title: Freehand real-time MRI-guided lumbar spinal injection procedures at 1.5 T: feasibility, accuracy, and safety.
abstract: OBJECTIVE
  The purpose of this study was to test the hypothesis that freehand real-time MRI-guided lumbar spinal injection procedures are feasible, accurate, and safe when performed with a clinical open-bore 1.5-T MRI system.
  
  
  METHODS
  A retrospective analysis was made of spinal injection procedures performed over an 18-month period. Forty-nine procedures were performed on 37 patients (23 women, 14 men; mean age, 36 years; range, 18-48 years). A rapid FLASH 2D MRI sequence (TR/TE, 9.3/3.5; slice thickness, 5 mm; acquisition time, 1 second) was used for real-time needle placement with freehand technique. Data assessed were type of procedure, qualitative and quantitative image quality, dimensions of needle artifact, rate of successful drug delivery, rate of vascular uptake, time requirements, and occurrence of complications.
  
  
  RESULTS
  Among the 49 procedures, 22 (45%) were nerve root injections, 18 (37%) were facet joint injections, and nine (18%) were epidural injections. The quality of real-time FLASH 2D MR images was sufficient in all cases. Contrast-to-noise ratios were sufficiently high for good delineation of relevant structures. The needle artifact made was remarkably constant with an average overestimation of length of 1.0 +/- 0.2 [SD] mm. Drug delivery was successful in all selective nerve root injections and epidural injections. The rate of successful drug delivery was 89% (16 of 18) for facet joint injections. No complete intravascular injections occurred. The mean table time was 36 minutes (range, 23-75 minutes). The mean real-time MRI time was 38 seconds (range, 12-185 seconds). No major complications occurred.
  
  
  CONCLUSIONS
  We accept the hypothesis that freehand real-time MRI-guided lumbar spinal injection procedures are feasible, accurate, and safe when performed with a clinical open-bore 1.5-T MRI system. We note that real-time MRI guidance has the additional advantage of a complete absence of patient and operator exposure to ionizing radiation.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, 600 N Wolfe St., Baltimore, MD 21287, USA. jan.fritz@gmx.net
authors.forename: Jan
authors.initials: J
authors.lastname: Fritz
authors.forename: Christoph
authors.initials: C
authors.lastname: Thomas
authors.forename: Stephan
authors.initials: S
authors.lastname: Clasen
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Lewin
authors.forename: Phillipe L
authors.initials: PL
authors.lastname: Pereira
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D003287:Contrast Media; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007278:Injections, Spinal; D008159:Lumbar Vertebrae; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012449:Safety
chemical_list: D003287:Contrast Media