Background and purpose <p>Previous studies have shown that long axial field-of-view (LAFOV) ⁶⁸Ga-PSMA-11 PET/CT can significantly improve the detection rate compared to short axial field-of-view (SAFOV) ⁶⁸Ga-PSMA-11 PET/CT in prostate cancer. However, the diagnostic efficiency between the two scans was compared in different cohorts, not directly within the same patients. Whether LAFOV ⁶⁸Ga-PSMA-11 PET could improve image quality, enhance lesion quantification, and impact patient treatment decisions in the same patients remains unclear. To address this research gap, we performed a direct comparison of LAFOV and SAFOV ⁶⁸Ga-PSMA-11 PET in the same cohort of prostate cancer patients to evaluate whether LAFOV ⁶⁸Ga-PSMA-11 PET could enhance lesion identification and modify clinical management compared to SAFOV ⁶⁸Ga-PSMA-11 PET.</p> Methods <p>Thirty-four patients with prostate cancer undergoing routine ⁶⁸Ga-PSMA-11 PET/CT were included and underwent a same-day dual-scanning protocol. Half of the patients first underwent a clinically routine SAFOV PET scan using continuous bed motion, followed immediately by LAFOV PET (5-minute acquisition in list mode); the other half underwent scanning in the reverse order. The image quality of LAFOV and SAFOV ⁶⁸Ga-PSMA-11 PET was compared using subjective scoring and objective parameters. Objective parameters, including maximum and mean standardized uptake values (SUVmax and SUVmean), signal-to-noise ratio (SNR), and tumor-to-background ratio (TBR), were measured and compared.</p> Results <p>LAFOV ⁶⁸Ga-PSMA-11 PET exhibited superior image quality compared to SAFOV PET based on both subjective and objective parameters. LAFOV ⁶⁸Ga-PSMA-11 PET had better image quality and higher lesion SUVmax, SNR, and TBR compared to SAFOV PET. In 17.65% of patients, LAFOV ⁶⁸Ga-PSMA-11 PET detected additional lesions that were unidentified on SAFOV ⁶⁸Ga-PSMA-11 PET. Compared to SAFOV ⁶⁸Ga-PSMA-11 PET, LAFOV ⁶⁸Ga-PSMA-11 PET detected additional lesions in 33.33% of patients with biochemical recurrence and 9.09% of patients with newly diagnosed prostate cancer, leading to significant changes in clinical management.</p> Conclusions <p>In this head-to-head comparison, LAFOV ⁶⁸Ga-PSMA-11 PET demonstrated superior image quality, enhanced lesion detection, and a significant impact on clinical management for both biochemical recurrence and newly diagnosed prostate cancer patients compared to SAFOV ⁶⁸Ga-PSMA-11 PET. These findings suggest that LAFOV ⁶⁸Ga-PSMA-11 PET may be the preferred imaging modality for comprehensive prostate cancer evaluation.</p>