title: Scintigraphic imaging of bacterial and fungal infection in granulocytopenic rats.
abstract: Scintigraphic imaging in granulocytopenic patients can be very useful to detect and localize infections, which often do not show localizing signs and symptoms. We studied the potential of 99mTc-labeled polyethylene glycol (PEG)-coated liposomes and 99mTc-labeled IgG to image bacterial and fungal infection in a granulocytopenic rat model. 67Ga-citrate was used as a reference agent.
  
  
  METHODS
  99mTc-PEG-liposomes, 99mTc-hydrazinonicotinate (HYNIC)-IgG or 67Ga-citrate was administered to granulocytopenic rats with a Staphylococcus aureus abscess or with unilateral invasive pulmonary aspergillosis. Imaging and biodistribution studies were performed.
  
  
  RESULTS
  All agents visualized the S. aureus infection from 1 h after injection onward. However, only with 99mTc-PEG-liposomes and with 99mTc-HYNIC-IgG did activity in the infectious foci increase with time up to 24 h. 99mTc-PEG-liposomes and 99mTc-HYNIC-IgG showed significantly higher accumulation in the infectious focus compared with 67Ga-citrate (1.33+/-0.31 and 1.40+/-0.16 percentage injected dose per gram [%ID/g], respectively, versus 0.31+/-0.04 %ID/g 24 h after injection; P<0.05). At 24 h after injection, abscess-to-muscle ratios were highest for 99mTc-liposomes (72.1+/-19.1), followed by 99mTc-HYNIC-IgG (18.3+/-3.3) and 67Ga-citrate (4.4+/-0.7). In pulmonary aspergillosis, both 99mTc-PEG-liposomes and 99mTC-HYNIC-IgG showed significantly higher uptake in the infected lung than did 67Ga-citrate (3.6+/-0.4 and 8.3+/-0.8 %ID/g, respectively, versus 1.3 %ID/g at 24 h after injection; P<0.05).
  
  
  CONCLUSIONS
  99mTc-PEG-liposomes and 99mTc-HYNIC-IgG performed better than did 67Ga-citrate in the localization of peripheral bacterial infection and fungal infection in the lung in granulocytopenic rats. The high focal uptake and high target-to-nontarget ratios of 99mTc-PEG-liposomes and 99mTc-HYNIC-IgG indicate that both radiopharmaceuticals may become valuable agents to image infection in granulocytopenic patients.
authors.affiliation: Department of Nuclear medicine, University Hospital Nijmegen, The Netherlands.
authors.forename: E T
authors.initials: ET
authors.lastname: Dams
authors.forename: M J
authors.initials: MJ
authors.lastname: Becker
authors.forename: W J
authors.initials: WJ
authors.lastname: Oyen
authors.forename: O C
authors.initials: OC
authors.lastname: Boerman
authors.forename: G
authors.initials: G
authors.lastname: Storm
authors.forename: P
authors.initials: P
authors.lastname: Laverman
authors.forename: S
authors.initials: S
authors.lastname: de Marie
authors.forename: J W
authors.initials: JW
authors.lastname: van der Meer
authors.forename: I A
authors.initials: IA
authors.lastname: Bakker-Woudenberg
authors.forename: F H
authors.initials: FH
authors.lastname: Corstens
mesh_terms: D000038:Abscess / Q000150:complications / Q000000981:diagnostic imaging*; D000380:Agranulocytosis / Q000150:complications*; D000818:Animals; D001228:Aspergillosis / Q000150:complications / Q000000981:diagnostic imaging*; D002951:Citrates; D004337:Drug Carriers; D005708:Gallium; D005710:Gallium Radioisotopes; D007074:Immunoglobulin G; D008081:Liposomes; D008172:Lung Diseases, Fungal / Q000150:complications / Q000000981:diagnostic imaging*; D008297:Male; D009135:Muscular Diseases / Q000150:complications / Q000000981:diagnostic imaging; D015609:Organotechnetium Compounds; D011092:Polyethylene Glycols; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D051381:Rats; D017208:Rats, Wistar; D013203:Staphylococcal Infections / Q000150:complications / Q000000981:diagnostic imaging*; D013667:Technetium
chemical_list: D002951:Citrates; D004337:Drug Carriers; D005710:Gallium Radioisotopes; D007074:Immunoglobulin G; D008081:Liposomes; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C099153:technetium Tc 99m hydrazinonicotinate-IgG; D011092:Polyethylene Glycols; D013667:Technetium; D005708:Gallium; C103850:gallium citrate