Gratz Stefan, Rennen Huub J J M, Boerman Otto C, Oyen Wim J G, Mast Peter, Behr Thomas M, Corstens Frans H M
Department of Nuclear Medicine, University Medical Center Nijmegen, The Netherlands.
J Nucl Med. 2002 Jul;43(7):918-24.
Radiolabeled autologous leukocytes are the gold standard for imaging infectious foci in patients. Good results have also been reported for radiolabeled heterologous leukocytes from noninfected donors. Until now, the 2 methods have not been directly compared. In this study, we compared the infection-imaging potential of 99mTc-hexamethylpropyleneamine oxime (HMPAO)-labeled autologous granulocytes with that of 99mTc-HMPAO-labeled granulocytes from either infected or noninfected donors in rabbits with Escherichia coli infection.
The radiolabeled granulocyte preparations were studied in rabbits with an E. coli infection in the left calf muscle. The soft-tissue infections were scintigraphically visualized after injection of 18 MBq of either 99mTc-HMPAO purified autologous granulocytes or radiolabeled purified heterologous granulocytes from infected or noninfected donor rabbits. Gamma camera images were acquired at 2 min and at 1, 2, and 4 h after injection. After the last image, the rabbits were killed and uptake of the radiolabel in the dissected tissues was determined.
The 99mTc-HMPAO autologous granulocytes and heterologous granulocytes from infected donors accurately revealed the infectious focus in the calf muscle at 2 h after injection. At 4 h after injection, a significantly better (P < 0.05) delineation of the infection was established with the 99mTc-HMPAO autologous granulocytes and 99mTc-HMPAO heterologous granulocytes from the infected rabbits than with the heterologous granulocytes from noninfected donors. With both cell preparations, the intensity of uptake in the infected calf muscle continuously increased until 4 h after injection. The 99mTc-HMPAO heterologous granulocytes from noninfected donors showed no significant increase in contrast after 2 h after injection. Absolute uptake in the infected calf muscle was much higher for 99mTc-HMPAO autologous granulocytes (7.81 +/- 1.21 percentage injected dose [%ID]) and 99mTc-HMPAO heterologous infected granulocytes (8.91 +/- 1.92 %ID) than for the radiolabeled heterologous noninfected granulocytes (2.32 +/- 0.75 %ID) (P < 0.04) at 4 h after injection. The ratio of infected muscle to noninfected contralateral muscle was significantly higher for 99mTc-HMPAO autologous granulocytes and 99mTc-HMPAO heterologous granulocytes from infected donors than for 99mTc-HMPAO heterologous granulocytes from noninfected donors (5.53 +/- 1.09, 3.86 +/- 0.75, and 1.86 +/- 0.31, respectively; P < 0.05).
For nuclear medicine imaging of infection, purified granulocytes derived from infected rabbits are superior to purified granulocytes derived from noninfected donor rabbits. In addition, autologous granulocytes gave similar results to heterologous granulocytes from infected donor rabbits, suggesting the need for intrinsic cell activation for specific granulocyte migration.
放射性标记的自体白细胞是对患者感染灶进行成像的金标准。对于来自未感染供体的放射性标记的异源白细胞，也有良好结果的报道。到目前为止，这两种方法尚未进行直接比较。在本研究中，我们比较了用99m锝-六甲基丙烯胺肟（HMPAO）标记的自体粒细胞与用99mTc-HMPAO标记的来自感染或未感染供体的粒细胞对感染大肠杆菌的兔的感染成像潜力。
在左小腿肌肉感染大肠杆菌的兔中研究放射性标记的粒细胞制剂。在注射18MBq的99mTc-HMPAO纯化自体粒细胞或来自感染或未感染供体兔的放射性标记纯化异源粒细胞后，通过闪烁扫描对软组织感染进行可视化。在注射后2分钟以及1、2和4小时采集γ相机图像。在最后一幅图像采集后，处死兔子并测定解剖组织中放射性标记的摄取情况。
99mTc-HMPAO自体粒细胞和来自感染供体的异源粒细胞在注射后2小时准确显示了小腿肌肉中的感染灶。在注射后4小时，与来自未感染供体的异源粒细胞相比，99mTc-HMPAO自体粒细胞和来自感染兔的99mTc-HMPAO异源粒细胞对感染的描绘明显更好（P<0.05）。对于两种细胞制剂，感染的小腿肌肉中的摄取强度在注射后4小时之前持续增加。来自未感染供体的99mTc-HMPAO异源粒细胞在注射后2小时后对比度无明显增加。在注射后4小时，99mTc-HMPAO自体粒细胞（7.81±1.21注射剂量百分比[％ID]）和99mTc-HMPAO异源感染粒细胞（8.91±1.92％ID）在感染的小腿肌肉中的绝对摄取量远高于放射性标记的异源未感染粒细胞（2.32±0.75％ID）（P<0.04）。与来自未感染供体的99mTc-HMPAO异源粒细胞相比（分别为5.53±l.09、3.86±0.75和1.86±0.31；P<0.05），99mTc-HMPAO自体粒细胞和来自感染供体的99mTc-HMPAO异源粒细胞在感染肌肉与未感染对侧肌肉中的比值明显更高。
对于感染的核医学成像，来自感染兔的纯化粒细胞优于来自未感染供体兔的纯化粒细胞。此外，自体粒细胞与来自感染供体兔的异源粒细胞结果相似，表明特定粒细胞迁移需要内在细胞激活。
