title: Patterns and Time Dependence of Unspecific Enhancement in Postoperative Magnetic Resonance Imaging After Glioblastoma Resection.
abstract: OBJECTIVE
  Postoperative magnetic resonance imaging (MRI) is recommended soon after glioma surgery to avoid reactive nonneoplastic contrast enhancement indistinguishable from tumor. The purpose of this study was to analyze these patterns of postoperative contrast enhancement at 3 T to define the optimal time frame for postoperative MRI.
  
  
  METHODS
  MRI for 206 glioblastoma surgeries in 173 patients who underwent pre- and postoperative and at least 1 follow-up 3T MRI for each surgery were analyzed retrospectively. Postoperative MRI was assessed in consensus by 2 neuroradiologists, blinded to the time after surgery. Postoperative contrast enhancement marginal to the resection cavity was analyzed and classified as vascular, linear, or nodular. The cause of the contrast enhancement (ie, reactive vs. tumor) was assessed by comparing pre-, postoperative, and follow-up MRI.
  
  
  RESULTS
  Within 45 hours after surgery, reactive enhancement appeared in 17.9% of cases. After 45 hours, the fraction of reactive changes increased to 34.1%. Linear enhancement was more often reactive (66.1%, 39/59 cases), whereas nodular enhancement was mainly residual tumor (93.2%, 68/73 cases). Specificity of nodular enhancement was high for tumor recurrence/tumor progression (91.5%).
  
  
  CONCLUSIONS
  To avoid an increasing number of MRIs with reactive contrast enhancement, postoperative MRI at 3 T should be performed within 45 hours after surgery. However, reactive contrast enhancement can occur at all time points. In these cases, the pattern of the contrast enhancement may help to differentiate its cause.
authors.affiliation: Department of Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany. Electronic address: stefanie.bette@tum.de.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Bette
authors.affiliation: Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Gempt
authors.affiliation: Department of Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Huber
authors.affiliation: Department of Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Boeckh-Behrens
authors.affiliation: Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Ringel
authors.affiliation: Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Meyer
authors.affiliation: Department of Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Zimmer
authors.affiliation: Department of Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Jan S
authors.initials: JS
authors.lastname: Kirschke
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging / Q000601:surgery; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D003287:Contrast Media; D005500:Follow-Up Studies; D019786:Gadolinium DTPA; D005909:Glioblastoma / Q000000981:diagnostic imaging* / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging; D019635:Neurosurgical Procedures; D011182:Postoperative Care / Q000379:methods; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA
keywords: 3 Tesla; Early postoperative enhancement; Glioblastoma; Postoperative MRI