Lumbar nerve root blocks using MRI – the effectiveness and safety of ultrasound/MRI fusion image guidance

Objective: To compare the outcome of nerve root injection guided by ultrasound/MRI fusion with radiofrequency needle tracking (eTRAX©) and the same procedure undertaken by fluoroscopic guidance. Methods: This is a retrospective audit of anonymised clinical records from before and after a change in the imaging technique used to perform nerve root blocks. We studied 181 consecutive patients who had undergone a nerve root block, the first 124 guided by fluoroscopic technique and the next 57 guided by ultrasound/MRI fusion with radiofrequency needle guidance. Using pain diaries, we reviewed the outcome scores at 24 h and 2 weeks. We recorded the use of analgesia, the patient’s satisfaction, complications and the duration of the procedures. Results: Completed pain diaries were returned by 61% in the fluoroscopy group and 67% in the fusion imaging group. The visual analogue pain score was reduced at 24 h by 3.29 [standard deviation (SD) 2.35] for the fluoroscopy group and by 3.69 (SD 2.58) in the fusion group (p 0.399). At two weeks the pain reduction was 3.27 (SD 2.57) for the fluoroscopic group and 4.21 (SD 2.95) for the fusion group (p 0.083). There was no statistically significant difference between the groups. The patient’s satisfaction scores were similar for both groups. The procedure by the two guidance methods took a similar time to perform. There were no serious complications in either group. One patient in the fusion-guided nerve root block group experienced paraesthesia in the nerve distribution for 2 h. Conclusion: Ultrasound/MRI fusion imaging with needle tracking is an effective alternative to fluoroscopic image-guided injection. Advances in knowledge: Fusion imaging guidance provides the same outcome as fluoroscopic guidance. Fusion imaging guidance avoids the need for ionising radiation.

Magnetic resonance imaging-guided lumbar nerve root infiltrations: optimization of an in-house protocol

Background For the treatment of radicular pain, nerve root infiltrations can be performed under MRI guidance in select, typically younger, patients where repeated CT exams are not desirable due to associated radiation risk, or potential allergic reactions to iodinated contrast medium. Methods Fifteen 3 T MRI-guided nerve root infiltrations were performed in 12 patients with a dedicated surface coil combined with the standard spine coil, using a breathhold PD sequence. The needle artifact on the MR images and the distance between the needle tip and the infiltrated nerve root were measured. Results The distance between the needle tip and the nerve root was 2.1 ± 1.4 mm. The visual artifact width, perpendicular to the needle long axis, was 2.1 ± 0.7 mm. No adverse events were reported. Conclusion This technical note describes the optimization of the procedure in a 3 T magnetic field, including reported procedure time and an assessment of targeting precision.