RT Journal Article SR Electronic T1 The Impact of Monosodium Glutamate on 68Ga-PSMA-11 Biodistribution in Men with Prostate Cancer: A Prospective Randomized, Controlled Imaging Study JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1244 OP 1251 DO 10.2967/jnumed.120.257931 VO 62 IS 9 A1 Armstrong, Wesley R. A1 Gafita, Andrei A1 Zhu, Shaojun A1 Thin, Pan A1 Nguyen, Kathleen A1 Alano, Rejah A1 Lira, Stephanie A1 Booker, Kiara A1 Gardner, Linda A1 Grogan, Tristan A1 Elashoff, David A1 Allen-Auerbach, Martin A1 Dahlbom, Magnus A1 Czernin, Johannes A1 Calais, Jeremie YR 2021 UL http://jnm.snmjournals.org/content/62/9/1244.abstract AB 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 because of the 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: Sixteen men with prostate cancer were randomized (1:1) into oral ingestion and oral topical application (“swishing”) arms. Each subject underwent 2 68Ga-PSMA-11 PET/CT scans within 14 d under baseline and MSG conditions. The salivary glands and whole-body tumor lesions were segmented using qPSMA software. We quantified tracer uptake via SUVmean and SUVmax and compared parameters within each patient. Results: For the oral ingestion arm, salivary gland SUVmean and SUVmax decreased on average from the control scan to the MSG scan by 45% ± 15% (P = 0.004) and 53% ± 11% (P < 0.001), respectively. Tumor lesion SUVmean and SUVmax also decreased by 38% (interquartile range, −67% to −33%) and −52% (interquartile range, −70% to −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.