title: Imaging features of a gelatin-thrombin matrix hemostatic agent in the intracranial surgical bed: a unique space-occupying pseudomass.
abstract: OBJECTIVE
  Absorbable gelatin-thrombin matrix is increasingly being used in neurosurgical procedures; unlike other hemostats, the stable matrix is left undisturbed and fills the surgical bed after achieving hemostasis. We investigated the immediate postoperative radiographic imaging appearance of the gelatin-thrombin matrix in intracranial operative beds.
  
  
  METHODS
  Thirty-one consecutive patients (18 men, 13 women; mean age, 59 years) with 34 surgical cavities, had 31 brain MRIs and 9 head CTs performed ≤ 48 hours postoperatively. They were retrospectively reviewed. Images were evaluated independently by 2 neuroradiologists blinded to the surgical techniques. Surgical beds were evaluated for the presence of the gelatin-thrombin matrix, which appeared as pseudoair material (Hounsfield units ≤ -100) on CT, had characteristic T2-hypointense speckles in a T2-hyperintense background, and demonstrated complete gradient-recalled echo hypointensity on MR imaging. To determine the diagnostic performance of imaging features for the detection of the gelatin-thrombin matrix, the Fisher exact test for the association between imaging features and the presence of the gelatin-thrombin matrix and κ analysis for interobserver agreement were performed.
  
  
  RESULTS
  Hemostasis was achieved with standard methods in 12 surgical beds and with the gelatin-thrombin matrix in 22 beds. Interobserver agreement was substantial. The gelatin-thrombin matrix demonstrated pseudoair hypoattenuation (88% sensitivity, 100% specificity, 90% accuracy; P = .067, κ = 0.74) and distinctive T2-hypointense speckles in a background of T2-hyperintensity (81% sensitivity, 85% specificity, 82% accuracy; P = <.001, κ = 0.76). Combined characteristic T2 speckles and gradient-recalled echo hypointensity increased the specificity (81% sensitivity, 100% specificity, 88% accuracy; P = < .001).
  
  
  CONCLUSIONS
  The unique appearance (pseudoair on CT, T2 speckles with gradient-recalled echo hypointensity) of the gelatin-thrombin matrix should not be mistaken for gossypiboma, pneumocephalus, and/or hematoma.
authors.affiliation: From the Departments of Radiology (L.J.B., I.Z.H., K.O.L., S.M., S.W.).
authors.forename: K O
authors.initials: KO
authors.lastname: Learned
authors.forename: S
authors.initials: S
authors.lastname: Mohan
authors.forename: I Z
authors.initials: IZ
authors.lastname: Hyder
authors.forename: L J
authors.initials: LJ
authors.lastname: Bagley
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.forename: J Y
authors.initials: JY
authors.lastname: Lee
mesh_terms: D000328:Adult; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D005260:Female; D005781:Gelatin Sponge, Absorbable / Q000494:pharmacology; D005909:Glioblastoma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D018325:Hemangioblastoma / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D006488:Hemostasis, Surgical / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data; D008297:Male; D008577:Meningeal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D008579:Meningioma / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D019635:Neurosurgical Procedures / Q000379:methods*; D015588:Observer Variation; D012189:Retrospective Studies; D013917:Thrombin / Q000494:pharmacology; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data
chemical_list: D013917:Thrombin