2017年7月28日，澳大利亞治療產品管理局（TGA）評估了含釓對比劑（GBCA）的最新信息，告知消費者和醫務人員在磁共振成像掃描過程中使用GBCA后，少量釓可能會沉積在腦中。目前尚未確定大腦中釓沉積的有害影響，但TGA正在與這些產品的生產企業合作，修改產品安全性信息。

GBCA注射到患者的靜脈中，可以增強內臟器官、血管和組織的磁共振成像掃描質量。磁共振成像掃描可幫助醫務人員診斷疾病狀況。GBCA有兩種類型：線型和環型。已發表的研究發現，與環型GBCA相比，線型GBCA可能會在大腦中產生更多的釓沉積。TGA將繼續監測上述風險，必要時采取進一步措施。

TGA告之患者和醫務人員，釓在腦中沉積僅與磁共振成像掃描中使用的GBCA有關，不涉及用于其他成像程序的其他類型的對比劑。GBCA的產品信息中曾提示釓“不會穿過完整的血腦屏障”，在某些情況下，釓不會在正常腦組織中蓄積。現在越來越多的證據表明這可能發生。

雖然目前尚未發現大腦中釓沉積的有害影響，但TGA和生產企業正在更新產品信息，并建議審慎使用GBCA，尤其是線型GBCA。TGA建議在必須使用GBCA的情況下，應使用最低有效劑量，并謹慎選擇GBCA種類。TGA還建議除非臨床必須，應避免重復使用這些對比劑進行掃描。

參考文獻：

●   Cao, Y, Huang, DQ, Shih, G, & Prince, MR (2016). Signal Change in the Dentate Nucleus on T1-Weighted MR Images After Multiple Administrations of Gadopentetate Dimeglumine Versus Gadobutrol. AJR Am J Roentgenol, 206, 414-9.

●   Flood TF, Stence NV, Maloney JA, Mirsky DM. (2016) Pediatric Brain: Repeated Exposure to Linear Gadolinium-based Contrast Material Is Associated with Increased Signal Intensity at Unenhanced T1-weighted MR Imaging. Radiology. Jul 28:160356.

●   Kanda, T, Ishii, K, Kawaguchi, H, Kitajima, K, & Takenaka, D (2014). High signal intensity in the dentate nucleus and globus pallidus on unenhanced T1- weighted MR images: relationship with increasing cumulative dose of a Gd-based contrast material. Radiology, 270, 834-41.

●   Kanda T, Fukusato T, Matsuda M, Toyoda K, Oba H, Kotoku J, et al. (2015a). Gd-based Contrast Agent Accumulates in the Brain Even in Subjects without Severe Renal Dysfunction: Evaluation of Autopsy Brain Specimens with Inductively Coupled Plasma Mass Spectroscopy. Radiology 2015 Jul;276(1):228- 232.

●   Kanda, T, Osawa, M, Oba, H, Toyoda, K, Kotoku, J, Haruyama, T, Takeshita, K, & Furui, S (2015b). High Signal Intensity in Dentate Nucleus on Unenhanced T1-weighted MR Images: Association with Linear versus Macrocyclic Gd Chelate Administration. Radiology, 275, 803-9.

●   Mcdonald, RJ, Mcdonald, JS, Kallmes, DF, Jentoft, ME, Murray, DL, Thielen, KR, Williamson, EE, & Eckel, LJ (2015). Intracranial Gd Deposition after Contrast-enhanced MR Imaging. Radiology, 275, 772-82.

●   Murata N, Gonzalez-Cuyar LF, Murata K, Figner C, Dills R, Hippe D, & Maravilla KR (2016). Macrocyclic and Other Non-Group 1 Gd Contrast Agents Deposit Low Levels of Gd in Brain and Bone Tissue: Preliminary Results From 9 Patients With Normal Renal Function. Invest Radiol. 2016 Feb 8.

●   Radbruch, A, Weberling, LD, Kieslich, PJ, Eidel, O, Burth, S, Kickingereder, P, Heiland, S, Wick, W, Schlemmer, HP, & Bendszus, M (2015a). Gd retention in the dentate nucleus and globus pallidus is dependent on the class of contrast agent. Radiology, 275, 783-791.

●   Ramalho, J, Semelka, RC, Alobaidy, M, Ramalho, M, Nunes, RH, & Castillo, M (2016). Signal intensity change on unenhanced T1-weighted images in dentate nucleus following gadobenate dimeglumine in patients with and without previous multiple administrations of gadodiamide. Eur Radiol. 2016 Feb 24.

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本文摘自《藥物警戒快訊》 第8期(總第172期)