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NCT Number: NCT07531329

Delayed PSMA PET/CT Imaging for Diagnosing Clinically Significant Prostate Cancer in Biopsy-Naïve Men With Suspected Prostate Cancer

Brief Summary This prospective, multicenter study evaluates whether delayed PSMA PET imaging improves diagnostic efficacy for detecting clinically significant prostate cancer (Gleason score ≥7) compared with standard imaging in patients with suspected newly diagnosed prostate cancer. Each patient serves as their own control, with diagnostic performance compared between standard (60-minute) and delayed (2-3 hour) acquisitions.

Background PSMA PET has transformed prostate cancer imaging, with emerging evidence suggesting delayed acquisition may further improve diagnostic accuracy by increasing tumor-to-background ratio. Recent studies demonstrate that delayed imaging significantly reduces equivocal findings and enhances detection of clinically significant prostate cancer.

Need While standard PSMA PET is well-validated, prospective multicenter data specifically evaluating the incremental diagnostic value of delayed imaging for clinically significant prostate cancer in treatment-naïve patients are lacking. This study addresses this gap by systematically comparing standard and delayed imaging in a large, well-defined cohort.

Primary Outcome The primary outcome is to compare the area under the curve (AUC) of delayed SUVmax versus standard SUVmax for detecting clinically significant prostate cancer (csPCa), and to determine whether delayed imaging is superior to standard imaging.

Secondary Outcomes

1. Optimal diagnostic thresholds for delayed imaging

1. Determine the optimal threshold for delayed SUVmax using ROC analysis with the Youden index; 2. Determine the optimal threshold for ΔSUVmax (delayed minus standard SUVmax); 3. Validate the sensitivity, specificity, and AUC of these thresholds in an independent validation set. 2. Biopsy avoidance potential In patients with PI RADS 4-5 lesions, calculate the negative predictive value (NPV) using a predefined high threshold to estimate the proportion who could safely avoid biopsy. 3. Diagnostic performance in key subgroups Compare the AUC of delayed SUVmax versus standard SUVmax for csPCa detection in patients with PI RADS 2-3 and in those with PI RADS 4-5. 4. Additional lesion detection Proportion of patients with additional csPCa lesions detected only on delayed imaging, and the proportion whose PI RADS category would be upgraded based on these findings. 5. Clinical decision impact Proportion of patients in whom management recommendations would change after incorporating delayed imaging results, compared with standard imaging alone. 6. Exploratory subgroup analyses Stratify by PSA level (<4, 4 10, >10 ng/mL) and PSA density (<0.10, 0.10-0.20, >0.20 ng/mL/cc) to identify subgroups that derive the greatest benefit from delayed imaging; additionally, explore combined subgroups such as PI RADS 3 with PSA 4-10 or PSAD 0.10-0.20.

Inclusion Criteria

1. Suspected prostate cancer based on elevated PSA (≥4.0 ng/mL) or clinical symptoms 2. Undergo PSMA PET (standard + delayed) prior to prostate biopsy 3. Willing to undergo prostate biopsy 4. Provide written informed consent Exclusion Criteria

1. Prior prostate cancer treatment before PSMA PET imaging 2. Other malignancy within past two years 3. Investigator-judged risk of serious complications interfering with study conduct

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Key information

Conditions

Treatment-naive Prostate Cancer Disease Genital Diseases Genital Diseases, Male Genital Neoplasms, Male Male Urogenital Diseases Molecular Imaging Neoplasms Neoplasms by Site Pathologic Processes Pathological Conditions, Signs and Symptoms Prostatic Diseases Prostatic Neoplasms Suspected Prostate Cancer Urogenital Diseases Urogenital Neoplasms

Age range

18 year and older

Sex eligibility

Male

Study type

Observational

Primary location

The First Hospital of Lanzhou University, Lanzhou, Gansu, China

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About this study

Study Design and Objective This is a prospective, multicenter diagnostic accuracy study designed to evaluate whether delayed PSMA PET imaging improves diagnostic efficacy for clinically significant prostate cancer (csPCa) compared with standard imaging in patients with suspected newly diagnosed, treatment-naïve prostate cancer. Each patient serves as their own control.

Imaging Protocol

All enrolled patients undergo dual-time-point PSMA PET/CT before biopsy:

  • Standard acquisition: whole-body imaging at approximately 60 minutes post-injection.
  • Delayed acquisition: pelvic-focused imaging at 2-3 hours post-injection.

Reference Standard All patients undergo prostate biopsy using 12-core systematic biopsy plus targeted biopsy when indicated. Histopathology serves as the reference standard. csPCa is defined as ISUP grade group ≥2.

Primary Outcome To compare the area under the receiver operating characteristic curve (AUC) of delayed SUVmax versus standard SUVmax for detecting csPCa, and to determine whether delayed imaging is superior to standard imaging.

Secondary Outcomes

  • Optimal diagnostic thresholds for delayed SUVmax and ΔSUVmax, with internal validation;
  • Negative predictive value (NPV) and biopsy avoidance potential (especially in PI-RADS 4-5 patients);
  • Diagnostic performance in key subgroups (PI-RADS 2-3 vs. 4-5);
  • Proportion of patients with additional csPCa lesions detected only on delayed imaging;
  • Proportion of patients whose management would change after incorporating delayed results;
  • Exploratory subgroup analyses by PSA level, PSA density, and combined gray-zone subgroups.

Statistical Analysis The primary analysis will compare paired AUCs using the DeLong test . Secondary analyses will use appropriate paired tests with adjustment for multiple comparisons. Missing data will be handled by complete-case analysis.

