title: Hollow manganese oxide nanoparticle-enhanced MRI of hypoxic-ischaemic brain injury in the neonatal rat.
abstract: OBJECTIVE
  To determine the utility of hollow manganese oxide nanoparticle (HMON)-enhanced MRI in depicting and monitoring apoptotic area following hypoxic-ischaemic injury in a neonatal rat brain and to evaluate the longitudinal evolution of hypoxic-ischaemic brain injury (HII) up to 21 days.
  
  
  METHODS
  The institutional animal care and use committee approval was obtained. The Rice-Vannucci model of HII was used in 7-day-old rat pups (n = 17). MRI was performed 1, 3, 7, 14 and 21 days after HII with intraperitoneal injection of HMON. Relative contrast values in the injured hemisphere and mean apparent diffusion coefficient values were calculated at each time point. Apoptosis and reactive astrogliosis were detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labelling (TUNEL) and glial fibrillary acidic protein staining, and the distribution and intensity of immunohistochemical staining were directly compared with those of HMON enhancement on MRI.
  
  
  RESULTS
  The dorsolateral thalamus, hippocampus and remaining cortex of the injured hemisphere showed HMON enhancement from 3 to 21 days after HII. The mean relative contrast values in the dorsolateral thalamus showed an increase from a negative value at 1 day to 16.5 ± 4.8% at 21 days. The apoptotic cells and reactive astrocytes were observed on immunohistochemical staining from 1 to 21 days after HII. The accumulation of apoptotic cells regionally matched with the areas of HMON enhancement, while that of reactive astrocytes did not.
  
  
  CONCLUSIONS
  The areas of HMON enhancement showed best spatial agreement with those of apoptosis on TUNEL staining. Both HMON enhancement and TUNEL-positive cells were observed up to 21 days after HII. Advances in knowledge: The strength of our study is the visualization of apoptotic area in vivo using HMON-enhanced MRI, and we also showed that HII has a prolonged evolution lasting for several weeks.
authors.affiliation: 1 Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Tae Yeon
authors.initials: TY
authors.lastname: Jeon
authors.affiliation: 1 Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Ji Hye
authors.initials: JH
authors.lastname: Kim
authors.affiliation: 2 Department of Radiology and Center for Molecular and Cellular Imaging, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Geun Ho
authors.initials: GH
authors.lastname: Im
authors.affiliation: 2 Department of Radiology and Center for Molecular and Cellular Imaging, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jae-Hun
authors.initials: JH
authors.lastname: Kim
authors.affiliation: 2 Department of Radiology and Center for Molecular and Cellular Imaging, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jehoon
authors.initials: J
authors.lastname: Yang
authors.affiliation: 1 Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: So-Young
authors.initials: SY
authors.lastname: Yoo
authors.affiliation: 2 Department of Radiology and Center for Molecular and Cellular Imaging, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jung Hee
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D003287:Contrast Media; D020925:Hypoxia-Ischemia, Brain / Q000000981:diagnostic imaging*; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging / Q000379:methods*; D017895:Manganese Compounds; D053758:Nanoparticles; D010087:Oxides; D051381:Rats
chemical_list: D003287:Contrast Media; D017895:Manganese Compounds; D010087:Oxides; C027424:manganese oxide