Assessment of 18F-DCFPyL PSMA PET/CT and PET/MR quantitative parameters for reference standard organs: Inter-reader,...

Area of Science:

• Nuclear Medicine
• Radiochemistry
• Oncology

Background:

• Prostate specific membrane antigen (PSMA)-based radiotracers are crucial for prostate cancer assessment.
• Quantitative variability and reference standards are essential for clinical and research applications of PSMA PET imaging.
• This study focuses on evaluating the quantitative variability of PSMA-based [18F]DCFPyL (PyL) PET quantitative reference standards.

Purpose of the Study:

• To assess the quantitative variability of PSMA-based [18F]DCFPyL (PyL) PET quantitative reference standards.
• To determine the reliability of liver, blood pool, and parotid gland as reference normal organs for PET imaging.
• To compare quantitative measurements between whole-body PET/CT and whole-body PET/MR.

Main Methods:

• Consecutive patients with biochemically recurrent prostate cancer underwent whole-body PET/CT followed by whole-body PET/MR after PyL injection.
• Two independent readers defined regions of interest (ROIs) in the parotid gland (whole gland and 1-cm spheres), liver, and blood pool.
• Bland-Altman analysis, interquartile range (IQR), and coefficient of variance (CoV) were used to evaluate inter-reader and inter-subject variability.

Main Results:

• Minimal inter-reader variability was observed for SUVmean in the blood pool, liver, and whole parotid gland for both PET/CT and PET/MR.
• Greater inter-reader variability was noted for 1-cm parotid gland ROIs.
• Comparing PET/CT to PET/MR, blood pool SUVmean slightly decreased, while liver and parotid gland SUVmean slightly increased, with absolute bias ranging from 0.45-1.28.
• Inter-subject variability was higher in the parotid gland compared to liver and blood pool.

Conclusions:

• Liver, blood pool, and whole parotid gland quantitation demonstrate promise as reliable reference normal organs for clinical and research PET applications.
• The use of smaller parotid gland ROIs (1-cm spheres) may introduce significant variability, potentially limiting their utility.
• PSMA-based [18F]DCFPyL (PyL) PET offers valuable quantitative data for prostate cancer assessment when appropriate reference standards are employed.