MRI-controlled facet block--technique and initial results

In a clinical study, 5 patients with chronic low back pain were treated by MR-guided facet injection of the motion segments L4/L5 and L5/S1. For the infiltration, special nonmagnetic needles were used. The investigations were carried out in an MR unit having a field strength of 1.0 tesla. In all patients, MR visualisation of the facet joints and measurement of the distance to the reference point was readily accomplished. Placement of the special MR needle, however, proved difficult in situations in which the needle had to be advanced through dense fibrous tissue. Nevertheless, the needle was successfully placed at the first attempt in two patients; in all other patients a second attempt was necessary. The entire procedure took about 30 to 40 minutes per patient. The needles were identified without any artefacts. All the patients were pain-free for at least 3 weeks after injection.