Abstract
Background: The prostate-specific membrane antigen (PSMA) has been targeted for PET imaging and radioligand therapy (RLT) in patients with prostate cancer. Xerostomia is a common side effect of RLT due to high salivary gland uptake of PSMA-radioligands. Here we aimed to determine the impact of monosodium glutamate (MSG) administration on PSMA-radioligand biodistribution within healthy organs and tumor lesions by using 68Ga-PSMA-11 PET imaging. Methods: 16 men with prostate cancer were randomized (1:1) into oral ingestion and oral topical application (‘swishing’) arms. Each subject underwent two 68Ga-PSMA-11 PET/CT scans within 14 days under baseline and MSG conditions. Salivary glands and whole-body tumor lesions were segmented using qPSMA software. We quantified tracer uptake via mean and maximum standardized uptake values (SUVmean and SUVmax) and compared parameters within each patient. Results: For the oral ingestion arm, salivary gland SUVmean/max decreased on average from Control to MSG scan by 45±15% (P = 0.004) and 53±11% (p<0.001), respectively. Tumor lesions SUVmean/ max also decreased by 38% (IQR -67%, -33%) and -52% (IQR -70%, -49%), respectively (P = 0.018). Swishing had no significant effect on 68Ga-PSMA-11 accumulation in normal organs or tumor lesions. Conclusion: Oral ingestion but not topical application of MSG reduced 68Ga-PSMA-11 uptake in salivary glands. Tumor uptake also declined, therefore, the clinical application of MSG is unlikely to be useful in the framework of RLT.
- Copyright © 2021 by the Society of Nuclear Medicine and Molecular Imaging, Inc.
This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.
SNMMI members
Login to the site using your SNMMI member credentials
Individuals
Login as an individual user