title: Assessment of musculoskeletal infection in rats to determine usefulness of SPIO-enhanced MRI.
abstract: OBJECTIVE
  The objective of our study was to evaluate the usefulness of superparamagnetic iron oxide (SPIO)-enhanced MRI in experimental models of infectious disease and to analyze the intracellular uptake of SPIO.
  
  
  METHODS
  Nine rats with infectious arthritis of the knee or soft-tissue infection were imaged on an MRI unit on days 4-6 after i.v. injection of a bacterial suspension. All animals were imaged on a T2-weighted fast spin-echo sequence before and 24 hours after administration of SPIO. The nine rats were classified into two groups according to the dose of SPIO. We calculated the relative signal-to-noise ratio (SNR) change and compared the relative SNR change with the histologic findings. We analyzed iron-loaded cells and the intracellular uptake of iron particles according to the dose of SPIO.
  
  
  RESULTS
  The SNR value decreased in proportion to the increase in the number of iron-laden macrophages or fibroblasts in the wall of the soft-tissue abscess (p < 0.01). The intracellular uptake of iron particles was shown in fibroblasts as well as in macrophages, and their uptake in the fibroblasts was greater than that in the macrophages (p < 0.05). There was no statistically significant difference in the intracellular uptake of iron particles according to the dose of SPIO (p > 0.1).
  
  
  CONCLUSIONS
  SPIO-enhanced MRI can be useful in evaluating infectious disease of the joint or soft tissue and is influenced by the uptake of iron particles in fibroblasts as well as macrophages.
authors: Department of Radiology, Bundang CHA General Hospital, College of Medicine, Pochon CHA University, Kyonggi-do 463-712, Korea.
authors: Sang Min
authors: SM
authors: Lee
authors: Sang Hoon
authors: SH
authors: Lee
authors: Hae Youn
authors: HY
authors: Kang
authors: Seung Yon
authors: SY
authors: Baek
authors: Sung Moon
authors: SM
authors: Kim
authors: Myung Jin
authors: MJ
authors: Shin
mesh_terms: D000818:Animals; D001168:Arthritis / Q000175:diagnosis*; D003287:Contrast Media; D005290:Ferric Compounds; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018461:Soft Tissue Infections / Q000175:diagnosis*; D013203:Staphylococcal Infections / Q000175:diagnosis*
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide