Neuroradiology and MRI Unit, Grenoble Alpes University Hospital, CS 10217, Grenoble Cedex 9, France, CLINATEC Research Facility, LETI, CEA Grenoble, Grenoble, France, Adult Radiology Department, Necker Hospital, Paris V University, Paris, France, Pain Management Unit, Grenoble Alpes University Hospital, Grenoble, France, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States, Neurosurgery Unit, Grenoble Alpes University Hospital, Grenoble, France

Objective: To assess the feasibility of greater occipital nerve (GON) intermediate site infiltration with MRI guidance. Methods: Eleven consecutive patients suffering from chronic refractory cranio-facial pain who underwent 16 GON infiltrations were included in this prospective study. All of the procedures were performed on an outpatient basis in the research facility of our institution, with a 1.5 T scanner. The fatty space between inferior obliquus and semispinalis muscles at C1-C2 level was defined as the target. Technical success was defined as the ability to accurately inject the products at the target, assessed by post-procedure axial and sagittal proton density-weighted sequences. Clinical success was defined as a 50% pain decrease at 1 month. Results: Technical success was 100%. GON was depicted in 6/11 cases on planning MRI sequences. Mean duration of procedure was 22.5 min (range 16–41). Clinical success was obtained in 7/11 included patients (63.6%) with a mean self-reported improvement of 78%. Conclusion: Interventional MR-guidance for GON infiltration is a feasible technique offering similar results to an already established effective procedure. It may appear as a useful tool in specific populations, such as young patients and repeat infiltrations, and should be considered in these settings. Key Points: • MR guidance for GON infiltration is a feasible technique. • Preliminary results are in agreement with other guidance modalities. • MR guidance may be seen as a useful tool in specific populations. • Specific populations include young patients and repeat infiltrations. • Target patients may also include patients with potentionally previously reported complications (torticollis). © 2017, European Society of Radiology.

Greater occipital nerve, Headache, MR guidance, MRI, Neuralgia

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