUVmax, SUVA50) were evaluated.ResultsRCmax (phantom) and SUVmax (patients) increased significantly when reducing the frame duration. Significantly lower deviations were observed for RCA50 and SUVA50, respectively, making them more appropriate to compare PET studies at different number of counts. No statistical significant differences were observed when using post-filtering and reducing the frame time to 4 min (RCA50, reference 20 min, phantom) and to 3 min (SUVA50, reference 10 min, patients).ConclusionsFor hybrid aminoacid brain imaging, frame duration (or injected activity) can potentially be reduced to 30% of the standard used in clinical routine without significant changes on the quantification accuracy of the PET images if adequate reconstruction settings and quantitative measures are used. Frame times below 4 min in the NEMA phantom are not advisable to obtain quantitative and reproducible measures.