The image quality and feasibility of solitary delayed [68 Ga]Ga-PSMA-11 PET/CT using long field-of-view scanning in patients with prostate cancer.

Background: Previous studies have demonstrated that delayed [⁶⁸ Ga]Ga-PSMA PET/CT imaging improves lesion detection compared to early [⁶⁸ Ga]Ga-PSMA PET/CT in patients with prostate cancer. However, the sole use of delayed [⁶⁸ Ga]Ga-PSMA PET/CT has been limited due to the insufficient number of photons obtained with standard PET/CT scanners. The combination of early and delayed [⁶⁸ Ga]Ga-PSMA standard PET/CT may be considered, and it is challenging to incorporate into a high-demand clinical setting. Long field-of-view (LFOV) PET/CT scanners have higher sensitivity compared to standard PET/CT. However, it remains unknown whether the image quality of solitary delayed [⁶⁸ Ga]Ga-PSMA LFOV PET/CT imaging is adequate to satisfy clinical diagnostic requirements. Therefore, the purpose of this study was to evaluate the image quality of delayed [⁶⁸ Ga]Ga-PSMA LFOV PET/CT and examine the feasibility of utilizing delayed [⁶⁸ Ga]Ga-PSMA LFOV PET/CT imaging alone in patients with prostate cancer.

Methods: The study sample consisted of 56 prostate cancer patients who underwent [⁶⁸ Ga]Ga-PSMA-11 LFOV PET/CT scanning between December 2020 and July 2021. All patients were subjected to early LFOV PET/CT imaging at 1-h post-injection as well as delayed LFOV PET/CT imaging at 3-h post-injection using [⁶⁸ Ga]Ga-PSMA-11. The image quality and diagnostic efficiency of solitary delayed [⁶⁸ Ga]Ga-PSMA-11 LFOV PET/CT imaging was analyzed.

Results: The results showed that delayed [⁶⁸ Ga]Ga-PSMA-11 LFOV PET/CT yielded satisfactory image quality that fulfilled clinical diagnostic benchmarks. Compared to early imaging, delayed [⁶⁸ Ga]Ga-PSMA-11 LFOV PET/CT demonstrated heightened lesion SUVmax values (11.0 [2.3-193.6] vs. 7.0 [2.0-124.3], P < 0.001) and superior tumor-to-background ratios (3.3 [0.5-62.2] vs. 1.7 [0.3-30.7], P < 0.001). Additionally, delayed [⁶⁸ Ga]Ga-PSMA-11 LFOV PET/CT detected supplementary lesions in 14 patients (25%) compared to early imaging, resulting in modifications to disease staging and management plans.

Conclusions: In summary, the findings indicate that the image quality of delayed [⁶⁸ Ga]Ga-PSMA-11 LFOV PET/CT is satisfactory for meeting clinical diagnostic prerequisites. The use of solitary delayed [⁶⁸ Ga]Ga-PSMA-11 LFOV PET/CT imaging in prostate cancer simplifies the examination protocol and improves patient compliance, compared to [⁶⁸ Ga]Ga-PSMA-11 standard PET/CT which necessitates both early and delayed imaging.