Lumbar dorsal root ganglion displacement between supine and prone positions evaluated with 3D MRI

• Published in: Magnetic resonance imaging 2023-12, Vol.104, p.29-38
• Main Authors: Abel, Frederik, Fiore, Jake, Belanger, Marianne, Sneag, Darryl B., Lebl, Darren R., Tan, Ek T.
• Format: Article
• Language: English
• Subjects: 3D MRI; Adult; Aged; Dorsal root ganglion; Female; Ganglia, Spinal - diagnostic imaging; Humans; Imaging, Three-Dimensional - methods; Lumbar spine; Lumbar Vertebrae - diagnostic imaging; Magnetic Resonance Imaging - methods; Male; Middle Aged; Patient Positioning - methods; Prone Position; Prospective Studies; Reproducibility of Results; Supine Position
• ISSN: 0730-725X; 1873-5894; 1873-5894
• DOI: 10.1016/j.mri.2023.09.006

Pre-operative lumbar spine MRI is usually acquired with the patient supine, whereas lumbar spine surgery is most commonly performed prone. For MRI to be used reliably and safely for intra-operative navigation for foraminal and extraforaminal decompression, the magnitude of dorsal root ganglion (DRG) displacement between supine and prone positions needs to be understood. A prospective study of a degenerative lumbar spine cohort of 18 subjects indicated for lumbar spine surgery. Three-dimensional T2-weighted fast spin echo and T1-weighted spoiled gradient echo sequences were acquired at 3 T. Displacement and cross-sectional area (CSA) of the bilateral DRGs at 5 motion levels (L1–2 to L5-S1) were determined via 3D segmentation by 2 independent evaluators. Wilcoxon rank-sum tests without correction for multiple comparison were performed against hypothesized 1-mm absolute displacement and corresponding 24% CSA change. DRG mean absolute displacement was  0.99, mean = 0.707 mm, 95% confidence interval (CI) = 0.659 to 0.755 mm), with the largest directional displacement in the dorsal-to-ventral direction from supine to prone (mean = 0.141 mm, 95% CI = 0.082 to 0.200 mm). Directional displacements caudal-to-cephalad were 0.087 mm (95% CI = 0.022 to 0.151 mm), and left-right were −0.030 mm (95%CI = −0.059 to −0.001 mm). Mean CSA change was within 24% (p > 0.99, mean = −8.30%, 95% CI = −10.5 to −6.09%). Mean absolute displacement was largest for the L1 (mean = 0.811 mm) and L2 (mean = 0.829 mm) DRGs. Minimal, non-statistically significant soft tissue displacement and morphological area differences were demonstrated between supine and prone positions during 3D lumbar spine MRI.