title: Cerebral edema attenuated inversion recovery MR sequence in low magnetic field: a feasibility study.
abstract: OBJECTIVE
  Minimally invasive neurosurgery requires methods to specify surgical boundaries of target tissue, such as brain tumors. This study investigated technical possibilities and clinical usefulness of adapting edema attenuated inversion recovery (EDAIR) pulse sequences to suppress magnetic resonance signal from cerebral edema in brain tumor patients.
  
  
  METHODS
  A resistive 0.23-T magnetic resonance scanner with magnitude-encoded inversion recovery sequences was used. Twenty-eight separate scanning tests in 25 neurosurgical brain tumor patients were performed on the day before surgery. An inversion recovery sequence with several inversion times between 150 and 2,200 ms was tested. The same sequences were also used intraoperatively and postoperatively.
  
  
  RESULTS
  T(1) relaxation time of brain edema varied from case to case. An inversion recovery sequence with an inversion time of 400-800 milliseconds attenuated brain edema and seemed to help in demarcating gross brain tumor for surgical resection. These features were helpful for the evaluation of resectable tumor tissue particularly using neuronavigation techniques.
  
  
  CONCLUSIONS
  According to these preliminary findings, inversion recovery sequences supplement other imaging modalities and assist neurosurgeons in evaluating different surgical trajectories and in estimating brain tumor volume before craniotomy.
authors.affiliation: Department of Neurosurgery, Oulu University Hospital, P.O. Box 21, 90029 OYS, Finland. jani.katisko@oulu.fi
authors.forename: Jani P A
authors.initials: JP
authors.lastname: Katisko
authors.forename: Sanna K
authors.initials: SK
authors.lastname: Yrjänä
authors.forename: Juho
authors.initials: J
authors.lastname: Tuominen
authors.forename: Salla-Maarit
authors.initials: SM
authors.lastname: Kokkonen
authors.forename: Eero
authors.initials: E
authors.lastname: Ilkko
authors.forename: Jari
authors.initials: J
authors.lastname: Erkkilä
authors.forename: Hagen
authors.initials: H
authors.lastname: Shiffbauer
authors.forename: John P
authors.initials: JP
authors.lastname: Koivukangas
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000150:complications / Q000473:pathology / Q000601:surgery; D001921:Brain / Q000473:pathology*; D001929:Brain Edema / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology / Q000601:surgery; D001932:Brain Neoplasms / Q000150:complications / Q000473:pathology / Q000601:surgery; D002648:Child; D003937:Diagnosis, Differential; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement; D007430:Intraoperative Care; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018242:Neuroectodermal Tumors, Primitive / Q000150:complications / Q000473:pathology / Q000601:surgery; D038361:Neuronavigation; D019635:Neurosurgical Procedures; D011182:Postoperative Care; D012815:Signal Processing, Computer-Assisted