Clinical application of PRIMARY score in diagnosing clinically significant prostate cancer: a comparative study using ⁶⁸Ga-PSMA-11 and ¹⁸F-PSMA-1007 positron emission tomography/computed tomography

Introduction

The PRIMARY score is a five-category scale designed to identify clinically significant prostate cancer (csPCa) using gallium-68 (⁶⁸Ga)-prostate-specific membrane antigen (PSMA)-11 positron emission tomography/computed tomography (PET/CT; ⁶⁸Ga-PSMA PET) (1). It was originally developed in the PRIMARY trial and incorporates anatomical location, imaging patterns, and tracer intensity to improve diagnostic accuracy for prostate cancer. Several studies (2-4) have since validated its reproducibility and clinical applicability. It has also been incorporated into the latest standardized PSMA PET/CT assessment system, the prostate cancer molecular imaging standardized evaluation (PROMISE) (5).

In recent years, the application of fluorine-18-labeled (¹⁸F)-PSMA-1007 PET/CT has become increasingly common, with growing evidence supporting its potential to replace ⁶⁸Ga-PSMA-11 PET/CT in certain clinical scenarios (6-8). ¹⁸F-PSMA-1007 offers several physical advantages over ⁶⁸Ga-PSMA-11, including a longer half-life, lower positron range, and superior image resolution (9-11). These characteristics allow for clearer and more precise detection of lesions. Additionally, ¹⁸F-PSMA-1007 is excreted via the hepatobiliary system rather than the urinary tract, resulting in lower bladder background activity and providing an advantage in detecting local recurrences and lesions near the bladder and urethra (12).

¹⁸F-PSMA-1007 and ⁶⁸Ga-PSMA-11 have distinct biological characteristics, and the clinical utility of applying the PRIMARY score to ¹⁸F-PSMA-1007 PET/CT remains unclear. This study therefore aimed to evaluate the performance of the PRIMARY score in diagnosing prostate cancer using ¹⁸F-PSMA-1007 PET/CT, with a comparative analysis against ⁶⁸Ga-PSMA-11 PET/CT. We present this article in accordance with the STARD reporting checklist (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-1661/rc).

Methods

Patient population

Patients who underwent PSMA PET/CT between January 2018 and December 2023 and were clinically suspected of having prostate cancer were included. During this period, ⁶⁸Ga-PSMA-11 was used between 2018 and 2021, and ¹⁸F-PSMA-1007 was adopted between 2021 and 2023 based on tracer availability at our institution. All patients included underwent PSMA PET/CT followed by systematic biopsy. The inclusion criteria were as follows: (I) men were considered eligible if there was clinical suspicion of prostate cancer based on an abnormal prostate-specific antigen (PSA) level (<20 ng/mL) or abnormal results on digital rectal examination after assessment by a urologist; (II) no prior definitive treatment for prostate cancer; and (III) availability of PSMA PET/CT imaging and corresponding histopathology. The exclusion criteria were as follows: poor-quality imaging, history of other malignancies, and prior negative prostate biopsy. A total of 192 patients were retrospectively enrolled. All relevant clinical data, including age, PSA levels at the time of imaging, and pathology results, were collected. This study was approved by the Ethics Committee of The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China (No. II2023-026-02). Written informed consent was provided by all participants prior to inclusion in the study. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments.

PET/CT imaging

The PET/CT imaging was conducted using either ⁶⁸Ga-PSMA-11 or ¹⁸F-PSMA-1007 as radiotracers. The radiotracers were provided by Atom High-Tech Isotope Pharmaceutical Co., Ltd. (Guangzhou, China), with a radiochemical purity of 92–98%. Patients were not required to undergo any special dietary preparation prior to imaging. At 60 minutes after the intravenous injection of 2.0 MBq/kg of the radiotracer, whole-body PET/CT images were obtained using a GE Discovery series PET/CT scanner (GE Healthcare, Chicago, IL, USA), covering the region from the top of the head to the mid-thigh. The scan was performed over 6–7 bed positions, with 2–4 minutes per position. A low-dose, non-contrast CT scan (120 keV, 70–220 mA) was used for attenuation correction and anatomical localization. The PET scans were reconstructed using the ordered-subset expectation maximization (OSEM) algorithm in combination with VUE Point FX software (GE Healthcare), utilizing time-of-flight information and point spread function correction (3 iterations, 24 subsets). Reconstructed images included transverse, coronal, and sagittal slices, as well as maximum intensity projection (MIP) images. On the GE AW workstation, prostate lesion regions of interest (ROIs) were delineated on fused PET/CT images. The system automatically calculated the maximum standardized uptake values (SUVmax) of the primary prostatic lesions.

