Kowalski Jörg, Henze Marcus, Schuhmacher Jochen, Mäcke Helmut R, Hofmann Michael, Haberkorn Uwe
Department of Nuclear Medicine, University of Heidelberg, Heidelberg, Germany.
Mol Imaging Biol. 2003 Jan-Feb;5(1):42-8. doi: 10.1016/s1536-1632(03)00038-6.
[111In]-DTPAOC (Octreoscan(R)) has been shown to be very useful in the detection of somatostatin receptor (SSTR) positive tumors and their metastases using either conventional scintigraphy or single photon emission computed tomography (SPECT). The main drawback of this method is the limited spatial resolution and a somewhat low receptor affinity of the radiopeptide. Due to the increased spatial resolution and the ability of quantification, an agent for positron emission tomography (PET) imaging of SSTR is desirable. This communication shows our initial experience using [68Ga]-DOTA-D-Phe(1)-Tyr(3)-Octreotide (DOTATOC) in comparison to [111In]-DTPAOC-SPECT in patients with neuroendocrine tumors.
Four patients, two male and two female (46-55 years old) have been examined by [111In]-DTPAOC scintigraphy and within one month by [68Ga]-DOTATOC-PET. All of them suffered from neuroendocrine tumors and/or their metastases. DOTATOC has been labeled using the positron-emitting generator-nuclide 68Ga (t(1/2) 68 minutes). In two patients with previously known localization of tumor, dynamic PET scans after intravenous bolus-injection of 181+/-17 MBq [68Ga]-DOTATOC until 120 minutes post-injection were acquired. In all patients, the static PET-scans have been acquired after 45 or 60 minutes post-injection (SUV1) and 140 minutes post-injection (SUV2).
Similar to [111In]-DTPAOC, [68Ga]-DOTATOC showed the highest uptake in the spleen, followed by the kidneys and the liver. A clear delineation of the pituitary gland could only be achieved by PET. The highest SUVs were found at a plateau between 45 and 90 minutes with a maximum 60 minutes post-injection. Due to the fast tracer accumulation in the tumor and the rapid clearance of the compound, resulting in high tumor to background ratios even 40 minutes after injection, the short half life of 68Ga is reasonable. In two patients more findings have been revealed by [68Ga]-DOTATOC-PET as compared to the [111In]-DTPAOC-SPECT. In comparison to the [111In]-DTPAOC-SPECT [68Ga]-DOTATOC-PET seems to be superior especially concerning small findings with low tracer uptake. Both [111In]-DTPAOC-SPECT and [68Ga]-DOTATOC-PET were less sensitive in the detection of liver metastases of neuroendocrine tumors compared to computerized tomography CT because they showed a lower uptake than the surrounding liver tissue.
According to our initial experiences in a limited number of patients, [68Ga]-DOTATOC is a promising PET tracer for imaging neuroendocrine tumors and their metastases. In comparison to the [111In]-DTPAOC-scan it seems to be superior especially in detecting small tumors or tumors bearing only a low density of SSTRs. It offers excellent imaging properties and very high tumor to background ratios. Further evaluation of [68Ga]-DOTATOC in a larger number of patients is certainly justified.
已证明，使用传统闪烁扫描法或单光子发射计算机断层扫描（SPECT），[111In]-二乙三胺五乙酸奥曲肽（Octreoscan®）在检测生长抑素受体（SSTR）阳性肿瘤及其转移灶方面非常有用。该方法的主要缺点是空间分辨率有限，且放射性肽的受体亲和力略低。由于空间分辨率提高以及具备定量能力，因此需要一种用于SSTR正电子发射断层扫描（PET）成像的试剂。本报告展示了我们使用[68Ga]-DOTA-D-苯丙氨酸（1）-酪氨酸（3）-奥曲肽（DOTATOC）与[111In]-二乙三胺五乙酸奥曲肽-SPECT对比，对神经内分泌肿瘤患者进行检查的初步经验。
4例患者，2男2女（46 - 55岁），接受了[111In]-二乙三胺五乙酸奥曲肽闪烁扫描，并在1个月内接受了[68Ga]-DOTATOC-PET检查。他们均患有神经内分泌肿瘤和/或其转移灶。DOTATOC使用发射正电子的发生器 - 核素68Ga（半衰期68分钟）进行标记。在2例先前已知肿瘤定位的患者中，静脉推注181±17 MBq [68Ga]-DOTATOC后，直至注射后120分钟进行动态PET扫描。在所有患者中，注射后45或60分钟（SUV1）以及注射后140分钟（SUV2）进行静态PET扫描。
与[111In]-二乙三胺五乙酸奥曲肽类似，[68Ga]-DOTATOC在脾脏中的摄取最高，其次是肾脏和肝脏。只有通过PET才能清晰描绘垂体。最高SUV值出现在45至90分钟的平台期，注射后60分钟达到最大值。由于示踪剂在肿瘤中快速积累且化合物快速清除，即使在注射后40分钟肿瘤与背景比值仍很高，因此68Ga的短半衰期是合理的。与[111In]-二乙三胺五乙酸奥曲肽-SPECT相比，[68Ga]-DOTATOC-PET在2例患者中发现了更多结果。与[111In]-二乙三胺五乙酸奥曲肽-SPECT相比，[68Ga]-DOTATOC-PET似乎更具优势，尤其是对于示踪剂摄取低的小病灶。与计算机断层扫描（CT）相比，[111In]-二乙三胺五乙酸奥曲肽-SPECT和[68Ga]-DOTATOC-PET在检测神经内分泌肿瘤肝转移方面敏感性较低，因为它们的摄取低于周围肝组织。
根据我们在有限数量患者中的初步经验，[68Ga]-DOTATOC是一种用于神经内分泌肿瘤及其转移灶成像的有前景的PET示踪剂。与[111In]-二乙三胺五乙酸奥曲肽扫描相比，它似乎更具优势，特别是在检测小肿瘤或SSTR密度低的肿瘤方面。它具有出色的成像特性和非常高的肿瘤与背景比值。对[68Ga]-DOTATOC在更多患者中的进一步评估当然是合理的。
