title: Tonsillar pulsatility before and after surgical decompression for children with Chiari malformation type 1: an application for true fast imaging with steady state precession.
abstract: BACKGROUND
  We hypothesize that surgical decompression for Chiari malformation type 1 (CM-1) is associated with statistically significant decrease in tonsillar pulsatility and that the degree of pulsatility can be reliably assessed regardless of the experience level of the reader.
  
  
  METHODS
  An Institutional Review Board (IRB)-approved Health Insurance Portability and Accountability Act (HIPAA)-compliant retrospective study was performed on 22 children with CM-1 (8 males; mean age 11.4 years) who had cardiac-gated true-FISP sequence and phase-contrast cerebrospinal fluid (CSF) flow imaging as parts of routine magnetic resonance (MR) imaging before and after surgical decompression. The surgical technique (decompression with or without duraplasty) was recorded for each patient. Three independent radiologists with different experience levels assessed tonsillar pulsatility qualitatively and quantitatively and assessed peritonsillar CSF flow qualitatively. Results were analyzed. To evaluate reliability, Fleiss kappa for multiple raters on categorical variables and intra-class correlation for agreement in pulsatility ratings were calculated.
  
  
  RESULTS
  After surgical decompression, the degree of tonsillar pulsatility appreciably decreased, confirmed by t test, both qualitatively (p values <0.001, <0.001, and 0.045 for three readers) and quantitatively (amount of decrease/p value for three readers 0.7 mm/<0.001, 0.7 mm/<0.001, and 0.5 mm/0.022). There was a better agreement among the readers in quantitative assessment of tonsillar pulsatility (kappa 0.753-0.834), compared to qualitative assessment of pulsatility (kappa 0.472-0.496) and qualitative assessment of flow (kappa 0.056 to 0.203). Posterior fossa decompression with duraplasty led to a larger decrease in tonsillar pulsatility, compared to posterior fossa decompression alone.
  
  
  CONCLUSIONS
  Tonsillar pulsatility in CM-1 is significantly reduced after surgical decompression. Quantitative assessment of tonsillar pulsatility was more reliable across readers than qualitative assessments of tonsillar pulsatility or CSF flow.
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, 505 Parnassus Ave, L-352, San Francisco, CA, 94143, USA, alireza.radmanesh@ucsf.edu.
authors.forename: Alireza
authors.initials: A
authors.lastname: Radmanesh
authors.forename: Jacob K
authors.initials: JK
authors.lastname: Greenberg
authors.forename: Arindam
authors.initials: A
authors.lastname: Chatterjee
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Smyth
authors.forename: David D
authors.initials: DD
authors.lastname: Limbrick
authors.forename: Aseem
authors.initials: A
authors.lastname: Sharma
mesh_terms: D000293:Adolescent; D001139:Arnold-Chiari Malformation / Q000601:surgery*; D055424:Cardiac-Gated Imaging Techniques; D002648:Child; D002675:Child, Preschool; D019299:Decompression, Surgical; D004388:Dura Mater / Q000601:surgery; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D014066:Palatine Tonsil / Q000098:blood supply*; D011673:Pulsatile Flow; D012189:Retrospective Studies