Data Monitoring An independent data monitor reviews data integrity and protocol adherence. No interim analysis is planned. The study complies with the Declaration of Helsinki and local regulations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Patients with suspected prostate cancer and a PSA level ≥4.0 ng/mL
  • Patients who undergo PSMA PET imaging (including delayed phase imaging) prior to prostate biopsy
  • Patients who are willing to undergo prostate biopsy
  • Patients who provide written informed consent to participate in the study

Exclusion criteria

  • Patients who have received any prior prostate cancer-related treatment before the initial PSMA PET scan
  • Patients with a history of other malignancies within the past two years
  • Patients judged by the study investigator to be at risk for serious complications that could interfere with the normal conduct of the study

Treatment and study plan

[⁶⁸Ga]Ga-PSMA PET/CT with Delayed Pelvic PET-Only Acquisition

Diagnostic Test

All enrolled patients undergo a dual-phase PSMA PET/CT imaging protocol consisting of: (1) a standard whole-body PET/CT acquisition performed at approximately 60 minutes after intravenous administration of [⁶⁸Ga]Ga-PSMA-11; and (2) a delayed pelvic PET acquisition performed at approximately 2-3 hours post-injection (exact timing to be standardized across participating centers based on local protocols and clinical workflow). The delayed phase does not include a separate CT scan; images are reconstructed using the CT dataset obtained from the initial whole-body acquisition for attenuation correction.

Primary outcomes

  1. Area Under the Curve (AUC) of Delayed SUVmax vs. Standard SUVmax for csPCa

    Time frame: [Time Frame: Baseline (comparison of standard vs. delayed images)]

    Compare the AUC of delayed SUVmax versus standard SUVmax for detecting clinically significant prostate cancer (ISUP grade group ≥2) using the DeLong test , to determine whether delayed imaging is superior.

Secondary outcomes

  1. Optimal Threshold of Delayed SUVmax for csPCa

    Time frame: Baseline

    Determine the optimal cutoff of delayed SUVmax for diagnosing clinically significant prostate cancer using ROC analysis with the Youden index.

  2. Optimal Threshold of ΔSUVmax (Delayed Minus Standard) for csPCa

    Time frame: Baseline

    Calculate ΔSUVmax (delayed SUVmax minus standard SUVmax) and determine its optimal percentage-change cutoff for diagnosing clinically significant prostate cancer using ROC analysis with the Youden index.

  3. Diagnostic Performance of Optimal Thresholds in Validation Cohort

    Time frame: Baseline

    Apply the derived thresholds to a temporally separate validation set to assess sensitivity, specificity, and AUC.

  4. Negative Predictive Value for Biopsy Avoidance in PI-RADS 4-5 Patients

    Time frame: Baseline

    In patients with PI-RADS 4-5 lesions, calculate the negative predictive value using a predefined high threshold to estimate the proportion who could safely avoid biopsy.

  5. AUC of Delayed vs. Standard Imaging in PI-RADS 2-3 and PI-RADS 4-5 Subgroups

    Time frame: Baseline

    Compare the AUC of delayed Imaging versus standard SUVmax for csPCa detection separately in patients with PI-RADS 2-3 (target of PRIMARY2 study) and PI-RADS 4-5.

  6. Proportion of Patients with Additional csPCa Lesions Detected Only on Delayed Imaging

    Time frame: Baseline

    Calculate the proportion of patients who have additional csPCa lesions identified exclusively on delayed images that were not seen on standard images.

  7. Proportion of Patients with Change in Clinical Management After Delayed Imaging ( Exploratory)

    Time frame: Baseline

    Proportion of patients for whom management recommendations (biopsy vs. surveillance) would change after incorporating delayed imaging results, compared with standard imaging alone.

  8. Exploratory Subgroup Analyses by PSA and PSAD

    Time frame: Baseline

    Compare AUC of delayed vs. standard SUVmax for csPCa detection stratified by PSA level (<4, 4-10, >10 ng/mL) and PSA density (<0.10, 0.10-0.20, >0.20 ng/mL/cc); additionally explore combined gray-zone subgroups (e.g., PI-RADS 3 with PSA 4-10 or PSAD 0.10-0.20).

  9. Inter-Observer Agreement for SUVmax Measurement of the Most Suspicious Intraprostatic Lesion on Standard and Delayed PSMA PET/CT (Intraclass Correlation Coefficient, ICC, Exploratory)

    Time frame: Baseline

    Two nuclear medicine physicians independently identify the most suspicious intraprostatic lesion on both standard and delayed images and measure its maximum standardized uptake value (SUVmax) once per lesion. Inter-observer agreement for SUVmax measurement will be assessed using the intraclass correlation coefficient (ICC, two-way random model, absolute agreement). ICC values with 95% confidence intervals will be reported separately for standard and delayed imaging. Higher ICC indicates better measurement consistency.

Study contacts

Contact information is provided by the study sponsor or research team.

Jianhua Jiao, MD.

CONTACT

[email protected]

+86 18700919857

Sponsors and collaborators

Lead sponsor

Xijing Hospital

Other

Collaborators

  • Affiliated Hospital of Qinghai University
  • Air Force Military Medical University, China
  • General Hospital of Ningxia Medical University
  • LanZhou University
  • National Translational Science Center for Molecular Medicine
  • Shaanxi Provincial People's Hospital
  • The Second Affiliated Hospital of Shaanxi University of Chinese Medicine
  • Weinan Central Hospital
  • Yan'an University Affiliated Hospital

Registry information

Acronym: DEPICT

Important dates

Study start
2021
Primary completion
2027
Study completion
2028
First posted
Apr 15, 2026
Registry last updated
Apr 15, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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