Ultralow Dose PET Imaging of SSTR2 Radiotracer Uptake

This research study aims to evaluate an investigational ultralow dose PET imaging technique for neuroendocrine tumor detection and monitoring. "Investigational" means that the procedure or drug being studied is not yet approved by the U.S. Food and Drug Administration (FDA) for the specific use being tested in this research. The PET imaging technique used in this study is considered investigational because it is being tested at an ultralow radiation dose that has not yet been approved for clinical use. The radiotracer, Gallium-68 (68Ga)-Dotatate, is FDA-approved for detecting neuroendocrine cancer at standard doses.

68Ga-Dotatate is often found to be taken up at higher levels in in neuroendocrine tumors. In this study, investigators will use a very small amount of this tracer (less than 1/20th of the standard dose) along with advanced PET imaging technology to see if it is possible to create clear images while using much less radiation. This study aims to develop a safer imaging technique that could potentially be used more frequently for screening and treatment response.

Investigators will enroll individuals with and without neuroendocrine tumors to evaluate how ultralow dose PET imaging detects radiotracer uptake in different type of tissue.

Approximately 200 people will be enrolled in this study at the Nuclear Imaging Institute.

• 68Ga-Dotatate (Drug), also known as CT scan, PET scan, blood collection: Participants will be injected with 68Ga-DOTATATE and imaged for up to 3 hours on a PET scanner

Primary outcomes

• Signal-to-Noise Ratio (SNR) [Evaluated annually (once per year), based on pooled images acquired during the preceding 12-month period.]: Measurement of signal-to-noise ratio for image quality assessment across different scan durations, reconstruction techniques, and artificial intelligence (AI)-enhanced image reconstructions. Unit of Measure: SNR (unitless, numeric ratio)
• Contrast-to-Noise Ratio (CNR) [Time Frame: Evaluated annually (once per year), based on pooled images acquired during the preceding 12-month period.]: Measurement of contrast-to-noise ratio for image quality assessment across different scan durations, reconstruction techniques, and AI-enhanced image reconstructions. Unit of Measure: CNR (unitless, numeric ratio)
• Coefficient of Variation (COV) [Evaluated annually (once per year), based on pooled images acquired during the preceding 12-month period.]: Measurement of the coefficient of variation in selected regions for evaluating image consistency across different scan durations, reconstruction techniques, and AI-enhanced image reconstructions. Unit of Measure: Percentage (%)
• Spatial Resolution (Full Width at Half Maximum - FWHM) [Evaluated annually (once per year), based on pooled images acquired during the preceding 12-month period.]: Assessment of spatial resolution using full width at half maximum (FWHM) across different scan durations, reconstruction techniques, and AI-enhanced image reconstructions. Unit of Measure: Millimeters (mm)
• Target-to-Background Ratio (TBR) [Evaluated annually (once per year), based on pooled images acquired during the preceding 12-month period.]: Assessment of target-to-background ratio for evaluating SSTR2-expressing tissue contrast across different scan durations, reconstruction techniques, and AI-enhanced image reconstructions. Unit of Measure: Ratio (unitless numeric ratio)
• Qualitative Image Quality Score (Likert Scale) [Evaluated annually (once per year), based on pooled images acquired during the preceding 12-month period.]: Independent qualitative evaluation of overall image quality, lesion detectability, image noise, and artifacts by nuclear medicine physicians, assessed using a 5-point Likert scale. Unit of Measure: Score on Likert Scale (1-5; 1 = worst, 5 = best)
• Inter-reader Agreement (Weighted Kappa Statistics) [Evaluated annually (once per year), based on pooled images acquired during the preceding 12-month period.]: Measurement of agreement among readers evaluating qualitative image quality scores, analyzed using weighted kappa statistics. Unit of Measure: Weighted kappa statistic (numeric value ranging from 0 to 1, 0 = no agreement, 1 = perfect agreement)

Sex: All, ages: 18 Years to 120 Years, accepts healthy volunteers

Inclusion Criteria:

* Age ≥18 years.
* Ability to provide informed consent and comply with study procedures.
* For female participants: Must not be pregnant or breastfeeding; Negative pregnancy test required for women of childbearing potential.

Exclusion Criteria:

* Participants who have exceeded NRC regulation for annual radiation exposure from prior research-related scans, including this study (50 millisievert \[mSv\] total).
* More than four prior enrollments in this study.
* Participants with severe claustrophobia, chronic pain, or musculoskeletal conditions that prevent completion of the PET scan
* Medication \& Prior Treatment Exclusions: SSTR targeted therapies
* Pregnant or breastfeeding individuals (negative pregnancy test required)
* Inability to provide informed consent
* Any condition that, in the investigator's judgment, may compromise participant safety or study integrity.