PRIMARY score assessment

All PET/CT images were independently evaluated in a blinded manner by two experienced nuclear medicine physicians. In case of disagreement, the final score was reached through consensus discussion. The images were analyzed according to known anatomical zones: peripheral zone (PZ), central zone (CZ), and transition zone (TZ).

The PSMA pattern for each patient was categorized into four types: no pattern, diffuse TZ/CZ, focal TZ, and focal PZ (1). Lesions that did not clearly fit into these categories, such as those with uneven radiotracer uptake in the CZ, were placed into an undefined category. The SUVmax of suspicious prostate lesions was measured for each patient.

The PRIMARY score was assessed according to previously published studies (1), with the following criteria: Score 1: no significant intraprostatic PSMA pattern; Score 2: diffuse activity in the TZ or symmetrical CZ activity without extending to the prostatic edge, or non-uniform CZ uptake; Score 3: focal TZ activity, visually at least twice as intense as the background, as further differentiated using MIP imaging; Score 4: focal PZ activity, with no minimum SUV intensity threshold; Score 5: SUVmax >12.

In this study, PRIMARY scores of 1–2 were considered PET/CT negative, whereas scores of 3–5 were defined as PET/CT positive. The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of the PRIMARY score were calculated for diagnosing csPCa using both ⁶⁸Ga-PSMA-11 PET/CT and ¹⁸F-PSMA-1007 PET/CT.

Histopathology

Histopathological results were obtained from biopsy samples (with at least 12 cores, depending on prostate volume) or surgical specimens. Additional targeted cores were obtained under transrectal ultrasound guidance when suspicious lesions were present. For patients who underwent both biopsy and surgery, the final pathological diagnosis was based on the surgical specimen. An International Society of Urological Pathology (ISUP) grade group of 2 or higher was considered indicative of csPCa.

Statistical analysis

All statistical analyses were conducted using R 4.3.1 (https:www.R-project.org). The Shapiro-Wilk test was used to evaluate the normality of the data. Categorical variables were expressed as rate (%) and analyzed using the Chi-squared test (χ²) or Fisher’s exact test, where appropriate. Continuous variables were reported as mean ± standard deviation (for normally distributed data) or median with interquartile range (for non-normally distributed data). Group differences for normally distributed continuous variables were assessed using the independent samples t-test, whereas the Wilcoxon rank-sum test was employed for non-normally distributed continuous variables.

To evaluate the diagnostic performance of ⁶⁸Ga-PSMA-11 PET/CT and ¹⁸F-PSMA-1007 PET/CT, receiver operating characteristic (ROC) curve analysis was conducted, with comparisons made using the DeLong test. Additionally, a logistic regression model was employed to explore the relationship between SUVmax and PSMA pattern types (no pattern, non-focal, focal). A P value of less than 0.05 (P<0.05) was considered statistically significant.

Results

Demographic and clinicopathological characteristics

A total of 192 patients were included, with 59 undergoing ⁶⁸Ga-PSMA-11 PET/CT and 133 undergoing ¹⁸F-PSMA-1007 PET/CT, as shown in Table 1. The mean age was 69.6 years for the ⁶⁸Ga-PSMA-11 group and 68.6 years for the ¹⁸F-PSMA-1007 group, with corresponding PSA levels of 10.4 and 10.8 ng/mL, respectively (P>0.05).

