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.