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S. Wampl, I. Rausch, T. Traub-Weidinger, T. Beyer, M. Gröschl, J. Cal-González:
"Quantification accuracy of neuro-oncology PET data as a function of emission scan duration in PET/MR compared to PET/CT";
European Journal of Radiology, 95 (2017), 257 - 264.

Objectives: To 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.
Methods: Twenty 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.
Results: RCmax (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).
Conclusions: For 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.

Positron emission tomography PET/CT PET/MRI Radiation dose reduction SUV accuracy