Continuous bed motion versus step-and-shoot acquisition in LAFOV PET/CT: insights from multi-phantom and patient...

Continuous bed motion (CBM) allows flexible extension of the scan range compared to conventional step‑and‑shoot (S&S) acquisition but has not yet been evaluated in long axial field‑of‑view (LAFOV) PET/CT. This study systematically assessed the impact of CBM on image quality, noise, and quantitative performance in the Biograph Vision Quadra LAFOV PET/CT using multi‑phantom and patient scans compared to S&S.

A uniform tube phantom and a NEMA IEC phantom, positioned centrally and off-centre, were scanned across bed speeds (2.8-50 mm/s), sensitivity modes and scan ranges (106 and 150 cm) to evaluate image uniformity, axial count profiles, noise and contrast recovery coefficients (CRC). Ten oncological patients receiving [¹⁸F]PSMA-1007 or [¹⁸F]FDG underwent sequential CBM (2.8 mm/s, 378 s) and S&S (300 s) scans. Image noise, net true counts, and liver and lesion SUV values were compared using paired statistics and Bland-Altman analysis, along with PSMA expression scores.

For comparable count statistics and image noise, CBM required a prolonged acquisition (378 s) to match the S&S (300 s) protocol, resulting in comparable image quality for phantoms and patients. CRC and image uniformity were preserved across all evaluated conditions, even at the FOV's axial edge (50.5 cm) for 8.4 mm/s (22 mm sphere: CRC 76% S&S vs. 71% CBM). In patient scans, minor differences in axial count profiles, net true counts, and SUV values (SUV_mean bias - 0.1 (liver) and - 0.8 (lesions)) did not affect clinical scores.

The prolonged CBM protocol provides image quality and quantitative performance comparable to S&S in LAFOV PET/CT. While the reconstructed image range remains constrained by CT coverage, the patient scan comparison with 106 cm scan range, together with extended range phantom measurements, indicate that CBM can support scan range extension beyond 106 cm without compromising diagnostic accuracy.