Method

Consecutive prospective two cohort comparative study. A similar method performed during CT guided NRBs was employed to guide needle placement for transforaminal nerve root injections with the aid of static MR images and fluoroscopy.

Axial MR images at the level of the target nerve root were used. An angle of inclination of 60 degrees was created from the nerve root to the skin of the back, the apex of this to represent the site of needle introduction. Triangulation on the MRI enabled the lateral entry point to be determined.

The transforaminal injections were then performed with the simple expedient of a skin marker line at the appropriate lateral distance from the midline for needle entry. The radiation dose and fluoroscopic time as measured by the image intensifier were recorded. This method was performed for 20 patients and compared to the same parameters for 23 previous patients in whom the transforaminal injections were performed without such a technique.