indium-oxine and gallium-citrate

With a current annual mortality rate of around 35% worldwide, infection remains a significant concern, and the diagnosis and localization of infectious foci is an important health issue. As an established infection-imaging modality, nuclear medicine plays a vital health-care role in the diagnosis and subsequent effective treatment of this condition. Despite the development of several newer radiopharmaceuticals, (67)Ga and leukocyte imaging procedures have maintained their established place for infection. Several techniques in nuclear medicine significantly aid infection diagnosis, including imaging with (111)In-oxine-, (99m)Tc-hexamethylpropyleneamine oxime-, and (99m)Tc-stannous fluoride colloid-labeled leukocytes and with (67)Ga-citrate. Each radiopharmaceutical has specific advantages and disadvantages that make it suitable to diagnose different infectious processes (e.g., soft-tissue sepsis, inflammatory bowel disease, osteomyelitis, occult fever, fever of unknown origin, and infections commonly found in immunocompromised patients). After finishing this article, the reader should be able to identify the properties of an ideal radiopharmaceutical for infection imaging, list a range of available infection-imaging radiopharmaceuticals, compare the relative results of a range of radiopharmaceuticals used internationally to detect infection in the body, understand several common infectious processes that can be diagnosed using nuclear medicine techniques, and select an appropriate radiopharmaceutical to image a range of infectious processes.

Topics: Citrates; Fever of Unknown Origin; Gallium; Humans; Infections; Irritable Bowel Syndrome; Leukocytes; Nuclear Medicine; Organometallic Compounds; Osteomyelitis; Oxyquinoline; Practice Patterns, Physicians'; Predictive Value of Tests; Radiopharmaceuticals; Reproducibility of Results; Sensitivity and Specificity; Sepsis; Technetium Compounds; Technetium Tc 99m Exametazime; Tin Fluorides; Tomography, Emission-Computed

We compared 125I-labelled recombinant human interleukin-8 (125I-IL-8) with 111In-labelled human leukocytes (111In-WBC) and 67Ga-citrate for scintigraphic depiction of acute sterile inflammatory lesions in rats. Radioiodination of IL-8 was catalysed by chloramine-T, and human leukocytes were radiolabelled with 111In-oxine. Inflammatory lesions were induced in male rats by subcutaneous injection of 2% carrageenan suspension into their left hindlimbs. Twenty-four hours later, each rat received 1.8-3.7 MBq (50-100 microCi) of a single agent by intravenous injection. Sequential whole-body scintigrams were obtained between 0 and 96 h post-injection. Activities in the lesion-bearing and control hindlimbs were expressed as regional percent injected activity corrected for physical decay (%IA) by reference to concurrently imaged standards, and for 125I-IL-8 by direct tissue counting at necropsy as well. 125I-IL-8 displayed appropriate electrophoretic mobility, retained chemotactic and high-affinity receptor-binding activity in vitro, and exhibited exponentially decreasing activity in most tissues beginning shortly after intravenous injection. Scintigrams showed asymmetrically increased activity in the lesion-bearing hindlimb for all three agents. By scintigraphy, 125I-IL-8 activity in the lesion-bearing hindlimb reached a zenith 1-3 h post-injection at 4.8 +/- 0.5 %IA and decreased exponentially thereafter, with little change in lesioned-to-control limb ratios (mean L/C = 3.0 +/- 0.7) over the imaging period. By direct tissue counting, abscess-associated mean IL-8 activity per gram of tissue increased to four times that of adjacent muscle and nearly seven times that of contralateral muscle by 24 h post-injection. Lesion-bearing hindlimb 111In-WBC activity also rose rapidly, reaching 4.2 +/- 0.6 %IA by scintigraphy at 3 h and an eventual plateau (maximum of 4.5 +/- 0.4 %IA) by 24 h. 67Ga scintigraphic activity in the lesion-bearing hindlimb peaked briefly at 3-6 h post-injection (9.2 +/- 0.5 %IA) and subsequently declined to a constant level of about 7.5 %IA. However, L/C for 111In-WBC and for 67Ga-citrate each averaged only 1.5 +/- 0.3 over the imaging period, compared with a mean L/C of 1.2 +/- 0.2 for a blood pool radiotracer. We conclude that 125I-IL-8 is rapidly and selectively concentrated in regions of acute inflammation, presumably by high-affinity binding to IL-8 receptors on neutrophils within the inflammatory focus. Radioiodinated IL-8 offers an attractiv

Topics: Animals; Carrageenan; Citrates; Female; Gallium; Gallium Radioisotopes; Humans; Indium Radioisotopes; Inflammation; Interleukin-8; Iodine Radioisotopes; Leukocyte Transfusion; Leukocytes; Male; Organometallic Compounds; Oxyquinoline; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Tissue Distribution; Tomography, Emission-Computed; Transplantation, Heterologous