In the ⁶⁸Ga-PSMA-11 group, 21 patients (35.6%) had csPCa, compared to 31 patients (23.3%) in the ¹⁸F-PSMA-1007 group. The distribution of pathological findings did not differ significantly between the two subgroups, including the proportions of non-cancer cases, non-csPCa cases (ISUP 1), and csPCa cases (ISUP 2–5) (P>0.05). However, the median SUVmax was 5.2 in the ⁶⁸Ga-PSMA-11 group and 7.3 in the ¹⁸F-PSMA-1007 group (P<0.001). The distribution of PSMA patterns also differed significantly between the two groups (P<0.001). In the ⁶⁸Ga-PSMA-11 PET/CT group, the distribution of PSMA patterns was as follows: 26 patients had no pattern, 9 had diffuse TZ/CZ, 10 had focal TZ, and 18 had focal PZ. Two patients were classified as undefined due to CZ heterogeneity. In the ¹⁸F-PSMA PET/CT group, 15 patients had no pattern, 64 had diffuse TZ/CZ, 49 had focal TZ, and 56 had focal PZ, with 15 classified as undefined for the same reason.

PRIMARY score

The distribution of csPCa across PRIMARY scores is presented in Table 2. The corresponding ISUP grades for each score in the ⁶⁸Ga-PSMA-11 and ¹⁸F-PSMA-1007 PET/CT groups are shown in Figure 1, with significant differences observed between the two tracers (P<0.001). Among patients who underwent ⁶⁸Ga-PSMA-11 PET/CT, csPCa was identified in 1 of 26 (3.8%) patients with a PRIMARY score of 1, 3 of 9 patients (33.3%) with score 2, 2 of 8 patients (25.0%) with score 3, 8 of 9 patients (88.9%) with score 4, and all 7 patients with score 5. In the ¹⁸F-PSMA-1007 PET/CT group, csPCa was identified in none of the 15 patients with score 1, 1 of 38 (2.6%) patients with score 2, 5 of 26 patients (19.2%) with score 3, 13 of 36 patients (36.1%) with score 4, and 12 of 18 patients (66.7%) with score 5. Figure 2 presents representative cases of benign lesions confirmed by histopathology that showed positive PET/CT findings (PRIMARY scores 3–5) on ¹⁸F-PSMA-1007 PET/CT.

Figure 1 Distribution of overall ISUP grade group by PRIMARY score. ¹⁸F, fluorine-18-labeled; ⁶⁸Ga, gallium-68; ISUP, International Society of Urological Pathology; PSMA, prostate-specific membrane antigen.

Figure 2 Benign lesions (PRIMARY scores 3–5) on ¹⁸F-PSMA-1007 PET/CT. (A-G) MIP images; (H-N) corresponding PET/CT images. (A-C,H-J) PRIMARY score 3, central zone uptake visible against low prostate background; (D-F,K-M) PRIMARY score 4, lesions in prostate peripheral zone; (G,N) PRIMARY score 5, multiple uptake foci in prostate, SUVmax 15. ¹⁸F, fluorine-18-labeled; MIP, maximum intensity projection; PET/CT, positron emission tomography/computed tomography; PSMA, prostate-specific membrane antigen; SUVmax, maximum standardized uptake value.

Diagnostic performance of PRIMARY score and SUVmax

As shown in Table 3, for ⁶⁸Ga-PSMA-11 PET/CT, the PRIMARY score achieved a sensitivity of 80.95%, specificity of 81.58%, accuracy of 81.36%, PPV of 70.83%, and NPV of 88.57% in diagnosing csPCa. In comparison, for ¹⁸F-PSMA-1007 PET/CT, the sensitivity was higher at 96.77%, but specificity was lower at 50.98%, with accuracy at 61.65%, PPV at 37.50%, and NPV at 98.11% (P>0.05).

As shown in Figure 3, the ROC curve for the PRIMARY score in diagnosing csPCa with ⁶⁸Ga-PSMA-11 PET/CT demonstrated an area under the curve (AUC) of 0.915 [95% confidence interval (CI): 0.813–0.972], which was significantly higher than the AUC for SUVmax (0.744, 95% CI: 0.614–0.849) (P<0.001). For ¹⁸F-PSMA-1007 PET/CT, the AUC for the PRIMARY score and SUVmax were 0.833 (95% CI: 0.758–0.892) and 0.811 (95% CI: 0.734–0.873), respectively, with no significant difference between them.

