Palestro C J, Love C, Bhargava K K
Department of Nuclear Medicine and Radiology, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY, USA.
Q J Nucl Med Mol Imaging. 2009 Feb;53(1):105-23.
The ability to radiolabel inflammatory cells that migrate to foci of infection was a significant milestone in the evolution of infection imaging. More than 20 years after being approved for clinical use in the United States, labeled leukocyte imaging using cells labeled with [(99m)Tc]exametazime or [(111)In]oxine remains the radionuclide procedure of choice for diagnosing most infections in the immunocompetent population. In the central nervous system, labeled leukocyte imaging is useful for differentiating infection from tumor; in the postoperative setting, this test facilitates the differentiation of infection from normal postoperative changes. Labeled leukocyte imaging accurately diagnoses mycotic aneurysms and infected prosthetic vascular grafts. In patients with fever of unknown origin, a negative study excludes, with a high degree of certainty, infection as the source of fever. Labeled leukocyte imaging accurately diagnoses pedal osteomyelitis and is useful for distinguishing infection from the neuropathic joint in this population. Together with bone marrow imaging, the labeled leukocyte study is the imaging procedure of choice for diagnosing prosthetic joint infection. There are limitations to the test. Most of the leukocytes labeled are neutrophils, and the procedure is most useful for detecting neutrophil-mediated inflammatory processes, i.e., bacterial infections. It is less useful for illnesses in which the predominant cellular response is other than neutrophilic, such as most opportunistic infections and spinal osteomyelitis. The in vitro labeling procedure is time consuming and is not routinely available. Results of in vivo leukocyte labeling methods have been variable; none are available in the United States. Labeled leukocyte imaging suffers from inherently poor quality images. Single photon emission compute tomography/computed tomography improves lesion localization, and will undoubtedly improve the accuracy of the test. Efforts to develop methods of labeling white cells with positron emitting compounds are underway and, if successful, should further strengthen the role of nuclear medicine in infection imaging.
对迁移至感染灶的炎性细胞进行放射性标记的能力是感染成像发展过程中的一个重要里程碑。在美国被批准用于临床20多年后，使用[（99m）Tc]依沙美肟或[（111）In]奥克辛标记细胞的标记白细胞成像仍然是免疫功能正常人群中诊断大多数感染的首选放射性核素检查方法。在中枢神经系统中，标记白细胞成像有助于区分感染与肿瘤；在术后情况下，该检查有助于区分感染与正常术后改变。标记白细胞成像可准确诊断霉菌性动脉瘤和感染的人工血管移植物。在不明原因发热的患者中，一项阴性研究可高度确定地排除感染是发热的原因。标记白细胞成像可准确诊断足部骨髓炎，并且有助于在该人群中区分感染与神经性关节病。与骨髓成像一起，标记白细胞检查是诊断人工关节感染的首选成像方法。该检查存在局限性。大多数标记的白细胞是中性粒细胞，该检查方法最适用于检测中性粒细胞介导的炎症过程，即细菌感染。对于主要细胞反应不是嗜中性的疾病，如大多数机会性感染和脊髓骨髓炎，其用处较小。体外标记过程耗时且并非常规可用。体内白细胞标记方法的结果一直存在差异；在美国均不可用。标记白细胞成像的图像质量天生较差。单光子发射计算机断层扫描/计算机断层扫描可改善病变定位，无疑将提高检查的准确性。目前正在努力开发用发射正电子的化合物标记白细胞的方法，如果成功，应会进一步加强核医学在感染成像中的作用。
