title: MR follow-up of small experimental intracranial haemorrhages from hyperacute to subacute phase.
abstract: OBJECTIVE
  To compare pulse sequences in revealing intracranial bleeding from the hyperacute to subacute phase.
  
  
  METHODS
  We injected 0.3-1 ml of autologous blood into the brain of 8 rabbits. MR imaging was performed immediately after haematoma creation and then at determined intervals up to 9-12 days. All images were analysed by two observers. After the last MR investigation, the brain was fixed in formalin. The last MR images were compared to the fixed brain sections and to the histologic findings.
  
  
  RESULTS
  T2*-weighted GE sequences, both conventional spoiled and echoplanar sequences, revealed the intraparenchymal haematomas as hypointensities in all but 1 case, which was negative from the second day onward (a rabbit with 0.3 ml blood injected). The signal patterns remained unchanged during the follow-up. The haematoma sizes and shapes corresponded well to gross pathology. Blood in the cerebrospinal fluid (CSF) space was detected with T2*-weighted GE sequences in a great majority of the examinations during the first 2 days. The cases with the smallest injected volume of blood were negative. SE sequences were rather insensitive. The FLAIR sequence often revealed blood in CSF spaces but not in the brain.
  
  
  CONCLUSIONS
  T2*-weighted GE sequences are capable of revealing very small intraparenchymal haemorrhages from the hyperacute to the subacute phase, and blood in CSF spaces during at least the first 2 days.
authors.affiliation: Departments of Radiology, University Hospital, SE-751 85 Uppsala, Sweden.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Alemany Ripoll
authors.forename: O
authors.initials: O
authors.lastname: Gustafsson
authors.forename: B
authors.initials: B
authors.lastname: Síösteen
authors.forename: Y
authors.initials: Y
authors.lastname: Olsson
authors.forename: R
authors.initials: R
authors.lastname: Raininko
mesh_terms: D000208:Acute Disease; D000818:Animals; D002543:Cerebral Hemorrhage / Q000473:pathology* / Q000503:physiopathology; D004195:Disease Models, Animal; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D011817:Rabbits; D012680:Sensitivity and Specificity; D013997:Time Factors