Figure 3 ROC curve analysis of the PRIMARY score and SUVmax for diagnosing csPCa. ¹⁸F, fluorine-18-labeled; ⁶⁸Ga, gallium-68; AUC, area under the curve; CI, confidence interval; PSMA, prostate-specific membrane antigen; ROC, receiver operating characteristic; SUVmax, maximum standardized uptake value.

PSMA patterns and SUVmax

Table 4 illustrates the distribution of SUVmax across different PSMA pattern types. In both the ⁶⁸Ga-PSMA-11 PET/CT and ¹⁸F-PSMA PET/CT groups, the median SUVmax progressively increased across the pattern types. However, in the ⁶⁸Ga-PSMA-11 group, there was no statistically significant difference between SUVmax and csPCa in any of the PSMA patterns based on univariate logistic regression analysis. In contrast, for patients in the ¹⁸F-PSMA-1007 PET/CT group with a focal PSMA pattern, there was a statistically significant association between SUVmax and csPCa (P<0.001), with an odds ratio (OR) and 95% CI of 1.065–1.349. As depicted in Figure 4, the likelihood of diagnosing csPCa increased as SUVmax increased in the focal PSMA pattern in the ¹⁸F-PSMA-1007 group.

Figure 4 Predicted probability of csPCa by PSMA patterns. ¹⁸F, fluorine-18-labeled; ⁶⁸Ga, gallium-68; csPCa, clinically significant prostate cancer; PSMA, prostate-specific membrane antigen; SUVmax, maximum standardized uptake value.

Discussion

⁶⁸Ga-PSMA-11 PET/CT

This study confirmed the effectiveness of the PRIMARY score in diagnosing prostate cancer using ⁶⁸Ga-PSMA-11 PET/CT, showing a sensitivity of 80.95% and specificity of 81.58%. The slightly lower sensitivity compared to other studies might be due to differences in patient selection criteria (1,2). Previous studies have excluded patients identified as low-risk by multiparametric magnetic resonance imaging (mpMRI) (1), whereas our study included all patients without mpMRI screening, leading to the inclusion of more benign cases (54.2%, 32/59). This selection bias could explain the difference in sensitivity. Additionally, although there were only 4 false negatives among patients with PRIMARY score of 1–2, these accounted for 19.0% (4/21) of all csPCa cases, which may also have contributed to the reduced sensitivity.

Despite these limitations, the detection rate for csPCa in patients with a PRIMARY score of 3–5 remained high at 25.0%, 88.9%, and 100%, respectively. Particularly, in patients with SUVmax >12, all patients were diagnosed with csPCa, demonstrating the high specificity of SUVmax in identifying high-risk patients. This finding aligns with other studies (1,2), showing that SUVmax >12 is an effective indicator for csPCa, particularly for early diagnosis.

Additionally, the ROC curve analysis showed that the AUC for the PRIMARY score in diagnosing prostate cancer using ⁶⁸Ga-PSMA-11 PET/CT was 0.915, significantly higher than the SUVmax AUC of 0.744 (P<0.001). This indicates that the PRIMARY score provides superior diagnostic performance compared to relying on SUVmax alone. These results further support the use of the PRIMARY score as a standard evaluation tool.

When analyzing different PSMA patterns, we found no significant correlation between SUVmax and csPCa across any different patterns in the ⁶⁸Ga-PSMA-11 group. This may be partly due to the small sample size of only 21 csPCa cases, which could have led to potential overfitting. Nevertheless, an increasing trend in csPCa detection was observed with rising SUVmax in the focal pattern, as shown in Figure 4. This suggests that although SUVmax may not significantly improve diagnostic accuracy in some patterns, it remains valuable in specific scenarios.

¹⁸F-PSMA-1007 PET/CT

Applying the PRIMARY score in ¹⁸F-PSMA-1007 PET/CT revealed low specificity (50.98%), with 50 out of 80 patients scoring 3–5 being false positives. This high false-positive rate may stem from two main factors. First, the higher radiotracer uptake with ¹⁸F-PSMA-1007 increases the detection of both malignant and benign lesions. Second, the complexity of the PRIMARY scoring system, which adds variability and uncertainty, particularly in patients with scores of 3–5. In terms of sensitivity, our findings for ¹⁸F-PSMA-1007 PET/CT (96.77%) are in line with those reported by Mookerji et al. (13), who found that ¹⁸F-PSMA-1007 correctly identified csPCa in >90% of patients undergoing radical prostatectomy.

