Brammer David W, Riley Janet M, Kreuser Steven C, Zasadny Kenneth R, Callahan Michael J, Davis Michael D
Pfizer Global Research and Development, Ann Arbor, MI, USA.
J Am Assoc Lab Anim Sci. 2007 Sep;46(5):42-5.
The 18F isotope of fluoro-2-deoxy-D-glucose (FDG) is a radiotracer commonly used in positron emission tomography (PET) for determining regional metabolic activity in the brain. However, in rats and many other species with nictitating membranes, harderian glands located just behind the eyes aggressively incorporate 18F-FDG to the extent that PET images of the brain become obscured. This radioactive spillover, or 'partial volume error,' combined with the limited spatial resolution of microPET scanners (1.5 to 2 mm) may markedly reduce the ability to quantify neuronal activity in frontal brain structures. Theoretically, surgical removal of the harderian glands before 18F-FDG injection would eliminate the confounding uptake of the radioactive tracer and thereby permit visualization of glucose metabolism in the frontal brain. We conducted a pilot study of unilateral harderian gland adenectomy, leaving the contralateral gland intact for comparison. At 1 wk after surgery, each rat was injected intravenously with 18F-FDG, and 40 min later underwent brain microPET for 20 min. Review of the resulting images showed that the frontal cortex on the surgical side was defined more clearly, with only background 18F-FDG accumulation in the surgical bed. Activity in the frontal cortex on the intact side was obscured by intense accumulation of 18F-FDG in the harderian gland. By reducing partial volume error, this simple surgical procedure may become a valuable tool for visualization of the frontal cortex of rat brain by 18F-FDG microPET imaging.
氟代 - 2 - 脱氧 - D - 葡萄糖（FDG）的18F同位素是一种放射性示踪剂，常用于正电子发射断层扫描（PET）以确定大脑中的区域代谢活性。然而，在大鼠和许多其他具有瞬膜的物种中，位于眼睛后方的哈德氏腺会大量摄取18F - FDG，以至于大脑的PET图像变得模糊不清。这种放射性溢出，即“部分容积误差”，再加上微型PET扫描仪有限的空间分辨率（1.5至2毫米），可能会显著降低量化额叶脑结构中神经元活动的能力。从理论上讲，在注射18F - FDG之前手术切除哈德氏腺将消除放射性示踪剂的混淆摄取，从而能够观察额叶脑区的葡萄糖代谢情况。我们进行了一项单侧哈德氏腺切除术的初步研究，保留对侧腺体作为对照。术后1周，每只大鼠静脉注射18F - FDG，40分钟后进行20分钟的脑部微型PET检查。对所得图像的审查显示，手术侧的额叶皮质更清晰，手术床处只有背景性的18F - FDG积聚。完整侧额叶皮质的活性被哈德氏腺中强烈的18F - FDG积聚所掩盖。通过减少部分容积误差，这种简单的手术程序可能成为通过18F - FDG微型PET成像观察大鼠脑额叶皮质的一种有价值的工具。
