TY - JOUR T1 - The Impact of Monosodium Glutamate on <sup>68</sup>Ga-PSMA-11 Biodistribution in Men with Prostate Cancer: A Prospective Randomized, Controlled Imaging Study JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1244 LP - 1251 DO - 10.2967/jnumed.120.257931 VL - 62 IS - 9 AU - Wesley R. Armstrong AU - Andrei Gafita AU - Shaojun Zhu AU - Pan Thin AU - Kathleen Nguyen AU - Rejah Alano AU - Stephanie Lira AU - Kiara Booker AU - Linda Gardner AU - Tristan Grogan AU - David Elashoff AU - Martin Allen-Auerbach AU - Magnus Dahlbom AU - Johannes Czernin AU - Jeremie Calais Y1 - 2021/09/01 UR - http://jnm.snmjournals.org/content/62/9/1244.abstract N2 - 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 &lt; 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. ER -