Although ¹⁸F-PSMA-1007 provides higher image quality, its diagnostic performance for csPCa within the PRIMARY scoring system is inferior to that of ⁶⁸Ga-PSMA-11. This discrepancy is likely driven by two major factors: differences in radiotracer characteristics and the greater interpretative complexity of the PRIMARY scoring system.

The improved imaging quality of ¹⁸F-PSMA-1007 can be attributed to its lower positron emission energy (0.65 MeV compared to 1.90 MeV for ⁶⁸Ga-PSMA-11), which reduces tissue scatter and enhances spatial resolution (9). Additionally, ¹⁸F-PSMA-1007 exhibits higher affinity and internalization in prostate cancer cells, further improving image clarity (10,11). In our study, lesions detected using ¹⁸F-PSMA-1007 PET/CT demonstrated significantly higher radiotracer uptake, with SUVmax values of 7.3 compared to 5.2 for ⁶⁸Ga-PSMA-11 (P<0.001). This aligns with findings from Kuten et al., showing a median SUVmax of 8.7 for ¹⁸F-PSMA-1007 and 6.9 for ⁶⁸Ga-PSMA-11 (14). Despite its superior imaging quality, prior studies have shown little difference between the two tracers in tumor staging, although ¹⁸F-PSMA-1007 is better at detecting benign lesions (6,15). The lack of renal clearance in ¹⁸F-PSMA-1007 also provides a clearer background, particularly improving visibility in regions around the urethra and bladder. In our study, the ¹⁸F-PSMA-1007 group detected more patterns overall compared to the ⁶⁸Ga-PSMA-11 group, as shown in Table 1. The pattern-to-case ratio was 1.5 (199/133) for ¹⁸F-PSMA-1007 versus 1.1 (65/59) for ⁶⁸Ga-PSMA-11, indicating a higher proportion of patients with multiple lesions in the ¹⁸F-PSMA-1007 group. This increased detection includes both malignant and benign lesions, and the enhanced detection rate with ¹⁸F-PSMA-1007 PET/CT may be one of the factors contributing to the higher false-positive rate.

The complexity of the PRIMARY scoring system may also be a significant factor contributing to inconsistencies in diagnosis. Further analysis revealed significant differences in lesion patterns between the two tracers. The ⁶⁸Ga-PSMA-11 group had more cases with no pattern, whereas the ¹⁸F-PSMA-1007 group showed a higher prevalence of diffuse TZ/CZ and focal patterns. Additionally, ¹⁸F-PSMA-1007 revealed more focal lesions than ⁶⁸Ga-PSMA-11, which may explain the overall higher PRIMARY scores observed. These patterns, especially in multiple small focal lesions, increased the difficulty in determining the degree of radiotracer uptake and lesion location, further heightening diagnostic uncertainty. This made lesion classification more challenging and increased variability in interpretation.

Moreover, although the initial PRIMARY score classified CZ heterogeneity as a score of 2, these patterns were not thoroughly analyzed in earlier research (1). Our research reveals that these undefined patterns are primarily associated with csPCa cases. In particular, undefined patterns were more frequently observed in ¹⁸F-PSMA-1007 images. In this study, 15 undefined patterns were identified in the ¹⁸F-PSMA-1007 group, including one case of csPCa; the remaining cases consisted of six non-csPCa lesions and eight benign lesions. Similarly, the ⁶⁸Ga-PSMA-11 group displayed two undefined patterns, both of which were csPCa.

The PRIMARY score in ¹⁸F-PSMA-1007 PET/CT does not significantly outperform SUVmax alone for csPCa diagnosis, as indicated by their similar AUC values (0.833 for the PRIMARY score and 0.811 for SUVmax). In the focal pattern, the likelihood of diagnosing csPCa increases significantly with rising SUVmax, surpassing 75% when SUVmax exceeds 20, as shown in Figure 4. Given the high false-positive rate of the PRIMARY score, incorporating SUVmax may help to improve diagnostic accuracy. Additionally, although mpMRI remains the standard method for diagnosing csPCa, the superior sensitivity of the PRIMARY score with ¹⁸F-PSMA-1007 PET/CT suggests that it could reduce unnecessary biopsies, particularly in patients with ambiguous mpMRI results. This approach offers the potential to optimize prostate cancer diagnosis, maintaining high sensitivity for csPCa while minimizing overdiagnosis.

