Histo-image-based FastPET Reconstruction for Whole-Body 82-Rubidium Blood-Flow Imaging: A Performance Assessment

: Introduction Positron Emission Tomography (PET) image reconstruction is traditionally performed using analytical or iterative algorithms, which can be time-consuming and prone to increased noise in low-count frames. Deep learning methods, such as FastPET, offer rapid reconstruction with improved noise suppression. This study aimed to evaluate the quantitative performance of a revised FastPET approach for dynamic whole-body 82 Rb PET imaging on a long axial field-of-view (LAFOV) scanner, using iterative PSF-TOF reconstruction as the reference standard. Methods Forty-one patients underwent rest–stress 82 Rb PET/CT scans on a LAFOV PET/CT system. List-mode data were reconstructed into 35 dynamic frames and static images corresponding to last 3 minutes using both FastPET (3D U-Net with residual blocks) and PSF-TOF OSEM. Image quality was assessed using signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Organ uptake values, time activity curves (TACs), and the tracer blood to tissue influx rate (i.e. K 1 ) from a one-tissue compartment model were compared between methods. Results Static FastPET images showed 2.4 times higher SNR and 2.3 times higher CNR at rest, and it was 2.8-times higher for both metrics under stress conditions (p < 0.001). Organ uptake values measured from FastPET images correlated strongly with values derived from PSF-TOF images (R 2 = 0.823–0.997). Absolute TAC area under the curve differences were less than 6% for all organs and conditions. No significant differences were observed in regional K 1 values between methods for myocardium, kidneys, spleen, or other regions. Conclusion FastPET enables accurate, high-quality dynamic 82 Rb PET reconstruction with approximately a 70% reduction in computation time compared to standard PSF-TOF reconstruction. It preserves quantitative parameters and temporal dynamics while providing enhanced SNR and CNR, supporting its potential application in dynamic 82 Rb PET imaging workflows.