title: MRI of transforaminal lumbar interbody fusion: imaging appearance with and without the use of human recombinant bone morphogenetic protein-2 (rhBMP-2).
abstract: OBJECTIVE
  To describe the vertebral endplate and intervertebral disc space MRI appearance following TLIF, with and without the use of rhBMP-2, and to determine if the appearance is concerning for discitis/osteomyelitis.
  
  
  METHODS
  After institutional review board approval, 116 TLIF assessments performed on 75 patients with rhBMP-2 were retrospectively and independently reviewed by five radiologists and compared to 73 TLIF assessments performed on 45 patients without rhBMP-2. MRIs were evaluated for endplate signal, disc space enhancement, disc space fluid, and abnormal paraspinal soft tissue. Endplate edema-like signal was reported when T1-weighted hypointensity, T2-weighted hyperintensity, and endplate enhancement were present. Subjective concern for discitis/osteomyelitis on MRI was graded on a five-point scale. Generalized estimating equation binomial regression model analysis was performed with findings correlated with rhBMP-2 use, TLIF level, graft type, and days between TLIF and MRI.
  
  
  RESULTS
  The rhBMP-2 group demonstrated endplate edema-like signal (OR 5.66; 95% CI [1.58, 20.24], p = 0.008) and disc space enhancement (OR 2.40; 95% CI [1.20, 4.80], p = 0.013) more often after adjusting for the TLIF level, graft type, and the number of days following TLIF. Both groups had a similar temporal distribution for endplate edema-like signal but disc space enhancement peaked earlier in the rhBMP-2 group. Disc space fluid was only present in the rhBMP-2 group. Neither group demonstrated abnormal paraspinal soft tissue and discitis/osteomyelitis was not considered likely in any patient.
  
  
  CONCLUSIONS
  Endplate edema-like signal and disc space enhancement were significantly more frequent and disc space enhancement developed more rapidly following TLIF when rhBMP-2 was utilized. The concern for discitis/osteomyelitis was similar and minimal in both groups.
authors.affiliation: Department of Radiology and Medical Imaging, University of Virginia, 1218 Lee Street, Box 800170, Charlottesville, VA, 22908, USA, mf3kx@hscmail.mcc.virginia.edu.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fox
authors.forename: Judd M
authors.initials: JM
authors.lastname: Goldberg
authors.forename: Cree M
authors.initials: CM
authors.lastname: Gaskin
authors.forename: Michelle S
authors.initials: MS
authors.lastname: Barr
authors.forename: James T
authors.initials: JT
authors.lastname: Patrie
authors.forename: Francis H
authors.initials: FH
authors.lastname: Shen
authors.forename: Bennett
authors.initials: B
authors.lastname: Alford
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage*; D015299:Discitis / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000150:complications / Q000473:pathology* / Q000628:therapy*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011292:Premedication / Q000379:methods*; D011994:Recombinant Proteins / Q000008:administration & dosage; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000009:adverse effects* / Q000379:methods; D016212:Transforming Growth Factor beta / Q000008:administration & dosage*; D016896:Treatment Outcome
chemical_list: D055396:Bone Morphogenetic Protein 2; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2