Although in our study, a PRIMARY score of 5 (SUVmax >12) demonstrated high specificity for diagnosing prostate cancer in ⁶⁸Ga-PSMA PET/CT, the findings differed slightly for ¹⁸F-PSMA PET/CT. Although 18 cases met the criteria for a PRIMARY score of 5 with SUVmax >12, the small sample size (only 18 cases) limits the reliability of raising the SUVmax threshold as a criterion for PRIMARY score 5. In general, cases with PRIMARY scores of 3–5 are classified as having a focal uptake pattern. Adopting a higher SUVmax threshold could result in some patients initially classified as a PRIMARY score of 5 being reassigned to scores of 3 or 4. However, this reclassification does not compromise the overall diagnostic efficacy of PRIMARY scores 3–5 as a positive standard for identifying suspected prostate cancer cases. These patients would still be considered PET/CT-positive and meet the diagnostic criteria.

This study has some limitations. The sample size difference between the two groups reflects their different clinical usage periods and may have impacted the statistical power. Although no significant differences were observed in baseline clinical characteristics between the two tracer groups, a prospective head-to-head comparison would provide more robust evidence and help minimize potential confounding. As a retrospective, single-center study, its findings need to be validated through large-scale, multicenter prospective trials. Our study cohort consisted of patients who underwent systematic biopsy, which remains the standard and widely accepted diagnostic approach in routine clinical practice. Therefore, our findings are applicable to patients undergoing systematic biopsy and may not be directly generalizable to those receiving MRI-targeted biopsy. Additionally, evaluating the added value of mpMRI image comparisons and the implementation of MRI-guided targeted biopsy will be a key focus of future research. Although we observed that the PRIMARY score applied to ¹⁸F-PSMA-1007 PET/CT does not significantly enhance the diagnostic efficiency for csPCa, future efforts will focus on refining the standardized assessment method for ¹⁸F-PSMA-1007 PET/CT. In subsequent studies, we plan to further refine the application of the PRIMARY score in ¹⁸F-PSMA-1007 PET/CT and conduct a more detailed investigation to determine the optimal SUVmax threshold for defining PRIMARY score 5. The goal is to enhance diagnostic accuracy for csPCa, reduce misdiagnoses and unnecessary biopsies, and ultimately improve patients’ quality of life.

Furthermore, the findings of our study may help to define the clinical utility of the PRIMARY score across different radiotracers. Although mpMRI remains the standard in current guidelines, PSMA PET/CT has demonstrated potential value in specific clinical scenarios, including patients with contraindications to MRI (e.g., claustrophobia, cardiac pacemaker, severe obesity) and those enrolled in active surveillance protocols (16,17). Although our study was not designed to evaluate these subgroups directly, the performance of the PRIMARY score across both ⁶⁸Ga-PSMA-11 and ¹⁸F-PSMA-1007 suggests its potential as a complementary imaging tool. Moreover, previous studies have reported the feasibility of PSMA PET/CT in guiding targeted biopsy in men with high suspicion of csPCa, and its diagnostic accuracy may depend on factors such as the number of targeted cores, fusion technique, and operator expertise (18,19). The limitations of PSMA PET/CT in the detection and staging of ductal carcinoma should also be acknowledged (20). These insights highlight the need for future prospective trials to refine the integration of PRIMARY scoring into clinical pathways, particularly in settings of diagnostic uncertainty or where mpMRI is not feasible. Our study thus provides a technical foundation for such investigations and emphasizes the role of the PRIMARY score as a practical and reproducible assessment method that can enhance personalized diagnostic strategies for prostate cancer.

