title: Biokinetics of (99m)Tc-UBI 29-41 in humans.
abstract: Antimicrobial peptides have been proposed as new agents to distinguish between bacterial infections and sterile inflammatory processes. (99m)Tc-UBI labeled by a direct method has shown high in vitro and in vivo stability, specific uptake at the site of infection, rapid background clearance, minimal accumulation in non-target tissues and rapid detection of infection sites in mice. The aim of this study was to establish a (99m)Tc-UBI biokinetic model and evaluate its feasibility as an infection imaging agent in humans. Whole-body images from 6 children with suspected bone infection were acquired at 1, 30, 120, 240 min and 24 h after (99m)Tc-UBI administration. Regions of interest (ROIs) were drawn around source organs (heart, liver, kidneys and bladder) on each time frame. The same set of ROIs was used for all 6 scans and the cpm of each ROI were converted to activity using the conjugate view counting method. Counts were corrected by physical decay and by the background correction factor derived from preclinical phantom studies. The image sequence was used to extrapolate (99m)Tc-UBI time-activity curves in each organ and calculate the cumulated activity (A). Urine samples were used to obtain the cumulative percent of injected activity (% I.A.) versus time renal elimination. The absorbed dose in organs was evaluated according to the general equation described in the MIRD formalism. In addition, (67)Ga-citrate images were obtained from all the patients and used as a control. Biokinetic data showed a fast blood clearance with a mean residence time of 0.52 h. Approximately 85% of the injected activity was eliminated by renal clearance 24 h after (99m)Tc-UBI administration. Images showed minimal accumulation in non-target tissues with an average target/non-target ratio of 2.18 +/- 0.74 in positive lesions at 2 h. All infection positive(99m)Tc-UBI images were in agreement with those obtained with (67)Ga-citrate. The mean radiation absorbed dose calculated was 0.13 mGy/MBq for kidneys and the effective dose was 4.34 x 10(-3)mSv/MBq.
authors.affiliation: Universidad Autónoma el Estado de México, Estado de México, Mexico.
authors.forename: Laura
authors.initials: L
authors.lastname: Meléndez-Alafort
authors.forename: Jeannette
authors.initials: J
authors.lastname: Rodríguez-Cortés
authors.forename: Guillermina
authors.initials: G
authors.lastname: Ferro-Flores
authors.forename: Consuelo
authors.initials: C
authors.lastname: Arteaga De Murphy
authors.forename: Ruth
authors.initials: R
authors.lastname: Herrera-Rodríguez
authors.forename: Eleni
authors.initials: E
authors.lastname: Mitsoura
authors.forename: Carlos
authors.initials: C
authors.lastname: Martínez-Duncker
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002951:Citrates / Q000493:pharmacokinetics; D003198:Computer Simulation; D005240:Feasibility Studies; D005260:Female; D005708:Gallium / Q000493:pharmacokinetics; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007700:Kinetics; D008297:Male; D008657:Metabolic Clearance Rate; D008954:Models, Biological; D009928:Organ Specificity; D010000:Osteitis / Q000000981:diagnostic imaging* / Q000378:metabolism*; D010446:Peptide Fragments / Q000493:pharmacokinetics; D019047:Phantoms, Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012269:Ribosomal Proteins / Q000493:pharmacokinetics*; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation / Q000379:methods; D014915:Whole-Body Counting
chemical_list: D002951:Citrates; D010446:Peptide Fragments; D019275:Radiopharmaceuticals; D012269:Ribosomal Proteins; C040469:ribosomal protein S30; D005708:Gallium; C103850:gallium citrate