A Virtual Clinical Trial to Detect Changes in Tumor Uptake with PET using Lesion Embedding

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Radiochemistry

Background:

• Accurate tumor response assessment is crucial for effective cancer therapy.
• Standardized Uptake Value (SUV) changes in Positron Emission Tomography (PET) are used to monitor treatment efficacy.
• Virtual clinical trials (VCTs) offer a novel approach to evaluate imaging system performance.

Purpose of the Study:

• To model and evaluate the capability of long axial field of view (LAFOV) PET scanners in detecting early tumor response to therapy.
• To assess the impact of scan duration, patient body mass index (BMI), and SUV metrics on detection performance.
• To determine the primary factors influencing the accuracy of therapy response assessment using PET imaging.

Main Methods:

• A virtual clinical trial (VCT) was performed using patient data from a PennPET Explorer scanner.
• Lesions with varying standardized uptake values (SUV) were embedded in lung and liver organs within bootstrapped datasets.
• Receiver Operating Characteristic (ROC) curves and Area Under the Curve (AUC) were generated to quantify detection performance.

Main Results:

• LAFOV PET scanners demonstrated effective detection of early tumor response, even with short scan durations (1 minute) or reduced radiotracer activity.
• Performance, measured by AUC, showed minimal sensitivity to scan duration, patient BMI, or SUV metric type (SUVmean, SUVmax).
• Scanner spatial resolution and the absolute change in lesion uptake were identified as the primary determinants of detection performance, rather than count statistics or organ background uptake.

Conclusions:

• High-sensitivity LAFOV PET scanners can reliably detect early therapeutic responses in tumors.
• Optimal performance is achievable with short scan times, making PET more accessible and efficient.
• Spatial resolution is a critical factor; standard PET scanners with comparable resolution may achieve similar results after sensitivity compensation.