Conclusions

The high diagnostic accuracy of the PRIMARY score in ⁶⁸Ga-PSMA-11 PET/CT makes it a suitable tool for diagnosing csPCa, although the higher false-positive rate in ¹⁸F-PSMA-1007 PET/CT remains a limitation. Further exploration and validation of the PRIMARY score in ¹⁸F-PSMA-1007 PET/CT are required before its broader clinical application.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STARD reporting checklist. Available at https://qims.amegroups.com/article/view/10.21037/qims-2025-1661/rc

Data Sharing Statement: Available at https://qims.amegroups.com/article/view/10.21037/qims-2025-1661/dss

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-1661/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China (No. II2023-026-02). All participants provided written informed consent prior to enrollment.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Emmett L, Papa N, Buteau J, Ho B, Liu V, Roberts M, Thompson J, Moon D, Sheehan-Dare G, Alghazo O, Agrawal S, Murphy D, Stricker P, Hope TA, Hofman MS. The PRIMARY Score: Using Intraprostatic (68)Ga-PSMA PET/CT Patterns to Optimize Prostate Cancer Diagnosis. J Nucl Med 2022;63:1644-50. [Crossref] [PubMed]
2. Emmett L, Papa N, Counter W, Calais J, Barbato F, Burger I, et al. Reproducibility and Accuracy of the PRIMARY Score on PSMA PET and of PI-RADS on Multiparametric MRI for Prostate Cancer Diagnosis Within a Real-World Database. J Nucl Med 2024;65:94-9. [Crossref] [PubMed]
3. Emmett L, Papa N, Hope TA, Fendler W, Calais J, Burger I, et al. Beyond Prostate Imaging Reporting and Data System: Combining Magnetic Resonance Imaging Prostate Imaging Reporting and Data System and Prostate-Specific Membrane Antigen-Positron Emission Tomography/Computed Tomography PRIMARY Score in a Composite (P) Score for More Accurate Diagnosis of Clinically Significant Prostate Cancer. J Urol 2024;212:299-309. [Crossref] [PubMed]
4. Guo S, Zhang J, Wang Y, Jiao J, Li Z, Cui C, Chen J, Yang W, Ma S, Wu P, Jing Y, Wen W, Kang F, Wang J, Qin W. Avoiding unnecessary biopsy: the combination of PRIMARY score with prostate-specific antigen density for prostate biopsy decision. Prostate Cancer Prostatic Dis 2024;27:288-93. [Crossref] [PubMed]
5. Seifert R, Emmett L, Rowe SP, Herrmann K, Hadaschik B, Calais J, Giesel FL, Reiter R, Maurer T, Heck M, Gafita A, Morris MJ, Fanti S, Weber WA, Hope TA, Hofman MS, Fendler WP, Eiber M. Second Version of the Prostate Cancer Molecular Imaging Standardized Evaluation Framework Including Response Evaluation for Clinical Trials (PROMISE V2). Eur Urol 2023;83:405-12. [Crossref] [PubMed]
6. Rauscher I, Krönke M, König M, Gafita A, Maurer T, Horn T, Schiller K, Weber W, Eiber M. Matched-Pair Comparison of (68)Ga-PSMA-11 PET/CT and (18)F-PSMA-1007 PET/CT: Frequency of Pitfalls and Detection Efficacy in Biochemical Recurrence After Radical Prostatectomy. J Nucl Med 2020;61:51-7. [Crossref] [PubMed]
7. Jochumsen MR, Bouchelouche K. PSMA PET/CT for Primary Staging of Prostate Cancer - An Updated Overview. Semin Nucl Med 2024;54:39-45. [Crossref] [PubMed]
8. Abrahamsen BS, Tandstad T, Aksnessæther BY, Bogsrud TV, Castillejo M, Hernes E, Johansen H, Keil TMI, Knudtsen IS, Langørgen S, Selnæs KM, Bathen TF, Elschot M. Added Value of 18FPSMA-1007 PET/CT and PET/MRI in Patients With Biochemically Recurrent Prostate Cancer: Impact on Detection Rates and Clinical Management. J Magn Reson Imaging 2025;61:466-77. [Crossref] [PubMed]
