Nuclear Medicine Unit, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola, Italy.
Medical Physics Unit, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola, Italy.
Eur J Nucl Med Mol Imaging. 2017 Dec;44(13):2189-2194. doi: 10.1007/s00259-017-3791-4. Epub 2017 Aug 11.
Urea-based prostate-specific membrane antigen (PSMA) ligands labelled with Ga or Lu are new tracers with great potential for theranostic approaches in prostate cancer. However, clinical studies have shown that the kidneys are one of the off-target organs along with the salivary and lacrimal glands. In the kidneys, PSMA is physiologically expressed in the apical epithelium of the proximal tubules, and mannitol acts as an osmotic diuretic in these tubules. We investigated the potential of mannitol to reduce renal uptake of Ga-PSMA.
Kidney uptake (SUVmax) was calculated in nine patients undergoing Ga-PSMA PET/CT at baseline (b-PET/CT) and after intravenous infusion of 500 ml of 10% mannitol (m-PET/CT). Two different infusion schemes for mannitol were used: (1) 500 ml mannitol was infused over 40 min after Ga-PSMA administration (A-infusion) and (2) 250 ml mannitol was infused over 15 min before and again after Ga-PSMA administration (B-infusion).
In patients receiving the A-infusion, mean SUV increased by 11.9% and 7.4% in the right and left kidney, respectively. In patients receiving the B-infusion, mean SUV decreased by 24.3% and 22.4% in the right and left kidney, respectively.
Our preliminary findings indicate that mannitol may play a role in reducing off-target Ga-PSMA renal uptake. Administration of the osmotic diuretic should be rapid and start before Ga-PSMA injection. These results warrant dosimetric studies in patients treated with Lu-PSMA to find the best scheme for mannitol administration.
基于尿素的前列腺特异性膜抗原（PSMA）配体与 Ga 或 Lu 标记，是具有治疗前列腺癌潜力的新型示踪剂。然而，临床研究表明，肾脏是除唾液腺和泪腺之外的一个非靶器官。在肾脏中，PSMA 在近端肾小管的顶膜上皮中生理性表达，甘露醇在这些肾小管中作为渗透性利尿剂。我们研究了甘露醇降低 Ga-PSMA 肾脏摄取的潜力。
在 9 名患者中，在 Ga-PSMA PET/CT 基线（b-PET/CT）和静脉注射 500ml 10%甘露醇（m-PET/CT）后，计算肾脏摄取（SUVmax）。使用两种不同的甘露醇输注方案：（1）在 Ga-PSMA 给药后 40 分钟内输注 500ml 甘露醇（A 输注）；（2）在 Ga-PSMA 给药前和给药后 15 分钟内分别输注 250ml 甘露醇（B 输注）。
在接受 A 输注的患者中，右肾和左肾的 SUV 分别平均增加了 11.9%和 7.4%。在接受 B 输注的患者中，右肾和左肾的 SUV 分别平均减少了 24.3%和 22.4%。
我们的初步发现表明，甘露醇可能在降低非靶标 Ga-PSMA 肾脏摄取方面发挥作用。渗透性利尿剂的给药应迅速，并在 Ga-PSMA 注射前开始。这些结果需要在接受 Lu-PSMA 治疗的患者中进行剂量学研究，以找到甘露醇给药的最佳方案。
