Digital PET/CT allows for shorter acquisition protocols or reduced radiopharmaceutical dose in [¹⁸F]-FDG PET/CT

Ziel/Aim To establish the feasibility of shorter acquisition times (and by analogy, applied activity) on tumour detection and lesion contrast in digital PET/CT.

Methodik/Methods Twenty-one randomly selected patients who underwent oncological [¹⁸F]-FDG-PET/CT on a digital PET/CT were retrospectively evaluated. Scan data were reconstructed in list mode acquisition for a standard 2 min/bed position (bp), 1 min/bp and 30s/bp (100 %, 50 % and 25 % time or applied activity respectively). Scans were randomised and read by two nuclear medicine physicians in a consensus read. Readers were blind to clinical details. Scans were evaluated for the number of pathological lesions detected. Measured uptake for lesions was evaluated by maximum and mean standardised uptake value (SUV_max and SUV_mean respectively) and tumour-to-backround ratio (TBR) were compared. Agreement between the three acquisitions was compared by Krippendorf’s alpha.

Ergebnisse/Results Overall n = 100 lesions were identified in the 2min and 1min/bp acquisitions and n = 98 lesions in the 30s/bp acquisitions. Agreement between the three acquisitions with respect to lesion number and tumour-to-background ratio showed almost perfect agreement (K’s α=0.999). SUV_max, SUV_mean and TBR likewise showed >98 % agreement, with longer acquisitions being associated with slightly higher mean TBR (2min/bp 7.94 ± 4.41 versus 30s/bp 7.84 ± 4.22, p < 0.05).

Schlussfolgerungen/Conclusions Shorter acquisition times have traditionally been associated with reduced lesion detectability or the requirement for larger amounts of radiotracer activity. These data confirm that this is not the case for new-generation digital PET-scanners, where the known higher sensitivity results in clinically adequate images for shorter acquisitions. Only a small variation in the semi-quantitative parameters SUV_max, SUV_mean and TBR was seen, confirming that reduction of acquisition time or (by analogy) applied activity can be reduced as much as 75 % in digital PET/CT without apparent clinical detriment.