9. Sanchez-Crespo A. Comparison of Gallium-68 and Fluorine-18 imaging characteristics in positron emission tomography. Appl Radiat Isot 2013;76:55-62. [Crossref] [PubMed]
10. Giesel FL, Hadaschik B, Cardinale J, Radtke J, Vinsensia M, Lehnert W, Kesch C, Tolstov Y, Singer S, Grabe N, Duensing S, Schäfer M, Neels OC, Mier W, Haberkorn U, Kopka K, Kratochwil C. F-18 labelled PSMA-1007: biodistribution, radiation dosimetry and histopathological validation of tumor lesions in prostate cancer patients. Eur J Nucl Med Mol Imaging 2017;44:678-88. [Crossref] [PubMed]
11. Kesch C, Kratochwil C, Mier W, Kopka K, Giesel FL. (68)Ga or (18)F for Prostate Cancer Imaging? J Nucl Med 2017;58:687-8. [Crossref] [PubMed]
12. Dietlein F, Kobe C, Hohberg M, Zlatopolskiy BD, Krapf P, Endepols H, Täger P, Hammes J, Heidenreich A, Persigehl T, Neumaier B, Drzezga A, Dietlein M. Intraindividual Comparison of (18)F-PSMA-1007 with Renally Excreted PSMA Ligands for PSMA PET Imaging in Patients with Relapsed Prostate Cancer. J Nucl Med 2020;61:729-34. [Crossref] [PubMed]
13. Mookerji N, Pfanner T, Hui A, Huang G, Albers P, Mittal R, et al. Fluorine-18 Prostate-Specific Membrane Antigen-1007 PET/CT vs Multiparametric MRI for Locoregional Staging of Prostate Cancer. JAMA Oncol 2024;10:1097-103. [Crossref] [PubMed]
14. Kuten J, Fahoum I, Savin Z, Shamni O, Gitstein G, Hershkovitz D, Mabjeesh NJ, Yossepowitch O, Mishani E, Even-Sapir E. Head-to-Head Comparison of (68)Ga-PSMA-11 with (18)F-PSMA-1007 PET/CT in Staging Prostate Cancer Using Histopathology and Immunohistochemical Analysis as a Standard. J Nucl Med 2020;61:527-32. [Crossref] [PubMed]
15. Hoberuck S, Lock S, Borkowetz A, Sommer U, Winzer R, Zophel K, Fedders D, Michler E, Kotzerke J, Kopka K, Holscher T, Braune A. Intraindividual comparison of [(68) Ga]-Ga-PSMA-11 and [(18)F]-F-PSMA-1007 in prostate cancer patients: a retrospective single-center analysis. EJNMMI Res 2021;11:109.
16. Pepe P, Pepe L, Tamburo M, Marletta G, Savoca F, Pennisi M, Fraggetta F. (68)Ga-PSMA PET/CT and Prostate Cancer Diagnosis: Which SUVmax Value? In Vivo 2023;37:1318-22. [Crossref] [PubMed]
17. Pepe P, Roscigno M, Pepe L, Panella P, Tamburo M, Marletta G, Savoca F, Candiano G, Cosentino S, Ippolito M, Tsirgiotis A, Pennisi M. Could 68Ga-PSMA PET/CT Evaluation Reduce the Number of Scheduled Prostate Biopsies in Men Enrolled in Active Surveillance Protocols? J Clin Med 2022;11:3473. [Crossref] [PubMed]
18. Bianchi L, Cangemi D, Farolfi A, Sgro CMP, Giorgio AD, Castellucci P, et al. PSMA-Targeted Biopsy With Fusion Guidance for Detecting Clinically Significant Prostate Cancer in Men With Negative MRI-Feasibility and Diagnostic Performance of a Pilot Single-Center Prospective Study. Clin Genitourin Cancer 2025;23:102348. [Crossref] [PubMed]
19. Pepe P, Pennisi M. Targeted Biopsy in Men High Risk for Prostate Cancer: (68)Ga-PSMA PET/CT Versus mpMRI. Clin Genitourin Cancer 2023;21:639-42. [Crossref] [PubMed]
20. Pepe P, Pepe L, Curduman M, Pennisi M, Fraggetta F. Ductal prostate cancer staging: Role of PSMA PET/CT. Arch Ital Urol Androl 2024;96:12132. [Crossref] [PubMed]